OEP A262A2E as input transformer ?

[Fablab]

I'd like to know if it is possible to use the OEP A262A2E as input transformer  or if  it is usable only in the output           

Thank you

 

[Michael Tibes]

'The A262A2E from OEP is a high performance audio transformer. This device is specifically designed for direct PCB mounting on a 0.1inch grid. Each transformer is constructed with dual windings on the primary and secondary providing a wide range of impedance matching ratios to suit many input, interstage and output applications.'

From the first link coming up with a google search...

Michael

 

[Fablab]

Thank you Michael, but one thing is what you read on the first link coming up with a google search, another thing  is to ear the same thins form a person who has tried it 

 

[RuudNL]

I wouldn't use them as output transformers.
They can't handle high output levels with low distortion.

 

[Michael Tibes]

This is maybe so long ago already, that it got forgotten - but if I remember right this transformer was originally intended as an input and got 'abused' in the group development process of the GroupDIY's predecessor forum for the original G1176 as output due to the lack of available and affordable alternatives and also because people liked it's 'good dirty' sound in that application. There should be very extensive discussions about this in very old topics. For example here: https://groupdiy.com/index.php?topic=3474.0
Also some classic research about input xformers including the A262A2E: http://www.jlmaudio.com/Neve%20transformer%20info.htm

Anyway, you didn't ask how it sounds as an input, but if it was suitable. Afaik it was originally intended as an input, so it was considered suitable by some people ;-) I can't comment on the sound because I only used them as outputs in a G1176 as a coloring tool so far. I guess the OEPs are considered mid level quality and most people here spend the extra bucks to go more or less 'high end' (while it is certainly highly subjective which sounds better).

Michael

 

[Fablab]

Michael, I agree with you about the really good coloring work of these transformers.
A friend of mine used a this transformer in the output of a mic preamp and when I had the possibility to compare it with the same preamp with a different (hi end) output transformer ... I preferred the one with the OEP
My question  is to understand (eventually someone has tried them) how they work in input or if it is better to use them in output as normally they are used (for possible distortions or other problems)
I asked because in the past I tried to use other transformers usually used in output with not too good results (although from the producer there were no contraindications about their use)

 

[Michael Tibes]

Why not just try it? It's cheap, put it in front of a 5534 (or whatever opamp you like) gain makeup stage and you should have a quick test setup which provides enough gain for most signals in rock / pop. It should easily reveal how the oep performs as input and whether you like it or not - which is the part you probably won't get an answer for in a forum anyway ;-)
For a rough evaluation you could even run it of 9V batteries if you don't have a psu at hand. They will last long enough to judge whether it sucks totally or if you want to get more invested.

Michael

 

[12afael]

http://www.jlmaudio.com/Neve%20transformer%20info.htm  I use it on a neve circuit and it is my favourite preamp, I don´t know if it is due to my custom made output transformer but it work.

errata: I use a  A262A3E on the neve

 

[Fablab]

Thank you, I'll buy it!

 

[12afael]

I remember Jens (Jensenmann) told me that his favorite transformers for 1176 were OEP. Provably not the exact model but they work at the output. Low distortion??? maybe no but what I like of transformers is the distortion.

some years ago I visited Bo Hansen at Gothenburg he was testing some OEP version of Neve 10468. I don´t know if they are in production or not.

 

[12afael]

I just notice the  A262A3E is the one that I have on my neve circuit.

 

[Fablab]

Thank you 12afael!

 

[Bo Deadly]

Earlier versions of the UREI 1176 used the UTC O-12 transformer in reverse for a 500R:200R step down. Stepping down made sense for that circuit since the FET will distort at high levels. So the OEP A262A2E with the 150R+150R primaries in series and the 600R+600R secondaries in parallel give you 600R:150R which is just right for a UTC O-12 replacement. So if you need to step-down for use with a FET compressor or VCA where the signal level needs to be attenuated anyway, then this would be a good input transformer. But otherwise, it may not be right. It depends on what you're using it for precisely.

 

[abbey road d enfer]

I'd like to know if it is possible to use the OEP A262A2E as input transformer  or if  it is usable only in the output           

Just look at the specs; the inductance of a series-wired primary is 500mH, which results in an impedance of 160 ohms at 50Hz, 60 ohms at 20Hz. It does not adhere to the bridging rule, where the load impedance is 10x the source impedance. Since the primary inductance directly loads the microphone, it results in a passive high-pass filter, which may be what you need sometimes, but not always. Typically, high-perf mic xfmr's have a primary inductance of 5-20H.
Worse than that, it means the windings have a low turn count, resulting in increased induction in the magnetic core, and thus in more distortion. Again, that may be what you want, but not always.
An incidental consequence is that the HF resonance peak will be situated much higher than the 20kHz boundary, and of higher amplitude, as shown by JLM's experiments. This may or may not be an issue,but one must be aware of it.
OEP are not audio xfmr specialists; historically they made power xfmr's. They don't use the special high-Ni-content laminations that are mandatory on high-perf mic xfmr's.
There's a good reason why they are much cheaper than the competition.
These xfmr's are better suited for outputs, where the impedance of the driver is near-zero. I've had pretty good results with OEP output xfmr's, using them with a negative-impedance driver.

 

[shabtek]

... the UTC O-12 transformer in reverse for a 500R:200R step down. Stepping down made sense for that circuit since the FET will distort at high levels. So the OEP A262A2E with the 150R+150R primaries in series and the 600R+600R secondaries in parallel give you 600R:150R...

                          two 600Ω windings in parallel is still 600Ω...the winding ratio you propose is 1:1, this unit would need to be reversed to achieve a step-down, both sides either series OR parallel