Strange 'balanced' output circuit?

[L´Andratté]

Wow, that´s called *Epic Fail*

 

[JohnRoberts]

Back when schematics were all hand drawn, mistakes were more common and far worse.

JR

 

[PRR]

> AUX send level control R443 and

This gives a semi-Audio taper with a cheap linear pot.

At 50%, gain is 1:1.3 or 2dB; at 100% it is 1:7.6 or 17.6dB (as Duke says). The 15dB drop from "10" to "5" spreads a useful part of the gain change range. A single linear pot is only a part-cent cheaper than single audio taper, but for stereo gain knobs a dual linear is far more likely to track (without costly trim) than a dual Audio pot.

 

[ruffrecords]

> AUX send level control R443 and

This gives a semi-Audio taper with a cheap linear pot.

On the schematic is says 50KG - does that mean LIN??

I still don't understand why they need such a convoluted circuit to get a semi audio taper with a LIN pot. All you do is slug it with half its value and you get 10dB down at the centre.  Most Neve AUX sends worked that way. For 15dB at the centre just slug it with 5K4. Worst case load on the op amp is practically the same as their circuit but you save an op amp.

Cheers

ian

Cheers

Ian

 

[abbey road d enfer]

> AUX send level control R443 and

This gives a semi-Audio taper with a cheap linear pot.

On the schematic is says 50KG - does that mean LIN??

I would say it's an "S" curve, a somewhat linear middle portion with log and antilog-ish ends, similar to those used in well-designed "swinging-input" graphic equalizers, allowing a large-ish value that gives a low noise gain, but permits smooth end-of-travel control.
In graphic EQ's, where 30 or 31 faders end up paralleled, that's very important, because the noise gain is directly related to the number of faders.

 

[JohnRoberts]

> AUX send level control R443 and

This gives a semi-Audio taper with a cheap linear pot.

On the schematic is says 50KG - does that mean LIN??

I would say it's an "S" curve, a somewhat linear middle portion with log and antilog-ish ends, similar to those used in well-designed "swinging-input" graphic equalizers, allowing a large-ish value that gives a low noise gain, but permits smooth end-of-travel control.
In graphic EQ's, where 30 or 31 faders end up paralleled, that's very important, because the noise gain is directly related to the number of faders.

I used "S" taper back in my old kit company in the '70s so I could use the same pots for Baxandall EQ (flat at 50%) as volume controls, but i was cheap.

JR

 

[Gene Pink]

On the schematic is says 50KG - does that mean LIN??

When designating letters for tapers, they probably should have skipped "G".

When I looked at that schematic, the first thing that came to mind:

Damn, that's one heavy pot, 50 Kilograms? Hope it's not PC-mounted.
;-)

Gene

 

[abbey road d enfer]

I used "S" taper back in my old kit company in the '70s so I could use the same pots for Baxandall EQ (flat at 50%) as volume controls, but i was cheap.

No one 's gonna blame you for that; "cheap" is a quality for a designer.