what to build with these transformers

[salomonander]

hey
i bought a bunch of old gardners mu7525 transformers. they are 600:300/1200. so im thinking of what i could build with them. at the moment i can only imagine them as mic inputs for some neve clones. which would make sense. but are there other uses also?
there is a drawing on the lower right of the attached document that confuses me. does it provide a way of running them 600:600?

thanks a lot

edit: at this point im not sure if they are 600:300/1200 or 600:600/600... can you help me to find this out?  i attached another tech sheet to the end of this thread that suggests the latter. it says "denoted perallel/serial connections. im too dumb please help.

 

[gyraf]

1:1.41 ?

I would use it for input (possibly output, depending on core size?) on a NTP 179-120 compressor...

Jakob E.

 

[salomonander]

thanks jakob. i should have mentioned that i have way too many comps already.
what i really need is nice eqs like pultecs but i dont see how i could use them for line inputs. please correct me if im wrong. so i tought of a neve build. these should work for a 1073 type right?

 

[CJ]

will work for pultec line input

 

[PRR]

> a way of running them 600:600?

Not really.

That needs _two_ transformers, gives an in, an out, and an in/out. All must be terminated in 600 Ohms. This is an occasional connection in telephone systems, essentially unknown in audio studio work.

Obviously any _two_ 600:XX transformers may be worked back to back to give 600:600, but at double losses and cost. There is usually some better solution.

 

[salomonander]

alright. thanks for your input. still wondering... will these work as mic inputs for a neve type preamp with hi low imp switch?

 

[ruffrecords]

I notice to the side of the pic ypu posted a drawing showing how to use the transformer as a hybrid. Made me think they might be ideal as a mic splitter?

Have you got a copy of publication G5 which gives the full specs?

Cheers

Ian

 

[salomonander]

will work for pultec line input

thanks. can you explain me how? it would normally be a 600:600 right? putecs woud be my ideal build. i have a big grayhill stock left as well. ps: id go for a solid state version wuith 2520s tough. would that work?

 

[salomonander]

I notice to the side of the pic ypu posted a drawing showing how to use the transformer as a hybrid. Made me think they might be ideal as a mic splitter?

Have you got a copy of publication G5 which gives the full specs?

Cheers

Ian

hey Ian

i attache one more paper. but its really tough to read. they seam to measure very, flat tough (0.5 from 20hz-30khz). i know that neve used them as mic inputs for some of their early germanium desks. would they work with an ez1290? can anyone tell?

 

[salomonander]

cant attach for some reason. but i did send this to you via email some days ago asking if they co9uld be used as pultec inputs or outputs. the attachement is in that mail

 

[ruffrecords]

cant attach for some reason. but i did send this to you via email some days ago asking if they co9uld be used as pultec inputs or outputs. the attachement is in that mail

Ah, now it all makes sense. That attachment says they are good to +12dBm which is a little on the low side for a line input.

Cheers

Ian

 

[salomonander]

cant attach for some reason. but i did send this to you via email some days ago asking if they co9uld be used as pultec inputs or outputs. the attachement is in that mail

Ah, now it all makes sense. That attachment says they are good to +12dBm which is a little on the low side for a line input.

Cheers

Ian

but fine for mic input? can you tell me if these will work on an ez1290 build as mic input?  cheers

 

[ruffrecords]

but fine for mic input? can you tell me if these will work on an ez1290 build as mic input?  cheers

Should be fine for that. The gain will be 3dB less and the noise will not be optimum but the differences should be very small.

Cheers

Ian

 

[salomonander]

thanks ian

looks like they are really not perfect for anything after all are we talking about a significant increase in noise? i think i might rather return them than building some frankenstein that might not even work properly. or - anyone want 11 of these?

 

[wolcott]

Couldn't these work with a 990 opamp ?
low ratio and all ?

 

[API]

They are specified as one of several input transformers in the Neve 1058 manual.

 

[ruffrecords]

thanks ian

looks like they are really not perfect for anything after all are we talking about a significant increase in noise? i think i might rather return them than building some frankenstein that might not even work properly. or - anyone want 11 of these?

No, the noise increase will be very small. At most it will be 3dB at the highest gain setting and should bet less at lower gains.

Cheers

Ian

 

[salomonander]

thanks. that sounds not so bad at all. does anyone have schematics for the old neve preamps that shows how the transformer is integrated in the circuit? i found one schemo but it lackss the input xformer. or is this since one was able to plug different ones in place?

have these preamps ever been done as a diy pcb?

thanks a lot for all your replies.

 

[API]

Here is the B100 preamp schematic .
I have at least one unpopulated B100 card that i could scan if someone wants to make some of these.

 

[API]

And here is the B104 output amp with externally mounted transistor.