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
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almarg
9,670 posts
 

Ramtubes 11-22-2018

@almarg

It would help to quote the original question so we can follow this.

It appears to be an answer but im not getting it.

Roger, my previous post was a response to your post that immediately preceded it, about the need or lack thereof for large amounts of amplifier headroom.

And implicit in my post was agreement with your earlier statement that "over 100 watts is only justified by either high listening levels or insensitive speakers or both together. Excess headroom is a myth," at least as far as I am concerned.

Best regards,
-- Al
ramtubes's avatar
ramtubes OP
460 posts
 
@mapman 

Lifelike SPL for me is that what one might hear at a similar live performance in the good seats, not too close but not too far away.

I want my gear to be able to handle it all including perhaps sitting close to the percussion at the symphony or in small club proximity to a rock band. I want to be able to hear it all. I might not be able to in reality but if I can be convinced its very close in my own unique room then that is good enough.

At the same time I want to preserve my sense of hearing so most of the time I would strive to avoid SPLs higher than the mid 80s or so. But I want my system to do it all and never break a sweat no matter what I may ask of it at any given time. That was a key design goal in putting together the setup I’ve had now for several


Ok, some would say mid 80's is lower than a symphony close up. What are your peaks?

My system doesnt sweat but i know its limits via an oscilloscope on my equipment rack. It lets me see how close I get to clipping on various music. 

Would you like to share what you have put together along with some important numbers like speaker SPL/watt, Amp power, Listening distance, anything else?
mapman's avatar
mapman
22,341 posts
 
"Some" would be right of course. 😉

I often listen to peaks a lot louder. You would have to talk very loudly even sitting next to me to be heard. But it never actually sounds that loud which is usually a good omen that distortion is well under control.

System is OHM F5 series 3 speakers (12" Walsh style drivers in refurbed vintage OHM F cabs), Bel Canto ref1000m amps, 500 w/ch into 8 ohm, 1000 into 4 ohm. Room is 20x30 L shaped with speaks in base of L facing toward the long dimension. I normally sit about 10-12 feet back from speakers but they are quite omnidirectional so my listening location can vary.


Sometimes I sit ~4 feet in front and slightly to the left of the left speaker to get a more up close perspective. You can actually do that and retain a coherent  soundstage from most any perspective with these speakers which is perhaps their most unique feature.

I do not have spl measurements but will give that a shot with my cell phone over the weekend maybe and report back.

mapman's avatar
mapman
22,341 posts
 
Not my exact pair but there is a pic of the OHm f5 series 3 speakers on this page and mine are identical. 

http://www.e-bnlcafe.com/audioweb/speakers.htm

noromance's avatar
noromance
9,865 posts
 
Question: Tube Phono preamp. Would replacing the 1N4007 diodes (in bridge config) in power supply with HEXFREDs or Schottkys improve it? The bridge feeds a CRC filter which then feeds a tube regulator. Thanks.
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