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
prof
3,479 posts
 
Question:

What type of sonic issues occur as tubes get old? 


I had a tube in my CJ power amp fail, and the local shop said it was getting time to replace all the tubes.  But what is likely to happen if they are just left and keep on running?  Is it eventual failure?  Or does the sound start to alter in any way? Frequency response?  Dynamics, whatever?

I have the same question for my CJ preamp.  I know one aspect of tubes getting old: it now has a raised background "hiss" that it didn't have years ago when I bought it (so I've just bought replacement tubes).  But other than possible tube noise floor raising...is the actual sound likely to alter in any way as tubes age?

Thanks.
jetter
3,043 posts
 
I am very interested in the answer to prof's questions above. Especially as it pertains to what impact aging tubes will have on the sonics of a preamp, other than "hiss"?  I think another way of asking the question is that if you replace a set of aged preamp tubes (having no hiss) with an identical new set, will you hear a difference?
michaellent's avatar
michaellent
204 posts
 
 I’ve been studying electronics and simple circuits. I bought and assembled an $18 DIY speaker kit. It worked first time! It was my first assembly. I wasn’t perfect, before turning it on and I noticed that a 10k was in the wrong place. It was hard taking it out. Anyway after all this discussion, I bought the only remaining DIY audio preamplifier for $525. Just a few minutes ago. Roger, thanks for the inspiration!
Bentunderground
Michael Lent
bdp24's avatar
bdp24
9,874 posts
 
@ieales, thanks for finding the exact Forum to which I was referring. My six month estimate turns out to have actually been almost a year!
4krow
80 posts
 
Actually, after looking at the Harmon Kardon Citation 1 pre-amp, I noticed that all of the EQ that was mentioned about it pertained to phono, not tone controls. Yes, there are tone controls, but that is all they are. The adjustment is not flexible except for the plus and minus positions. I would rather have a tone control that can be set to a particular frequency... in fact, once the unit was at my house, maybe then I could determine those needed frequencies and change out capacitors/resistors to adjust to the needed frequency. Or, to get a bit fancier, as i mentioned before, there could be two or three choices, per a switch to choose which turnover frequency that you would want to use. Much better than a 33 band EQ in my opinion, and in some cases even a parametric EQ.
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