2. amps-preamps
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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
robertrs
6 posts
 
Roger,

Thank you and the other SME's (Subject Matter Experts) for this wonderful thread, although much of it is over my head it is still a great read.
Stereophile just reviewed online yesterday the Cary Audio SLI-100 integrated, I only read JA's measurement section. Are the measurements results a function of the circuit design, layout-topography, or part quality?
georgehifi's avatar
georgehifi
4,966 posts
 
robertrs
Stereophile just reviewed online yesterday the Cary Audio SLI-100 integrated, I only read JA’s measurement section. Are the measurements results a function of the circuit design, layout-topography, or part quality?
The way is it is made, it’s performance (8ohm) tap into a simulated easy speaker load (black wavy trace)
https://www.stereophile.com/content/real-life-measurements-page-2
https://www.stereophile.com/images/1218Cary100fig02.jpg
it does becomes a bit of a tone control, varying it’s frequency response up to +/- 4.5db!!! A good amp should be almost flat.

This is probably as a result of it’s 4.4ohm!! output resistance, that’s a damping factor of under 2 !!! From the 4 ohm tap, it’s 2.3 ohms!!, still to high in my books.

Not good to me, unless you purposely want to change the way a recording is meant to be listened to by the recording engineers, into today's semi demanding speaker loads, it will be fine into very easy to drive speakers, but they usually have their own set of problems   

Cheers George
clio09
2,978 posts
 
Right now I am using the Acoustat servos with my modified Acoustat Model 2’s until Roger makes another run of his. Roger has made DD amps in the past for some folks overseas using them with Acoustat panels. The amps are an all tube design where the Acoustat servos had a solid state device for the input.

Here is some basic information for now until Roger chimes in:

http://tubeaudiostore.com/eslelodidram.html
robertrs
6 posts
 
George,

Thanks for your assessment, I am not interested in the amp, just trying to apply some of the knowledge that is being dispensed here.

I am not totally clear George, you said "the way it is made", is the issue the transformers, basic circuit, or the assembly topography?

Thanks in advance!
mental
1,029 posts
 
Old two channel amp had a hum, friend told me cut the equipment ground prong off. Hum went away, never understood that.
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