Gyraf Pultec and OEP trafo

[Hulk]

I'm working on the Gyraf Pultec and I'm going with the Lundahl LL5402 output trafo as recommended but I also have some OEP A262A2E and A262A3E that I want to use for a balanced input.

I have Gustavs PCB but the holes in the PCB for the optional input trafo (designed for a LL5402) does not fit the OEP trafo pins at all.

Is there a way around this - I think I have to use the OEP A262A2E for the input trafo right??
Do you just connect the OEP trafo to the PCB using wire and how do you fasten the OEP trafo/screening can to the PCB???

 

[gyraf]

You'll need to mount the OEP on an external piece of PCB, maybe a piece of veroboard..

Jakob E.

 

[Hulk]

Ok thanks!!

 

[matthias]

if I'm right, for the pultec input you need a trafo tha has 600ohms on both sides, so the oep A262A7E would fit best here...??

 

[Hulk]

Then the A262A2E is not good ides as input trafo??
Specs here (pdf)

 

[gyraf]

Yes, the 'A2E can be wired 600:600 (primaries in series, secondaries in parallel), and is useable for Pultec input transformer..

Jakob E.

 

[Hulk]

I'm about to wire up my OEP A262A2E as input trafo for my Gyraf Pultec but I'm not sure how to do it right so I need some help!

On the PCB (Gustav's) you can see the numbers - to the left on the picture the numbers are 1, 2, 3(E), 4 and 5 - on the right side the numbers are 6, 7, 9 and 10. On the OEP trafo the numbers are:

Pri:
S1, S2, F1 and F2

Sec:
S1, S2, F1 and F2

I have soldered pin number 9 to the screening can.

How do I connect the pins???

 

[Michael Krusch]

A mounting hint: You can glue the OEP upside down on the board and connect the pins with short wires. I have successfully used silicon for that.

 

[matthias]

do you really want to use the A2E ??

There's a transformer test here:
http://www.jlmaudio.com/Neve transformer info.htm

and the A2E is delared as "not useable"

 

[rafafredd]

I think you can use it with the primary in series and the secondary in parallel... for a 2:2 turns ratio...

 

[Kev]

I'm busting to make a suggestion here.

Long ago there was a picture at the old Group DIY birth place.
It was the passive EQ from Jakob on a Kev styled PCB.
It had a number of transformers. I can't get the specified transformers at a respectable price so I put some cheapies on it.

These cheapies like the OEP don't really have enough iron to handle the higher levels into 600ohms ... yes they call it saturation.
If you drop the level you get less Iron stuff happening and so less saturation.

wait for it
... it was suggested above that you could " ... primary in series and the secondary in parallel .... "

:roll:

two primaries doesn't mean it has to be a Dual primary trafo ...
look at the original picture and count the transformers.
:shock: ... sorry Joe ... I did promise not to tell.

 

[gyraf]

[quote author="matthias"]the A2E is delared as "not useable"[/quote]

That depends very much on the application - and the ears that listen.

JLM's tests are valid only for that single application, and even then only from a measurement-perspective.

The OEP's are very, very good transformers for the price - and in certain circuits they sound superior to much more expensive iron.

But I haven't tried them for the Pultec circuit - you're on your own here. Please be sure to report back with impressions..!

Jakob E.

 

[gary o]

I have made a Gyraf Pultec EQ with the EOP A2E & no ouput tran at all at the mo, IMHO it sounds great, tho I have nothing to compare it to, surely it cant be beaten on value for money, im gonna try it out in some of my other projects where I currently have Sowters.

Thanks ..........................Gary O.

 

[Hulk]

You can allways change the A2E input trafo to the LL5402 if you do not like the OEP but I'm going to try the A2E as input trafo - I'll post samples when it's done!

But where does the individaul pins of the OEP go on the PCB so the pri are serial and the sec are parallel??

 

[Flatpicker]

[quote author="Kev"]...two primaries doesn't mean it has to be a Dual primary trafo ...[/quote]LOL! A solution so obvious that we are oblivious to it! I had a similar revelation the other day while trying to find alternatives for driving low impedance loads. I guess when solutions are as close as the nose on our face, we forget that we have to look cross-eyed to see them. :wink:

 

[Flatpicker]

[quote author="gyraf"]...and the ears that listen...JLM's tests are valid only for that single application, and even then only from a measurement-perspective...[/quote]So true! Technical aspects must always be considered, but in the end, it?s the ?ear? that decides. That?s why we love analog/audio electronics so much (and why I?m here in the first place!). If it was all cut-and-dried like digital circuitry, it wouldn?t be the least bit fun.

The OEP's are very, very good transformers for the price - and in certain circuits they sound superior to much more expensive iron

Jakob, could you elaborate more? I haven?t tried the OEPs yet and it would very helpful to know where you?ve used them with good success.

 

[Hulk]

hmm tried to work itout my self - can someone confirm if this is correct!!

 

[Hulk]

Can I use a 2 x 15V /30VA toroid for the Gyraf Pultec??

Any comments to my OEP wireings??

 

[matthias]

no!! it has to be 12V ...

 

[Hulk]

hmm just looked at the schematics and it says 220:12 or 220:15??