Playing with hybrid amp: SRPP + MOSFET - diyAudio
Go Back   Home > Forums > Amplifiers > Tubes / Valves

Tubes / Valves All about our sweet vacuum tubes :) Threads about Musical Instrument Amps of all kinds should be in the Instruments & Amps forum

Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 15th December 2011, 07:32 AM   #1
diyAudio Member
 
Join Date: Sep 2011
Default Playing with hybrid amp: SRPP + MOSFET

Just finished a new audio amp. It's my first hybrid design. 6N8P is used as preamplifier. 2 IRFP240 forms class A output stage. I had built more than 15 amplifiers in the past 3 years but this is the most favorite one. Althought it has 0.27% THD (1KHz, 1W, 8Ohm), much higher than the JLH amplifier (0.03%) I designed a few weeks before, but it sound sweet, and the background is dead silent. .

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.
__________________
www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services
Chat with me
  Reply With Quote
Old 15th December 2011, 07:55 AM   #2
Banned
 
Join Date: Oct 2011
interesting, can you post the circuit? do you have plan to sell kits on your website?
  Reply With Quote
Old 15th December 2011, 10:20 AM   #3
DF96 is offline DF96  England
diyAudio Member
 
Join Date: May 2007
Why SRPP? Unless correctly designed and loaded it can have high distortion, as you find.
  Reply With Quote
Old 15th December 2011, 12:32 PM   #4
Yarpen is offline Yarpen  Poland
diyAudio Member
 
Join Date: Sep 2004
Location: Poland
It's look nice ! Can you post the schematic etc?
  Reply With Quote
Old 15th December 2011, 12:38 PM   #5
diyAudio Member
 
Join Date: Sep 2011
The MOSFET has 1300pf Cg so it needs low output impedance to drive, especially when the freq is high. SRPP because the output impedance is low. I think the distortion is acceptable for a hybrid amp. I believe 50% of the distortion is cause by the mosfet. It's a design without global feedback.

Quote:
Originally Posted by DF96 View Post
Why SRPP? Unless correctly designed and loaded it can have high distortion, as you find.
__________________
www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services
Chat with me
  Reply With Quote
Old 15th December 2011, 12:42 PM   #6
Skorpio is offline Skorpio  Denmark
diyAudio Member
 
Join Date: Mar 2004
Location: Denmark
I would suggest to use the valve for both channels and load the anodes with CCS (DN2540 cascode). Then use the low impedance output, you will get an Ro of 200-500 Ohm and good drive for the MOS-FET input...

I have done this with a 12BH7A and DN2540 CCS to drive a F4 design without the JFET input...
  Reply With Quote
Old 15th December 2011, 01:09 PM   #7
diyAudio Member
 
Join Date: Sep 2011
Default schematic

Sure! here it is..Modified slightly from the beta version after testing.
Quote:
Originally Posted by Yarpen View Post
It's look nice ! Can you post the schematic etc?
Attached Images
File Type: jpg autonjp-sch.jpg (508.6 KB, 560 views)
__________________
www.siliconray.com High Quality Audio Enclosures, Amp Kits, Amplifiers, PCB Fab Services
Chat with me
  Reply With Quote
Old 15th December 2011, 01:23 PM   #8
diyAudio Member
 
Join Date: Apr 2003
Location: Eastern Pennsylvania
Quote:
Originally Posted by siliconray View Post
Sure! here it is..Modified slightly from the beta version after testing.
Perhaps I'm missing something, but that schematic doesn't appear to go to your hybrid amplifier.
__________________
Ken

Last edited by Ken Newton; 15th December 2011 at 01:25 PM.
  Reply With Quote
Old 15th December 2011, 04:21 PM   #9
Cassiel is offline Cassiel  Libya
diyAudio Member
 
Cassiel's Avatar
 
Join Date: Sep 2004
Location: Madrid
Schematic?
__________________
Making friends
  Reply With Quote
Old 15th December 2011, 06:04 PM   #10
diyAudio Member
 
Join Date: Nov 2011
Location: thailand
Schematic and sound this one. Tank.
  Reply With Quote

Reply


Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hybrid project with inverted SRPP Stee Solid State 7 22nd August 2014 11:15 PM
Excellent SRPP power amp of MOSFET wensan Pass Labs 119 28th February 2012 08:46 AM
Help with hybrid mosfet valve amp samvel65 Tubes / Valves 57 27th January 2010 11:35 PM
Hybrid Srpp gianmaria Tubes / Valves 20 30th November 2009 04:59 PM


New To Site? Need Help?

All times are GMT. The time now is 07:12 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2