Selecting Line Input Transformer.. Help!

[Fezzle]

Hello DIY people,

I'm hoping somebody would be able to help me with selecting a line input transformer for my Studer A80 RC record cards... Please bear with me as I have very little electronics tech skills or knowledge. On these cards are currently two Studer 1:1 line input transformers, and I'd like the best performing replacement for the job..
I have my eye on the Jensen JT-11P-1 for high specs, it has impedance of 10K-10K. however dont know if this is suitable for the surrounding ampifier/circuit. Also if I was to use these on the cards they are the absolutem maximum size that will fit each card.. and with both cards flush next to each other the transformers would probably be just touching each other... could this be problematic/affect performance channel to channel?
I would really appreciate it if somebody could look at the record card schematic for me and advise me on whether it would work well or not, I could e-mail it in PDF. I dont know whether its suitable or if there are better choices but either way your comments are most welcome.

Thanks for reading! Dave

 

[tommy1000]

From what I understand their problem is phase shift in the record amplifier; about 130 to 140 degrees at the top end, which makes them sound a bit 'soft'. I don't think changing the input transformers will improve this.

Hope this helps.

 

[Fezzle]

Tommy, Sir Clive might well be right on that one, however I'm pretty sure he was talking about the multitrack VU models. The RC has discrete electronics, mine are being rebuilt and Im pretty sure a higher performance transformer would improve things somewhat in terms of transparency and phase deviation

 

[JMFahey]

I'd trust far more what Willy Studer chose than what I might find asking at Hobby Forums.
But that's me of course.

 

[Fezzle]

Good point and I do, however Willy Studer chose that part 30 years ago, and a transformer is a transformer, a modern day Jensen will outperform those Studer parts by quite some margin so with some guidance I have no problem at all in trusting good old physics mate

 

[Dante Marone]

I'm pretty sure BudP does transformers for a living, you might want to PM him.

 

[tommy1000]

The RC has discrete electronics, mine are being rebuilt

Who is rebuilding them for you and what components are beeing changed?

 

[Tajzmaj]

If you already decided that Jensen is the one than buy one and try. You have probably found such advice on the internet...
But my advice would be don't touch. Those Studer transformers are probably very hi quality produced maybe by Lundahl or some other good European company. Modern Jensen might outperform old Studer but maybe not in given circuit. Original transformer is 100% very good matched to surrounding circuit. You can try, but don't be disappointed if there won't be any benefit.
Cheers

 

[Fezzle]

@ tommy, Jim Williams in Carlsbad, new low noise op amp build without the BC's, new low esr electrolytics, bypass with films, better EQ caps and resistors all round, remove output transformers.

@Taj, if its the transformer is a 1:1, and sees appropriate values around it, it is role is the same. Only with less distortion, time based smear, slew limitation, much better bandwidth etc etc for the following amps to make even worse. I dont doubt the Studers is decent quality, but I would rather there wasnt one there at all, and thats not possible here so I will take the next best thing, that is most definately done best by Jensen.

I do however submit that some of the differences in performance, may not suit the following circuit., fro all I know there could be some tricks going on there where perhaps bandwidth needs to be limited, phase etc Which is precisely why I will consider advice from somebody who knows how iron operates well , and, has looked at the schematic and is happy to give me thought out empirical reasons on there findings. Otherwise I stand by my default.

Thanks anyways!