[sdiy] 909 attack mod

[Fredrik Carlqvist]

You could try:

1. decrease the value of R44 (to increase click sound level)
2. decrease the value of R45 (to increase noise sound level)
3. increase the value of VR3 (to increase range for attack)

Changing the value of VR3 from 500 to 5k will decrease the attack
sound(s) by 10dB when ATTACK is turned to a maximum. 

If you replace R44 with a 4k7 resistor, this will increase the click by
roughly 6dB, as will changing R45 to 1k for the noise part.

I haven't tried this, but it's a fairly straight-forward mixer circuit.


Fredrik C


-----Original Message-----
From: owner-synth-diy at dropmix.xs4all.nl
[mailto:owner-synth-diy at dropmix.xs4all.nl] On Behalf Of gregory zifcak
Sent: den 18 februari 2006 21:05
To: synth-diy at dropmix.xs4all.nl
Subject: [sdiy] 909 attack mod

hi, i'm trying to increase the range of a 909 BD attack control (varies
the level of a click sound). i expected to find that the attack pot was
just a grounded attenuator in line with a resistor, but that's not the
case:

http://hardware.freepage.de/raf909/

i'm not familiar with the configuration of the pot (vr3). how can i
increase the maximum level of the attack sound? what sets the level of
VCA q6?

thanks for any suggestions,
greg