ROG Double Drive

[mcalaff]

Hello!

Someon has made the ROG Double Drive?

http://www.runoffgroove.com/doubled.html
http://solderman.fatabur.se/Dr%20jekyll%20Mr%20hyde/DIY_rhcp.jpg

I made this pedal using a Soldersound Dr. Jekyll & Mr. Hyde PCB design but I have some problems.

It sounds noisy with oscillations and ony disappears a little when the "jiggle" chanel is activated.

I tried to adjust finely the rimpot but...

Someone had this problem?

[stecykmi]

i built one a few years back on an etched version of the ROG-supplied board.

i would ensure that you are using a low-noise power supply as the circuit is sensitive to noisy power supplies (like most high gain circuits). a battery can be used, even just for temporary testing purposes.

failing that, check the first gain stage for the cause of the noise. i would use an audio probe to see if the oscillation is present just after the gain stage.

if it's not there, you may have a problem around 4049 chip. make sure the feedback capacitors (100p, 47p, 470p, etc...) are properly connected to the circuit, if they are not, the gain stage might be prone to oscillation.

[Vallhagen]

By a quick look: I dont see the 470uF 100Ohms parts for the +V of the IC, on the solderman layout? Am i blind or isnt it there?

That power filtering is important.

Cheers

[mcalaff]

Thanks!

I use a BOSS PSA 230S but just today I bought a decent power supply. I have a C4049 and a C4049 buffered and the worst results goes to the buffered version.

If I can tomorrow I check the capacitors, all the pcb and make a audio record.

Yes, the 470uF and the 100R resistor are omitted but I modified the the Soldersound PCB to use this parts.

[mcalaff]

I added too the diode protection

[Vallhagen]

You shall use the 4049U, unbuffered version. But you allready noticed that:)
as you have fixed the power filtering thing...
... next thing i would do is checking the input buffer stage.

[mcalaff]

Hi,

I make a sound test:

0:00-0:40 adjusting the trimpot on "bounce" chanel.
0:40-0:60 sorry ground is disconnected.
0:60-1:24 "jiggle" chanel.
1:24-1:38 "bounce" chanel.

https://soundcloud.com/calaff-customfx/rog-dd/s-NPJ55

I use a 4049UBE and J201

Thx!

[Vallhagen]

Hi again.

First; obviously you can dial away those nasty oscillations with the input stage trimmer. Good so far.
I do hear the highpitched noise though. Can you affect that at all with the trimmer?

Then... as you play it in the soundclip, its not boxed at all, means open for any interference in the air?
Also, how far are you from unity volume?
And, do you feed it with a battery or wallwart? You really should try a battery, just to close out the possibility of a bad supply.

I have played a lot with the 4049UBE, and also the stage layout from the circuit you have built, the Double D. But actually i have never done it exactly as the original schematic with jFET input and output buffers. Some from my experience:

You cant really play the Bounce part with full gain. It is simply too much. I dont mind though, i think its good when the usable range of a pot is less than the possible min-max-settings on the knob. It means that the circuit is fully used. Though, in this case I would replace the 10k resistors in serie with the gain pots with 1k.

Also, the circuit needs to be tamed a bit treble-wise. it needs some sort of treble-cut/tone control.

On my designs i have separated the +VDC rails for the 4049 and for "the other parts". Im not sure it affects this design, but maybe it does. As i said earlier, the 4049 is sensitive for correct power filtering.

Cheerio

[mcalaff]

Hi! and thanks!

Adjusting the trimpot I delete the oscillation but ony reducing the volume. The noise not disappears.

On the soundclip the volume is at 75% aprox. and the gain at maximum.

Yes the PCB is unboxed and I use crocodile cables to connect the jacks. The pots and the switch are wired on the PCB.

I use a Carl Martin Pro Power to power the PCB.

Next test: put into a box and use a battery.

Thanks another time!

And sorry but my english is so bad... and googleized...