Mosfet vs. Bipolar revisited and the Belles 350A

The following is a Post I saved regarding Amp Designs!Its a good read.
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Remember reading that a one benchmark about how good an amp is can be measured at how much power can be delivered when Halfing the Impedance rating. As an example lets say an amp is stated to deliver 200watts at 8ohms and then delivers 400watts at 4ohms then deliver 800wats into 2ohms.Does the ability to double it's rated output that way tell you anything about the amps ability besides being able to drive a wider range of speakers? TIA,ABEX

Actually, it tells you several things.

1. It tells you the designer was using his head while working, and recognizes the fact that nasty things like impedance drops, phase shifts, etc actually do exist, operate in real life like it or not, and attempt to modify the amp's performance into real world speakers, as opposed to lab test loads (usually a bank of high power resistors);

2. It tells you the power supply of that amp has been really well done, no skimping. No output stage can deliver real world power into real world speakers if it doesn't have an energy pool to draw that power from;

3. It tells you the output section in particular, but also the whole amp, has been conceived with proper capability to negotiate even very difficult loads, which gives you freedom to choose among speakers according to taste, and not to have to think about drive capabilities, and

4. It tells you the amp's performance, such as distortion and frequency response, will be modified very little by even evil loads, which is a hallmark of any good design.

As a sideline, it also tells you whoever designed it, was one competent designer and worthy of respect.

On the other hand, however important that is, it's not the only factor deciding on the overall quality of the sound. Let me put it this way - such an amp stands a better chance of sounding good than another without such capabilities.

This means less than perfect loads will not curtail the amp’s dynamics, and that it will in fact drive almost anything somebody decided to call a speaker.

Cheers,
DVV
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I'd do more than that - I'd say power supplies are THE place to start. It's quite simple - the whole product rests on power supplies, without good power supplies, the rest is usually meaningless, and in any and all cases devalued.

The most common and sensible tweak of any product is modding the power supplies. No matter how poor it may sound, after that mod it will sound better, every time, never fails.

Of course, those are absolutes, and there is a relativity factor here as well. If you have to double the product's price to get a 15% improvement in sound, well, that's hardly rational, is it?

there are TWO things I'd say to you:

1. By all means, do start from the power supplies, and
2. Remember, it's all a balance, to have significant gains you need to mod at least a few things, never just one.

BTW, you found some good brains to pick; Audi has one of the best electrical arrangements in the entire car industry, in my view, better than Mercedes-Benz and BMW. Your paw-in-law sure knew what to pick, kudos to him.
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The Belles is a great amp for the price, he has always designed very good products but was not well known.

I am not a technician, so any analysis of the over 100 amps experienced in the past 30 years comes by hearing alone. I am part of the generation that only had bipolars, and a few exotic variations in the 70s, and every year someone had "the" answer to improve their sound. My first "breakthru" amp was a Tandberg 3006. I did not know why, but it stayed in the system for 5 years, even as I was actively trading for profit other amps. At some point, the suggestion of "mosfet" as the reason was given to me. So, I tried that line. Hitachi, B&K, Muse - had strengths and irritations. They went, the Tandberg - three models over a 10 year period - kept returning to my system.
I did get the unexpected opportunity to possess an OCM200, which is a Belles design. Normally $1400 amps would be out of my range, but this one came cheap, so I listened. I would say that I have never had any amp that overall as a full range amp I would rate superior to the OCM200. Everything the previous writer said about his Belles is dittoed for the OCM. If I was listening to a single speaker full range, the OCM200 would still be with me. It is only because of one of its STRENGTHS that I very reluctantly let it go. It has the slam, slightly elevated bottom octave energy of the Bryston line - a wonderful attribute. But, I use a satelite/sub system, and the bottom octave energy actually put too much low energy into the satelites. The synergistic effect was to bloat the 80 - 120 hz energy region in my room. No combination of crossover/equalization would solve the problem without breaking the seemless transition. Oh how I wanted to keep it, but I had to face the facts.
A Tandberg integrated amp - 3012 - now handles the satelites. The Tandberg is "normal" regarding bass - and normal is excellent without slam. From 100hz up, there is no loss of detail, depth, musicality using the Tandberg. I actually prefer the integrated over the Tandberg power amp. The front end controls also make fine tuning, and timbre changes - such as music versus movies - a snap. I have compared the Tandberg with CJ, new generation Adcom, Coda, Kinergetics, new generation Denon. The 20 YEAR OLD DESIGN of the Tandberg 3012 proves to me the point of design execution. I have stopped "auditioning".
While I have a slight preference for mosfets, I concur that design execution and system synergy are the most important factors in personal system satisfaction. But I had an advantage in being a heavy trader. As a heavy trader, you get to eliminate the bull, the marketing, the snob appeal, the reviewers, and judge the product for what it actually does. I can buy whatever I really want, yet I love the fact that my system is made up of no individual component with a market value of more than $350!!
But, so that my opinion my be lowered to its appropriate level, I confess to using anyones leftover interconnects and hardware store 12 gauge cord for the speakers. I cannot hear differences at this level, and it breaks my heart to read the ads listing $1200 of 1998 recommended component interconnects now for sale at $400. I am VERY glad that I do not hear at this level of resolution.
But that's another topic.
jrobin out.

Jrobin
I do hear differences,but as you I do not think any of my components are vastly expensive.With the exception of the amp and speakers nothing is over $400.

Price is relative when it comes to audio and I can put my system against things costing many times more without flinching.There are more variables that make a good system than what the final cost is.

Do not know how many times I have shaked my head after hearing some components costing alot more and not getting good results,but people buy things without knowing or doing research into what they are getting.

I look at speakers as musical instraments as well as furniture.Other components as appliances that must perform the best for the $$ I am willing to pay for them.

Some of my equiptment is 20yrs.+ old that is still reliable and is good enough for my taste.

JMO

I tend to do as the last couple of posters have done, I buy stuff and listen to it. That way, I know if it will please me or not. I also buy just for the opportunity to listen and then sell if I don't want to keep it.
Zaikesman, what I meant was that the amp has excellent lower frequency transparency. Some amps sound wonderful through the mids and highs with superb transparency but in the lower frequencies, they lose control and sounds become less distinct and jumbled sounding(less resolution and transparency.) You don't get that see through to a kick drum or bass.
The Belles has a damping factor of well over 1000. Maybe that is why the Vandersteen's thrive on this amp. My Theta never had the low frequency control of this amp. Also, since Vandy subs(2WQ) take on the sound of the amp, now they sound considerably faster.
Since this amp has not been well reviewed, I bought it as an unknown entity on a friends recommendation. I did see in Soundstage where the reviewer pretty much conveyed my same thoughts about the amp. I caught this review right after the tornado's pass by the coast, lightning struck my front yard pine and knocked out my big screen TV last night. (along with a few other things)