How to connect a Blend circuit to an overdrive ? [SOLVED]

[antonis]

For Vcc =9V, make R1 = 100k, R2 = 150k, R_E = 4k7, input cap 470nF, output cap 1μF and BJT any high gain smal signal amplifier..

[eh la bas ma]

Thanks to your help, I manage to build the buffer circuit on perfboard, and connect it to the Bass OD.

It's a full success, no weird oscillations anymore. Blend control is working perfectly !

I know it's a "quick hack", for me it's a huge mod with many benefits.

If I understand correctly, blend pot allows to pan between signal going through gain stage 1 and the buffer, which is a unity gain stage, and fully clockwise, the signal going through all three gain stages, bypassing the buffer.

Buffer transistor is a 3904. It reads :

E = 9.87  V        Edit : I made a mistake with the pinouts.   C= 9.87 V
B= 5.34 V                                                                             B= 5.34 V
C= 4.70 V                                                                             E= 4.70 V

Q1 J113 is set at 7.50V
Q2 2N5457 is set at 6.50V
Q3 J113 also set at 6.50V

This is how it looks like, I am sure you'll notice the professionalism of the wiring.





I couldn't dream of a better ending : a blend control and a bass boost toggleswitch !

i always needed a couple of additional effects like compressors and preamps to use this circuit. Now it's able to hold its ground on its own, I can get a lot more of interesting sounds from it.

It's a second life for this Bass Od, a rebirth !

I can't thank you enough, you all have been really great. I will be grateful to you each time I'll use it !

Glory to Antonis, FiveSeven, PRR and Mark Hammer ! May your soldering iron tips always remain clean, and your damp sponges always wet !

[antonis]

Good work Justin..

But, I think, you've mixed up Emitter & Collector readings..

Buffer transistor is a 3904. It reads :

E = 9.87  V
B= 5.34 V
C= 4.70 V

[duck_arse]

you should draw up your completed circuit, with all mods, present it as a thing, a project, a pedal. someone else might be wanting the same thing you've ended up with.

[GibsonGM]

Time for a write-up, and possibly even some sound clips or a vid!

[eh la bas ma]

https://soundcloud.com/ehlabas-ma-chaussure/bass-overdriver-modswav

Warning : Due to the nature of the test, there can be some volume increases and decreases.

This a loop station sending a bass recording to the Bass OD, the OD is sending the signal directly in an other loop station, recording this demo. No other effects are involved.

1/ from 0:00 to 1:39'

Drive at 12'

2/ from 1:40 to 3:04

Drive set at max gain

3/from 3:05 to 4:18

Drive set at 3/4 of rotation

During these intervals, I only modify the Blend setting, and play a bit with the bass boost toggleswitch (you can hear the click).
I use the Volume knob to lower the level when I turn the blend CW, toward wet signal.

[antonis]

Good work, Justin..

Just a minor comment:
You were in lockstep with my suggestion about 2N3904 buffer input cap, which cap set in series with C2 resulted into 140nF buffer input cap (about 18Hz HPF corner frequency..)
Dunno if it's OK for bass guitar..