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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terry9
2,348 posts
 
Thanks for all your help, Roger. You really have opened up a stack of stuff for me to do. Much, much appreciated.

Hate to be pedantic, but I think that the 45uF figure should be 4.5uF, which is less of a problem: (75**2)  *  (800  *  10**-12)  = 4.5  *  10**-6. Your other concerns with the Vanderveen (got it right this time?) transformer remain an area of intense interest (and research!) to me. Thanks again!
jcder
28 posts
 
Fascinating thread.  Thank you!   If you dont mind, could you provide a quick list of your favorite (currntly available) tube preamps?   I don't need a phono stage.   It will need it to accept input from my PS Audio DAC, and to drive my vintage Audio Research (sorry) tube amp.   For what it's worth, I do plan to ultimately sell the AR amp and upgrade to a different make...   
georgehifi's avatar
georgehifi
10,312 posts
 
could you provide a quick list of your favorite (currntly available) tube preamps?
I don't know about Roger, but the best bag for buck for me is the Schiit Freya it has everything, it's three preamps in one to suit all "flavours" and it has probably the best mechanical volume control you can get.
 And Mike Moffat is no design slouch, his designs made Theta audio what it was when it was on top, now it's gone by the wayside just like Rowland Krell ect, when the real designers left or sold out, and the accountants moved in.
What Mike has done is given the goods on the inside with the Schiit brand but the outside is low cost utilitarian, so the customer is not paying $KKK's for CNC machined polished chassis, that do nothing for the sound.
http://www.schiit.com/products/freya

Cheers George 
bdp24's avatar
bdp24
9,868 posts
 
@jcder, everyone is going to recommend his own pre in answer to your question. Here are a couple to consider: There is a Hovland HP-100 listed on Audiogon right now (at an asking price of $2350), a fine line stage (I heard it in Brooks Berdan’s reference system for quite a while). The EAR-Yoshino 868L line stage, another good one, occasionally pops up for around $3,000. The 868 has one true balanced (via transformer) XLR input, if that matters to you. EAR Designer Tim de Paravicini very much strikes me as the UK’s equivalent of Roger Modjeski; old school EE’s with good ears and lots of knowledge and talent.
clio09
3,360 posts
 
Yes the Beveridge RM-1 with RM-2 power supply. A legendary component in my opinion with 2 phono inputs. Roger broke the mold with this one. If you have a chance to buy one get it, they show up for around $1000 on eBay. It will most likely need to be refurbished but all in you will have a full function line stage that will rival anything out there regardless of cost.
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