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-   -   transformers? (http://www.diyaudio.com/forums/solid-state/42897-transformers.html)

cunningham 20th October 2004 12:49 AM

transformers?
 
What do you guys think of using interstage audio transformers for coupling say, preamp to amp, or somewhere in between? Low power, 100mW... shielded?

frequency responce?

noise?

inductive componants?

and any other details that might come to mind.

djk 20th October 2004 08:06 AM

The ones in the Mouser and DigiKey cat are for phone use, no bandwidth.

http://www.edcorusa.com/transformers.../pc10k-10k.htm

http://www.edcorusa.com/transformers...wsm10k-10k.htm

If you want it in a box:

http://www.edcorusa.com/sound/matchers/s2s10k_10k.htm

Jensen are better, but 10X the cost.

richie00boy 20th October 2004 08:45 AM

They have the advantage of high isolation so no ground loops and it's easy to configure them for common-mode rejection. However. you pay for this by worse frequency response all round, size, susceptibility to magnetic fields and to get a decent part you need to spend a lot of money (relatively).

cunningham 21st October 2004 02:34 PM

Thanx for the info

To be more precise, something like the 429-7209 transformer (500Ohm:500Ohm) on this page of the mouser catalog. Is it possible to build a passive filter to sort of even the freq. responce?


http://www.mouser.com/catalog/619/609.pdf

djk 22nd October 2004 01:13 AM

'audio' in this context means 'telephone'(300hz).

Buy the $5 ones from Edcor, they go to 30hz.

quasi 22nd October 2004 05:49 AM

Never never never transformer couple within a solid state amp.

All the benefits gained for the solid state architecture (slew, speed, noise, distortion, frequency response) will be compromised.

This is why you don't find them in commercial solid state amps / pre-amps.

All transformers exhibit a frequency dependant impedance. This makes them very useful in power supplies but not in audio.

Except maybe the design from Susan Parker with the mosfet -transformer coupled output. I personally don't like the idea but it's a different approach that is interesting and well suited to complex loads ie; very long multiple speaker runs. (Outside the scope of this thread).

The only reason they are used in valve amps is to isolated the speakers (and people) from the stupid voltages inside.

Elso Kwak 22nd October 2004 06:58 AM

Quote:

Originally posted by quasi
Never never never transformer couple within a solid state amp.

All the benefits gained for the solid state architecture (slew, speed, noise, distortion, frequency response) will be compromised.

This is why you don't find them in commercial solid state amps / pre-amps.

All transformers exhibit a frequency dependant impedance. This makes them very useful in power supplies but not in audio.

Except maybe the design from Susan Parker with the mosfet -transformer coupled output. I personally don't like the idea but it's a different approach that is interesting and well suited to complex loads ie; very long multiple speaker runs. (Outside the scope of this thread).

The only reason they are used in valve amps is to isolated the speakers (and people) from the stupid voltages inside.

Well, you obviously never heard of Steve Eddy...... :clown:
http://www.q-audio.com/

quasi 22nd October 2004 07:14 AM

Well, you obviously never heard of Steve Eddy......

This is a commercial marketing site not a research site.

With respect, I don't pay any attention to marketers. (in audio anyway).

Still I'd be interested to see how you can get get 0.25 hz through a transformer that is smaller than my car ...There is probably a lot of other stuff in there (at least I hope there is).

Carondimonio 22nd October 2004 07:18 AM

Quote:

Originally posted by quasi

Still I'd be interested to see how you can get get 0.25 hz through a transformer that is smaller than my car ...
What would anybody need 0.25 Hz for in audio?:scratch:

quasi 22nd October 2004 07:20 AM

ok ok ok ...maybe you can get 0.25hz through a transformer smaller than my car.

It would take a lot ( i mean a real lot) of wire on the secondary and primary ...actually maybe the winding would as big as my car ....oh well you get the picture.


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