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.


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analogluvr
859 posts
 
Why would dual mono volume controls  be ill advised?
apogee14151617
11 posts
 
This is kind of an obtuse question, but why do some amplifier manufactures say to use a preamp between their amplifiers and the streamer when you are only using a streamer and power amp, no vinyl and no other sources.  I understand the need for a volume control and to have the impedance's low for the streamer/DAC and high for the power amp.  My streamer/Dac is <100 ohms and the power amp is 47K.  There is an implication that the preamp does other things that affect the SQ.  Any idea what those are?  An Allegri+ addresses the impedance problem and give a volume control and is extraordinarily transparent on my Ribbon Speakers.   My amp and steamer is very high end.  Is there more?    
bdp24's avatar
bdp24
9,821 posts
 
@analogluvr, too fiddly.
ieales's avatar
ieales
1,201 posts
 
@bdp24 - dual controls are not too fiddly if they are 1db or less stepped

@apogee14151617 - all components active and passive alter the sound. There is no electrical reason to have a preamp if the source has output level control or the amp has input level control. I use a passive 1db stepped resistor of my own design. It has a sound, but everything does.
atmasphere's avatar
atmasphere
11,841 posts
 
why do some amplifier manufactures say to use a preamp between their amplifiers and the streamer when you are only using a streamer and power amp, no vinyl and no other sources. I understand the need for a volume control and to have the impedance's low for the streamer/DAC and high for the power amp. My streamer/Dac is <100 ohms and the power amp is 47K. There is an implication that the preamp does other things that affect the SQ.
The answer is highly system dependent of course, but one reason is that a preamp is or should be designed to minimize artifacts occurring from the interconnect cable between the preamp and amp. Sometimes digital sources are not very good at this. A second reason is that a preamp can provide a fairly high impedance load for the source, meaning that the latter does not have to work as hard to make its signal. This could result in lower distortion- and no place better in the system to get things right!
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