2. amps-preamps
  3. 140029-80294

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.


ramtubes

Showing 3 responses by jafox

jafox
1,470 posts
 
Hello Roger,

Years and years ago I re-tubed my ARC SP-10 with your RAM tubes and the phono stage quieted down mighty well.  And then a year or so later I heard your RM200 amp at a dealer in Phoenix and that was a very nice sound as well.  Thirty years later, I have a question that I imagine you or some of the other techie gurus might be able to answer.

I swap between amps with some that only have single-ended inputs and others with only balanced inputs and others with both.  My preamp has outputs for both.  I recently acquired a very nice 4m balanced IC.  For the cases when I want to use the single-ended input only amp, the CAT JL-3 monos, I will need to use an XLR to RCA adapter into the amp.  The adapter I bought has the neg line tied to ground.  But this results in the preamp's neg output line being shorted to ground which does not seem to be a good thing.  Would it make more sense to put a 10k, 50k, 100k, etc., resistor inside the adapter from the the neg pin to ground to more accurately simulate what the cable would otherwise see as the amp's input impedance?

Any thoughts here would be greatly appreciated.

John


jafox
1,470 posts
 
Thank you for the responses above.  The preamp is Aria WV5, the last design by Michael Elliot of Counterpoint 10 years ago.  The last thing I want to do is to put anything else in the line such as a transformer.

My experience has been that the most sensitive cable in the system is the IC from line stage and amp, where I was using ARC, BAT, Aesthetix, Counterpoint, Wolcott and CAT.  Just putting some cheap 4-5m RCA IC here is going to destroy much of what my system can achieve with a good IC here.  And so why not just use one leg of the XLR cable when I have a single-ended amp?  I just thought it might be a good idea to not just float the negative line.
jafox
1,470 posts
 
Thank you Roger and AL.  Fortunately, the adapters I bought have 2 small screws to allow the case to be opened.  I can cut the wire soldered from the negative to ground.  I will give this a try.
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