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


I closed the cable and fuse thread because the trolls were making a mess of things. I hope they dont find me here.

I design Tube and Solid State power amps and preamps for Music Reference. I have a degree in Electrical Engineering, have trained my ears keenly to hear frequency response differences, distortion and pretty good at guessing SPL. Ive spent 40 years doing that as a tech, store owner, and designer.
.
Perhaps someone would like to ask a question about how one designs a successfull amplifier? What determines damping factor and what damping factor does besides damping the woofer. There is an entirely different, I feel better way to look at damping and call it Regulation , which is 1/damping.

I like to tell true stories of my experience with others in this industry.

I have started a school which you can visit at http://berkeleyhifischool.com/ There you can see some of my presentations.

On YouTube go to the Music Reference channel to see how to design and build your own tube linestage. The series has over 200,000 views. You have to hit the video tab to see all.

I am not here to advertise for MR. Soon I will be making and posting more videos on YouTube. I don’t make any money off the videos, I just want to share knowledge and I hope others will share knowledge. Asking a good question is actually a display of your knowledge because you know enough to formulate a decent question.

Starting in January I plan to make these videos and post them on the HiFi school site and hosted on a new YouTube channel belonging to the school.


128x128ramtubes

@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?
correct me if I’m wrong.
That has been my attempt in the past. I try to do it without personal attacks- the principle being: attack the argument, not the poster.

A promotional device in what manner? Do you think Roger is using this thread to try and sell more products? Since you called out Roger on this I will say you are walking a fine line here Ralph, especially given what you once told me in a conversation we had about marketing. The thread was started so that Roger can share his knowledge and experience with the community. He has requested that other designers not respond to the questions asked of him, and from my perspective it’s not that you don’t bring value to the discussion (and I get it’s a public forum), but when you bring up the self promotion stuff, I have to agree with George that it is the pot calling the kettle black.
You consistently promote balanced differential designs, not always mentioning products specifically, although correct me if I am wrong, but you have mentioned the MP-1 was one of the first balanced preamps in high end audio on more than one occasion. I have read many threads where you reference how your preamps solve the issue of cable artifacts coloring the sound, that you make them unity gain with a buffered output, and you have mentioned or alluded to your amplifier designs many a time as well. Granted you do so in a gentlemanly manner and as a means to educate. However, isn’t that what Roger is doing as well?
No. And I agree, its a fine line!

Tony, Roger is a friend of yours so this might be sensitive, but here’s the difference. I just try to present the facts and nothing else. I don’t see Roger doing that here; take a look at the attacks in his post just prior. I’ve got no problem with his answering questions; I’ve been doing that here for over 20 years. The difference is in that context he also sees fit to attack others- Cary, ARC, Atma-Sphere (and also me personally) and so on. And lots of mention of his amps and preamps that goes beyond just the facts. In my case when I mention our gear I make no claims about the sound, just statements about what it is- for example that our preamps are balanced. Take a look at the examples you cite. When I’ve made that statement you quoted (and others that Roger quoted), it was simply fact with zero comment about how the equipment sounds or performs, with the exception of the fact that if the equipment supports the balanced standard, then the cables used will be transparent. Go take a look. The reason for this is the audiogon rules- I can’t (or thought I can’t) just get up and say how great my stuff is while demeaning others. ’I was so amazed how this detergent cleaned the stains that that other detergent couldn’t.’ That’s *advertising*.

BTW I kept my mouth shut about this until specifically asked. FWIW, I’m a moderator on another site, and I know better than to attack others personally as we see in Roger’s posts below (and previous). I have a thick skin, which is why I know better than to return in kind:

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.

....

Roger:


The problem here is simple: you cannot disprove anything that I’ve posted, while I can prove that its real, and have already done so on this thread. This might be the 4th time I’ve pointed this out. I am simply pragmatic; which to the best of my ability you seem to equate with ’pseudo science’. How much proof do you need? The problem here is not that I am wrong, nor is it that you don’t have engineering talent- yours are some of the better transformer coupled amps I’ve seen. But right now it seems that when presented with something that you don’t know about, it appears that you’d rather dismiss it than cause your hand to move and investigate (re.: cartridge loading, power rules). Good engineering practice is good science. In my case, I see if I can measure it; that’s how I found out that power cords can affect equipment performance both measurably and audibly.
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.
If you really believe this then you missed the boat about what this is about.


Put it another way: Flat frequency response from any speaker in any room is flat out (if you will pardon the expression) **impossible**. You can’t name a single speaker measured by anyone that is really in fact actually flat. Plus, you can’t fix it with an equalizer- they don’t have the resolution.


We like to think speakers are flat, but such thinking is engaging in made up stories. Its fantasy.


And it turns out that for the last 80(!) years we’ve known that distortion is interpreted by the ear as tonality! See the Radiotron Designer’s Handbook, 3rd edition (page 67 IIRC). This fact is indisputable.


So what can we conclude? Certainly that the ear places an extreme emphasis on certain distortions (again, see the Radiotron), while not caring nearly so much about others.


Since feedback causes those distortions out of its application (see Norman Crowhurst), its a **guarantee** that any amp that employs it will have some coloration (brightness) due to the reasons stated above.


Brightness is the single biggest objection that people raise about audio reproduction. Women tend to have more intact hearing than men and its common for them to raise objections to brightness more than men. Anyone here with a GF or wife can attest to this. So maybe feedback to achieve a voltage source isn’t the way to go; women are after all part of the marketplace (WAF).

As I pointed out in my email to you a few days ago, in the old days before the voltage rules were introduced (1950s), speakers had to deal with the issue of unknown voltage response in amps because a lot of amps (SETs for example) didn’t employ feedback. This is the Power Paradigm, and if it irks you that I put a name to it, I’m sorry - you weren’t around when I did that- I also use ’power rules’ and ’power source’ as alternates. These speakers had controls on them to adapt the speaker to the voltage response of the amp. JBL, EV, Altec, Acoustic Research, KLH... you’ve seen these controls! I have to imagine that you must have thought they were to adjust the speaker to the room?

Some modern speakers have these controls too - Sound Lab ESLs, Classic Audio Loudspeakers and plenty more, if they are designed for amps with a high output impedance (power source). The Sound Labs aren’t, but because ESLs aren’t Voltage Paradigm devices; they need the controls in order to work with voltage source amps.


The idea of the modern Power Paradigm is simple: just don’t make the distortions to which the ear is keenly sensitive, and after that do your best to get flat response from the speaker. The Voltage Paradigm has it the other way ’round.
This is why I advocate the ZERO autoformer, as it allows you to adjust the voltage response of the amp without using feedback, which I regard as the bigger sin for reasons stated above.

Quite simply I (and other designers like those that make SETs) am not trying in my designs to do what you are trying to do. I’m trying to do what SETs do, but without so much distortion (coloration) and with wider bandwidth. Its not woo voodoo- I don’t go in for that anymore than you do; its all just engineering once you know what the problem is, which is stated above, but ad nauseum: the ear converts distortion into tonality. Get rid of the distortion, and the presentation **can** be more neutral.
This is why I advocate the ZERO autoformer,
It would be far more creditable of you to advocate the use of a different amp to handle the problem properly, even if it’s not OTL.
Instead of this costly band-aid autoformer "fix" all the time, that "enables" an OTL to be used under diminished sonics.
Maybe your new venture into Class-D will show another side.