SansAmpGT2 Switching

mydementia · August 31, 2006, 10:30:52 AM

I thought I'd try an over-achiever pedal after my Shaka Tube (parts in the mail) and zeroed in on the SansAmpGT2 from Tonepad (http://www.tonepad.com/getFile.asp?id=79). I've read through all the information I could find on the switches and still don't understand how they work. I saw that someone used rotary switches instead...
If anyone can help with switch wiring on this beast, I would greatly appreciate it.
Thanks in advance.
Mike

theman · August 31, 2006, 12:56:31 PM

I built this a while back, and it did take me a while to figure out the switch wiring ... it's a bit confusing. Anyways, here's a wiring diagram. It is shown looking into the back of the enclosure. You can match up the switch labels with the labels on the PCB. After wiring, the is PCB folded down over the pots and switches, oriented such that the component side is DOWN, and the trace-side UP. This is because of space reasons in the box I used. I also switched the positions of the bass and treble pots (on the front, from left to right, the order is DRIVE, LEVEL, LOW, HI). I also switched the positions of the switches so that left to right it is AMP:MOD:MIC which made more sense to me rather than have the MIC switch first. You can get the Alco switches from Small Bear. It is a pain to wire these up because they don't use solder lugs ...

You need to take care in wiring this up because of the very high gain. I still get some squeals, but only at almost max treble and level settings (which is already extremely loud). The input and output wires need to be far from other wires/components, or shielded. However, it's hard to shield all the wires coming and going to the switches.

Critical for the sound is using the TLC2262 for all ICs except IC1 which can be a TL072CP or any compatible dual op-amp. I use a NE5532 (more current draw, however), and it sounds more pristine and cleaner, with the TL072CP warmer, but a bit more muffled in comparison. The NE5532 might sound too crisp and bright for some, but you can always tame it with a little EQ on your amp. I find this better than trying to coax any crispness or clarity from something which lacks it to begin with ...

BTW, the Behringer GDI21 is a clone of the GT-2 as well, but I think it uses SMT components. For $30, it cannot be beat! It sounds a bit warmer with less clarity than a GT-2 clone built with premium components (metal film R's, poly caps, etc.), but for high-gain, they are close. The GDI21 has a bit more oomph in the bass, but not as tight. The GDI21 also has an XLR out as well. Amazing for the price ...

Have fun!

mydementia · September 12, 2006, 10:33:33 PM

Found these 4P3T switches at my local surplus store...would they work for this project? (Aside from being twice as large as necessary

)
Maybe this will be another good 60-cent find...

Thanks for looking.
Mike

Aharon · September 13, 2006, 07:49:45 AM

Just check with your tester if you are not sure.Pin 0 should connect with 1/2/3 in each throw.The good thing that comes to mind with those switches is that the extra connectors could be used for LEDs to tell you what settings you are on .
Great.

Aharon

mydementia · September 13, 2006, 10:20:09 AM

I'm pretty sure these switches are 1-2 / 2-3 / 3-4 connected...but I'll check them out this evening.
Any thoughts on what to do with big switches like this?
Thanks again for looking.
Mike

KaptenSpark · September 13, 2006, 12:36:57 PM

Isn't it possible to use standard rotary switches instead of those strange ones suggested?

Aharon · September 13, 2006, 02:12:02 PM

Yes,rotary switches are fine.
Aharon

mydementia · October 18, 2006, 10:53:03 PM

Just finished populating the board, wiring the pots, and running the wire for the switches...
When I use 3P4T rotary switches, I just wire the '0' lug to the pole and 1, 2, 3 to the 'T's' - right? This would give the three positions:
0-1
0-2
0-3

Just want to be sure before I solder my last 24 joints...

Thanks in advance.
Mike

Izzy · October 18, 2006, 11:00:53 PM

I wanted to try this pedal too. I wanted to nkow is it possible to do on a strip board?

mydementia · October 19, 2006, 09:59:46 AM

Izzy,
I saw your question on the other post and still don't get it...
ANY circuit can be built on stripboard...it's just a matter of the incredible pain in the ass a circuit of this size would be to build and (especially) to debug.

If you can't make your own PCB's - I highly recommend buying one from Tonepad...then they'll help you debug.

Mike

Izzy · October 19, 2006, 10:49:15 AM

Thanks.

Thats what I mean , this circuit is huge so I was wondering if this would fit in 1 stripboard or not, haha may be 2 is needed.

I dont want tot buy PCB because I wanted to make this so that i can learn not because I really need it. If I buy PCB then its gonna be easy, haha.

mydementia · October 19, 2006, 11:03:43 AM

Izzy - you do realize that stripboard comes in 8x10 sheets (probably bigger...that's just the largest one I've purchased). If you're looking to learn - try some of the projects from the layout archive found here. You can build your own stripboard layout from the schematics or modify a PCB layout for stripboard. You can do all these things using bancika's DIY Layout Creator software (sticky on top of this board).

The SansAmp has a LOT of parts. Translates to a lot of solder joints --> lots of chances for shorting across strips --> lots of frustration.
I think what you'll learn by trying to do this project on stripboard is that it's really easy to build a complicated circuit that doesn't work...

Just my 2-cents.
Mike

Izzy · October 19, 2006, 11:21:23 AM

hahah yeah you are right.

I guess I should use one of these board.

http://www.smallbearelec.com/Categories.bok?category=PC+Boards+and+Prototyping

Izzy · October 19, 2006, 05:49:21 PM

I dont get , how those Amp, MIC, MOD switch are labeled over here.

whats 2A, 2B, 1A, 1B, 3A,3B?
Can somebody explain?

Izzy · October 19, 2006, 09:21:09 PM

Anyone?

mydementia · October 19, 2006, 10:33:34 PM

Howdy y'all. I just finished the Sansamp tonight and have to say it's awesome.
I haven't boxed it up yet...so I'm not sure which models I was diddling through, but there's a HUGE range of tones in this thing.
Definitely have some squeel on the higher gain settings...have to keep reading up on the remedies here...but I really like it.
Here are a few snapshots of my build process...

Awesome stuff...and a fun build. It worked on the second try (had signal going to ground somewhere causing low output on the first fire...no problem). I still want to try the recommended dual op-amps (TLC2262) - I got a bunch of TL072's on ebay so that's what I used here. Anyone know a good place to get TLC2262's? I plan to shoehorn this into a 1590BB with no switch... I hope it all fits!!

Izzy, I'm not sure what you're asking. The Tonepad site clearly states that Switch 1=Mic, 2=Mod, 3=Amp. I used 4P3T rotary switches for mine because I was too lazy to order the Lorin's from Smallbear...

Thanks to Tonepad for an awesome project file and to FP for a great PCB.

Mike

Izzy · October 19, 2006, 10:49:55 PM

I mean I dont get how the switching works.

Why there are 6 switch shown?

mydementia · October 20, 2006, 09:39:10 AM

Izzy,
The switches are DP3T's (two pole, three throw)...and there are three of them (see the last picture in my build post). You connect the '0' to the pole and 1-2-3 to the 'legs'. I used rotary switches - they're big...but readily available and work just fine.

Fp-www.Tonepad.com · October 20, 2006, 04:01:28 PM

cool

saemskin · October 20, 2006, 05:34:03 PM

Quote from: Izzy on October 19, 2006, 10:49:55 PM
I mean I dont get how the switching works.

Why there are 6 switch shown?

Each switch has 8 pins, 4 on each side A and side B. Thus S3A and S3B are both switch 3. If you look closely at the pics dude posted you can see this

News:

SansAmpGT2 Switching