Basic Audio - Scarab Deluxe [traced]

[Intripped]

...but where is the 5th film cap?
i see in the pics that there are 5 film caps, but this version has 4 only

[jalmonsalmon]

...but where is the 5th film cap?
i see in the pics that there are 5 film caps, but this version has 4 only

There is a post earlier where John says to remove C8...
I assume that missing cap has something to do with the Tone since I saw it posted on an earlier schematic

[rs]

Hey guys is it me or theres a capacitor and a resistor missing?

[IvIark]

Well there's definitely one extra cap and resistor in the gut shots. Maybe the resistor is current limiting for the supply or something?

[storyboardist]

My guess is that the tone control is probably more like the Hot Silicon/Mictester Tonebender. If ~arph's guesses on the comoponent values from the first page are right, the 8n2 cap is very close to the other tone control components...

This would be my guess:

[storyboardist]

Found out I made a mistake on my perf layout (thanks to deadmenonly for the heads up and partial verify of the layout), so disregard the layout on page 2. Here's the updated one:



I made another layout reflecting the last schematic I posted with the extra tone control components:


(Just added another row on the right side for the extra resistor and cap)

[roseblood11]

Nice, but which one is correct now? John?

[~arph]

My guess is that the tone control is probably more like the Hot Silicon/Mictester Tonebender. If ~arph's guesses on the comoponent values from the first page are right, the 8n2 cap is very close to the other tone control components...

This would be my guess:

This one i guess, it also makes more sense. The dubious 10k parallel with the 50k pot is gone too. I guess we just have to build one and find out if it's close.

[IvIark]

Someone verified it with my layout and said it sounds excellent. But it could be excellent and wrong of course.

[jalmonsalmon]

Someone verified it with my layout and said it sounds excellent. But it could be excellent and wrong of course.

I made one with your layout Mark and it sounds excellent indeed and it can stand up to my Ge Tone Bender too which is excellent! Fired up the 1st time... just need to box her up and call it done

[roseblood11]

I made one with your layout Mark and it sounds excellent indeed

Sure, but we still don't know, what's correct. There's definitely a fifth capacitor...

[roseblood11]

What we still don't know is, if John selects the transistors for a certain hfe...

-----------------

As I want to try both variations of the tone control, I added a switch to IvIarks layout:

[jalmonsalmon]

What we still don't know is, if John selects the transistors for a certain hfe...

-----------------

As I want to try both variations of the tone control, I added a switch to IvIarks layout:

[ Image ]

Sweetness... I need to order up some 2N5088s, imo I would select the lowest gain transistors out of a nice batch, and maybe try out some others with higher gains. I will try out this layout in a few days.
Thanks for the added tone control on this layout!

[HEAD]

What we still don't know is, if John selects the transistors for a certain hfe...

Any high gain tranny will do it. I prefer BC550 though... very low noise. Some 47pF caps across the collector-emittor-path of Q2 and Q3 will let it sound even smoother! A James tone controll fits also very nice. A did a build with mictester powser supply filter instead of the 47µF cap and an additional bjt output buffer after the volume pot. Near perfect to my ears!

[roseblood11]

Nice one, Helge!
Looks like the bigger brother of a "hot silicon" you posted a few years ago, if I remember that right?!

- the extra smoothing cap connects collector and base ... I hope
- the trimmer is the collector resistor for Q3?
- you are talking about this power conditioner? viewtopic.php?t=14410&p=164328
What's the voltage drop here? I read that R.G. talked about a much higher drop than you actually measured?

[HEAD]

Nice one, Helge!
Looks like the bigger brother of a "hot silicon" you posted a few years ago, if I remember that right?!

- the extra smoothing cap connects collector and base ... I hope
- the trimmer is the collector resistor for Q3?
- you are talking about this power conditioner? viewtopic.php?t=14410&p=164328
What's the voltage drop here? I read that R.G. talked about a much higher drop than you actually measured?

Thx! I build several versions of this basic circuit. Nearly every peer guitarist plays now one build by me.
To answer your questions:
- Yes.
- No. In this case it's a 100k trim pot replacing the 47k feedback-r between q2 and q3. Gives you a better control over the max available gain and compression.
- Yes. For the voltage drop I didn't care because it had no audible effect to my ears. But as far as I remember it was ~0.4V since I always use a 1N5817 schottky diode.

[kinski]

What we still don't know is, if John selects the transistors for a certain hfe...

-----------------

As I want to try both variations of the tone control, I added a switch to IvIarks layout:

[ Image ]

Hey roseblood11, did you ever build your vero with the tone switch? If so, can you hear much of a difference between the two? Any thoughts?

[roseblood11]

Has anyone built the version with the tone switch? I never tried it...

[roseblood11]

Has anyone tried to bypass the first transistor, similar to the Fender Bender? Would be great to get a sound similar to a Fuzz Face out of this circuit...

[Cub]

Found this on the blog of drdFX Stompboxes. A nice post and a link to a project PDF with a PCB layout for a 1590A ! There's also one for 125B enclosures, though the contributors to this thread already got you covered for that.
http://drdfx.hu/en/ankh/