Beyer STR/BV 37 939 and T-161 (AEM-161): looking for info

Not wanting to abuse the Kubi-groupbuy thread I thought I'd better ask here in a fresh thread:

Looking for info on the Beyer STR/BV 37 939.



It's 'almost' mentioned in the pdf from Jakob:
http://www.gyraf.dk/schematics/Beyer_1969.pdf

but the last three digits don't match.

Who knows ratio/impedances/pinning ?


The eBay sale will also include :

T-161 (AEM-161) audio output transformer

A generous move to add that, but I've never heard of that;
so let's hope it's nice & usable and not a big piece of iron that needlessly increases shipping :wink:

Thanks!

Peter

£1.70, Peter.

One pound, seventy!!! :evil:

I'm not giving you any help! :razz:



PS. Good luck.

As it happened I caught this one two minutes before the end (OK, I did follow it). I should have already been on my way to somewhere, but this week is TX-week, so please excuse me for spending those two minutes.
Or just don't, I confess that I've have been bidding on a TX with unknown ratio... please refrain from making some real-world comparisons... :twisted:

[quote author="rodabod"]£1.70, Peter.

One pound, seventy!!! :evil:

I'm not giving you any help! :razz:
[/quote]

You... you ... !!!!

But did you see this:

Postage and packaging (UK): £3.85

Click to expand...

Let's just see what it'll be to the Netherlands...

Roddy has the info, but he won't tell... :sad:

So anyone else perhaps ?

Thanks!

Peter

Just got a reply from the friendly people at Beyer.

It's a 1:4 TX (600:10k).
Prim has a centre tap and is bifilar wound.

Nice, that's usable! :thumb:

Who knows it's of interest for figuring out the pinout etc related types, so I've uploaded it here:
http://www.twin-x.com/groupdiy/albums/userpics/TR145_BV35939.PDF


What would you suggest for using this as a mic-pre input TX?
Just use the 600 Ohm prim or enter on the centre tap and one of the outer connections ? (for 150 Ohms)

Thanks!

Peter

[quote author="clintrubber"]Roddy has the info, but he won't tell... :sad:
[/quote]

Ok, I admit it, I didn't know anything. :razz: Well done getting the info. :thumb:

Well, 1:4 should be good as either 1:4 or 1:8 for a mic preamp - pretty versatile.

I suppose consider the impedance you'll be getting at the secondary for 200 Ohms - either 3.2K or 12.8K.

Possibilities....

[quote author="rodabod"][quote author="clintrubber"]Roddy has the info, but he won't tell... :sad:
[/quote]

Ok, I admit it, I didn't know anything. :razz: Well done getting the info. :thumb: [/quote]
Cheers to the friendly folks at Beyer :thumb:

Well, 1:4 should be good as either 1:4 or 1:8 for a mic preamp - pretty versatile.

Click to expand...

I'm not worthy, I just got these at a steal and now they seem to have a nice usable ratio. :green:

I suppose consider the impedance you'll be getting at the secondary for 200 Ohms - either 3.2K or 12.8K.

Possibilities....

Click to expand...

Must admit I forgot whether using just half of an unsplit primary was OK or not...

The specsheet mentions 16H of prim inductance for the complete primary (sec unloaded) at a source impedance of 600, so I guess that using just half of it at a lower source impedance would do fine!

Cheers,

Peter

[quote author="clintrubber"]
Must admit I forgot whether using just half of an unsplit primary was OK or not...
[/quote]

IIRC, there is only a -1db penalty for doing so. I was wondering what the correct configuration would be, though. Center-tap grounded and signal applied to one or the other side? Other side left unconnected or grounded?

[quote author="skipwave"][quote author="clintrubber"]
Must admit I forgot whether using just half of an unsplit primary was OK or not...
[/quote]

IIRC, there is only a -1db penalty for doing so. I was wondering what the correct configuration would be, though. Center-tap grounded and signal applied to one or the other side? Other side left unconnected or grounded?[/quote]

Hi,

The idea then would be:
No grounding, apply balanced signal (mic) between one of the outer ends & the centre tap. Other outer end is left unconnected.

Would work I assume, but I might be ignoring bad consequences.

Curious, where would the -1dB penalty come from ?

Bye,

Peter

I was thinking secondary but saying primary. Doh!

The -1db is, I think, meaning a small additional loss beyond the expected insertion loss. Can't recall why exactly, though it seems logical to have some deviation from normal operation, I'll have to dig that thread up again.

[quote author="skipwave"]The -1db is, I think, meaning a small additional loss beyond the expected insertion loss. Can't recall why exactly, though it seems logical to have some deviation from normal operation, I'll have to dig that thread up again.[/quote]
Hi,

OK, I see. Intriguing! :grin:

The higher ratio (1:8 i.s.o. 1:4) will of course more than make up for it, but that wasn't the thing here of course.

Bye,

Peter

I don't see why you would want to tie one side of the primary to earth...

I would just use one outer terminal plus the centre tap whilst paying attention to polarity obviously.

Roddy

[quote author="rodabod"]I don't see why you would want to tie one side of the primary to earth...[/quote]

Right, I was just being a space cadet and thinking secondary.

Might have been remembering this thread, which was discussing using half the primary of an outputtransformer. Hence the question about what to ground. :?
http://www.groupdiy.com/index.php?topic=3923&postdays=0&postorder=asc&start=47

I'm working on about two hours sleep, been at the office all day after being in the studio until 3:30AM recording a band called Man Man. But it was fun! :green:
http://wearemanman.com/
http://myspace.com/wearemanman

[quote author="skipwave"]using half the primary of an outputtransformer. [/quote]

Ah, I see.

Yes, at the output primary we are unbalanced, hence grounding one side, and the same goes for the secondary of the input transformer. Cool.

That band sounds interesting!