Tube Hybrid 25W Class-A, Opinions? - 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 16th April 2003, 12:58 AM   #1
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Default Tube Hybrid 25W Class-A, Opinions?

I'm considering building this very nice hybrid amp, Class-A 25W:

http://www.diyaudio.de/html/25_25w_hybrid.html

It has balanced inputs, Lundahl input and interstage transformers, Absolutely no capacitor in the signal path
Zero dB feedback and 2-stage current amplification using Hitachi® Mosfets as driver and Sanken® bipolar power transistors.

Any comments on the tube preamp section?
Seems a very nice desing.

Thanks for your comments.

Bye.
  Reply With Quote
Old 16th April 2003, 01:26 AM   #2
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Default The missing capacitors...

Quote:
Absolutely no capacitor in the signal path
Hi Algar_emi !!

Nice project...but i count 4 capacitors in the signal path in each channel...
__________________
Jorge
  Reply With Quote
Old 16th April 2003, 01:36 AM   #3
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Default I don't see the caps

I checked again but I didn't see any caps. Where do you find them?

Bye.
  Reply With Quote
Old 16th April 2003, 01:47 AM   #4
PassFan is offline PassFan  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Central FL
It looks involved, expensive and redundant. I'm not trashing it but, why go from tube to mosfet to bipolar. Aren't each one of these kind of a contradiction in sound. I mean if you like the sound of tube's then I could almost see the mosfets, but bipolars don't sound like either one of those. They are unique unto themselves aren't they? I am in no way questioning your taste, merely making some observations and asking some questions. Maybe I'm too simple at times. Do you know anyone who has heard it? After all, that's what it's all about.
  Reply With Quote
Old 16th April 2003, 01:48 AM   #5
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Default Re: I don't see the caps

Quote:
Originally posted by Algar_emi
I checked again but I didn't see any caps. Where do you find them?
Only in one channel...and not quoting the plastic bypass

C27-C34-C3-C4....

Bye
__________________
Jorge
  Reply With Quote
Old 16th April 2003, 02:03 AM   #6
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Default The follower of the follower...

Quote:
Originally posted by PassFan
It looks involved, expensive and redundant. I'm not trashing it but, why go from tube to mosfet to bipolar. Aren't each one of these kind of a contradiction in sound. I mean if you like the sound of tube's then I could almost see the mosfets, but bipolars don't sound like either one of those.
Questions about sound a part (subjectives) ...the reason why the designer use a bipolar follower after a source follower is for to lower the output impedance..as the amp don't have overall feedback

For instance if the mosfet output impedance is 1 or 2 Ohms...after the bipolar folower this became the (current gain of the transistor times)..less..

Exe. output mosfet impedance mosfet 2 Ohms... current gain of the transistor 50...the output impedance become 2/50=0,04
__________________
Jorge
  Reply With Quote
Old 16th April 2003, 02:21 AM   #7
PassFan is offline PassFan  United States
diyAudio Member
 
Join Date: Aug 2001
Location: Central FL
Default Re: The follower of the follower...

Quote:
Originally posted by Tube_Dude


Questions about sound a part (subjectives) ...the reason why the designer use a bipolar follower after a source follower is for to lower the output impedance..as the amp don't have overall feedback

For instance if the mosfet output impedance is 1 or 2 Ohms...after the bipolar folower this became the (current gain of the transistor times)..less..

Exe. output mosfet impedance mosfet 2 Ohms... current gain of the transistor 50...the output impedance become 2/50=0,04
Thanks


  Reply With Quote
Old 16th April 2003, 02:29 AM   #8
diyAudio Member
 
Algar_emi's Avatar
 
Join Date: Oct 2002
Location: Canada, Qc
Default How does it sound?

Yes you are right. It is what i'm trying to find and no answer yet. Please any comment on this kind of hybrid desing will be appreciated.

I expect this desing to sound kind like a pathos hybrid, see http://www.pathosacoustics.com/classiceng.htm

I don't mind a complex project, see my dac: I started my new Tube DAC

This kind of coupling transfo are used (I think) inside the Nagra preamp...
  Reply With Quote
Old 16th April 2003, 03:00 AM   #9
diyAudio Member
 
Tube_Dude's Avatar
 
Join Date: Mar 2002
Location: Aveiro-Portugal
Default The Pathos...

Quote:
I expect this desing to sound kind like a pathos hybrid,
I don't ...as the Pathos doesn't use interstage transformers...so your's will have another "flavour"...

But try your project...and repport!!

cheers
__________________
Jorge
  Reply With Quote
Old 16th April 2003, 03:46 AM   #10
JoeBob is offline JoeBob  Canada
diyAudio Member
 
JoeBob's Avatar
 
Join Date: Nov 2001
Location: Montreal, Canada
I'd say go for it if you're up to the complexity. I use a tube/MOSFET hybrid and I very much enojy it, it's alot simplier (I think the simplier the better, to an extent). So while some may not like hybrids, I can vouch that they can sound great.
  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
Very different hybrid... opinions? DrG Solid State 23 2nd October 2008 02:24 PM
Hybrid Class A / Class B design. GK Solid State 27 1st January 2007 02:30 AM
Class A Tube BJT Hybrid jerluwoo Tubes / Valves 33 17th October 2006 09:04 AM
Opinions on my low-voltage hybrid headphone amp (this time with the right file) JHawk24821 Headphone Systems 2 1st August 2004 04:49 PM


New To Site? Need Help?

All times are GMT. The time now is 02:15 PM.


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