Center Channel Amp

[Wireless]

Hello everyone, I thought I would enter the fray and ask for some advice on amplification.

I'm currently using a Classe CAV-75, 75w x 6, bridged to provide three channels at 150w x 3 to drive my center and surround speakers, Waveform MCs at around 83 db sensitivity. Do you think anything would be gained in terms of sound quality if I were to upgrade to either 3 monoblocks or a stereo and mono amp?

Thanks!




John
My HT Picts

[ThomasW]

Your question is puzzling, you talk about increasing amplifier power, the speakers low efficiency, then ask about sound quality. A more powerful amp isn't going to increase the sound quality, only the max output, and that only a limited amount. Classe' makes very high quality amps, and I'd guess that 150 watts RMS is pretty close to the total power handling of this speaker.

This speaker is really designed for listening to chamber music in a small to medium sized room, not for HT use.

The primary limiting factor is that a 5" 2-way can only push a finite amount of air even when driven by a very large amp.

So I doubt that increasing the amplifier wattage significantly is going to accomplish what you want, unless the speaker's existing output is just slightly less than desired.

A wiser investment might be to get center that has higher displacement, meaning more or larger drivers. Center channel speakers should IMO be the same or as close as possible to the size of the mains, given the amount of info encoded in that channel.




theAudioWorx
Klone-Audio

[Lexman]

Personally, I don't know the speakers, so I can't comment on their efficiency. I do agree that Classe' has a great reputation, so power wise, your probably feeding them a good 150 watts, if not more. But I have seen a 100 watt Rotel amp come up anemically short driving 2 Infinity Kappa 7.1s. However,the 125 watt Proceed AMP5, does great with them. The Proceed is likely comparable with 200 watt amps from Rotel or Parasound, just guessing. Way under rated power wise. Of course, admitedly, it was my HPA-2 at 250 watts that I really formed my opinion about the difference in wattage. However, these speakers have 10" woofers, and are capable of going into the teens in terms of Hz. So, it takes some power to effectively drive them. I can't say your speakers are like that. But the lower the effeciency, the greater likelihood that you come up short. The odds on that increase as the bass woofer increases in size.

Hope that helps,
Lex

[Wireless]

Thanks for the responses. To me, whether it is dynamic range or frequency response, it either sounds better or it doesn't. The MCs were reviewed in the July/August SGHT and the Mach 17s were "A" full range rated by Stereophile until recently. I was off a little bit on the MCs efficiency - 84.5 db - not much better.

I'm using the Proceed AVP to cross these speakers over at 120 hz to the woofer section of the Mach 17s (2 12" woofers per cabinet, flat to 25hz,
-3db at 20hz). My concern is that unlike Classe's other amps, which double their power as impedence halves, they don't even rate the CAV at 4 ohms.
Thomas I promise you that this home theater system is equally adept at shaking concrete floors as chamber music, which it also does with finesse!

Maybe It is an effect of the mind - My main left and right speakers are amplified by three 150w amps, 450w per side total and it just feels like a mismatch.




John
My HT Picts

[ThomasW]

John

Again I repeat my question are you looking for better sound or higher output?

I've followed John Otvos's designs since the beginning of Waveform. And I'm well aware of the positive reviews the MCs have received. But I'm also aware of the fact that increased "radiating resistance" is a primary issue when trying to get higher SPLs from small bookshelf sized speakers.

Now if the "feels like a mismatch" statement is based is simply the published rated output power from the amps, then this is a psychological issue. Whether or not the amp doubles it's power with halving the load doesn't matter in the real world; if there is sufficient power to play the speakers at the SPLs you want, and if the sound quality is up to your expectations.

The fact that the L&R mains have the "potential" of 450 watts each isn't important, if that amount of power isn't needed or being used. So the idea of throwing more watts just for the sake of "matching" the mains doesn't make unless it's going to serve a functional purpose.




theAudioWorx
Klone-Audio

[Wireless]

Better sound. No matter how briefly satisfied, it seems there always may be a way to acheive better sound. As far as output, this system will play without distortion far louder than I could ever listen, so that wouldn't be the goal. I thought my impressions were probably phycho-acoustic in nature. I thank you for your input, and will keep things the same for now.




John
My HT Picts

[Wireless]

Better sound. No matter how briefly satisfied, it seems there always may be a way to acheive better sound. As far as output, this system will play without distortion far louder than I could ever listen, so that wouldn't be the goal. I thought my impressions were probably phycho-acoustic in nature. I thank you for your input, and will keep things the same for now.




John
My HT Picts

[Markj]

If you look at my profile you will notice Classe’ amps. To give a little back ground of were I am coming from I will launch into the short story of my HT road to enjoyment.

I started my HT experience with an Onkyo receiver when all I was watching was VHS tapes so DPL was all I needed. Then I added the Classe’ CAV-150 because the Onkyo could not handle my new speakers. Then the Onkyo was replaced by the Casablanca and by this time VHS tapes were being replaced by DVDs.
So that is basically how I moved into DD and the direction that my system was being developed.

Now the CAV-150 just did not give me the quality that I was listening for. It was configured 6X150 with one channel not being used. So I added a CA-300 to drive my main speakers and I bridge the CAV-150 to a 3x300 amp, which was driving my center and rear speakers. Now when I was listening to two channel music this system really sound nice. But the HT seemed to lack something. I guess I was destine to upgrade my CAV-150 because it blow and I had to take it to the shop. When I was talking to the sales guy while he was writing up the ticket for the CAV-150 he mentioned that he had a demo CA-300 and CA-100 that he was going to sell at a good price. This was the time when Classe’ changed their new amps to the new design and look. Well he made me a deal in which I traded in the CAV-150 for the other two amps which are now in my system. The CA-100 bridged to a 1x350 driving my center channel.

So what does this have to do with your CAV-75? Well I think the CAV-150 bridged was not as good sounding as a CA-300. I don’t think that the CAV-150 is as sturdy in design as the CA-300. I was talking to someone else at an audio show and he mentioned that the CAV-150 was designed more like the CAP-150 (integrated amp). I believe he is right. I have enjoyed the CA-300 much more and have no regrets on trading up for them.

So if you think you need more power but like the Classe’ sound then I would recommend going for their stereo or mono block amps. I think the CAV-150 and CAV-75 did not change their insides at all but just changed to the new Classe’ shell. These are good amps if you don’t need to push them. My CAV-150 was always running hot but the CA-300,100 are just barely warm after pushing them hard.

[ThomasW]

Markj

I'm pretty sure that your Apogee's are considerably more revealing of the differences in power amps than most "piston" drivers are




theAudioWorx
Klone-Audio