Xotic - SL Drive

General documentation, gut shot, schematic links, ongoing circuit tracing, deep thoughts ... all about boutique stompboxes.
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aion
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Post by aion »

A semi-original from Xotic... some RAT similarities, but plenty of differences compared to your average RAT clone.

Schematic:
Xotic SL Drive schematic
Xotic SL Drive schematic

Full tracing journal here:
https://aionfx.com/news/tracing-journal-xotic-sl-drive/

PCB available here:
https://aionfx.com/project/silvanus-amp-drive/

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John G
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Post by John G »

I did a reverse on my sl a couple of years ago. I see some differences.
R19 (270 OHM) IN SERIES WITH THE H/MID CUT SWITCH AND C11. I measured C11 as 100nF.
C12 and R18 were placed before the tone pot just after R17.
I believed the IC was an NE5532, BASED ON THE CURRENT DRAW OF THE PEDAL.
Hay !! I could have got it all wrong ??
John

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Post by Ichabod_Crane »

You're talking about R19, a resistor that seems missing in the Aion tracing. Maybe there are different edition of this pedal? That resistor could explain a different value for C11 capacitor.

While, C12 and R18 placed before the Tone pot change drastically the Tone pot action, I guess, and it will work just exclusively thank to the C11 and Hi/Mid cut switch. But once you open the switch maybe the Tone pot lose almost its function.
I have to try it with my software emulator.

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aion
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Post by aion »

John G wrote: 26 Nov 2023, 05:58 I did a reverse on my sl a couple of years ago. I see some differences.
R19 (270 OHM) IN SERIES WITH THE H/MID CUT SWITCH AND C11. I measured C11 as 100nF.
It's possible this was a revision of some sort, and the missing R19 and R20 in the numbering would certainly support this - but mine definitely did not have a resistor. It goes directly to the bias voltage on the 2nd board via header pin 6. 100n is a very steep treble cut and so I would wonder if that might have been an inaccurate measurement (possible if it was measured in-circuit). A series resistor would reduce the impact of the 100n, though not by much if it was only 270R.
John G wrote: 26 Nov 2023, 05:58 C12 and R18 were placed before the tone pot just after R17.
As Ichabod said, this would mean that the tone knob would have very little effect unless the DIP switch was engaged, because otherwise there's no C for the R-C filter, just a fixed cut.
John G wrote: 26 Nov 2023, 05:58 I believed the IC was an NE5532, BASED ON THE CURRENT DRAW OF THE PEDAL.
That's a good catch... I just reviewed my photos and realized that the IC was sanded so it is not necessarily a TL072 as it says in my schematic.. I think I just used that model in the CAD drawing and forgot that it wasn't actually confirmed when it came time to publish. I'll get it corrected.

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Post by John G »

Hi, As I have stated I could have got it wrong.
My reasoning is this, to me the tone cut (treble) cct comprises tone pot(50KC) and C12, R18 a variable low pass filter that is permanently fixed. The C11, R19 is an additional HF cut via sw3. If this switched network was after the Tone pot then its operation will depend on the position of the 50Kc pot.
John

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Post by roseblood11 »

aion wrote: 24 Nov 2023, 16:45 A semi-original from Xotic...
Please make pcb's for the Xotic Super Sweet and Super Clean boosters

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Post by aion »

roseblood11 wrote: 28 Nov 2023, 23:37
aion wrote: 24 Nov 2023, 16:45 A semi-original from Xotic...
Please make pcb's for the Xotic Super Sweet and Super Clean boosters
In progress :) Got them both traced but didn't get the boards done in time for this past batch. (They're almost identical btw, as you'd imagine)

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Post by roseblood11 »

Great, thx!
Will the pcb fit in a 1590b?

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Post by aion »

roseblood11 wrote: 30 Nov 2023, 13:08 Great, thx!
Will the pcb fit in a 1590b?
Nope, since 2018 everything has been 125B minimum.

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Post by roseblood11 »

I didn't understand that decision.

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Post by Ichabod_Crane »

I think that 125B boxes in these period are a bit harder to find and more expensive.
Those are bigger than 1590B, but maybe is convenient to have the input and output in the upper side.

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Post by aion »

roseblood11 wrote: 02 Dec 2023, 00:02 I didn't understand that decision.
For 1590B, you have to use side-mounted jacks unless you use the 1590B2 or 1590BS, which are taller but much harder to find globally. A 1590B with side jacks takes up more horizontal room than a 125B with top jacks, even if you use low-profile plugs (and it's significantly wider if you use standard plugs).

When I first started out, I used 1590B because I was really concerned about space efficiency. But when I realized that it wasn't actually as compact as I thought, I decided to switch to something that was much more universal in the industry (JHS, EQD, Wampler, etc. all use 125B) and equally or more space efficient, as well as being easier to build.

It's not going to be everyone's preference, but neither was the old format!

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Post by szukalski »

Top mount with 1590B is definitely possible but it restricts you to certain jacks and you need to get smart about component placement (no caps near the top of the board). Not exactly what you want if a bunch of people are going to build your work.

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Post by twotees »

Why no caps near the top of the board??

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Post by mauman »

twotees wrote: 03 Dec 2023, 22:18 Why no caps near the top of the board??
With top-mount jacks in a 1590B, they will probably overlap the north end of the board, so anything sticking up from the PCB there (like a cap) will get in the way of the jacks. Resistors and diodes are usually OK there, if they lay flat, and sometimes you can make EL caps work by laying them over, depending on diameter. If all else fails, you can eliminate the battery space and slide the footswitch and PCB far enough south to miss the jacks. Sometimes.

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Post by John G »

Hi, I Should of added in my above posts, that this pedal really comes into its own when using an 18v power source.
Better dynamics and note definition.John

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