DIY F5 pure class A power amp(Nelson Pass design)

For the serious and not so serious in audio: DoItYourself and Tubes (SET, PP, Vintage).

Moderator: kabubi

DIY F5 pure class A power amp(Nelson Pass design)

Postby endrik35 » Thu Jan 27, 2011 8:15 am

Hi guys, me and my fabulous and gifted friend Leslie(brainf) finally finished our Nelson Pass designed B1 preamp. We heard its sonic qualities in a different preamp casing before and was amazed. But I decided to dress it in a more aesthetic looking case to match it's blissfull sonic qualities. All I can say is that Mr. Nelson Pass is truly a Godsent audio guru who shares what he knows to the DIY'er community. Had this DIY pre-amp A-B'ed with a popular tube pre-amp, lightspeed pre-amp and a known solid state pre-amp. This pre-amp came out on top. I kid you not! The simplicity of his design is striking and logical. The gain of this pre-amp is only +1,uses only 2 j-fets with mundorf and wima caps although the choice of caps depends on you. The sound has a slight tube-like quality, clean,natural, detailed and silent without sounding sterile and lifeless! Many thanks to Loi Lazaro for the fabulous pre-amp casing, John Poscablo for the free wooden knobs, Obet for the wooden feet and Amber machine shop and their accurate drilling! I almost forgot Raon where Les was able to get a vintage Dell PSU, 18V psu. We sometimes use two 9V batteries also to good effect. Hope you could build one yourself guys or you are free to have a listen at my house anytime soon! :)

Here's a link if you want to buid one:
http://www.enjoythemusic.com/diy/0708/f ... lifier.htm


Here are some pics. . .

Image

Image

Image

Image

Image

Image

Image

Image
Last edited by endrik35 on Sat Sep 15, 2012 7:00 am, edited 3 times in total.
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby brainf » Thu Jan 27, 2011 9:06 am

A pleasure collaborating with you on this project Doc! It's one-of-a-kind and done in the true spirit of DIY. :)
User avatar
brainf
Citizen
Citizen
 
Posts: 52
Joined: Wed Nov 19, 2008 3:51 pm
Location: Metro Manila

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby Tjaderman » Thu Jan 27, 2011 11:58 am

Congratulations to both of you!! :clap: :clap: :clap: Next week na tayo magkita, Doc!!
User avatar
Tjaderman
Citizen
Citizen
 
Posts: 269
Joined: Mon Aug 04, 2008 10:56 am
Location: San Pedro, Laguna

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby tony » Thu Jan 27, 2011 12:42 pm

brainf wrote:A pleasure collaborating with you on this project Doc! It's one-of-a-kind and done in the true spirit of DIY. :)


congrats brainf, you have really come a long way......keep on truckin'........ :clap: :clap: :clap:
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby brainf » Thu Jan 27, 2011 12:51 pm

tony wrote: congrats brainf, you have really come a long way......keep on truckin'........ :clap: :clap: :clap:


Coming from you Tony that's high praise indeed! Thank you for all your pointers and tips over email on my other diy forays - every nugget counts! :)
User avatar
brainf
Citizen
Citizen
 
Posts: 52
Joined: Wed Nov 19, 2008 3:51 pm
Location: Metro Manila

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby tony » Thu Jan 27, 2011 1:18 pm

D1 is a generic 1N914 type diode, and D2 is a generic LED for indicating power the board. All of the transistors are N channel JFETs. The stock parts are 2SK170's, LSK170's or 2SK370's, and you can use substitutes having Idss between than 5 and 10 milli-Amps and transconductance numbers from 5 to 30 milli-Siemens.


indeed, transcondctance is better than 6SN7 and closer to 6922/6DJ8/6H23..... 8)
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby endrik35 » Thu Jan 27, 2011 2:58 pm

Thanks Tony! Les was really the BRAINS behind this project. That's why his handle is brainf ;) Wanna share some pics of the B1 preamp hooked to the muse model 100 power amp driving the B&W 801 series 80 speakers. Hopefully, I can find the moolah to buy a bigger and more powerful amp to drive this beast but for low to moderate listening levels, this Muse amp is one gutsy performer and is making beautiful music with the B1's! :)

Image

Image

Image
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby endrik35 » Sat Jan 29, 2011 11:15 pm

Here's a couple of links which might interest you. Just connected this B1 pre-amp to the Onkyo M-506. It just gets out of the way of music. Precisely what a passive buffer's job should be! :)
Link:
http://www.passdiy.com/
http://www.firstwatt.com/
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby hypertriode » Sat Jan 29, 2011 11:38 pm

endrik35 wrote:Here's a couple of links which might interest you. Just connected this B1 pre-amp to the Onkyo M-506. It just gets out of the way of music. Precisely what a passive buffer's job should be! :)
Link:
http://www.passdiy.com/
http://www.firstwatt.com/


Thanks Doc! Really interesting projects ...
Congrats to you & brainf! :)
User avatar
hypertriode
Grand Master
 
Posts: 4433
Joined: Tue Jan 28, 2003 9:15 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby endrik35 » Sun Jan 30, 2011 7:32 am

Thanks Sir Rene. Newbies palang kame compared to yours truly! :) Si Leslie was the one who implemented the design and assembled the innards. Siya yung industrial engineer. Amuyong, casing fabrication at manpower lang ako. :) It's a very worthwhile project though IMHO :)
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby tony » Sun Jan 30, 2011 8:31 am

today's circuits revolve around topology.....unlike vintage ones that used conventional topologies......

thus we see the Aikido which uses the tubes's nolinearities to make a linear amp, Broskie' finaly found a way to develop a circuit that is not tube dependent, just like solid state designers have done the past 30 years or so....

the Broskie aikido cathode follower is the tube counterpart of this Nelson Pass's Buffer circuit....they work exactly the same way....

the jfet is one that has very simmilar characteristic as a triode tube.... :clap:
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby endrik35 » Sun Jan 30, 2011 6:09 pm

You are right on the money Tony. I'm doing some critical listening right now on the B1 pre-amp and the sound is tubey sans the hum and distortion asscociated with tubes. Add the low maintainance of Jfets, this pre-amp is definitely for keeps in my system. You really don't have to spend a lot of money to get the sound that you like! :)
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby tony » Sun Jan 30, 2011 7:09 pm

endrik35 wrote:You are right on the money Tony. I'm doing some critical listening right now on the B1 pre-amp and the sound is tubey sans the hum and distortion asscociated with tubes. Add the low maintainance of Jfets, this pre-amp is definitely for keeps in my system. You really don't have to spend a lot of money to get the sound that you like! :)


but tubes amps can be made without hum and hiss...i have done it several times already..... ;)

distortion spectra should be the same with triode and jfet in that topology, the only difference between them is the absence of filaments in the jfet.....as far as i am concerned, they can be treated as one and the same.... :D
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby brainf » Mon Jan 31, 2011 8:37 am

hypertriode wrote:
endrik35 wrote:Here's a couple of links which might interest you. Just connected this B1 pre-amp to the Onkyo M-506. It just gets out of the way of music. Precisely what a passive buffer's job should be! :)
Link:
http://www.passdiy.com/
http://www.firstwatt.com/


Thanks Doc! Really interesting projects ...
Congrats to you & brainf! :)


High praise coming from you Rene. I'm a fan of your creations too! :)
User avatar
brainf
Citizen
Citizen
 
Posts: 52
Joined: Wed Nov 19, 2008 3:51 pm
Location: Metro Manila

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby brainf » Mon Jan 31, 2011 9:18 am

tony wrote:today's circuits revolve around topology.....unlike vintage ones that used conventional topologies......

thus we see the Aikido which uses the tubes's nolinearities to make a linear amp, Broskie' finaly found a way to develop a circuit that is not tube dependent, just like solid state designers have done the past 30 years or so....

the Broskie aikido cathode follower is the tube counterpart of this Nelson Pass's Buffer circuit....they work exactly the same way....

the jfet is one that has very simmilar characteristic as a triode tube.... :clap:


Hi Tony! Your profound knowledge of vacuum tubes, circuits and componentry never fail to amaze me. The reason I decided to do build this was because it was "unconventional" - from the design philosophy to to the implementation i.e. the elegant use of the jfets. It was well worth the effort and the sound isn't anything like I've experienced in SS pre-amps (and some all-tube ones, for that matter!). Kinda like having the best of both worlds. :lol: Having only a rudimentary knowledge of electronics and simple repair/troubleshooting circuitry, your insights contribute immensely in my appreciation of the care and expertise that go into good circuit design. Thank you! :clap: :clap: :clap:
User avatar
brainf
Citizen
Citizen
 
Posts: 52
Joined: Wed Nov 19, 2008 3:51 pm
Location: Metro Manila

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby endrik35 » Tue Feb 01, 2011 9:18 pm

Found and borrowed this DIY acrylic B1 casing pic from the net. Nice! :) Wanna build one for me and Leslie's next project. . . B2 and B3 :)

Image

Image

Image
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby brainf » Wed Feb 02, 2011 8:04 am

endrik35 wrote:Found and borrowed this DIY acrylic B1 casing pic from the net. Nice! :) Wanna build one for me and Leslie's next project. . . B2 and B3 :)



Haha! What's that I hear - B2 *AND* B3? Nice looking acrylic cases though - wonder how well they'll fare in terms of shielding external noise... (I doubt it...)
User avatar
brainf
Citizen
Citizen
 
Posts: 52
Joined: Wed Nov 19, 2008 3:51 pm
Location: Metro Manila

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby JoeyGS » Wed Feb 02, 2011 4:37 pm

Hi Endrik and Leslie,

Congrats. I heard that B1 really sounds tubey :clap:

Would you mind telling us what parts were used?

Regards,
JoeyGS
User avatar
JoeyGS
Fanatic
Fanatic
 
Posts: 1638
Joined: Mon Jul 04, 2005 12:45 pm
Location: Sta. Rosa, Laguna

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby endrik35 » Thu Feb 03, 2011 1:08 pm

Joey, the PASS B1 board was ordered from HK, the mundorf caps came from audio amplified. Casing came from Loi Lazaro. Other details I'd let Leslie to fill in the gap. Thanks :)
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: The First Watt B1 Buffer Preamplifier(Nelson Pass design)

Postby brainf » Thu Feb 03, 2011 4:18 pm

JoeyGS wrote:Hi Endrik and Leslie,

Congrats. I heard that B1 really sounds tubey :clap:

Would you mind telling us what parts were used?

Regards,
JoeyGS


Hi JoeyGS,

From Tony's insights on the circuit topology and characteristics of the JFETs in his posts above that's not surprising at all. :)

FWIW I used Mundorf MCaps (those white ones with red lettering) and Dale resistors for the critical components directly on the signal path; JFETs were matched pairs; PSU caps were Panasonic FCs; Volume pot is an Alps; and all internal wiring is single-core SCC.

The choice of components used are the distilled experience from previous DIY projects so no guesswork in this project. :P

Hope this helps!
leslie
User avatar
brainf
Citizen
Citizen
 
Posts: 52
Joined: Wed Nov 19, 2008 3:51 pm
Location: Metro Manila

Next

Return to DIY and Tubes

Who is online

Users browsing this forum: Google [Bot] and 6 guests

cron