Does anyone care to ask an amplifier designer a technical question? My door is open.

Clio

The B4 is a First Watt product, it is a stereo active crossover with adjustable frequencies, slopes, and level, uses Jfets with no feedback.

@clio09, I read awhile back on a DIY forum that the assembled First Watt B4 was being discontinued, and Nelson was by that time providing info on the kit version. I just looked on the First Watt site, and the B4 is still listed. That doesn’t necessarily mean it is still available, of course, but give Reno Hi-Fi a call, maybe they have one left. It retailed for $1500.

Yes was aware it was a First Watt product just never saw it advertised as a kit. Nelson does have a crossover kit on the DIY Audio store but it's an analog version of the digital crossover used by Ziegfried Linkwitz, who asked Nelson to design it. I actually have the stuffed boards for this crossover as Nelson made them available at the recent Burning Amp.

Roger, 
           Thanks for this great thread! It is one of the best threads I have ever read on this website! Your time educating us non-technical prople is greatly appreciated. I still own the original Beveridge Model 2׳s and have a couple questions after reading your earlier comments about these speakers. You mentioned in an earlier post that the perfect room for these speakers is one that is 11’ W by 24’ long. You mentioned that they needed to be at least 6 feet from the rear wall facing each other. Then you commented on their amazing imaging saying that they should be 2 times 6ft or 12 feet area for imaging. Were you just saying that both speakers were 6 feet away from the rear wall or were you saying the speakers should be pulled 12 feet from the rear wall in this perfect room?

The original Beveridge amplifiers uses solid state inputs much like your RM-200. Is this because the high voltage needed for the speakers? It These Beveridge amplifiers weakness is their power transformers which I have had a few go bad on me. For this reason I keep a stash of these amps. Could you recommend a source for rewinding these power transformers because Jack at Electroprint has very little interest because of the enormous demand on the power transformer. Could you comment on this? I believe you might have come up with a work around for this issue. 
 Lastly, i have stayed away from your RM-1 (and RM-2 Power supply) Beveridge preamp because I have been told that the preamp is very hard on tubes used in it. This seems very much counter to your later works. Is this true or myth about the RM-1/2? If so, is there a later fix for this issue or should I just buy a later preamp of yours. I have used many preamps with the Beveridge 2’s. Currently I am using an old PS Audio 4 preamp in the passive mode. I obviously am
a fan of your work!

Roger,
           Thanks for this great thread! It is one of the best threads I have ever read on this website! Your time educating us non-technical prople is greatly appreciated. I still own the original Beveridge Model 2׳s and have a couple questions after reading your earlier comments about these speakers. You mentioned in an earlier post that the perfect room for these speakers is one that is 11’ W by 24’ long. You mentioned that they needed to be at least 6 feet from the rear wall facing each other. Then you commented on their amazing imaging saying that they should be 2 times 6ft or 12 feet area for imaging. Were you just saying that both speakers were 6 feet away from the rear wall or were you saying the speakers should be pulled 12 feet from the rear wall in this perfect room?

The speaker will be 6 feet from the rear wall. 12 feet is the depth of the image which is 6 ft to the wall and 6 more for the sound to return to the speaker. a 12 mSec delay feels like 12 feet.

Very nice speaker, hold on to it. I hope visitors appreciate it.

Lastly, i have stayed away from your RM-1 (and RM-2 Power supply) Beveridge preamp because I have been told that the preamp is very hard on tubes used in it. This seems very much counter to your later works. Is this true or myth about the RM-1/2? If so, is there a later fix for this issue or should I just buy a later preamp of yours. I have used many preamps with the Beveridge 2’s. Currently I am using an old PS Audio 4 preamp in the passive mode. I obviously am
a fan of your work!

The early runs of the preamp ran hot even though I ran the tubes at one half dissipation. I reduced it to 1/4 rated dissipation. We upgraded many but there are some high current ones out there.12 tubes makes some heat so it needs free air and not in a rack or stack. Many of them come to me with Ram tubes so I can tell last time we sold the customer tubes. Its typically 3 years. Now a tube can get noisy at any time and its a very low noise preamp so people use the MM input for cartridges  0,5 mV and up.. Therefore they would run the line higher and a noisy tube would be obvious.

Lets say this. For its 1978 vintage it something few can do. Its DC coupled, no output capacitor, many features for phono lovers. Try one out. Clean or better yet, replace the 12 pin connector from the power supply. 

If people want to know about RM-1s I will write up a white paper. If it was still in production I would be sending on to Stereophile for JA to bench text. There would be no drop off in the bottom or top end at any load, even a ohm. Output impedance is 100 ohms, very rare for tubes of the day.

I would say it rivals an SP10 in many ways and perhaps more reliable. 

More about Beveridge and the company on request. He was my mentor and very out of the box.