Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

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

805 Class A2 Amp
805 Class A2 Amp
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 23rd June 2019, 01:31 AM   #1
sganti is offline sganti  United States
diyAudio Member
 
Join Date: Apr 2008
Default 805 Class A2 Amp

Hi I just finished a 805 A2 amplifier with 211 as a driver with a mosfet source follower. These are mono-blocks, with 2 chassis per monoblock, one for power supply and one for the amp. Attached are the schematics and internal construction pictures. The plate chokes and output transformer is from Monolith Magnetics, chassis is from Landfall, power transformer is Heyboer -- all great folks to work with! Amazing sound that is effortless, with deep and wide soundstage. This replaces my 811A amp that used similar source follower circuit and meanwells for the filament supply with 6E5P as the driver

Thx
Sridhar
Attached Images
File Type: jpg Amp-Chassis-Left-Complete.jpg (783.0 KB, 447 views)
File Type: jpg PS-Chassis-Left-Complete.jpg (880.4 KB, 442 views)
File Type: png 805-211-Amp-V3.png (94.0 KB, 480 views)
File Type: jpg 805-211-BPlus-PD-Filament-Supply-V3.jpg (208.6 KB, 468 views)
File Type: jpg Left-Channel-In-System-2.jpg (498.7 KB, 440 views)
  Reply With Quote
Old 9th September 2019, 10:54 PM   #2
tubestyle is offline tubestyle  Canada
diyAudio Member
 
Join Date: Jan 2019
Location: NDIP
Very interesting design and amplifier. I am currently looking to find the best way to drive the 805 in A2.
I donít understand how to put all the pieces together, but trying to learn. Can you elaborate on the choice of the 211 and the driver circuit?

Peter.
  Reply With Quote
Old 11th September 2019, 08:54 PM   #3
sganti is offline sganti  United States
diyAudio Member
 
Join Date: Apr 2008
The choice of 211 is purely hedonistic :-), I have always been wanting to build an amp with a power tube as a driver. I don't think you need that at all. You can do a similar two stage with a high gain tubes and constant current plate load and cap coupled to the mosfet source follower. Tubes I would have used if I went that route to build are
- triode connected C3g
- triode connected 6E5P
- Triode connected 7788
- Triode connected C3m -- may need a preamp
- 5687 -- may need a preamp
- etc

thanks
  Reply With Quote
Old 12th September 2019, 12:24 AM   #4
Pyka is offline Pyka  China
diyAudio Member
 
Join Date: Jul 2011
Is the 805 used by Shuguang Factory?
  Reply With Quote
Old 12th September 2019, 01:23 AM   #5
deafbykhorns is offline deafbykhorns  United States
diyAudio Member
 
Join Date: Aug 2004
Location: florida
Quote:
Originally Posted by sganti View Post
The choice of 211 is purely hedonistic :-), I have always been wanting to build an amp with a power tube as a driver. <snip>
I started with the 7788 and ended up with the 6E5P, 7788 was hard to tame, 6E5P worked well and very neutral. I used the Monolith IT to drive a GM70 into A2
  Reply With Quote
Old 12th September 2019, 01:11 PM   #6
sganti is offline sganti  United States
diyAudio Member
 
Join Date: Apr 2008
The 805 I used are NOS Amprex with a top cap. I do have PSVane 805 without the top cap, not tried them out yet

I use 6E5P in the 811A class A2 amp, similar circuit as 805. It was the predecessor to the 805 amplifier.

For 7788, I connect G2 and G3 to plate with 1K carbon comp grid stoppers, so far that seem to have stablized. I agree, 6E5P is an excellent and easy choice
  Reply With Quote
Old 12th September 2019, 03:16 PM   #7
deafbykhorns is offline deafbykhorns  United States
diyAudio Member
 
Join Date: Aug 2004
Location: florida
I meant to ask you where you find those aluminum bases at your tubes. Its a nice touch, very nice build BTW!
  Reply With Quote
Old 12th September 2019, 07:46 PM   #8
sganti is offline sganti  United States
diyAudio Member
 
Join Date: Apr 2008
The chassis are custom made by Landfall Systems in Dallas. Super nice folks, even do the CAD drawings for you.

They are my go to guys for the chassis now
  Reply With Quote
Old 13th September 2019, 01:12 AM   #9
deafbykhorns is offline deafbykhorns  United States
diyAudio Member
 
Join Date: Aug 2004
Location: florida
I used the same guys for my GM70 amps and 01a preamps. Sent them my cadd files which made assembly a piece of cake. I was talking about the alum base of the 811a
  Reply With Quote
Old 16th September 2019, 05:54 AM   #10
bbp is offline bbp  China
diyAudio Member
 
Join Date: Sep 2005
Quote:
Originally Posted by deafbykhorns View Post
I started with the 7788 and ended up with the 6E5P, 7788 was hard to tame, 6E5P worked well and very neutral. I used the Monolith IT to drive a GM70 into A2
How many watts you get from GM70 Class A2? Thank you.
__________________
Tuber, Vinyler
  Reply With Quote

Reply


805 Class A2 AmpHide 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Major difference between class A and class AB output (and proper AB biasing) easphyx Solid State 9 30th October 2016 06:20 AM
Leaving class A how to make this amp leave class A to AB when volume is increased? rhythmsandy Solid State 3 14th June 2016 01:16 AM
Contest: Linear Power Amp in a mint tin (class Aa, class AB, or class B) danielwritesbac Chip Amps 206 19th January 2013 08:52 PM
LM4702 or LME49810 work in class A mode to drive the output stages in class A/AB rhythmsandy Chip Amps 29 29th December 2012 11:54 AM
Collection of Class B topologies <100mA Idle and Sound closest by Class A tiefbassuebertr Solid State 37 27th July 2012 08:04 AM


New To Site? Need Help?

All times are GMT. The time now is 05:53 PM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki