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Sound quality of Class D vs Class AB amps

7K views 44 replies 5 participants last post by  shinjohn 
#1 ·
Sorry for the verbose posting (my first ever). My questions are at the bottom, but I thought that other members might also appreciate hearing about my new system, since I have some components that I haven't read a lot about on this site.

I just completed phase 1 of my audio overhaul in my '03 EX. I cheated a little and had Tweeter install everything for me (I didn't trust myself with the wiring) and this is what I have so far:

Kenwood Excelon KDC-X769 head unit
Kenwood Sirius tuner (came free with HU)
JL Audio 300/4 amp (under front passenger seat)
JL Audio VR650-CSi 6.5-inch components in front
JL Audio TR650-CXi 6.5-inch coax in rear

I was going to get the Alpine CDA-7995 but the Kenwood was on sale at $150 off the regular price and also came with a free Sirius tuner, so it was just too great a deal to pass up. Also, I'd listened to the Kenwood and Alpine together and hadn't noticed much of a difference in sound quality. The JL amp was also on sale, $200 off. It was refurbished but I was going to get an extended warranty anyway, so I didn't care too much about that. I was trying to get the most I could out of my budget.

The JL speakers were perfect for the type of sound that I like. I hate bright speakers, and these JLs were totally the opposite of bright. Very smooth, yet still detailed. I'd spent many many hours in many different showrooms before I settled on these.

Well the above actually blew my budget by several hundred dollars and I decided not to get a subwoofer in order to keep my marriage alive. I have a very good audiophile system at home and have somewhat converted my wife to the advantages of great sound quality, but I thought I would just go home without a sub, get the "you spent how much????" lecture from my wife, and then maybe persuade her to get a sub after she had cooled down over the next few months.

To be honest, the new gear sounded worse than the factory setup at first, which got me much worse than "you spent how much???" from my wife. I couldn't believe that speakers that sounded so smooth in the showroom sounded so bright in the van. However, after a 2-3 weeks of the speakers breaking in and playing around with the settings (I muted the internal amps in the HU, and also found that the Loudness function had been turned on, whcih brightened the sound), my system actually sounded better than at the store.

Well it sounds so good now that my wife wants to make it even better. She actually told me that she wanted a subwoofer! After reading a lot of posts on the subject, I've come to the conclusion that the best bang for the buck in terms of sound quality and convenience is the THOS. Now I just need to get an amp to drive it.

I've narrowed my search down to a couple of amps around the $200-250 mark: Alpine MRP-M350 ($199 for 200W class D one channel amp) and Kenwood Excelon KAC-X520 ($239 for 125W x 2 channel/ 500W x 1 channel).

The THOS sub only needs 100-200W, so it would seem that the Alpine would be perfect. I've heard it at the store with all the other components I've listened to (except driving a JL sub, not THOS) and it sounded good. However, I've read in various places that class D is very efficient but not necessarily musical, and that it produces more distortion than a class AB amp. So even though it sounded good, would a class AB amp sound better? If so, I picked the Kenwood as great value for money, since I've seen it for much more at other places. It also has a bass boost function that I can adjust directly from my head unit. However, it has much more power than I need and I wonder if I'll be adding too great a load for my battery/alternator.

At last we come to my questions... Does anyone have an opinion on class D amps or on sub amps in general? In my home system, I like my bass tight and fast and musical, not necessarily loud. I play a wide variety of music, ranging from alternative pop/rock to rap to jazz to classical.

Also, does anyone know how much current draw the battery will take without my headlights dimming? My JL amp has a 40A fuse and the Kenwood amp has a 60A fuse, although I seem to remember reading in the Kenwood specs that it actually uses 37A.

And finally, if I went with the Alpine, would I miss the Kenwood's bass boost feature? My wife likes to turn the bass up sometimes. Would she just use the EQ function on the head unit?
 
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#2 ·
Hello, and welcome!
Thanks so much for your detailed post. I enjoy hearing other people's experiences (good and bad) and I know others on the board appreciate your input.

I could comment on and on about your system, but let's get down to your questions:

- either of the amps you list would work fine in your system, esp. matched to THOS. In theory, the Class D topology would be "worse" on a sonic purity standpoint, but for bass, it usually doesn't matter. If you did not hear a difference between the two head units, I don't think you would notice between the Alpine and Kenwood amp.

- too much power (in the case of the Kenwood) is not a concern because you will bottom out the driver in THOS way before you reach the amp's output limit. Don't worry about it.

- so the bottom line for you is to shop for features here. The Kenwood is nice since it matches well to your head unit and its control features. Out of your choices, personally I like the Alpine due to the ability to add a separate remote bass level control. This is not an EQ, but a gain control, which I feel is the most appropriate way to control bass level. EQs are good if you want to smooth out response, but if you want to adjust bass based on type of music, etc.. its really better to have all your EQ settings done with and use a gain control for on the fly adjustment. But this is just my philosophy, and keep in mind too I'm a bit partial to Alpine gear vs. Kenwood. I chose the 7995 because in my head to head comparos, the Kenwood was not nearly as good to my ears..... The irony is that I used the JL 650 components as the speakers used in the comparo..

- one other note: keep in mind THOS is a bandpass sub, and although it is very clean, it lacks the control of a very well designed acoustic suspension sub enclosure (sealed box). IT sure is a great package though, and well worth its price.

Good luck and keep us posted on your progress!

p.s.- what type of home system do you have?
 
#3 ·
Welcome to OdyClub!

I have a THOS and I am very happy with it although in hindsight I would have, and may still, add a separate amp for it. This would give me a bit more out of the THOS unit and on-the-fly independent gain control of the bass. The THOS strikes a good balance between audio needs/wants and van functionality/space needs.

Thanks for the great post and let us know how it turns out.
 
#4 ·
Thanks for the welcomes and for the answers you've given me.

I should expand on what I meant when I said that I couldn't tell much of a difference between the Alpine and the Kenwood. I did most of my listening with the Alpine but then my wife said she wanted XM or Sirius radio and something had to be cut in order to get that (and I was already over budget). I really loved the JL speakers and amp, and wanted to keep them, and then I saw that the Kenwood was $200 less than the Alpine and came with free Sirius. However, rather than listen head to head and feel disappointed with with my compromise, I came back the next weekend and listened to the Kenwood against other head units in it's price range ($199). I liked it the best compared to it's peers and feel that it is still musical. Is it the best? No, but I feel like I made the necessary compromise to get the most out of my budget.

Anyway, that was an interesting comment that you (Shinjohn) made about gain control being better then EQ control. I think you're right, so I've started to veer towards the Alpine again! It's difficult because I'm essentially buying "blind" here. The store only has class D amps connected to the subs, so I would only be buying the Kenwood amp based on features and on the theory that it would be more musical than a class D amp. Maybe I should just go with the Alpine if I was happy with the sound I heard. I'll let you all know!

Shinjohn, you asked about my home setup. I have a "cosmopolitan" stereo system that I bought when I lived in England about 10 years ago: French Micromega separate CD drive and DAC, US preamp by Audio Research, English power amp by Chord and speakers by Castle. This follows the classic British theory of hi fi, which is to spend as much as you can on the CD player and the least on the speakers, the theory being that if you amplify a bad source through great speakers, it won't sound that great. I do think this system sounds great, even though the speakers don't have a lot of bass. But what bass they do have is very fast and musical. The treble could be a little smoother but the midrange (which is the attribute I treasure most) is just excellent.

I also have an American home theater which goes in the opposite direction. I'm using a cheap DVD player, a fairly expensive B&K receiver and very expensive Definitive Technology speakers (with built in subwoofers). This system doesn't sound quite as rhythmic and "bouncy" but it does sound purer, from the treble down to the bass. Again, the midrange is very liquidy, if you know what I mean - great for voices.

Not sure what all that tells me. Don't listen to other people's theories, just buy gear that you like listening to!

I did have some more questions, but my wife just told me to get off the PC...
 
#5 · (Edited)
bushmen said:
To be honest, the new gear sounded worse than the factory setup at first, which got me much worse than "you spent how much???" from my wife. I couldn't believe that speakers that sounded so smooth in the showroom sounded so bright in the van. However, after a 2-3 weeks of the speakers breaking in and playing around with the settings (I muted the internal amps in the HU, and also found that the Loudness function had been turned on, whcih brightened the sound), my system actually sounded better than at the store.....

I did have some more questions, but my wife just told me to get off the PC...
First of all, your posts are very good and easy to read. I can't put my finger on it but when reading them, its as if your talking to me in the same room. OK...I know exactly what you mean by breaking in speakers. I pooh poohed the idea until it happened to me. Once installed, my Dynaudio front speakers at least sounded better than stock, but sounded the same as or slightly worse than my old sedan's install comprised of raw Vifa and Peerless component drivers with self made crossovers.

But, just like others on the net said, over several weeks and most definitely over a month or two, the Dyns mellowed subsubstantially. Wow...what a difference! It is to the point now that THOS only adds the very low bass as many people think I have a subwoofer even if I have THOS turned off. Now I keep toying with the idea of replaceing my indoor Cambrige Soundworks Ensemble (early 90's) speakers with Dyns. Nah...I don't watch enough TV....but, maybe some for the PC?....:stupid:.

THOS is extremely good and is just the right ticket for great bass on a budget, is miles better than the factory option, buckets cheaper than the name brand option, and more convenient than the customer build option. Besides, the Odyssey is a people mover and when I have anyone in the bench seat, I have to turn the SUB gain down from the high range of 10-15 down to about 0-5 (total gain setting range is 0-15). The rear factory speakers are so poor in bass that with the THOS turned down to about 2-5 or so, it blends nicely with the rear speakers for those on the bench.

Go get yourselves a THOS (w/amp of course). You'll be grinning once you hear it. The only problem I see with THOS is you'll want to buy another model for your other cars once you see and hear it
 
#6 ·
It's late and I'm off to bed, but one quick thing I just realized... While you stated that you were looking at the Alpine MRP-M350, I was thinking of the MRD-M300. The reason I point this out is that the AccuClass D series has the remote control option, the V-Power MRPs do not.

I have much more to say about amps and what not... more when I'm not falling asleep....
 
#7 ·
Originally posted by rlpenny
OK...I know exactly what you mean by breaking in speakers. I pooh poohed the idea until it happened to me. Once installed, my Dynaudio front speakers at least sounded better than stock, but sounded the same as or slightly worse than my old sedan's install comprised of raw Vifa and Peerless component drivers with self made crossovers.

First, thanks for your kind words. This is the first time I've ever posted to a forum, and its great for you to make me feel so welcome.

As far as breaking in speakers are concerned, I remember reading about it in audio magazines and not believing it, but then I experienced it with my home theater. When my wife and I listened to the speakers at first, they had "one-note" bass and the treble was screechy. As we listened to them smooth out over the weeks, my wife was converted to the advantages of good audio equipment.

As I said earlier, she was the one that decided that we need a subwoofer, and in fact she bought me a JL 10w0 subwoofer for Christmas as a surprise. Even the salesman was in on the surprise because when I went to the store to secretly listen to subwoofers, he said that the sub that would have suited me the best had just been bought by someone (i.e. my wife).

It's a shame I couldn't keep it because I couldn't find anywhere in the Ody to put it. I wanted to secure it to something so that it didn't fly around if we stopped suddenly, but I also wanted to be able to use the third row. I thought I could possibly fit it directly behind the second row, but the magic seat bumped into it when I tried to put it in place.

Anyway, after being so disappointed that I'd never get a subwoofer into the van, I read all your reviews of THOS and I'm happy again.

rlpenny, I remember reading one of your threads that talked about setting the high and low pass filters when you got your THOS. What did you settle on? My front speakers have very good midbass too, although I'm sure your Dyns go lower. The JL specs say that they go down to 59Hz, which I think is more realistic than some of the numbers that the mass market speakers state. Since all my amps will have built in crossovers, I was thinking of setting the sub crossover to 80Hz, the fronts to 70 or 75 and the rears to 80 (since the rears don't seem to be putting out much bass). I'm sure I'll have to play around with it once it's all installed, but I'd be interested in your suggestions for starting point, especially since I've never used crossovers before.
 
#8 ·
originally posted by shinjohn
- one other note: keep in mind THOS is a bandpass sub, and although it is very clean, it lacks the control of a very well designed acoustic suspension sub enclosure (sealed box).
Do you mind elaborating on what you mean by lacking control? I don't have a lot of experience in subwoofers.

I don't think it matters too much because THOS seems to be the only sub that fits both my budget and my ody, and as long as I get better quality bass than I have now, I'll be happy. But I am interested in what to expect from it.
 
#9 · (Edited)
bushmen said:
First, thanks for your kind words. This is the first time I've ever posted to a forum, and its great for you to make me feel so welcome......

rlpenny, I remember reading one of your threads that talked about setting the high and low pass filters when you got your THOS. What did you settle on? My front speakers have very good midbass too, although I'm sure your Dyns go lower. The JL specs say that they go down to 59Hz, which I think is more realistic than some of the numbers that the mass market speakers state. Since all my amps will have built in crossovers, I was thinking of setting the sub crossover to 80Hz, the fronts to 70 or 75 and the rears to 80 (since the rears don't seem to be putting out much bass). I'm sure I'll have to play around with it once it's all installed, but I'd be interested in your suggestions for starting point, especially since I've never used crossovers before.
You're welcome:)

My system & crossover settings:
HPF = Flat
LPF (THOS) = 80Hz
Fronts: Dynaudio components w/passive xovers fed by a/d/s/ PH15 amp (50W per door) (was 100W per door)
Rears: factory (yuk!) fed by Alpine head unit (someday I'll feed 50W per side with the spare PH15 power relinquished by the fronts)
Subw: THOS fed by a/d/s/ PH15 amp (100W x 1)
Head unit: Alpine (I forget the model) 7914? or something.

I settled on 80Hz for the LPF (low pass filter) which means the THOS only gets signals below 80Hz. My head unit only does FLAT, 80, 90, etc. for LPF settings but 80Hz seems just about right for THOS.

I set the HPF (high pass filter) on the head unit to FLAT which means the front and rear speakers get a full 20-20kHz signal. I tried 80Hz for the HPF setting but it seemed to neuter the front Dynaudios as far as bass goes even though it made already very clear vocals even clearer. I prefer more mid-bass output from the front, if possible. I think in my setup a HPF setting of 65-70Hz would be peferct for the dyns as 80 is too high for them in my opinion. My head unit can only do FLAT, 80, 90, 100, 110, etc. for HPF settings. I sure wish it had 70. This is where having a newer amp like yours with crossovers would be helpful as I'm sure you have more settings than my head unit offers.
 
#10 ·
bushmen said:

I should expand on what I meant when I said that I couldn't tell much of a difference between the Alpine and the Kenwood. I did most of my listening with the Alpine but then my wife said she wanted XM or Sirius radio and something had to be cut in order to get that (and I was already over budget). I really loved the JL speakers and amp, and wanted to keep them, and then I saw that the Kenwood was $200 less than the Alpine and came with free Sirius. However, rather than listen head to head and feel disappointed with with my compromise, I came back the next weekend and listened to the Kenwood against other head units in it's price range ($199). I liked it the best compared to it's peers and feel that it is still musical. Is it the best? No, but I feel like I made the necessary compromise to get the most out of my budget.
I hear ya. That is an incredible deal with the Kenwood! Too good to pass on I'd say. Bang for the buck you made the right choice for sure.


Anyway, that was an interesting comment that you (Shinjohn) made about gain control being better then EQ control. I think you're right, so I've started to veer towards the Alpine again! It's difficult because I'm essentially buying "blind" here. The store only has class D amps connected to the subs, so I would only be buying the Kenwood amp based on features and on the theory that it would be more musical than a class D amp. Maybe I should just go with the Alpine if I was happy with the sound I heard. I'll let you all know!
Buying blind is very hard, and something I do not recommend for most. If you can audition, do so to see what differences you hear. However, relatively speaking, the quality (and importance) of the amp in this equation is not the biggest factor. Looking at the Kenwood, there would be some advantage to having the vast headroom afforded by the power rating, and the price you list is pretty darn good (hard to beat!). But I still favor the Alpine MRD-M300 as an alternative in the price range because I believe the feature set is better for your application. There are several reasons for this:
1) add on bass gain control knob (a fancy potentiometer)
2) built in variable 24dB/octave (steep slope) crossover
3) built in parametric eq
4) time correction (phase correction) circuitry
5) variable subsonic filter

#2 and #5 are particularly important, esp with THOS. As Robert describes, adjustments are hard to make if you have set points to work with, as in his head unit. The adjustability of the Alpine is sure nice, and will aid in system tweaking. A subsonic filter is highly recommended for a bandpass or vented subwoofer system design, to reduce cone excursion at low frequencies. This will allow the system to play cleaner and louder in its usable frequency range.


Shinjohn, you asked about my home setup. I have a "cosmopolitan" stereo system that I bought when I lived in England about 10 years ago: French Micromega separate CD drive and DAC, US preamp by Audio Research, English power amp by Chord and speakers by Castle. This follows the classic British theory of hi fi, which is to spend as much as you can on the CD player and the least on the speakers, the theory being that if you amplify a bad source through great speakers, it won't sound that great. I do think this system sounds great, even though the speakers don't have a lot of bass. But what bass they do have is very fast and musical. The treble could be a little smoother but the midrange (which is the attribute I treasure most) is just excellent.

I also have an American home theater which goes in the opposite direction. I'm using a cheap DVD player, a fairly expensive B&K receiver and very expensive Definitive Technology speakers (with built in subwoofers). This system doesn't sound quite as rhythmic and "bouncy" but it does sound purer, from the treble down to the bass. Again, the midrange is very liquidy, if you know what I mean - great for voices.
Very interesting. Your choices are close to as far apart as it gets. But I would say appropriate for their applications.

Personally, I dislike using subwoofers in a 2 channel (home) audio application. I like to either go without or use towers with an appropriately sized and matched amplifier. But all of the gear I've owned has really been mid-fi (relative to you) as my budget never allowed me to get what I truly wanted in a home setup...

On the flip side, subwoofers, in my view, are a must in the mobile environment due to the incredible low frequency noise floor. No matter how much sound damping and treatment you do, you'll never get the low f floor down low enough to hear subtlety in bass, with low f extension. That is why car EQ curves typically have an exagerated, and often rising low end. Psychoacoustically, this is what is needed to perceive a warm low end. In my Accord system, which I view as quite decent, I have (2) 12" subwoofers paired with 300W of dedicated power. It may sound like overkill, but my subs are relatively inefficient for 12s, and they were tuned for well damped, extended reponse. But yes, they play pretty darn loud too.

Another thing about my philosophy is that I tend to place more importance on speakers than anything else. Case in point, I have Dynaudio in both of my cars, and I've struggled with this, as I've tried to skimp on the Ody, only to give myself grief. My journey of "upgrading" the Ody system by being "sensible" and "modest" have only resulted in me doing what I knew before I started: getting the speakers I truly wanted, then making sure that the other components were appropriately matched for my application. Search my many posts and read about my system and you will see....

In any event, I could go on and on, but I hope some of this helps.
 
#11 ·
bushmen said:
Do you mind elaborating on what you mean by lacking control? I don't have a lot of experience in subwoofers.

I don't think it matters too much because THOS seems to be the only sub that fits both my budget and my ody, and as long as I get better quality bass than I have now, I'll be happy. But I am interested in what to expect from it.
What I mean is that THOS tends to resonate and sound muddier than a well designed, transient perfect or well damped acoustic suspension enclosure.

Enclosure designs are all about trade offs. With THOS, you are trading bandwidth (both low end and mid bass extension) and flat response for greater efficiency. The good news is that it uses a small ~6-7" driver, and therefore it has very fast, punchy, transient attack. But basically, you get a more peaky (resonant, one-notish) sound relative to a very nice sealed box, and more enclosure resonances and the like due to its thin design. Push it hard and it will "chuff chuff" with port noise. These are minor issues relative to its strengths however, all of which we have discussed in length before. Did you read my review of this sub I published for this site?

Anyhow, off to bed. 'Nite.
 
#12 ·
I still favor the Alpine MRD-M300 as an alternative in the price range because I believe the feature set is better for your application. There are several reasons for this:
1) add on bass gain control knob (a fancy potentiometer)
2) built in variable 24dB/octave (steep slope) crossover
3) built in parametric eq
4) time correction (phase correction) circuitry
5) variable subsonic filter
You're staring to win me over on the MRD-M300. I'll go take a listen to it.

Now you've explained it so well, it seems obvious that gain control is much better sonically than an eq-based bass boost. I'd never thought of it that way before.

The Kenwood also has a subsonic filter but I believe it is fixed, not variable. Given that THOS has limited low bass, do you think the subsonic filter should be set as high as 25 or 30Hz? I know, I know, I should really figure this out myself when I get the equipment, but since I don't have it yet, your opinion would be appreciated.

Could you explain the difference between a 24db/octave (Alpine)and 18db/octave (Kenwood) crossover. Does it just mean that there is less of an overlap between sub and speakers with a steep slope? If that's an advantage, do you think I should try to keep all my crossoves set to the same frequency (e.g. 70 or 75Hz) instead of setting the sub crossover to say 80Hz and allowing the fronts to go a little lower?

Finally, would you use the parametric eq to try to reduce the 60Hz peak you mentioned in your review or should I just leave the eq as flat? In my home audio, I don't use eq, but a car is a different beast entirely, as you said. In a way, a car is such a terrible place to listen to music, I don't want to spend too much money. On the other hand, I spend so much time in it, I want the best sound possible.

But all of the gear I've owned has really been mid-fi (relative to you) as my budget never allowed me to get what I truly wanted in a home setup...
I'm very lucky to have the equipment I have at home because I bought it all when I was single and had more money than sense and my goal in life was to have the best stereo equipment possible. Now I have a wife, baby, mortgage, car payment etc etc... I'm sure you know what I mean. My life is full of riches, just not the monetary kind.
 
#13 ·
shinjohn said:
On the flip side, subwoofers, in my view, are a must in the mobile environment due to the incredible low frequency noise floor. No matter how much sound damping and treatment you do, you'll never get the low f floor down low enough to hear subtlety in bass, with low f extension. That is why car EQ curves typically have an exagerated, and often rising low end.
No kidding. The Ody is quiet relative to other vans, but not to a semi-ideal listening environment. I bought 75 sq. feet of Brown Bead and one of these days when I am home and have some time I plan on insulating/dampening all of the doors and most of the floor. While I expect that this will help, I know a dedicated bass amp would really be nice. I may just go ahead and run the few extra wires needed while I have the van interior apart (again :)). SJ, you are starting to sell me on the MRD-M300. Your suggestion about the THOS' amp having a subsonic filter makes a lot of sense. Something for me to keep in mind when looking at amps.

I currently have the HPF on (80Hz I believe) for my fronts and I keep waffling back and fourth. There is definitely more bass--and I think warmer mids--when the HPF is off/flat, but when I crank the volume the bass becomes excessive and overpowers the front sound stage. I have even had problems with the cones hitting the speaker covers (factory in door) on certain bass-heavy tracks. I am hoping that adding the Brown Bead to the doors will improve the speaker's performance and maybe I'll be happier with the HPF setting (which is not adjustable).

Another little snag is that I don't think my HU has seperate sub outputs. :( Ideas? Maybe a new HU, there is a model above mine CDX-C90 link, newer but discontinued, it would interface with all of my other Sony stuff. Too bad that the new Sony HUs are so bad.
Maybe I'll keep my HU and bridge the bass and two channels of the MRP-F320 for the THOS, significantly upping the power to the THOS and use the other two channels for the rears and get a nice two channel amp for the Focals up front. What do you guys think?

This is a great thread BTW. It's nice to start the year off on a good note, a bass note. :D
 
#14 · (Edited)
bushmen said:

The Kenwood also has a subsonic filter but I believe it is fixed, not variable. Given that THOS has limited low bass, do you think the subsonic filter should be set as high as 25 or 30Hz? I know, I know, I should really figure this out myself when I get the equipment, but since I don't have it yet, your opinion would be appreciated.
Yep, you're right about the Kenwood. The Kenwood is set at 15Hz, while the Alpine is adjustable in 5 Hz increments from 15-50Hz. If you are specifically using THOS, I would say probably crank it closer to 35 Hz maybe even 40Hz, given the subs natural rolloff in reponse. Of course the best way is start low and adjust it upward until you start to hear a loss in low end extension. Best to use jazz with low f bass for this kind of test.


Could you explain the difference between a 24db/octave (Alpine)and 18db/octave (Kenwood) crossover. Does it just mean that there is less of an overlap between sub and speakers with a steep slope? If that's an advantage, do you think I should try to keep all my crossoves set to the same frequency (e.g. 70 or 75Hz) instead of setting the sub crossover to say 80Hz and allowing the fronts to go a little lower?
The difference simply is slope. The figures above define how fast the attenuation occurs wrt frequency. The higher the number, the steeper the crossover slope. If you have a set crossover frequency f, then in one case, you will get 24dB of attentuation in signal when you get one octave higher in frequency, the other case you only get 18 dB. Steeper slopes in general are favored with subs so as to produce less overlap with your primary speaker system, and to reduce phase/coherence problems associated with separate drivers producing the same frequency range from different locations wrt the listener. But this is not always a hard and fast rule of crossover design, because there are many intricacies that affect performance. Then if you talk about passive vs. active, different types of circuits, it gets immensely complex. I've actually written quite alot on crossover tuning, as I remember Robert and I had many conversations on the subject, so do search back and research for more info. But to give you some basic guidance, I would say set your low pass around 80Hz, and then experiment with the high pass based on your taste. There is a balance to strike between getting good "up front" mid-bass presence while also maintaining optimal clarity up and through the mid range when you use two way components up front and a rear mounted subwoofer. (Matt is learning ALL about this) Let the fronts play too much low bass and the midrange gets muddied as the driver uses its excursion to pound out 40-80Hz bass. Set the crossover too high and get great midrange clarity, yet the bass then sounds separate to the front sound stage. I would recommend starting low, ~45-50Hz, and crank up the high pass crossover f until you get the balance of sound you like.


Finally, would you use the parametric eq to try to reduce the 60Hz peak you mentioned in your review or should I just leave the eq as flat? In my home audio, I don't use eq, but a car is a different beast entirely, as you said. In a way, a car is such a terrible place to listen to music, I don't want to spend too much money. On the other hand, I spend so much time in it, I want the best sound possible. There is much, much more to this than I describe, but it gives you a sense for what you are trying to accomplish.
Well, I've said this on many occasions, and here's my take again. I generally avoid the use of EQs unless really necessary. I come from the mindset of putting the least amount of electronics in the signal path, to maintain purity of signal. Neither of my car audio systems use an EQ, parametric or otherwise. (though I prefer parametric EQs to graphic) I tend to attack resonance and response problems with enclosure design, component selection, system setup, etc...

Having said that, you can and may likely find good benefit to use the parametric eq to tune response of your sub. In theory, you just want to get the response as flat as possible in the usable range, using the EQ. In this case, it may be prudent to use it to reduce some of the 60-80Hz buzziness if that is bothersome. Again, you should try it without the EQ first, assess, and then adjust based on what your ears tell you.


I'm very lucky to have the equipment I have at home because I bought it all when I was single and had more money than sense and my goal in life was to have the best stereo equipment possible. Now I have a wife, baby, mortgage, car payment etc etc... I'm sure you know what I mean. My life is full of riches, just not the monetary kind.
Totally. I have two kids myself, and never did buy my ultimate system. Guess I got married fairly young, and then kept "putting it off" as my current system(s) are still decent, however dated and "mid-fi". But boy I am so blessed with my family...

Recently I've migrated to more "decor" friendly installs at home with decent in-walls in most rooms, outdoor speakers on the deck, and my 12 year old home theater speaker setup in the family room. It still rocks though!
 
#15 ·
mapcam235 said:
Another little snag is that I don't think my HU has seperate sub outputs. :( Ideas? Maybe a new HU, there is a model above mine CDX-C90 link, newer but discontinued, it would interface with all of my other Sony stuff. Too bad that the new Sony HUs are so bad.
Maybe I'll keep my HU and bridge the bass and two channels of the MRP-F320 for the THOS, significantly upping the power to the THOS and use the other two channels for the rears and get a nice two channel amp for the Focals up front. What do you guys think?

This is a great thread BTW. It's nice to start the year off on a good note, a bass note. :D
Hey Matt. Thanks for the input. Been too long, huh bud?
In regards to your dilemas, there are many makes/models of amps that feature pre-outs, so you can deal with just f/r pre-outs and still run multiple amplifiers. You simply daisy chain the amps.

In regards to your use of your 320, I'm not sure I'm following you. What exactly are you looking to accomplish with your amp/system upgrade? Let me know and maybe I can help you brainstorm. Is it more power to the sub? More crossover flexibility with the front HP filter? Better clarity in the front soundstage? More power up front? All of the above?
 
#16 ·
Yeah SJ, I've been out of town a lot and I have a bunch of other projects that take priority, but it's nice to get back into an audio chat.

shinjohn said:
In regards to your use of your 320, I'm not sure I'm following you. What exactly are you looking to accomplish with your amp/system upgrade? Let me know and maybe I can help you brainstorm. Is it more power to the sub? More crossover flexibility with the front HP filter? Better clarity in the front soundstage? More power up front? All of the above?
I think that I want more power to the sub, although if I have passengers in the back they mention that the bass is loud. To correct this problem I rarely have more then one passenger in the van. :) I am sure that a dedicated bass amp with subsonic filter and variable crossover will greatly improve the performance of the THOS, but now I am thinking that my money and amp space would be better spent upgrading the amp for the front components. A higher grade dedicated front amp will give me more control of the front sound stage and more power. I suspect that this will yield the greatest noticeable improvement in my listening experience, taking full advantage of the Focals which are bright, and could use some help in the upper mids.

If I go with that approach I can bridge the F320, giving more power to the THOS, but will this improve my bass situation? I still will not have on-the-fly control :( but the higher power may improve the driver's performance. What do you guys think?

I am going to limit myself to one more amp (for both space and money reasons) and I don't think that I feel like changing or upgrading my speakers at this point. The Focals are arguably the strongest speakers in the system and I interact with them the most because I am always driving. Ha, it seems that I just found my can opener and what's this, a can-o-worms. ;)

Thanks,
Matt
 
#17 ·
I think that I want more power to the sub, although if I have passengers in the back they mention that the bass is loud. To correct this problem I rarely have more then one passenger in the van.
Matt,

It sounds like a bass amp with its own gain control, like the MRD-M300, might be what you need. When you have passengers in the back, you can always turn down the gain.

Or alternatively, if you don't want to buy another amp, maybe you could drive your rears from your head unit, as rlpenny does, and bridge the 4 regular channels to your fronts to give you 100W to each speaker. If you're always in the drivers seat, and don't often have rear passengers, maybe that would work the best without costing you anything.

I'm glad you brought that up because when the baby's in the car, either my wife or I sit in the other second row passenger seat to pick up whatever he's thrown on the floor or give him new stuff to play with (and throw). That's why I went with good rear speakers instead of keeping the factory ones. But it sounds like I'm may have to adjust the sub's gain depending on whether I'm driving by myself or with a passenger. That makes the MRD-300 even more appealing to me. I'm going to go listen to one tomorrow.
 
#18 ·
bushmen said:
Matt,

It sounds like a bass amp with its own gain control, like the MRD-M300, might be what you need. When you have passengers in the back, you can always turn down the gain.

Or alternatively, if you don't want to buy another amp, maybe you could drive your rears from your head unit, as rlpenny does, and bridge the 4 regular channels to your fronts to give you 100W to each speaker. If you're always in the drivers seat, and don't often have rear passengers, maybe that would work the best without costing you anything.

I'm glad you brought that up because when the baby's in the car, either my wife or I sit in the other second row passenger seat to pick up whatever he's thrown on the floor or give him new stuff to play with (and throw). That's why I went with good rear speakers instead of keeping the factory ones. But it sounds like I'm may have to adjust the sub's gain depending on whether I'm driving by myself or with a passenger. That makes the MRD-300 even more appealing to me. I'm going to go listen to one tomorrow.
Sub Gain Control...
I agree...a dedicated gain control would be nice to have...and that wish comes from someone with an Alpine head unit that can enable SUB-W output control with just one push of a knob. I'd still prefer to have a dedicated knob to adjust sub output and not have to push the volume knob on the head unit and then turn the volume knob. Dedicated knob would be easy for wife or other's to use. If one's head unit does not have sub preout, then a dedicated 'fancy' pot (i.e. gain control) would be highly recommended.

Power for rear speakers...
Yep, I still have factory rears and power 'em with deck power (eeewwwh)! Since I'm using an amp and sub and deck pwr for the rears, fading can be touchy. Not hard...just touchy. Think of the head unit power being a fixed gain, thus your amp gains have to be coordinated with the fixed deck gain, which can limit your flexibility and operating range of the amp's gains.

For instance, to get normal front sound stage for me and equal f/r sound for middle passengers, I normally keep the 31-step FADER conrol almost all the way to the front at "+12 Front", whereas the head unit's FADER range is indicated from "-15 Rear" (full rear) to "+15 Front" (full front), with "--" being neutral. Ideally, I'd use an amp for all speakers so I could adjust the gain of each channel pair to get even sound in the middle of the van at the "--" neutral FADER setting.

My ultimate plan is get a decent quality coax for the rears and send 50W to each side. I'm seriously considering using smallish 4" coaxes in the rears so I can use baffles. Based on all the reports I've read about how hard it is to get an effective front ot rear seal in the rear speaker positions without custom fab work, I'm willing to invest a small amount in 4" coaxes and baffles to see if 4" speakers in baffles sound better than 6.5" speakers in a practically free air environment. I doubt baffles and 6.5" speakers would fit or even have enough effective space, thus my thought of using 4" speakers. Someone please tell me I'm silly for wanting to try this or that it is worth a shot and to go ahead and try it and report back.:)
 
#19 ·
Is this worth trying for sub amp...

ShinJohn or others....

Is this worth looking at http://www.crutchfield.com/S-4dA3sk2h6mX/cgi-bin/ProdView.asp?i=023PA2100 for use with THOS. Price seems very nice and it comes with the remote gain control. I've heard that the T class amp is not as clean as AB but more effecient than D and would make a decent sub amp.

I'm wondering if one could use this $130 amp in bridged mode to drive THOS. If I did this, I'd free up some a/d/s/ PH15 power to run 100W to each front door (rather than 50W now). THOS is now only getting a bridged 100W (very clean) from the PH15 but I've read that even though the PH15 is a well regarded and clean amp, its one weakness is in deep bass. THOS can handle 160W so I was thinking I'd get a noticeable improvement if I pumped in 160MW. 100W to THOS is fine in the garage but at 80mph, I wish I could get just a little more out of THOS and am wondering if I'd notice the extra power from 100W to 160W. At this point, my amp gain for the THOS channel is maxed out.

The Blaupunkt PA2100 seems rather small at H=1.945", W=8.725", D=5.82" once it is taken out of its plastic housing.

Any ideas on this amp, or should I just leave well enough alone and keep 50W to each door and 100W to THOS?
 
#20 ·
Thanks for all of the input. I am really torn a between a better amp for the fronts and a dedicated bass amp.

rlpenny said:
If one's head unit does not have sub preout, then a dedicated 'fancy' pot (i.e. gain control) would be highly recommended.
Yeah this seems like a good idea. Any brands that are notably good or bad?

Power for rear speakers...
Yep, I still have factory rears and power 'em with deck power (eeewwwh)!
My HU does not have an internal amp, only 4 volt pre-outs, so it looks like I may be into another amp.

I'm seriously considering using smallish 4" coaxes in the rears so I can use baffles. Based on all the reports I've read about how hard it is to get an effective front ot rear seal in the rear speaker positions without custom fab work, I'm willing to invest a small amount in 4" coaxes and baffles to see if 4" speakers in baffles sound better than 6.5" speakers in a practically free air environment. I doubt baffles and 6.5" speakers would fit or even have enough effective space, thus my thought of using 4" speakers. Someone please tell me I'm silly for wanting to try this or that it is worth a shot and to go ahead and try it and report back.:)
I've wondered this myself. I don't usually have passengers in the back, but the rear speakers are just disappointing and mostly due to the lack of enclosure. I know the idea of using 4" speakers has come up before, but I don't recall if anyone has done it. I think it's worth a shot.

-Matt
 
#21 · (Edited)
mapcam235 said:

I think that I want more power to the sub, although ....... A higher grade dedicated front amp will give me more control of the front sound stage and more power. I suspect that this will yield the greatest noticeable improvement in my listening experience, taking full advantage of the Focals which are bright, and could use some help in the upper mids.
I tend to agree here. The next logical upgrade in your system (in terms of bottleneck) would be a better amp for your front components. Getting a kick butt bass amp will do less on a SQ perspective, I think. Selecting an amp to drive components is a little different than selecting a bass amp however, and another long discussion could possibly ensue. I would recommend you looking at some higher end brands if you are going to do a front amp upgrade, and be prepared so spend a bit more money in terms of $$/watts.

Again, budget and personal preference will dicate which direction you go. But I see some danger here as if you start going down this path: it tends to lead to something much more sinister: a practical system overhaul to get the "sound" you really want.... You know, oh, now my amp and source are so good, I need better components...... followed by, boy, it sure would be nice if the low end were just as subtle and defined as the rest of the range... (meaning new sub and sub amp) It could get ugly.



If I go with that approach I can bridge the F320, giving more power to the THOS, but will this improve my bass situation? I still will not have on-the-fly control :( but the higher power may improve the driver's performance. What do you guys think?
This is where I am confused. How is it that bridging the F320 will get more power to your single sub? Bridging will give you (2) 100W channels in addition to your 120W sub channel. The sub channel does not benefit from bridging....



I am going to limit myself to one more amp (for both space and money reasons) and I don't think that I feel like changing or upgrading my speakers at this point. The Focals are arguably the strongest speakers in the system and I interact with them the most because I am always driving. Ha, it seems that I just found my can opener and what's this, a can-o-worms. ;)
Oh, but it is a bit of a can though..... Just one amp.... Hmmm.....
How about this one?

http://www.phoenixgold.com/reactor.html

You might want to upgrade your speakers though after this... ;) :D :D :eek:
 
#22 ·
rlpenny said:
My ultimate plan is get a decent quality coax for the rears and send 50W to each side. I'm seriously considering using smallish 4" coaxes in the rears so I can use baffles. Based on all the reports I've read about how hard it is to get an effective front ot rear seal in the rear speaker positions without custom fab work, I'm willing to invest a small amount in 4" coaxes and baffles to see if 4" speakers in baffles sound better than 6.5" speakers in a practically free air environment. I doubt baffles and 6.5" speakers would fit or even have enough effective space, thus my thought of using 4" speakers. Someone please tell me I'm silly for wanting to try this or that it is worth a shot and to go ahead and try it and report back.:)
Keep in mind that primarily what we are talking about here is bass and mid bass response. Since you already have a sub in the rear corner, I think it is less of an issue. But I will say this: the use of a 4" or 5.25" speaker may yield a tonal characteristic more favorable in certain frequency ranges. For instance, smaller mid bass drivers tend to blend better with their complementary tweeter, having a more tied together upper mid range to lower high end. But your mid bass will obviously suffer. Baffles can help that situation, IF you choose your speaker properly. It's parameters must dictate it to work well in a relatively small enclosure.

Silly for wanting to try? I dunno about that. :p If you have fun doing it, and get the type of sound you are after, its worth it. I've done lots of experiments just for fun, even though I expected less than optimal results. For me, it was part of my learning process. But if you are asking me if I would try it out, no, I wouldn't.
 
#23 ·
Re: Is this worth trying for sub amp...

rlpenny said:
ShinJohn or others....

Is this worth looking at http://www.crutchfield.com/S-4dA3sk2h6mX/cgi-bin/ProdView.asp?i=023PA2100 for use with THOS. Price seems very nice and it comes with the remote gain control. I've heard that the T class amp is not as clean as AB but more effecient than D and would make a decent sub amp.

I'm wondering if one could use this $130 amp in bridged mode to drive THOS. If I did this, I'd free up some a/d/s/ PH15 power to run 100W to each front door (rather than 50W now). THOS is now only getting a bridged 100W (very clean) from the PH15 but I've read that even though the PH15 is a well regarded and clean amp, its one weakness is in deep bass. THOS can handle 160W so I was thinking I'd get a noticeable improvement if I pumped in 160MW. 100W to THOS is fine in the garage but at 80mph, I wish I could get just a little more out of THOS and am wondering if I'd notice the extra power from 100W to 160W. At this point, my amp gain for the THOS channel is maxed out.

The Blaupunkt PA2100 seems rather small at H=1.945", W=8.725", D=5.82" once it is taken out of its plastic housing.

Any ideas on this amp, or should I just leave well enough alone and keep 50W to each door and 100W to THOS?
That's a pretty nice deal, given you get the gain control thrown in!

Here's my take: the added power isn't going to do too much for you in terms of cranking it up. The sub will hit the wall (literally)very quickly in terms of excursion. You probably will get just a little more SPL, but it won't be earth shattering (literally). THOS is relatively tame... But curious, you have an SPL meter, how loud can your sub play with the a/d/s currently configured? Check my review, I think I got ~115 dB on peak hold, really pushing the thing to its absolute limit.

Next, the subsonic filter on the Blau is practically useless in this case since it is tuned so low, and the crossover has a pretty shallow slope, but at least it is adjustable, which is nicer for tuning.

About your a/d/s: Don't get confused by what you read. Your amp is still conservatively rated, and will be putting out RMS power well above its spec (easily 20% or more greater), even at low frequencies. However, compared to amps that are built for competition or specifically for bass applications, yes, I agree it is not the best or even the cleanest. For raw bass power, I like Phoenix Gold, Precision Power, and well as some other brands.

I don't have personal experience with Blau amps, but I imagine it is not too bad, at least in line with other low to mid level amps. My take is if you really want to:

1) keep your budget low...
2) get wired remote bass control ...
3) get 100W/channel up front, and 40W/ch rear, all with outboard amps, solving your gain control problem to a certain degree...

Then I would say buying the amp is not a bad idea, and is quite economical at that. Just don't expect the quality or the quantity of the bass to improve dramatically.

Just my 2 cents.
 
#24 ·
Yesterday turned out a lot different than I expected. I went to the store to listen to an MRD-300 with the full intention of buying it, so that I could return home and order a THOS. However, this is what I ended up buying:

JL Audio 10W0 sub
Custom sub enclosure (to be placed between front seats, with tray screwed to top)
Alpine MRP-M350 amp

I feel like I ignored all your advice, but here's the method to my madness...

All my previous listening at the store had been with the above amp and sub, along with the other equipment that I had bought. Even my wife had listened to the amp/sub combo, which is why she bought me a 10W0 (in regular JL box) as a surprise Christmas present. The only reason I took the sub back was because I could not find anywhere to put it without having to move it whenever I raised the magic seat.

The store didn't have a MRP-M350 to listen to, but I saw that they had discounted it to $240, which is only $40 more than the MRD-M350. However I started chatting to the salesman and the store's installer (fully certified, not like a Best Buy installer) and they both told me that in their opinion, the cheaper Alpine had better sound quality. In fact, they said that quite a few customers had returned their MRD-M300s and swapped them for the cheaper amp.

While chatting to the installer about getting a THOS, he said "Why don't I build you a custom sealed enclosure between the front 2 seats?" He said he could do it for $100, so the total for the sub and enclosure ended up less than the THOS.

The final reason I went with this is because I've heard it and liked it. As I said before, I hate buying blind, so at least I know I'll be happy with this setup. I thought long and hard about the advantage of the remote gain control, but with the bass coming from the front of the van, I think that I'll have less need to turn it up and down. When my wife's in the back seat (next to the baby), she normally asks me to fade the music from the rears and I was thinking that I should probably also turn the bass down too, but in this situation, I may be able to get away without gain control. I know bass is meant to be non-directional but I've read too many posts in this forum that state the opposite.

Of course, I'm still not sure about my choices. Th install will probably be next weekend, leaving me lots of time to change my mind! Here are some things I'm thinking over:

- Upgrading the sub to a 10w3v2. But the store did not have any to demo and I'm not sure what this would add in terms of SQ. Also, I would either have to buy a more powerful amp or maybe run the MRP-M350 in 2ohm mode. Any thoughts?
- Using two 8inch 8w0 subs instead of 1 10inch 10w0. Are there any advantages to this? Possibly, less deep bass but more musical?
- The store also had a 2 channel class AB Alpine MRV-T320 which was priced the same as the class-D amp. This was not hooked up in the demo room, so I would be buying blind, but I would assume it would be at least as good as the 1 channel amp. This brings me back to my original question. Should I get the class AB amp? I would be losing the subsonic filter, but the installer told me that the subsonic is more relevant for ported and bandpass subs.

Shinjohn, I know you've listened to both JL subs and the THOS, and I believe you said you didn't like the "JL Audio sound". Was that just the subs or the speakers too? And what JL subs have you heard? As far as speakers are concerned, I prefer the JL Audio sound to the Boston sound (which I think you like), so maybe I should stick to the JL sub?

Also, if you have demo'd any of the Alpine amps head to head and preferred one to the other, I'd really like to know your preference.

As you can tell, I'm doing lots of second-guessing here. Normally I do a lot of intense auditioning when I buy audio equipment, so only being able to listen to a small sample of products is a little frustrating. However, as I said before, if I liked what I heard, maybe I should just go with it! I can't wait until it is all installed and I can stop worrying and start listening. Of course, then I can start thinking about upgrades...
 
#25 ·
For the reasons you mention, I'd say you did fine and you did not ignore our advice, you actually took it in and thought on it and made an informed decision. Had my wife let me put a box in between the seats, I'd have done the same as you with some type of enclosure. I too was looking at two 8's or one 10. Now that I have THOS, its only disadvantage is like you mention...that is...I have to turn it down when someone is in the very back.

With a sub in between the front seats turned to the level you like, you should have no complaints from anyone in the rear...unless it is from a teenager saying "turn it up!!"

Great posts and info and sharing with us and others that will read in the future your thought process. It is the thought process and the why behind other's decisions that most interested me when I started on odyclub.

Thanks again!
 
#26 ·
bushmen said:
I feel like I ignored all your advice, but here's the method to my madness...
Ditto on Robert's comment. It's all good. In the end, you need to make your own decision, that being an informed one.
We all base our decisions (and later recommendations) on personal experience and judgement. But in the end, with anything human, and dealing with subjective matter, there will always be a diversity of opinions, and a multitude of solutions.


The store didn't have a MRP-M350 to listen to, but I saw that they had discounted it to $240, which is only $40 more than the MRD-M350. However I started chatting to the salesman and the store's installer (fully certified, not like a Best Buy installer) and they both told me that in their opinion, the cheaper Alpine had better sound quality. In fact, they said that quite a few customers had returned their MRD-M300s and swapped them for the cheaper amp.
To be honest I have not compared these side to side, so I would not know. I'll tell you that I've heard lots of Alpine amps, and they are all decent in terms of sound quality. (though I truly do not consider any Alpine amp really "high end" per se).
BTW, Crutchfield sells the MRP-M350 for $199.99 and they are not the least expensive. If you paid $240, that seems excessive... Or maybe you mistyped...


While chatting to the installer about getting a THOS, he said "Why don't I build you a custom sealed enclosure between the front 2 seats?" He said he could do it for $100, so the total for the sub and enclosure ended up less than the THOS.
Sounds good. I've designed a dual 10" center console sub myself. It is in the process of being contructed. (one of those projects I have no real time for) So, I am with you here...

$100 is reasonable for an enclosure. Keep in mind the spare tire well underneath though. My enclosure is shaped like a trapezoid, to allow access to the tire well without moving the enclosure. I also designed in an integrated console, in lieu of the tray.

One last thing: hope you have a great installer! Then end result is only as good as the installers skills.


The final reason I went with this is because I've heard it and liked it. As I said before, I hate buying blind, so at least I know I'll be happy with this setup. I thought long and hard about the advantage of the remote gain control, but with the bass coming from the front of the van, I think that I'll have less need to turn it up and down. When my wife's in the back seat (next to the baby), she normally asks me to fade the music from the rears and I was thinking that I should probably also turn the bass down too, but in this situation, I may be able to get away without gain control. I know bass is meant to be non-directional but I've read too many posts in this forum that state the opposite.
I like to adjust bass level also with the style and type of music I listen too. Also depends on if I am cruising on the freeway (alot more road noise) or if I'm on local roads. But anyway, that's just me.

It's true that bass is "non-directional" but that does not mean its intensity in a vehicle does not vary with distance. Remember the r^2 rule from physics? True a vehicle is not anechoic either, but location of the sub relative to the listener is a very important variable in SPL.

It's getting late. I'm outta here. More answers in a later post..
 
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