DEMO Sabbath Drive, Tweed Sound and Marble Drive

[jjjimi84]

Build Rating

5.00 star(s)

A while back I got this solid state amp (Vox MV-50) in a trade and bought the matching cabinet to go with it. My son was playing a bit of guitar at the time and was having fun using it. Like most 11 year olds, he lost interest in guitar for now and is playing clarinet and loving it! I grabbed the little amp and started messing around with it and found it takes amp in a box style pedals really really well. This made me dig out as many as I could find painted and started filming with this thing right away. This is the first of a bunch of them coming out this month, I love this breed of pedals and am loving the sounds out of them.

3 DIY Amp In A Box Style Pedals

First trio out of the gate is the Tweed Sound;

Built in a tayda yellow enclosure, completely stock with a little dog painted on there with an epoxy pour coat.

Next up is the Marble drive in a bare enclosure with posca paint pens and a epoxy pour.



Last is the sabbath drive, in a red enclosure, flowers of the dead painted on there in an epoxy coat. All stock builds and just rippers!

 

[BuddytheReow]

All kinds of classic rock!

 

[AceHyzer]

Sounds killer, even through that little SS amp! I especially liked the Jimi riffs in the middle there.

 

[lowpitch]

Digging that Sabbath. I may have to put one in my next order. Seems noisy though. You think shortening the leads on the JFET adapter boards would help or is it just inherent to the circuit? Maybe someone else can chime in who built one?

 

[jjjimi84]

All kinds of classic rock!

This little amp has made me a solid state convert, it sounds really great and with amp in a box pedals, it slays!

Sounds killer, even through that little SS amp! I especially liked the Jimi riffs in the middle there.

Thank you! I have stolen the most from him, it comes out heavy some times.

Digging that Sabbath. I may have to put one in my next order. Seems noisy though. You think shortening the leads on the JFET adapter boards would help or is it just inherent to the circuit? Maybe someone else can chime in who built one?

That sabbath circuit was being a total bastard that day and was all kinds of noisy. I am sure there has got to be a @Chuck D. Bones version of it on here.

 

[micmac]

I built the Sabbath a few weeks back and remember that I used a vero transistor switcher to test a few trannies for Q1, the one in the treble booster. I tried a BC184B, a (2N or PN, can't remember) 2222A and a BC549C. With the gain half way up or so two of them were very noise while 2222A was fine. Soundwise I couldn't tell a difference. So I stuck with the 2222A. Just saying, might be a simple fix.

 

[micmac]

I think I was wrong about Q1. It looks like taking a lower gain transistor alleviates the symptoms, but doesn't fix the problem.

After I wrote the above yesterday night, I connected the pedal and played into it for a while. At 9V everything was fine, no noise even at full gain. After a while I replaced the 9V power supply with a 18V power supply. And as I turned the gain up, starting at about 3 o'clock, the noise was back. I would describe it as a humming or rumbling.

This morning I woke up and replaced the wires between the 3PDT and the input and output jack with RG174 shielded wire. No change.

Next I compared the Sabbath schematic with the Bohemia one, because I thought the circuits look pretty similar and I don't have this problem with the Bohemia (I double checked at 18V). And then I realized that they control the gain differently. The Bohemia changes the gain of the treble booster stage while the Sabbath changes the gain in between the two mu amp stages.

I thought maybe there's something off with the bias of Q4 or Q5. I remembered that I used PN4393 and my cheap T7 tester had measured a VGSoff of about -1,5V. So I took out Q4 and replaced it with a PN4393 with a VGSoff of ~ -2.1V. Checked, no noise. Took Q4 out and put the old one in again. Noise was back. Then I took Q5 out and put the -2.1V JFET in. Again the noise was gone. So for good measure I replaced both Q4 and Q5 with PN4393s with VGSoff of ca. -2.1V.

Then I replaced the 2N2222A in Q1 with a BC184B. Noise was still gone. So I left it like this, no noise, fun to play into.

P.S.: Found another issue I was playing along to some tunes and occasionally I heard sag/gating. Mostly single notes. I tried to find a way to recreate this easily and found that all I had to do was hit a single note hard directly over the bridge pickup. I tried this with two different guitars and it was like this with both. It only happened at 18V, though, at 9V it didn't. So I had an inkling that I needed to replace Q2 and Q3 (one of them might be enough I reckon from previous experience, see above) as well with lower VP. So I put -2.1V VP in and this problem was gone, too. It looks like this circuit is a little fickle as far as VP is concerned

I'll share my voltages (naming like in PedalPCB schemo):

Q1
C 5.80
B 2.04
E 1.47

Q2
D 4.93
S 1.55
G 0

Q3
D 8.92
S 5.96
G 4.24

Q4
D 4.14
S 1.39
G 0

Q5
D 8.92
S 5.84
G 4.24

Q6
D 8.92
S 5.27
G 4.03

Pretty much what this guy on diystompboxes.com ended up with.

 

[Damaraja]

A while back I got this solid state amp (Vox MV-50) in a trade and bought the matching cabinet to go with it. My son was playing a bit of guitar at the time and was having fun using it. Like most 11 year olds, he lost interest in guitar for now and is playing clarinet and loving it! I grabbed the little amp and started messing around with it and found it takes amp in a box style pedals really really well. This made me dig out as many as I could find painted and started filming with this thing right away. This is the first of a bunch of them coming out this month, I love this breed of pedals and am loving the sounds out of them.

3 DIY Amp In A Box Style Pedals

First trio out of the gate is the Tweed Sound;
View attachment 84939View attachment 84940
Built in a tayda yellow enclosure, completely stock with a little dog painted on there with an epoxy pour coat.

Next up is the Marble drive in a bare enclosure with posca paint pens and a epoxy pour.
View attachment 84941
View attachment 84942

Last is the sabbath drive, in a red enclosure, flowers of the dead painted on there in an epoxy coat. All stock builds and just rippers!
View attachment 84937
View attachment 84938

Cool looking pedals ️