SE 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 11th January 2004, 08:41 PM   #1
DVDHack is offline DVDHack  Australia
diyAudio Member
 
Join Date: Jan 2004
Location: Australia
Default SE Output Transformers

The general thoughts I'm picking up is that the Output Transformer is te key ingrediant in a SE 300B design.

Would some of you care to comment about the virtues of some of the beter known brands.

Hammond
Piltron
Tamura
Tango
Smaller suppliers

I'm thinking Tamura cause I want to do this once and they seem to have the best rep so far but their cost is several times that of a Hammond.

On smaller suppliers that you can't get a reference for eg I tried with Black Art OTF but no one has used them. How do I know if the TF is any good - its a bit expensive to "give it a try".

Please discuss and Many Thanks
__________________
Audio
  Reply With Quote
Old 12th January 2004, 08:28 AM   #2
diyAudio Member
 
Join Date: Jan 2003
Location: Sweden
I ordered mine from Sowter. Unbelievably good service and even better transformers. You can't go wrong with Sowter!

www.sowter.co.uk
  Reply With Quote
Old 13th January 2004, 11:34 AM   #3
Mike C is offline Mike C  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: South east Essex, UK
Default Odd rambling reply ...

First, 'DVDHack', how about letting us know your first name; DVDHack is so impersonal!

Some may argue against the OPT being 'the' single most important aspect of a SET, but I think all will accept its importance.

The problem with your request is that few of us have been able to do much direct comparison, as good OPTs are expensive. So you may have to gather as much info as you can, of whatever type, and filter it; that's what I did.

My experience is limited to ONE 300B SET, and ONE type of OPT, so what the hell do I know?
Well, that OPT is Lundahl, and results are excellent. No way can I say it's the best, I just don't know.
I suggest you research the point here; and also on Tube DIY Asylum where you'll find hundreds of posts ... most saying their choice is the best, which is where you have to apply that filter.

I have some specific points for you to consider.

Bandwidth:
It's suggested that, when plotted logarithmically, the total bandwidth of most good OPTs is surprisingly similar in magnitude.
Comparing two with upper limits of say 30kHz and 60kHz, you'll often find that the second one has a higher low frequency cutoff. So don't just take an impressive hf figure as a single figure of merit.

Specifications:
Of somewhat dubious value! It depends how the measurements were done. Possibly, measuring an OPT at very low power can give very high upper frequency measurements that cannot be met in use.
So, reliable descriptions of sound 'character' may be of more use.

Impedance:
Many designs use about 3kohm, perhaps 2.5kohm, impedance for a 300B. However, there can be benefits from using a higher impedance of say 5kohm; less distortion.
However, a lower impedance of say 3k will give more power. About 8 watts. I guess it's often used by professionals as, if the 300B's are run hard, they can just about claim 10 watts (at say 10% thd) and double figures has *so* much more street cred than a single figure wpc!
A 5kohm OPT will give about 6.5 watts at the point of clipping, compared to 8 watts or 8.5 with 3kohm. Possibly a good trade off for less distortion; something to consider, as the difference between 6.5 and 8.5 is really not a lot.
Oh, and 6.5 watts of pure SET sound, delivered from a really solid PSU, is a hell of a sight more powerful than you'd expect.

Good luck; keep feeding us your ideas.
  Reply With Quote
Old 14th January 2004, 12:17 AM   #4
Zoran is offline Zoran  Serbia
diyAudio Member
 
Join Date: Jan 2004
Location: Belgrade
If You want realy good OT go to "Bartolucci"
and of course Sowter have best quality price value and always good english sound...
__________________
###
  Reply With Quote
Old 14th January 2004, 04:26 AM   #5
DVDHack is offline DVDHack  Australia
diyAudio Member
 
Join Date: Jan 2004
Location: Australia
Well that's two for Sowter at least.

I take your point on lack of comparability unless you've owned a few but I got the impression that several people had gone through the process of Hammond and Piltron etc and formed an opinion.

There are references on the web stating people had "upgraded" their amp with better OTF but how do they know they are upgrading unless there is some sort of quality hierarchy?

I can't readily compare the sound so I am concerned I may miss the potential of Valve without ever realising it. I could spend a great deal on poor components and never realise.

Regards

Ralf
__________________
Audio
  Reply With Quote
Old 14th January 2004, 10:49 AM   #6
diyAudio Member
 
Brett's Avatar
 
Join Date: Jan 2002
Hola Ralf,

Try Lundahl. They are excellent and quite reasonably priced, and there is an Australian distributor who's good to deal with. As there is a shipment about to arrive (I have another order in), there may be a 4 week leadtime if you ordered them soon. I've tried the Hammond PP varieties and they suck compared to the Lundahls. I've used lots of them, and compared them to a number of other brands, so I have a good reference point to comment from*.
www.lundahl.se , specifically the 1663 (3k:8), probably around $A250ea (BUT check the pricing with Control Audio)

Control Audio Pty Ltd
Mr. Rick Dowel
Level 6, Westfield Towers
100 William Street
AU-Sydney NSW 2000
Australia

Phone +61 - (0)2 - 9368 7100
Fax +61 - (0)2 - 9368 7199
Email: sales@controldevices.net

A second choice, and another one to recommend is Lancroft.
http://www.users.bigpond.com/triode/
triode@bigpond.com

I have some of these too, and they're excellent.

* Caveat: can't give specific advice on SE OPT's as I don't build SE amps, but have built lots of PP's.
  Reply With Quote
Old 14th January 2004, 11:22 AM   #7
Mike C is offline Mike C  United Kingdom
diyAudio Member
 
Join Date: Nov 2003
Location: South east Essex, UK
Default Suggestions

These brands seem to have a good reputation:
Tamura, Tango, Magnequest, Lundahl, Plitron, SJS (used by Border Patrol).

At this level, differences in performance are probably not going to be great, and may be explained to some extent by how the passband is set relative to the audio spectrum; some oriental models with extended high frequency may, possibly, have a less extended bottom end. You may be able to make an intelligent choice if aware of this.

I tend to suggest that Lundahl set the passband pretty evenly on the spectrum, favouring neither highs nor lows. In conjunction with a 300B with extended top and bottom (TJ mesh plates), results seem good to me.

There are two suppliers in the Netherlands who produce amorphous core OPTs that appear to be of very high quality, worth a bit of research. I am very tempted to try these myself in a new SET project .... possibly to be called 'Sindy' and I'm sure people can guess why.

Given the lowish dollar, you might check pricing on the better ones from the USA?
Or see what's going on US Ebay for the far eastern makes (but avoid one particular US seller with many adverse comments on Tube DIY Asylum!).
  Reply With Quote
Old 14th January 2004, 12:05 PM   #8
diyAudio Member
 
Ouroboros's Avatar
 
Join Date: Dec 2003
Location: Nottingham UK
I had a couple of custom SE opts made by Sowter to work with the big DA100 100W triodes. The transformers perform very well.

The only possible problem might be that they don't LOOK all that special!

Chris.
  Reply With Quote
Old 14th January 2004, 02:49 PM   #9
diyAudio Member
 
Join Date: Jan 2003
Location: Sweden
I think my sowter-trannies looks sexeh!
  Reply With Quote
Old 14th January 2004, 04:29 PM   #10
KlausB is offline KlausB  Germany
diyAudio Member
 
KlausB's Avatar
 
Join Date: Dec 2003
Location: Dresden
Quote:
Originally posted by Brett


Try Lundahl. They are excellent and quite reasonably priced.

I fully agree. I made excellent experience with Lundahl line transformers.
Cheers

KlausB
  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
2a3 output transformers.... button_fly Tubes / Valves 3 10th October 2007 02:05 PM
Output Transformers eduardio Tubes / Valves 2 13th May 2005 02:42 PM
Using output transformers on Zen Amp? G Pass Labs 14 5th November 2004 11:54 PM


New To Site? Need Help?

All times are GMT. The time now is 06:22 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