Basic Audio - Scarab Deluxe  [traced]

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Re: REQ: Basic Audio Scarab Deluxe

Postby Intripped » 04 Jun 2014, 23:06

...but where is the 5th film cap?
i see in the pics that there are 5 film caps, but this version has 4 only
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Re: REQ: Basic Audio Scarab Deluxe

Postby jalmonsalmon » 04 Jun 2014, 23:48

Intripped wrote:...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 :hmmm:
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Re: REQ: Basic Audio Scarab Deluxe

Postby rs » 05 Jun 2014, 23:20

Hey guys is it me or theres a capacitor and a resistor missing?
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Re: REQ: Basic Audio Scarab Deluxe

Postby IvIark » 06 Jun 2014, 00:14

Well there's definitely one extra cap and resistor in the gut shots. Maybe the resistor is current limiting for the supply or something?
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Re: REQ: Basic Audio Scarab Deluxe

Postby storyboardist » 06 Jun 2014, 14:46

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:
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Re: REQ: Basic Audio Scarab Deluxe

Postby storyboardist » 07 Jun 2014, 14:20

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:

Image

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

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

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Re: REQ: Basic Audio Scarab Deluxe

Postby roseblood11 » 07 Jun 2014, 16:16

Nice, but which one is correct now? John? :secret:
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Re: REQ: Basic Audio Scarab Deluxe

Postby ~arph » 07 Jun 2014, 16:48

storyboardist wrote: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.
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Re: REQ: Basic Audio Scarab Deluxe

Postby IvIark » 07 Jun 2014, 21:03

Someone verified it with my layout and said it sounds excellent. But it could be excellent and wrong of course.
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Re: REQ: Basic Audio Scarab Deluxe

Postby jalmonsalmon » 08 Jun 2014, 23:08

IvIark wrote: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 :applause: 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 :mrgreen:
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Re: REQ: Basic Audio Scarab Deluxe

Postby roseblood11 » 09 Jun 2014, 19:57

jalmonsalmon wrote: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...
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Re: REQ: Basic Audio Scarab Deluxe

Postby roseblood11 » 16 Jun 2014, 22:50

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

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Re: REQ: Basic Audio Scarab Deluxe

Postby jalmonsalmon » 18 Jun 2014, 21:03

roseblood11 wrote: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! :lol:
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Re: REQ: Basic Audio Scarab Deluxe

Postby HEAD » 19 Jun 2014, 13:22

roseblood11 wrote: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! ;-)
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Re: REQ: Basic Audio Scarab Deluxe

Postby roseblood11 » 19 Jun 2014, 23:17

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?
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Re: REQ: Basic Audio Scarab Deluxe

Postby HEAD » 21 Jun 2014, 12:47

roseblood11 wrote: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? http://freestompboxes.org/viewtopic.php ... 0&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. :D
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.
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Re: REQ: Basic Audio Scarab Deluxe

Postby kinski » 31 Jul 2014, 19:16

roseblood11 wrote: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?
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Re: REQ: Basic Audio Scarab Deluxe

Postby roseblood11 » 31 Jul 2015, 20:45

Has anyone built the version with the tone switch? I never tried it...
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Re: Basic Audio - Scarab Deluxe

Postby roseblood11 » 07 Aug 2015, 14:38

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...
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Re: Basic Audio - Scarab Deluxe

Postby Cub » 19 May 2017, 22:26

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/
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