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.
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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.


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@stargazer   I must admit that I personally in my limited experience of owning new HiFi components I never experienced this marked change of sound during 'burn in process'. When you confirm that in regard solid state amplifiers it is the listener who is becoming accustomed to the change thats quite an assertion when you consider the host of people (professional and non professional) who claim to have actually heard and experienced the change of sound during the claimed burn in process. Its fascinating that such a divide exists among normal music lovers.

It is quite an assertion that I made. We know not what they heard, we know not what posessed them to make such claims. I assert that the change is so subtle as to be entirely imaginary. I have said to many who report such " Wow you have a really good imagination"

Look at it this way. There are professionals and non professionals who assert they have golden ears and they must say these things to support their ears. We dont know what someone is hearing. 

As I have posted previously ive been in a room with some golden ears where the system was "broken" and they didnt hear it. Given that who is really hearing what?
Roger, why did you switch the input to the 12AT7 from the 12AX7 on the Ram10 mkll?
@jlhaudio Roger, why did you switch the input to the 12AT7 from the 12AX7 on the Ram10 mkll?


Along with changing the bias system from fixed to cathode bias and changing the B+ I found the 12AT7 was a better choice. It has a lower saturation voltage than a 12AX7 and higher current. As far as we can determine the amps sound the same. We want them to. 
My pre-amps are unusual in many ways as they use only six subminiature tubes, are a voltage regulated design with no fuse/breaker necessary and have the stepped attenuator out of the signal path but operates by bleeding off voltage to ground to attenuate the volume. That’s what the manufacturer told me. Sounds as good or better than an EAR 912 with tubes rated for 100,000 hours and non-microphonic. The phono pre-amp is similarly designed without the attenuator.
I think it was Monster that did it to "burn in" their cables
When I consulted with Monster Pro in the 80s & 90s,AFAIR burn-in was never mentioned.

The first I heard of it was in the early naughts, but I had been in AA [Audiophile Anonymous] for a few years.