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

[Bernardduur]

Check, no mids

[George Giblet]

To get rid of the mid notch: put the R10 and C10 values back how they were in the original schematic and delete parts C15, C16, R18, R21.  These parts serve to mimic a typical bass amp EQ for the DI in the original.  For a mid control you can use any mid control you like. Place it before or after the bass/treble controls.    The Tech21 TRI-AC shows an example.  Unfortunately for the Bass unit adding the mid control will cause the signal to invert.

[tommy.genes]

While we're talking about this, can we identify what the various tone-shaping portions of the circuit are? Here are the ones I can recognize:

1. One just before the presence control including R3, R14, R15, C5, C6 and C7. This is a LPF yes?

2. The presence control is a freq-dependent gain (top boost?) by virtue of C11

3. One just before / including U2:C, another LPF?

4. The mid-notch George just described above with R18, R21, C15 and C16

5. U2:D has some tone tweaking, possibly in conjunction with #4?

6. U1:C has C22, which would make gain freq-dependent, yes?

7 . U1:D is obviously the TREBLE and BASS controls

Thanks,
-- Don P. --

[George Giblet]

> One just before the presence control including R3, R14, R15, C5, C6 and C7. This is a LPF yes?

Oh, forgot about that bit.   It's a kind of HPF *BUT* it also has a whoping deep notch!  To get rid of the notch pull R3 (100k).

You could try pulling that instead of, or as well as the R18, R21, C15 and C16 stuff.

[Ed: I might add that the plot I gave with the slight mid-notch  only shows the effect of R18 through C16 (and one of the low-pass filters).]

[Shakal]

OH yeah, but that's what I said, you don't need the "mid pot" to have mids.

[Shakal]

How do I make the VCC+ and VCC- of the TL074? 9V and GND? Or do I have to use 9V and -9V ?

[12afael]

I don´t see a big improvemet using a +- supply (but you can use two 9V in serie to have more headroom). just connect vcc to 9V and Vcc- to ground , remember VB is VCC/2-

[Shakal]

Ok, thanks.

So... No losses using GND as Vcc- ?

Vb it's on the schem, no problem with that. I just need to know about the Vcc- and Vcc+ cuz I'm making the layout.

[12afael]

I´m making a layout too it is 90 routed I just need to put the values and make some order with the names and values.
if you want to wait a couple of days it will be available here.

[Shakal]

REALLY?? 

Man!!! I will aprecciate that! I was killing myself on the layout!

Thanks!!

[funkbass187]

so i don't start with my own version for no reason, would that be a perf, etch or vero layout?

[Shakal]

I don't like perf or vero. PCB is better!

[funkbass187]

i prefer vero, but i guess this circuit might compel me to enter the world of etching.

[12afael]

PCB of course, too much parts for vero o perboards .

[Shakal]

Just curious...

Do you use Fibergrass boards? How do you etch it? How do you drill it?

[12afael]

I have a question about C33, it is near a specific op amp??? it don´t seems to be bias or supply filter(220uF is enough) maybe is a decoupling cap for a specific op amp in that case 47u is a very high value...

I use standard boards is not easy get fiberglass boards here, I use a laser printer and glossy paper and I have a big drill . my arm is crying out for a little one...   

[Shakal]

So, laser print + glossy paper really works huh...

Well.. I don't see any C33, even if I had I would not be able to answer, maybe George would.

[12afael]

the pcb that I´m routing is for the triangular ear schematic using 2 quad op amps and two dual op amps . if you don´t want the balanced output you can save one op amp for other project.

[12afael]

ok here is the pcb , part list and schematic all in one file trying to be like FP

http://download.yousendit.com/4A8AEB7F6152F83B
and
plexilandia.googlepages.com


this is an UNTESTED board, if you try it and it have an error please post it here.

enjoy
12afael

[michal_k]

thanks a milion, i'm gonna build and test it as soon as possible.