Dynaco Mark III output transformer variants

[Sue Anders]

Does anyone know if there were any differences in the circuits (schematics) between Dyna Mk III versions with A-431 (earlier?) or Z-216 output transformers? Are schematics for either or both posted somewhere? There's 40 pages! under the schematics link above!

Also there's special forums below for Eico, Fisher &c &c but not for the most popular tube audio of all time... Dynaco!! Maybe that should be added??
Thanks for your help!

 

[gadget73]

Is the Z216 the one with the 70 volt windings? I know there is some oddball Mark III variant with that setup, apparently for PA use.

 

[dcgillespie]

Besides the 70 volt model, there was also one that had balanced outputs as well (500 Ohms I believe). If I recall correctly, the 70 volt version still had traditional speaker output impedance taps, but the version with the balanced line winding did not.

Dave

 

[nerdorama]

I think the Z216 is just a later model of the same transformer. Possibly made in Japan if I remember. I have one but have never done anything with it.

 

[4r54r5]

I have 2 mk IIIs factory wired with the 70.7 v tap. I does have the 4 - 8 - 16 ohm taps as well. If you want I can open them up to get the OPT part number. LMK

 

[Tom Bavis]

The 70V was A-431-70, 500 Ohm was A431-500. Don't know if any early Mark IIIs used the A-430 from the Mark II - had only 8 and 16 outputs.

 

[Pio1980]

Afaik, a shorter secondary with all winding lengths in circuit yields better interleaved windings and better performance potential.
This could make a circuit difference in stabilization, but I'm not familiar with MK-3 variants.

 

[SS904]

Read about this a while back. I picked up an oddball set of A 431s myself (extra white secondary wire) and it turned out they were just the 70V versions. They are otherwise the same as the standard A 431 and sound as they should. In my reading I also found the later "Z" designated Dynaco transformers are said to be the same as the US made "A" designated transformers, but made in Japan.

 

[Sue Anders]

Thanks, found much the same info : the A-431 was used on the earlier models and the later Z-216 was essentially the same but supposedly made in Japan, no difference in their circuits/schematics. We have been offered one probably needing work and are curious about the transformers, evidently new ones are being made that are direct replacements if needed.

Be interesting to find out who made them, Dynaco (Acro early on, as Hafler started out with Keroes) output transformers seem to be universally respected, and Japan, of course also, with Tango etc there and a very strong HiFi culture in general. Sansui stared as a trans maker and were also very highly respected. I don't know if any EIA code would be on a Japanese product.