Upgrading output transformers - 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 7th December 2008, 03:58 PM   #1
tigro is offline tigro  Romania
diyAudio Member
 
Join Date: May 2006
Default Upgrading output transformers

I have Antique Sound Lab AQ1008DT monoblocks and thought about upgrading the original output transformers to Tamura
F2011. Did anybody perform a similar upgrade ? I would like
DIY-ers oppinion on the matter.

Thanks

Tigro
  Reply With Quote
Old 8th December 2008, 07:29 PM   #2
Jeb-D. is offline Jeb-D.  United States
diyAudio Member
 
Jeb-D.'s Avatar
 
Join Date: Nov 2005
Location: SoCal
Unless it's an exact fit, I wouldn't do it. You wouldn't want to turn your production quality chassis into a hack job.
  Reply With Quote
Old 8th December 2008, 08:23 PM   #3
kevinkr is offline kevinkr  United States
diyAudio Moderator
 
kevinkr's Avatar
 
Join Date: Sep 2004
Location: Boston, Massachusetts
Blog Entries: 6
I and others have done similar things on other amplifiers, and at worst to get something that looks nice you just order a nice piece (or 2) of copper or stainless steel plate in the appropriate dimensions online, measure and drill for the new transformers and for some of the mounting locations of the old transformers - if done with care you both stiffen the flimsy AQ chassis and end up with something that looks nice as well.

ASL HK makes very reasonable quality OPTs, but the Tamuras are still likely to be a rather significant improvement if you purchase one of their higher end products.
__________________
"Extraordinary claims require extraordinary evidence." - Carl Sagan
  Reply With Quote
Old 9th December 2008, 08:55 PM   #4
tigro is offline tigro  Romania
diyAudio Member
 
Join Date: May 2006
Dear Jeb

Thank you so much for your answer
  Reply With Quote
Old 9th December 2008, 08:55 PM   #5
tigro is offline tigro  Romania
diyAudio Member
 
Join Date: May 2006
Dear Kevin
Thank you for your answer.I'll consider your advice. The Tamura
F-2011 has a primary impedance of 3,4K which is a bit high for
4 KT88-s in parallel push pull.
There might be some Sowter transformers more suitable for this
job. I await Mr. Sowter's answer.

Regards

Tigro
  Reply With Quote
Old 10th December 2008, 05:51 PM   #6
diyAudio Member
 
richwalters's Avatar
 
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Quote:
Originally posted by tigro
The Tamura
F-2011 has a primary impedance of 3,4K which is a bit high for
4 KT88-s in parallel push pull.
This is serious power game. I presume you are upwards 520V B+ region. You won't get optimum throughput power with this Prim Z. You should be aiming around 2K A-A and you will have to take care of ringing with A and g2 snubbers. The best tranny I've used is the Sowter 8659 43% UL with 4 sep o/p windings for optimum quality and b/w.. Study the Sowter website p-p secondary configuration.
Beware they aren't cheap !

rich
  Reply With Quote
Old 17th December 2008, 09:05 PM   #7
tigro is offline tigro  Romania
diyAudio Member
 
Join Date: May 2006
Dear rich

Thank you very much for your answer. I already found the Sowter
site and I am in the middle of email exchange with Mr. Sowter Brian. I think I already found something suitable and it also fits the chassis mechanically.

Regards

Tigro
  Reply With Quote
Old 17th December 2008, 09:40 PM   #8
diyAudio Member
 
richwalters's Avatar
 
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Tigro;
The 8659 or variants are large transformers (?10Kg )and particulary smooth response using fixed bias around 60mA per tube. At 2/3 power I got a 10Khz square wave looking in pic. It all depends on the performance of the driver stage. When you get the power stage performing the square wave shown in pic, then you can't ask for more. The distortion is also very low.

richj
Attached Images
File Type: jpg 10khz 50w 8659 6550-12by7-ecf80.jpg (31.9 KB, 405 views)
  Reply With Quote
Old 17th December 2008, 11:30 PM   #9
diyAudio Member
 
Join Date: Jul 2003
Location: Ann Arbor, MI
hey Rich,
That is a nice looking response. What sort of amp is in front of it?
cheers,
Douglas
__________________
the Tnuctipun will return
  Reply With Quote
Old 18th December 2008, 03:34 PM   #10
diyAudio Member
 
richwalters's Avatar
 
Join Date: Sep 2003
Location: Alps:Tube amp designs over 150W, SMPS guru.
Quote:
Originally posted by Bandersnatch
What sort of amp is in front of it?
cheers,
Douglas
Both power amps in pic are my strong man studio "Samson & Goliath" class both capable of cruising 200W per channel with KT88's, one has a Sowter 8659 14 sect and other Majestic Partridge spec'd 18 sect, both British wound o/p trannies performing -3dB down around 50KHz. On listening both are close, -, --> I favour the Majestic on iron/winding technicals; requires less A-G2 snubbing but is 10% larger, more consistent construction and goes down to 15Hz and this one has reduced B+ running Tung-Sol 6550's (Rt side).
These heavy amps (each 55kg) are for those who like their music blinding loud or play clean MI (as I do): they use a variable B+ with a PFC converter for economic running. The 12BY7A driver stages & front end Concertina ECF80 are identical.
Those wanting a real UL p-p design challenge in the high end game have got one..every aspect must be math'ed out, including loop gains. Both amps can accept 35dB global nfb before instability sets in. This is a tough challenge as the winding parasitics are much higher than smaller designs, require careful snubbing as the energy is far higher and these amp designs cannot be slapped together as with lower powers. A simple mistake can be expensive in both tubes and patience.
Take note!

richj
Attached Images
File Type: jpg sam&gol red.jpg (65.6 KB, 383 views)
  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
Difference between SE output transformer and push-pull output transformers hilbert_mostert Tubes / Valves 12 8th March 2009 05:10 PM
Help identifying a pair of output transformers and power transformers mjk130 Parts 3 30th January 2009 10:44 AM
Pointers on upgrading CDP output stage. S.Spielbergo Digital Source 22 22nd February 2008 11:37 PM
upgrading to bal. output trannys redrabbit Solid State 7 1st January 2006 08:42 AM
SE Output Transformers DVDHack Tubes / Valves 32 19th January 2004 10:52 AM


New To Site? Need Help?

All times are GMT. The time now is 11:20 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