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.


128x128ramtubes
fsonicsmith's avatar
fsonicsmith
964 posts
 
Roger, I have two questions though the second is a doozy. 

1) What do you think of the Tungsol KT150?

2) What are your top 5 criticisms of the ARC Ref series components (i.e. the Ref 75SE or Ref 150SE amp and the Ref 6 preamp)?

I ask because I own and am proud to own the Ref 150SE and Ref 6 and more importantly, they deliver untempered joy and because while you said some negative things about Bill Johnson, you passed over the fact that Ward Fiebiger was the mind behind the latest designs. 


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. 
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