What should I do with my UTC A-22?

[babyhead]

DIYers-

I have had the good fortune to come across a UTC A-22 for cheap and wanted an opinion as to what I might build around it.

Pri Z= 500 with CT
Sec Z= 125 + 125

Maybe a GPultec or the output of the FFOC... or the input of a Bloo?

Thanks-
BH

 

[CJ]

You better let me "check it" first.

cj

 

[rafafredd]

I have some of those also. It seems that it´s a very intriguing transformer. I´m sure there will be a nice use for this one.

NYDAVE posted a schematic that used it a while ago. It was a dynair lineamp or something like this. This is not in fact what I think would be the best use for my A22, but maybe we could borrow the output stage for a micpreamp. Interestingly I thought that this wasn´t meant as a PP output transformer, as it´s a gapped core, and thus you don´t need DC cancelation etc.... And I don´t think it´s windings are perfectly symetrical, but Dynair used it in a PP circuit, feeding the output transfistors throught the primary of the transformer.

Also, it says 20mA, so I don´t think it would work well as a NEVE BA283 output transformer, but it should be worth trying. How much current do we have throught the windings of the trafo in a BA283 amp?

Now, what would be really interesting to try would be putting it inside a cathode follower, WCF or SRPP circuits that can drive 600Z, but with no coupling caps before it. It would be "inside" the circuit. I have thought about it but I´m not sure how would one implement it. :?

 

[babyhead]

Oh no!

I have seen what you do when you "check it"!

Although it would be entertaining...

-BH

 

[wilebee]

ribbon mic step up transformer Wil

Wilebee

 

[rafafredd]

ribbon mic transformer :?: a +30dBm gapped trafo?

 

[wilebee]

my bad I was thinking A-21 :? Wil

Wilebee

 

[babyhead]

Interesting...

So a G9 or a Pultec output without the bypass cap? What about a solid-state signal from something like an API, Hardy 990 or JLM style opamp? What are the pitfalls of using an (or this) input transformer on the output 1:1?

Thanks-

-BH

 

[CJ]

BH, the structure is all wrong for that. Notice that layer 5 should be grounded to the shield for maximum inductance:

:razz:

 

[babyhead]

And you want my A-22????

Layer 5 is pretty deep in there... What kind of circuit do you find this transformer in?

This is like a puzzle to me. :?

What about it backwards?

-BH

 

[CJ]

I was just funnin. It's almost summertime, which means mental dis-orders.

Seriously, the A-22 might or might not work on the end of an API. Let me check the inductances. I will be right back.

 

[babyhead]

I was just funnin. It's almost summertime, which means mental dis-orders.

You sure are rippin' the guitar!
:grin:

 

[CJ]

Hemroids.

 

[SonsOfThunder]

Completely different direction...

I used A-22 wired as 4:1 for CountryHick DI. Sounds very nice for Bass gtr, IMO.

Hope that's useful!
Charlie

 

[rafafredd]

It might work great, but I still think you can find other transformer for this purpose. The UTC A22 is a very high level iron, high quality iron with lots of headroom and an airgap. Not very easy to find iron like this one, specially today, so I still think a DI output transformer isn´t the best use for this one...

Still, if it sounds great and it actually pass audio often, nothing wrong with this... Better than sit in the closet like mine. :?

 

[babyhead]

I really don't have use for another DI... I have an Evil Twin :twisted:

However- I would like to use it for a TT project... I have waiting in the wings fabio 312s, 1176, Calrac, Pultec, & Forssell Optos... maybe for a discrete What.

I am leaning towards the comps next because today is the day that I lost I lost my 2254s and my GMLs. :sad: Not that they were ever really mine!

Thanks!

 

[CJ]

Rafa, sounds like you took the UTC apart?

 

[jhaible]

[quote author="rafafredd"]The UTC A22 is a very high level iron, high quality iron with lots of headroom and an airgap.[/quote]

Does anybody know for what purpose this was designed in the first place?
I mean, it can take 20mA of DC, and it's high level, but the DC isn't enough to build a SE output with all the bias current flowing thru the transformer *and* making ue of its full power capability at the same time. (Or is this wrong?)

JH. (also having two of these from ebay)

 

[rafafredd]

I guess it would stand more than 20mA OK. As I said, If I et crazy enought, I´ll probably try it in a 283 ne%$%$ve out stage,...

 

[NewYorkDave]

[quote author="jhaible"]
Does anybody know for what purpose this was designed in the first place?[/quote]

"Transistor interstage or output", according to UTC.

I'm going to end up with several of these if I decide to part out those Dynair line amps.