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.
.
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
ramtubes's avatar
ramtubes OP
460 posts
 
@russellstone

Hi. I was turned off tubes when a Mac 2275 couldn’t properly drive my ML Summit X’s (yep, ‘soft’ bass’). After some searching I found an Accuphase E-600 matched beautifully. My question is: how can Accuphase make a class A amp that runs cooler than many A/B amps, and substantially cooler than other class A amps that can give you serious burns when touched?


The Mac could not handle the low impedance. The Accuphase has lots of current. I looked it up, its 30 watts at 8 ohms, therefore low voltage supplies. A 30 watt class A amp can run cool, but not a 100 watt Class A. thats the difference. 

Here is a great example where 30 watts at 8 ohms is better than 75 watts from the Mac. Did you try the 4 ohm taps on the Mac? 
ramtubes's avatar
ramtubes OP
460 posts
 
Is there a particular Direct Drive Amp you can recommend to drive the panels? (Again I’m in a 240V 50Hz country).


I dont know of anyone making DD amps but myself. It a rather special thing.

ramtubes's avatar
ramtubes OP
460 posts
 
@rost 

 I´m using a balanced configured Pass SS XP20 pre with output impedence stated at 1K/leg, balanced and 200 ohm, single ended (according to manuel) driving tube monoblocks with rated input resistance at 47K.
     Amps have both RCA & XLR (only + phase) inputs. So my question is what input is preferable and why ?
     Your response will be greatly valued and appreciated.


If I understand your correctly the XLR is unbalanced + only. If that is the case there is no difference which input you use.
ramtubes's avatar
ramtubes OP
460 posts
 
@unreceivedogma

What you are doing sounds fine to me. Shows are shows and rarely a good place to judge a system. I'm lucky to fiind one system I like. 
ramtubes's avatar
ramtubes OP
460 posts
 
@prof 
If my amps are being run at levels that do not bring on distortion, why do they still have that classic "tube-amp" character even at those low listening levels? If it’s not the clipping characteristics that are coming in to play...what is it that produces that classic tube sound as I described it? 

I don't know what "classic tube-amp sound" is. I mean I don't design for it. I just make a good amp and I like to use tubes rather than transistors. 

Though I see some amps intentionally colored like this Cary SLI-100 Most of us designers dont do that.Good performance is not a mystery. I am tempted to call Cary and ask them what are they thinking. I read the review and the manufacturers comment. This is a sad turn for a company that was making some good stuff. 

I will be sad if anyone buys that amplifier, however someone will like it. There always someone.

With low damping the response modification will simply follow the impedance curve.  I set up an A/B this past week and we did some listening today. We could easily hear the differences, levels matched, carefully set up for instant comparison. If I were simply swapping amps not by a relay, I doubt the difference would be as apparent. 

I did one other thing that astounded me when we went from the QUAD 57 to a competent Alan Jones monitor I said... Why do people listen to little monitors when they can have a nice, room filling ESL?


More to discover