New or used output xformers to play around with? - 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 3rd April 2012, 01:02 AM   #1
diyAudio Member
 
Join Date: Sep 2007
Default New or used output xformers to play around with?

I'm looking for suggestions for PP output xformers for, mainly EL84s, but also EL80s since I have a few of those hanging around.

I've scanned eBay for many months looking for either fairly good or good xformers but think the prices, when compared to buying new ones from Edcore, are too high?

The amp I plan to build and play around with will not be for use as a amplifier in my main system, but rather for use in either my kitchen or my play room where I play around building things.

Currently, I plan on starting out with Eli's El Cheapo design, but using a power supply using xformers I have on hand.

My inclination is to keep saving up and buying full range Edcore xformers: 21W CXPP21-MS-8.6K for $57, 25W CXPP25-8-7.6K for $48, 25W XPP25-8CT-7.6K for $31.

But, I lack experience to judge if used xformers, like from Hammond organs, would be just as good, at a slightly lower cost? Or, are older xformers, like those in Heathkit EA3s, better than current production Edcore's

I'd appreciate any comments.

Best from Tucson
Bob
__________________
Still a novice with electronics.
  Reply With Quote
Old 3rd April 2012, 06:24 PM   #2
diyAudio Member
 
Join Date: Jun 2008
Hey Bob,

Edcore makes fine transformers, and you will also fine good ones in vintage hi-fi gear. One of the problems using organ parts is that you need identical pairs and that can be problematic when salvaging from mono gear. Junk shops often have old stereo consoles that can have pretty good iron. I salvaged a nice PP EL-84 Stromburg Carlson from a console that had very nice OTs.

So, if you want to re-use OTs, there are a few things to consider other than quality. They must fit your application too. Some OTs will just have three primary wires and two secondaries, meaning they only have one secondary winding. Others will have four, meaning they have taps for perhaps 4, 8 and 16 ohms. Obviously, the latter is usually better.

Also, the primary impedance is important as it must match your power tubes impedance. You can measure it by applying a low voltage AC signal to the primary and measuring the output voltage. A variac or an AC wall wart are both suitable sources. The ratio of voltages is equal to the winding ratio. The square of the winding ratio times the secondary impedance is the primary impedance. Let's say you have a winding ratio of 27 when measured against the middle tap (8R). The primary impedance calculation is: 27*27*8R=5832R.

I hope that helps. Happy hunting.

Dave
Phoenix

Last edited by Captn Dave; 3rd April 2012 at 06:27 PM.
  Reply With Quote
Old 3rd April 2012, 11:49 PM   #3
diyAudio Member
 
Join Date: Oct 2004
Location: Adelaide South Oz
Cheap Output Trannies (and lots of other stuff) from here.
Reliable Supplier.
How good is the EL84 PP Output Tranny - good but not great -when I pulled it out of an amp and replaced it with a Hammond 1608 I noted an immediate improvement BUT price is 1/4 of the Hammond.
mableaudio.com

The Mable trannies pulled form this HiFi Amp are now doing a fantastic job as output trannies in a pair of 6V6 push pull Guitar Amps.

Since you are in the US you may be better going with the Edcore, good trannies and once you factor in delivery costs (although Mable are pretty good in this regard) then prices will not be all that much different.

I've just bought a set of SE Output trannies and the power tranny for a stereo 300B SE from Mable. I use their EL34 amp power tranny in my latest Baby Huey build.

Cheers,
Ian

Last edited by gingertube; 3rd April 2012 at 11:53 PM.
  Reply With Quote
Old 4th April 2012, 12:37 AM   #4
diyAudio Member
 
Join Date: Apr 2004
Location: Monroe Township, NJ
Bob,

If you restrict yourself to triode wired "finals", Edcor's GXPP15-6-8K will allow you to try both 8 Ω and 4 Ω speakers.

To try UL mode "finals", buy Edcor's CXPP25-6-7.6K and you get the same flexibility with speaker impedance.

Do what you like in the B+ PSU dept., as long as at least 200 mA. are available and the rail comes in at about 355 V.
__________________
Eli D.
  Reply With Quote
Old 4th April 2012, 06:55 AM   #5
diyAudio Member
 
Join Date: Sep 2007
I appreciate the time everyone took to give information to me.

Finding used tubed gear here at Goodwill places has been a fruitless endeavor; been looking during the past 5-7 years.

Using my Variac to test output transformers is a great tip.

Eli's suggestion seems to resolve my dilemma.

Best from Tucson
Bob
__________________
Still a novice with electronics.
  Reply With Quote
Old 4th April 2012, 01:32 PM   #6
TheGimp is offline TheGimp  United States
diyAudio Member
 
TheGimp's Avatar
 
Join Date: Aug 2009
Location: Johnson City, TN
I've bought five or six consoles for the amps in them.

I've also bought several transformers and sets of transformers off Ebay in the past.

I no longer buy old transformers for use in amps as I consider them (1) a risk due to age, and (2) overly expensive compared to new production transformers (3) inferior to new production transformers.

In an apples to apples comparison, the Edcor XSE series 10W transformers are as good as or better than the original Magnavox (and other mfg) transformers I've seen in 6BQ5 pp systems. At $18us plus shipping, I don't see how buying used transformers is worth it.

The original Magnavox (and other mfg) transformers I've seen are no larger than the Edcor 10W transformers.

The GXPP for $26 are certainly a step up, and one could go to the 15W version and improve bass for $37 each.

Stepping up to the CXPP you are in a totally different class and on par with (or better than) old component system amp transformers.

My latest amp is a single end stereo amp with 6P41S output tubes. They are selectable for Triode strapped or UL.

I used the Edcor GXSE15-8-3.5K transformers, and driving a set of Klipsch Heresy speakers they sound fantastic.

Several of my granddaughters friends who have listened to the system are extremely impressed with the bass, which far exceeded my expectations.

This is at moderate listening levels.

My wife and granddaughter both have SE 6P1P stereo systems using Edcor XSE10-8-5K transformers in the bedrooms. These drive speakers built with FE103EN. They both can play them loud enough to drive me to the den. The poor little FE103s are going to be trashed and I'll have to build new speakers with bigger drivers.

Last edited by TheGimp; 4th April 2012 at 01:38 PM.
  Reply With Quote
Old 4th April 2012, 04:51 PM   #7
diyAudio Member
 
EddieRich's Avatar
 
Join Date: Jun 2011
Location: North of Boston
If you do plan on buying from Edcor, they have a long wait period. I ordered 3 transformers for my project on Feb. 23 and the order is still in the "processing" stage. Of course, the money came out of my bank account 3 days after the order, but since they make each order individually, there is a long lead time. Just keep that in mind as you plan your project(s).
  Reply With Quote
Old 4th April 2012, 06:28 PM   #8
TheGimp is offline TheGimp  United States
diyAudio Member
 
TheGimp's Avatar
 
Join Date: Aug 2009
Location: Johnson City, TN
Normal lead time from Edcor is six weeks.

If you ask them when you order, they can give you a better estimate depending on how busy they are.

Last edited by TheGimp; 4th April 2012 at 06:30 PM.
  Reply With Quote
Old 5th April 2012, 06:50 AM   #9
diyAudio Member
 
Join Date: Sep 2007
Thanks to both of you for your time and the additional information.

Your prose flows, is well organized, concise, and to the point Mr. Gimp.

Knowing that the Edcore xformers are at least equal to or better than the output xformers I have been chasing relievs me of the urge to keep checking eBay for my planned project.

Best from Tucson
Bob
__________________
Still a novice with electronics.
  Reply With Quote
Old 5th April 2012, 07:37 AM   #10
rmyauck is offline rmyauck  Canada
diyAudio Member
 
Join Date: Apr 2009
Other's to consider for EL 84 PP are the highly regarded Dynaco ST-35/SCA-35 Z-565 OPT's in used or reproduction. I don't have Edcor to compare to. Mike at Magnequest makes very high quality ones for more also , including ones with Nickel Lams for improved sonics.

Z565-48 17.5(35W) Watt Triode USA Dyna Clone Output Transformer for Dynaco MADE IN USA

Randy
  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
R-core xformers from China jarthel Tubes / Valves 3 7th June 2006 05:45 PM
what to do with isolation xformers? cowanrg Parts 10 11th June 2005 07:02 PM
SMPS xformers Mr Teal Parts 0 8th November 2004 04:47 AM
can i use these xformers for aleph-x? leadbelly Solid State 4 7th April 2003 05:20 AM


New To Site? Need Help?

All times are GMT. The time now is 06:14 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