Transformer at input of SOZ to convert unbalanced->balanced?

[psarin]

another newbie question -

can i convert unbalanced output of my preamp to balanced by inserting a 1:1 audio transformer at the input of the SOZ amplifier? i'm having trouble simulating this, so i was wondering if any of you experienced folks had an opinion?

also, an unrelated question: is it ok to convert a regulated +/- 40VDC power supply to a -20-0-+20VDC power supply using a couple of caps and resistors? (see figure below)

thanks

[Henrik]

Hi psarin

An inputtransformer is not a good solution here, you should look for something else. I used a linedriver (opamp) from burrbrown until I had finished my balanced zenlinestage.

This is the powersupply for for my SOZ.
It works rearley great!
This supply gives you +19, 0, -19 volt.
The 46 v is directly from the diode bridge.

The regulation is from Ciuffolis Powerfollower99.

http://www.geocities.com/ResearchTri.../my/index.html

[Nelson Pass]

Jensen Transformer in Hollywood makes a
wonderful line level balanced transformer for
this.

[Stefano]

...And wich is?

[hifimaker]

Is there a sonic improvement to externally converting an unbalanced source to a balanced source using methods, like the ones mentioned here?

I'm wondering if a balanced pre-amp or amp benefit from "balancing" an unbalanced upstream signal in this manner, ather than using existing unbalanced inputs?

-David

[Stefano]

I've found that jensen JT-11P-1 may have the caracteristics we are looking for, i wonder if is this that Nelson was thinking of, i suppose that this is the one used by jeff rowland d.g.

[Nelson Pass]

Responding to the last two posts, I believe the answer is yes
in both cases.

[tomchaoda]

Another way of unbalanced to balanced conversion is to utilize BB DRV134 chip. I know someone in Taiwan made a small kit available. The circuit looks simple enough!

Thomas

This is the image of that conversion:

[tomchaoda]

and the real kit looks like this:

[Steve Eddy]

Originally posted by Stefano
I've found that jensen JT-11P-1 may have the caracteristics we are looking for, i wonder if is this that Nelson was thinking of, i suppose that this is the one used by jeff rowland d.g.

The 11P-1's secondary unlike its primary isn't quite balanced due to the winding techniques used. You can wire it up for symmetrical output as per AS-060 though if you want to ideally balance it, you'd beed a little capacitance across one of the voltage divider resistors. I don't recall offhand how much capacitance would be required but you can EMail Jensen and they can tell you.

Another option would be to use an output transformer to balance the output of the source component. The JT-11-DMCF or DMPC would be a good choice. However if the source's output is capacitively coupled, you need to make sure it's got several hundred uF of capacitance in order to avoid low frequency resonance (which would result in some response peaking) due to the much lower primary inductance compared to input transformers.

se