A Question about SuSy and the X2

[metalman]

Quote from the 1998 article Super Symmetric Amplification by Nelson Pass

Su-Sy is an approach that takes advantage of balanced operation like no other design and requires a balanced input to retain the precisely matched behaviour. You can drive one input alone, and the circuit will amplify reasonably well, but it will not exhibit the very low distortion character of fully balanced operation.

Rev's 0 & 1 do not appear to use X-feedback, but assuming that the O and I of the UGS modules from Rev's 2 & 3 stand for Output and Input, it would appear that X-feedback is being used on the output gain stage. However, as the balanced inputs are converted to single-ended before being fed to the output stage, the quoted passage infers that the benefits of Supersymmetry will be negated. Am I interpreting this correctly, or am I being fooled by the mystery internals of the UGS?

My main motivation in asking this is to determine if my substantial effort to produce a fully balanced stereo stepped attentuator, and convoluted input/output switching arrangement for my CC-CCS-X-BZLS could have been avoided.

Care to comment Nelson?

 

[thomasfw]

Mr Nelson,

My head is burning with same question !!!
Please tell us some information !


Thomas

 

[Nelson Pass]

Rev's 0 & 1 do not appear to use X-feedback, but assuming that the O and I of the UGS modules from Rev's 2 & 3 stand for Output and Input, it would appear that X-feedback is being used on the output gain stage. However, as the balanced inputs are converted to single-ended before being fed to the output stage, the quoted passage infers that the benefits of Supersymmetry will be negated. Am I interpreting this correctly, or am I being fooled by the mystery internals of the UGS?

The earlier X2 circuits use very little X feedback, but it is there.

The UGS module, like all the later circuits, is perfectly happy
being driven single-ended. It just takes the difference between
the driven input and the grounded input.

The initial SuSy circuits of the X600 and X1000 required balanced
inputs for best operation, but we were able to remove that
restriction in subsequent product.

 

[Darry]

Hello M. Pass

Is It possible of driver X600 in single-end with this adaptor?

ADAPTOR, XLR PLUG/PHONO JACK; Connector type A:XLR Male; Connector type Bhono Jack

Thanks for the answer

Regards

Darry

 

[Nelson Pass]

Yes, but I beleive it simply allows you to connect the RCA
hot to input pin 2 of the XLR, and does not give balanced
performance.

You can drive the 600 and 1000 with single-ended inputs,
but they develop greater 2nd harmonic (and other) distortion.

 

[jh6you]

Re: Re: A Question about SuSy and the X2

The earlier X2 circuits use very little X feedback, but it is there.

Now I see there is a little X-feedback. And, I see that the Earth is round. I did not know that, when I play golf, actually I play with two balls: one small and one biggg. Yes, I should hit the small ball first and then hit the biggg ball. I do opposite way sometimes.

Regards