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Suggestion for push pull output transformer.

A

Alan0354

Super Member
I have been looking around at push pull output transformer. I looked at Edcor, Hammond, Sowter, Lundahl, Plitron, and this http://triodeelectronics.com/dytr.html

Any comment and suggestions?

I am willing to pay up to around $300 or so for each transformer, but how does the cheaper Edcor and Hammond measure up? How big a difference?

I look at Plitron, the spec is very good, close to 200KHz frequency.
 
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I've compared Triode's Dynaco clones to Hammond and Edcor. Triode is the best of those three, by a substantial margin. The performance metric where Hammond and Edcor fall short is HF response. My experience is with push pull output stages.

DynakitParts should be equivalent in performance to Triode's offerings.

I'm not sure about toroids as output transformers. What you potentially gain in frequency response you may lose in other areas. I have no experience there, however.
 
I have a pair of Edcor transformers on a modified Magnavox 9300. It does OK but Dave Gillespie's basically identical amp with the Triode Dynakit transformers performs better than mine does. The transformers are the only real difference, plus the HF tuning that results from the different transformers.
 
Sounds like the Edcor and Hammond are out of the contest from here and comments I read before. I don't mine paying more, I am willing to pay up to about $300 for each transformer. I was looking at Sowter and Lundahl, problem is when I got into the pricing, I found out the shipment can be very expensive from Europe, judging from the package I sent to Norway, It's very expensive. On top, they charge VAT and that amounts to over $500 each. I ain't willing to support those socialist countries!!! I did look for distributor here but I couldn't find any. That's why I am looking for alternatives. I budgeted about $1100 to $1200 to build an amp on a wood board( save the cost of the chassis) to give it a fair shake to compare to my SS amp.
 
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Affordable Lundahl in the US plus much more!

http://www.kandkaudio.com/about-us/

I've read lot's of positives on Plitron OPT's also (no negs) , but they are even pricier!

Hashimoto (make Sansui OPT's) is also sold in the US and I read of a fellow on diyaudio about 5-6 yrs back from the UK that used them (EI wound lowest cost 8K input model) (on a Tubelab PP EL84 diy amp (diyaudio forum) and was raving about them as he had tried others. The potted ones in cans are C cores.

Another name ( they are new) that comes up from the EU that people are loving is Monolith Magnetic and this diyaudio thread mentions them along with Lundahl etc. SE trans. mentioned only, but maybe helpful! AM may be overkill from reading the forms for some trans/amps so research!

http://www.diyaudio.com/forums/tubes-valves/6457-300b-se-opt-3.html

For a budget 5K primary the Hammond 100W 1650R (not RA) get's likes on the forums over less $ Hammonds etc. I found it for $140 ea.

I do believe you generally pay for what you get & good luck!
 
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The other question is what are you looking to build? The Dyna stuff has a lot less options than Edcor or Hammond so it may not fit your needs.
 
gadget73 said:
The other question is what are you looking to build? The Dyna stuff has a lot less options than Edcor or Hammond so it may not fit your needs.
Click to expand...

Dyna stuff has lots of examples including complete amplifiers.
 
gadget73 said:
The other question is what are you looking to build? The Dyna stuff has a lot less options than Edcor or Hammond so it may not fit your needs.
Click to expand...
I am still studying the load line for Class AB1 push pull. But so far, seems like 4K to 4.5K is close for a pair of KT88 for both UL and triode.
 
peterh said:
Dyna stuff has lots of examples including complete amplifiers.
Click to expand...
what I'm getting at is they have a finite number of options for the amp range. Edcor for example has a bunch, and you can just call them up and order whatever you want.

Alan0354 said:
seems like 4K to 4.5K is close for a pair of KT88 for both UL and triode.
Click to expand...

from memory the transformer used on the ST-70 falls in that range. A-431 I think? Or whatever is used on the Mark III since thats a 6550/KT88 amp.
 
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Sowter I guess is UK/EU only! Those Lundahl trans. being C core are much lighter compared to EI core trans plus no cover or potting so shipping has to be less!
 
Any comment between the conventional EI core vs C core vs torroidal?

Also any comment between Dynakit/Triode Dyna clone and those exotic Sowter/Lundahl? Sounds like Dynakit/Triode Dyna clone are both very good.

Thanks
 
Dyna had the performance per dollar crown and the current Dyna clones measure very close to the originals - still likely the best for the price if the impedance suits your circuit. Low-end Hammonds (1608, 1620) measure about like console transformers from the '60s - haven't measured any of their bigger ones (or any Edcors, for that matter). There are lots of transformers that measured better than Dyna's, but most were proprietary - Scott, Fisher, Bogen, H-K didn't sell transformers. C-cores and toroids can have better coupling than E-cores for better high frequency performance, but toroids won't tolerate any DC imbalance - inductance drops rapidly with any DC flux.

The Lundahl 1679 has half the leakage inductance of the Dyna A430, so high end is better, low end will be about the same.
 
This is what confuses me, I heard about C core cannot stand net DC current as inductance drops. But according to the Lindahl page, they spec the transformer both for PP and SE and you can see the power is still quite high for 1679 in SE mode. Like for the 4.5K, it's 105W for PP, but still 20W for SE. That means it's good for two power tubes in parallel in SE mode.

http://www.lundahl.se/tube-output/
 
Also, is it true for hifi, you don't match load for maximum power, you use lower primary impedance than max power to get lower distortion?
 
Yes, upon reading into Dynakit and Triode Dynaco clone, they only have 4.3K primary, not very useful. So back to square one except Lundahl have a distributor here.

Any other high quality output transformer?
 
I have no experience with Lundahls output transformers. But I can tell you from personal experience that some of their lower-level signal transformers sound wonderful. So I would personally be inclined to take a chance on them if I were in your shoes.
 
Alan0354 said:
Any other high quality output transformer?
Click to expand...
)

As I mentioned above, Monolith Magnetics (there might be a US dealer, but maybe ask) & Hashimoto (there is a dealer in the US) , which will cost even more than Lundahl!

The more expensive ones have more interleaving ( explained on the Sowter site) which takes much more time to do right and premium materials and design. This all helps the sonics of course as the OPT defines the quality of a tube amp. There is a really nice fellow that used to make OPT's in AUS , that has a great site still up explaining a lot! Lot's of schematics too!

http://www.turneraudio.com.au/output-trans-theory.htm


I found this test of vintage ones I read several years ago you might find interesting!

http://www.one-electron.com/Trans_Tests.html
 
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