PLAN B analog blog

From Peter Grenader:

There are two things you need to check:

1) is the amplitude of the two signals you are inputting iinto INJECT A and B equal in amplitude to begin with?

2) You need to adjust the trim pot on the second board - this effects the linearity of the cross fade . There is only one trimmer on that assembly - it's easy to find.

As far as the cross fade VC, like a VCA it does not accept bipolar control signals - only positive voltages and because of this  it can only move from one direction so yes, you need to offest the manual pot to acheive the xfade amount you need.

Jari's original post:

Yesterday I did some cross fading with M14. I used inject_a and 
inject_b inputs and got smooth cross fading both with xfade knob and 
vc_xfade input.

However, it is strange, that the xfade knob has to be set slightly over 
9 o'clock to get equal balance between inject_a and inject_b. This is, 
when no voltage is applied to the vc_xfade input. One would assume to 
get equal balance at 12 o'clock.

Furthermore, when I apply bipolar LFO sine into the vc_xfade, I have to 
readjust: To get "symmetrical" cross fade between inject_a only and 
inject_b only, the xfade knob has to be (carefully) set slightly under 
9 o'clock.

This is inconvenient in my opinion. It reminds the bandwidth/cross-fade 
knob of my M12, about which I complained earlier: Too much sensitivity 
near full counter clockwise position.

Best regards
Jari Jokinen

Thank you for your comments.

> There are two things you need to check:
>
> 1) is the amplitude of the two signals you are inputting iinto
> INJECT A and B equal in amplitude to begin with?

Checked. The equal balance is, when xfade knob is at slightly over 9 
o'clock. Signal at inject_B disappears completely at 2 o'clock (but 
comes back, if I insert a plug halfway in into vc_xfade).

> 2) You need to adjust the trim pot on the second board - this
> effects the linearity of the cross fade . There is only one trimmer
> on that assembly - it's easy to find.

Sorry. Would this change the knob response? Or does it affect sound - 
I don't want to lose the "equal power transfer"?

Best regards
Jari Jokinen
 

--- In PLAN_B_analog_blog@yahoogroups.com, "jalmari3" 
<jari.jokinen@...> wrote:
>
> From Peter Grenader:
> 
> There are two things you need to check:
> 
> 1) is the amplitude of the two signals you are inputting iinto 
INJECT A and B equal in amplitude to begin with?
> 
> 2) You need to adjust the trim pot on the second board - this 
effects the linearity of the cross fade . There is only one trimmer 
on that assembly - it's easy to find.
> 
> As far as the cross fade VC, like a VCA it does not accept bipolar 
control signals - only positive voltages and because of this  it can 
only move from one direction so yes, you need to offest the manual 
pot to acheive the xfade amount you need.
> 
> Jari's original post:
> 
> Yesterday I did some cross fading with M14. I used inject_a and
> inject_b inputs and got smooth cross fading both with xfade knob and
> vc_xfade input.
> 
> However, it is strange, that the xfade knob has to be set slightly 
over
> 9 o'clock to get equal balance between inject_a and inject_b. This 
is,
> when no voltage is applied to the vc_xfade input. One would assume 
to
> get equal balance at 12 o'clock.
> 
> Furthermore, when I apply bipolar LFO sine into the vc_xfade, I 
have to
> readjust: To get "symmetrical" cross fade between inject_a only and
> inject_b only, the xfade knob has to be (carefully) set slightly 
under
> 9 o'clock.
> 
> This is inconvenient in my opinion. It reminds the bandwidth/cross-
fade
> knob of my M12, about which I complained earlier: Too much 
sensitivity

> near full counter clockwise position.
> 
> Best regards
> Jari Jokinen
>