Does anyone care to ask an amplifier designer a technical question? My door is open.

@pwhinson 
I used to think that power was power with only minor differences in the sound.  However in trying to decide on the best amplifier for my Thiel 2.4s I've auditioned the Bel Canto m600s (their current production monblock), the Bryston 4 cubed stereo amp, and the Pass x150.8.  They were PROFOUNDLY different.  The Bel Canto rather oddly was very recessed the dark sounding, the Bryston was a little shrill with very little mid range "meat" on the bones but the Pass was JUST RIGHT.  Honestly, I'm being a little sarcastic here but these were not subtle differences.  I left the experience feeling that the "electrical" handshake between the power amp and the speaker is considerably more complicated than I originally imagined.  Thoughts?

Those are all big amplifiers. Given the low impedance in Thiels you want the amp with the most current. 

I would only listen to one amp at a time with one as a referene in a strict A/B test. Swapping amps has to much time between, levels are often not matched. I wish dealers had A/B boxes but its a lot of work and they dont want that kind of testing. You may find out the less expensive amp sounds the same or better. When you compare good amps with good specks they really cant sound much different, can they?

Now throw in a high distortion, low damping amp and you will hear that.

@fleschler  EAR 912 with tubes rated for 100,000 hours and non-microphonic.

I have looked at the rating of many tubes, last I looked Tim was using 7DJ8s. Those are 10,000 hour tubes If you get 10,000 be happy. 

Most tubes are rated for 10,000 hours and 10,000 turn-ons .So watch that. 

@grgr4blu I have enjoyed posts by Ralph and Ramtubes on this forum. They are both highly qualified as designers and manufacturers. They both provide answers to technical questions about gear. Sometimes, they include opinions based on their understanding of the science behind gear. Nevertheless, their posts are almost always informative to the membership here. Occasionally, they are self referential, although I do not view their contributions as self promotion that should be banned such as posts by Audiotroy which usually contain rank self promotion and, at other times, stealth promotion under the guise of informing the Audiogon community of his opinion ( almost always favoring the gear he sells) based upon his vast experience which he claims is more valuable than the opinions of other dealers who are out for the money--- while he is out to help the Audiogon community. Of course, these are extreme comparisons about what should and should not be permitted here. I suspect the line should be drawn somewhere in between the services provided by Ralph and Ramtubes and the disservice provided by Audiotroy. Might I add that Ralph and Ramtubes are not close to that line IMHO.

I toatlly agree about not promoting ones product and plan to watch it carefully. I would like to see people make some simple A/B boxes and will tell them how  for no charge. If I make one for someblody its a one off and not a product, just a tool, and a very good one. Perhaps I can make one and we can pass it around to those really interested and can convince me they can properly perform the experiment.

I will remind everyone that this thread is to answer and discuss technical topics. If you want me to answer personally pease direct the question to me.

Furthermore If anyone wants to debate a topic, be sure to have vetted sources to support your premise or be good at supporting it yourself. We have had a few on here that went on an on with no support, clairty or sensiblity. 

@atmasphere    But here's the kicker: This thread was put up as a promotional device. You can tell because the manufacturer is talking about his products, often more than once in many of his posts. This is against the Audiogon rules, but because I and others are posting here as well, the entire thread doesn't have to be taken down.

I notice on this account that Georgehifi isn't being taken to task; although while he is a manufacturer, he's not an amp designer. But this thread has drifted to the topic of preamps on occasion and on that account he's been posting too.

Ralph, Im sad to have to say all this but you have a very different about the owner ship of threads on Audiogon. of course it is a public forum, however it appears that most threads respect the OP as the moderator of his thread. 

 I think the original post is pretty clear. I am here to answer questions, educate and share the results of my experiments that I encourage others to have a go at some experiment that they may find very enlightening. 

I never imagined other amplifier designers would want to answer questions directed to me. If you think one of my answers is wrong you are wellcome to chime in but not with your paradigm or unsupported theories. I dont welcome any unsupported theories, poorly vetter answers from flawed articles.

Perhaps its time for you to start you own similar thread, Anyone who wants to ask Ralph a question can easily find him. 

You have a paradigm to promote with which I totally disagree. When I bring up that a widely varying impedance speaker will not sound as the designer intended, you bring your paradigm.. Perhaps your amp provides a tone control some like. I have 2 m-60s in my shop right now in my A/B test rack, anyone is welcome to come listen. One is stock one is my mod with feedback. It appears you have abandoned feeback on some psychological level rather than listening. We are just listening. 

So please dont bring your, not vettet, paradigm to a scientific discusstion which is in general disagreement with it. That is self promoting to a high degree. Why post here when you have known for years we disagree about damping, distortion, current, tube applications and a host of other things?  Ive read your paper over and over again and it makes little sense.

You are the only outside designer who has entered this thread.

When you answer questions from your point of view I have to deal with that and it makes more work for me. We already know what you are going to say you have said it 6,798 times. 

@atmasphere  Our MP-3 preamp is based on the first balanced preamp circuit ever sold to high end audio (our MP-1). It has a direct-coupled output (despite being a tube preamp) and has bandwidth to about 400KHz.

Hum, This is a bit self promoting of a current product. 

I will quote two products no longer made that were years before the MP-3.

David Manley had a balanced phono input (which is always going to have 3 DB more noise than unbalanced as it uses two input devices) It is also not necessary as the cartridge is a foating source. 

The RM-1 had Direct coupled output in 1978 and is lower noise than the MP-3. I have measured both. Clio was there for there and took notes.

Did you fix that RIAA yet?