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
fleschler
2,021 posts
 
That's interesting information concerning the 6SN7 tube.  My power amps use them (NOS 1948 Raytheons) as cathode followers and the 6CG7 as a pair as input tubes.

Now if the 6SN7 is not really a good audio tube, why does VAC use it on the entire line of amps as input tubes?   He could have used a 6SL7 or 6CG7 or variant.
tomic601's avatar
tomic601
12,957 posts
 
I have a garden hose MIT PC that is a PITA and made my Ayre amp sound worse...IMHO I think a well executed coldwelded moulded cord on quality Belden wire is in many cases superior to glam cables that put a ton of physical loading on connections ( internal to the connector and then into the IDc socket.....and to answer RM ? heat is bad, it is V or I converted, which means NOT good.

taking offers on the garden hose...ha

tomic601's avatar
tomic601
12,957 posts
 
and yes customer brought his Bob Carver Phase 400 in and wanted to hear it with Litz wire speaker cables into ADS 2030.....

kabooom......

in all fairness, we had a service department that saw a lot of fried Phase 400, you could look crosseyed at them, or so it seemed....
bdp24's avatar
bdp24
9,868 posts
 
@ramtubes, Roger, I know you consider the 6DJ8 superior to the 12AX7 for use in a phono stage, but let me ask you this anyway ;-) : how do you feel about substituting a pair of 5751’s in place of a phono amp’s 12AX7’s? I know the 5751 exhibits lower gain and noise (in the 1980’s I had a Dynaco PAS 2 that was "modified" by Frank Van Alstine, and he put in 5751’s. That pre was very quiet.), but are there trade-offs involved between the two tubes? Is the 5751 a true direct replacement for the 12AX7, regardless of application? Or are there circuit considerations? If used in an RIAA moving magnet phono stage (gain of 42dB or so), will the 5751 automatically provide a little more headroom/freedom from overload than the 12AX7?
prof
3,474 posts
 

Thanks for the note, Al!
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