Who played a Double Drive?

Thomas P. · November 16, 2003, 12:53:04 PM

I just saw the schematic and found the whole design quite interesting. Mow I'm thinking of building one and therefor ask if the sock unit is nice sounding?
I might build one anyway (since I worked hard on a PCB the last two hours :wink: ) but it would be great to hear some thoughs about it!

Ansil · November 16, 2003, 08:56:49 PM

some people say that you have to use the same opamps described but i did a modified version witha lm324 leaving out two opamps and got a great sound.

Marcos - Munky · November 17, 2003, 12:59:19 PM

I'm building one for my guitar teacher. Didn't finished it yet, but the soundclips sound very cool.

Thomas P. · November 17, 2003, 01:06:19 PM

Quote from: Marcos - MunkyI'm building one for my guitar teacher. Didn't finished it yet, but the soundclips sound very cool.

Did you do a layout? I did and if you like to post it I'll send it to you.

Marcos - Munky · November 17, 2003, 01:37:25 PM

Hey Tom, send me the layout. I used the one from Runoffgroove (now the new layout, the old one).

Arn C. · November 17, 2003, 02:41:03 PM

I built one when it first came out, can't remembe the sound tho. I did build it with two stompswitches, one for true bypass and one for "jiggle & bounce". I will plug it in tonight again and mess with it and tell you more tomorrow how it sounds to me.
Arn C.

Ansil · November 17, 2003, 02:58:44 PM

Quote from: Arn C.I built one when it first came out, can't remembe the sound tho. I did build it with two stompswitches, one for true bypass and one for "jiggle & bounce". I will plug it in tonight again and mess with it and tell you more tomorrow how it sounds to me.
Arn C.

that is the double D from runnoff groove.. we were talkin about the double drive.

www.sansamp.com

Arn C. · November 17, 2003, 03:21:33 PM

OOOps! sorry bout' that!
Made a pedal similar to that once tho.
I made two identical jordan bosstone circuits with bmp tone controls for each and put them in a pedal. I had a true bypass switch and a switch to toggle between each circuit. I named one (lead) and the other(rhythm).
I only used 3 pots(but each pot had two separate pots-like car radios)
I also used dual led to tell if I was using the lead or the rhythm and a separate led for in/out.
Arn C.

Marcos - Munky · November 17, 2003, 07:36:01 PM

I was thinked about the Double D too. It's the one that I'm building.

gtrmac · November 17, 2003, 08:11:25 PM

I'm interested in the Runoff Groove Double D also. The sound clips sound very good on his website and I'd like to do a PCB for this one but I'm just getting started with that stuff.

Gringo · November 22, 2003, 06:47:29 PM

I was looking at the schem of this baby, and i've got a couple of doubts:

http://www.axiomdrift.com/schematics/DD%20PN.gif

1. What jfets are used here?
2. Where do the diodes from the jfets gate go connected?
3. Has anyone made a pcb layout for it?

Thanks!

p1_ind · November 22, 2003, 09:39:50 PM

1. You could most likely use about any N channel jfet like a j201, mpf102, etc.
2. The diodes are connect to the switching circuit, when one of the inputs to the diodes on the jfets is high the other is low and vice versa so that it will switch from effect to bypass.
3. I can't help here, I haven't built one.

Good luck,
Adam

Gringo · November 23, 2003, 09:09:12 AM

What kind of switch/switching circuit is supposed to be used?

Could you explain it a bit more 'foolproof'?

Thanks for your answer!

Thomas P. · November 23, 2003, 11:38:44 AM

I think he drew the fets only to show that there is a switching circuit. It doesn't show all of it since most of us will leave it out and do 'ordinary' true bypass.
I believe it is a circuit like all Boss effects use to have.

Gringo · November 23, 2003, 02:08:14 PM

So, if i was to build it using true bypass, how should it be wired?

Removing the fets and wiring R18 to the non inverting input of the last op-amp would do the trick?

Does the output of the first op amp (marked A in the sch) need to be connected to the same point too? (the non inverting input of the last op)

I'm a little confused :oops:

Thomas P. · November 23, 2003, 02:35:14 PM

I think you should look at those fets like they were toggle switches. Only one of the can be closed at a time. This means if the one connected to the input IC is closed the other is open and you have bypass operation. The other possibility is that it is open and the other is closed. Now you have non-bypass aka effects mode.
If you like to have true bypass your switching appears outside of the circuit. Therefor you shloudn't connect those to points because whithout a fet this would give the clean signal to the output all the time.

Maybe now it's clear :wink:

Gringo · November 23, 2003, 03:10:29 PM

I think i got it right now

I should kill both fets and connect r18 to the + input of the last op amp, right?

Thanks for your help, and please correct me anyone if i'm wrong.

Maneco · November 23, 2003, 03:19:41 PM

Hi,
looks like r18 and the last opamp can be also omited,connect the 2,2 cap to the output of the tl072 buffer,and go with millenium bypass...

best

Maneco

Thomas P. · November 23, 2003, 03:23:50 PM

I wondered about this double buffer, too. I think you're right but I hate it to leave half an IC unused for some reason :wink:

J. Luja · November 23, 2003, 03:44:01 PM

try it like this

-Jeremy

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Who played a Double Drive?

Ansil

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