GM70 an 813 strapped in SE-UL - circuits? - 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 26th September 2008, 09:04 AM   #1
diyAudio Member
 
otto88's Avatar
 
Join Date: Dec 2007
Default GM70 an 813 strapped in SE-UL - circuits?

Does anyone have a tested circuit for a GM70 SE, or PSE; an 813 strapped in SE-UL?

My main speakers (Apogee hybrids) are only 84 dB, so 100 watts would be preferable. Though it might add too much to an already substantial project . .

I could go KT88 PP UL/ pentode mode, but would probably prefer SE.

How many watts would an 813 strapped in SE-UL produce?

Any suggestions on sources for OPTs and 240 volt power transformers?

Thanks
  Reply With Quote
Old 26th September 2008, 10:01 AM   #2
Cobra2 is offline Cobra2  Norway
DIY !
diyAudio Member
 
Cobra2's Avatar
 
Join Date: Apr 2002
Location: Stavanger, Norway
Send a message via Skype™ to Cobra2
Default 813

I have seen 45W in UL-SE mode. If you paralell 2 x 813, you shuld get close...

Arne K
__________________
Don't believe everything you think...
  Reply With Quote
Old 26th September 2008, 11:57 AM   #3
diyAudio Member
 
otto88's Avatar
 
Join Date: Dec 2007
Default suitability for ultralinear

Thanks Arne,

Parallel UL SE could be the way to go.

It doesnít have to be an 813 -

I have read that eg of the 6V6, 6L6, 5881, EL34, 6CA7, KT66, etc clan, the KT88 is best for running in ultralinear mode.

How can the suitability of tubes for ultralinear be determined?

Thanks
  Reply With Quote
Old 26th September 2008, 12:16 PM   #4
diyAudio Member
 
Join Date: Sep 2003
Location: London
I sympathise - I have Apogee Caliper Sigs.

First thing is, depends on room size. I drive my Apogees with a PPP 6S4 amp - can't be more than 10 watts. A SE300b wouldn't drive them at all. A PP KT88 amp drives them fine - all this in smallish rooms. So if your room is not too big, I'd say go with PP300b or PSE 300b.

I'm thinking 813 myself - I've bought a stock. Personally I build all DHT - not interested in the directly heated valves unless I have to use them for some reason. I prefer the sound of DHTs.

I'm thinking push pull 813 myself. I like SE but it's more important to me to be using DHTs. I don't want to go high voltage so I'm thinking 450v. But with 813 you can go higher.

Andy
  Reply With Quote
Old 26th September 2008, 12:34 PM   #5
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
hey-Hey!!!,
I have a similar valve to 813 running U-L at ~550V, the 4E27. Nearly pin-compatible with the 813, but at 5V instead of 10V on its cathode. I have special outputs made with multiple taps, and taken from the Peerless S-265-Q coil geometry.

I will swap to 813 as soon as my leisurely collection of a quad is complete. The filament supply is easily converted too... Bias will be similar. The U-L percentage is critical for the load matching; it changes the operating elvelope of the plate curves.
cheers,
Douglas
__________________
the Tnuctipun will return
  Reply With Quote
Old 26th September 2008, 02:14 PM   #6
Pyre is offline Pyre  Canada
diyAudio Member
 
Pyre's Avatar
 
Join Date: May 2006
Send a message via MSN to Pyre
Hello,

Have you checked out the GM70 group on Yahoo. Lots of tested schematics and advice.

http://groups.yahoo.com/group/GM70/

I am building a tubelab SE board driving a pair of GM70's right now but its in the build stage not the tested stage yet.

Shane
  Reply With Quote
Old 28th September 2008, 03:27 AM   #7
diyAudio Member
 
otto88's Avatar
 
Join Date: Dec 2007
Andy

Apogee Caliper Sigs with 10 watts? Even in a modest room, thatís amazing!
Apogee guru Graz suggests that Apogees need plenty of watts to sing to their best . .


I have only Centaur Minors, and 50-150 watts is recommended. The room is 5.3 * 6.7 * 3.5 m (c 17í * 21í * 12í) so I think I need 50+.

Douglas

> The U-L percentage is critical for the load matching; it changes the operating envelope of the plate curves.

Maybe its best to get OPTs with taps at say 40%, 50% and 60%, to allow thane amp to be better optimised.

Shane

Iíve been to the GM70 Yahoo group a little, but hadnít seen much there. I should go look more.

Has Tubelab said that his SE board could be used for GM70's?

What power and output iron will you use?? $?

Cheers
  Reply With Quote
Old 28th September 2008, 03:41 AM   #8
diyAudio Member
 
otto88's Avatar
 
Join Date: Dec 2007
Shane

How did you determine the (initial) component values for the SE board with GM70's?
  Reply With Quote
Old 28th September 2008, 05:02 AM   #9
diyAudio Member
 
Richard Ellis's Avatar
 
Join Date: Sep 2006
Location: Mar del Plata, a BIG seasonal getaway city, can see the Ocean from our residence.
Hows' this...An 813 strapped in UL.
_________________________________________Rick..... ........
Attached Images
File Type: jpg 813 recent.jpg (37.3 KB, 1338 views)
  Reply With Quote
Old 28th September 2008, 12:33 PM   #10
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
Quote:
Originally posted by otto88


Douglas

> The U-L percentage is critical for the load matching; it changes the operating envelope of the plate curves.

Maybe its best to get OPTs with taps at say 40%, 50% and 60%, to allow thane amp to be better optimised.

hey-Hey!!!,
Go lower than 40% too; on this I must say, " you may be pleasantly suprised ".
cheers,
Douglas
__________________
the Tnuctipun will return
  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
GM70/GM70 parafeed SET? louischia Tubes / Valves 10 4th December 2008 04:12 PM
Is your sub strapped down? Timn8ter Car Audio 12 1st August 2007 11:12 PM
Connecting Virtual Ground Circuits with True Ground circuits?? Minion Solid State 1 12th February 2007 02:28 AM
Research on tubes and circuits simple circuits Cazcotty Tubes / Valves 6 16th June 2006 01:50 PM
85 powersupply circuits 58 charge circuits gev Power Supplies 0 31st July 2005 12:27 PM


New To Site? Need Help?

All times are GMT. The time now is 09:41 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