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.


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@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!
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.
@4krow I believe most of the Japanese integrated amps have tone controls: Luxman, Accuphase and the newer Yamahas. I am a fan personally, my vintage Kenwood sounds so good. There is definitely something undeniably cool about switches, knobs and levers. All this purist approach is fine and good, but its also boring as hell.
But other than possible tube noise floor raising...is the actual sound likely to alter in any way as tubes age?
Yes. If their transconductance falls below the minimum values, the performance will suffer and can affect things like bandwidth, distortion and dynamic qualities. In a nutshell, can sound 'sleepy'.
Much better than a 33 band EQ in my opinion, and in some cases even a parametric EQ.
@4krow
Its **very** tricky to build a 33 band EQ that doesn't mess up the sound! Even a 10-band is challenging. Parametrics have a lot in common with the filters used in analog synthesizers- they are pretty complex circuit-wise and so they are going to have a sonic footprint even when set to flat. 

Thanks atmosphere!!
I'm being a bit lazy in getting around to changing the tubes in my CJ pre, but I'll see if I can note any difference other than (hopefully) lowering of noise floor.