TECH21 Sansamp BassDriver DI (or something like that) *SCHEM*

[Kornell]

Mine it's working.  I'm using the gt2 tonepad pcb beacuse they are very similar."Just" needs to add and extra board to get the blending part.



Now it's time to mod!!! 

[12afael]

can you make some test around the blend pot?
I regret to say that I have not had time to find a cure for the problem of the blend, at this moment a friend is testing the pedal so I do not have it here to test it.

I suspect a resistor between the first op amp output to the blend pot could make the trick.

my last board have a little issue on SW3. I want to update it with a final solution to the blend problem.

[Kornell]

can you make some test around the blend pot?

- No problem with the blend pot but I've got some ic voltage values I don't like.

- Following your pcb would be  pins 5&6 from IC1 that vary from 3.8-5 if I change the drive pot. 

- The rest of the voltages look OK.

So when you get your sansamp back please measure those voltage to compare. Thanks!.

[12afael]

mmm I will try to check that. it must be a issue with the load because the drive pot is one stage after the ic1b.
feedback should make the input impedance bigger , if it is changing too much could be part of the problem.

I will try to check it.

[Kornell]

- I've measured those values on my behringer clone of the bassdriver and has similar values. So I supose that's the way it is. 

- It sounds  good and that's what matters,no? 

- Before trying a proper mids control I'm going to replace the 100k and 22k that controls the two mid-notchs. I don't want to end with 8 pots, too much to drill...

[12afael]

any chance of have pictures of the guts of the behringer clone?

[Kornell]

It includes true bypass, mids control and a new blend control.

Ugly Inside: 
http://img510.imageshack.us/img510/7160/dscf0378ek5.jpg

Outside:
http://img258.imageshack.us/img258/3705/dscf0377vj3.jpg

If you want more inside pictures just tell me.

[O]

Was this project ever verified? I'm getting all the parts for it, but I want to make sure its going to work before I start.

Thanks!

[Kornell]

Was this project ever verified?

- The schem is correct, except maybe  a capacitor between the clean-buffered signal and the lug of the blend pot. It works without that capacitor.

- You can use the PCB that posted 12afael, that I believe it's been verified.

- Or you can adapt the sansamp GT-2 board as I did. Just need an extra board to include the blend function. I'll ask F.Peña permission to publish the modified board and schem.

Later I'll post some clip. 

[O]

Thanks Kornell, I would appreciate it.

[Kornell]

Quick and short clip: http://boomp3.com/m/b387fec9406e

Clock settings: Presence: 1:00 Drive: from 1:00 to 5:00 Blend 5:00 Bass&Treble 11:00

Mine is not the stock version because I feel it lacks some mids and has too much bass.
If you search on  the www there's lots of  clips using the original version.

[O]

Cool clip!

I think I know what I'll be building this weekend

[alejandro69]

I build it, seems to sound good but have a question about the volume. Looking with an oscilloscope with drive = 0 and level=10 the output signal is like the input signal in amplitude (no amplification) is that correct?

When I add drive the volume increase. Regards

[DimebuGG]

Is build this weeks ago using the schematic traced by DIZ(rectangular ear bass 21). 5 dual opamps except the DI circuit. I'm not sure if the schematic is correct though but anyway this schematic has a punch after all!!I mean after building it and tested it

[O]

Is build this weeks ago using the schematic traced by DIZ(rectangular ear bass 21). 5 dual opamps except the DI circuit. I'm not sure if the schematic is correct though but anyway this schematic has a punch after all!!I mean after building it and tested it

Any pics?

[DimebuGG]

It's just the GT-2 PCB and then modified. the 5th op amp is offboard.

I'll try to post pics.

[DimebuGG]

to anyone who wants to build 12afael's layout:

Lift off  R47 and R48...."+" side of C20 faces R25 and remove the other 2.2uF cap(C21) then put a jumper on it.

Remove C17( connected to CW of BLEND pot) also and install a jumper.

[O]

to anyone who wants to build 12afael's layout:

Lift off  R47 and R48...."+" side of C20 faces R25 and remove the other 2.2uF cap(C21) then put a jumper on it.

Remove C17( connected to CW of BLEND pot) also and install a jumper.

Does this fix the "blend cutting off" issue?

[9re9]

Sould I use linear or log for pots? Sorry for the stupid question...noob to the DIY world

[DimebuGG]

Sould I use linear or log for pots? Sorry for the stupid question...noob to the DIY world

Just use linear ones but if it doesn't suffice your taste then use audio tapered. Anyway i'm using 100K linear pots.