Xotic - SL Drive

aion · Post by **aion** » 24 Nov 2023, 16:45

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

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/

John G · Post by **John G** » 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.
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

Ichabod_Crane · Post by **Ichabod_Crane** » 26 Nov 2023, 08:54

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.

aion · Post by **aion** » 26 Nov 2023, 20:06

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.

John G · Post by **John G** » 26 Nov 2023, 20:57

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

roseblood11 · Post by **roseblood11** » 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

aion · Post by **aion** » 29 Nov 2023, 02:47

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)

roseblood11 · Post by **roseblood11** » 30 Nov 2023, 13:08

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

aion · Post by **aion** » 30 Nov 2023, 15:41

roseblood11 wrote: ↑30 Nov 2023, 13:08 Great, thx!
Will the pcb fit in a 1590b?

Nope, since 2018 everything has been 125B minimum.

roseblood11 · Post by **roseblood11** » 02 Dec 2023, 00:02

I didn't understand that decision.

Ichabod_Crane · Post by **Ichabod_Crane** » 02 Dec 2023, 10:12

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.

aion · Post by **aion** » 02 Dec 2023, 18:42

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!

szukalski · Post by **szukalski** » 03 Dec 2023, 17:41

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.

twotees · Post by **twotees** » 03 Dec 2023, 22:18

Why no caps near the top of the board??

mauman · Post by **mauman** » 04 Dec 2023, 00:02

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.

John G · Post by **John G** » 25 Dec 2023, 20:55

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

roseblood11 · Post by **roseblood11** » 07 May 2024, 22:45

aion wrote: ↑29 Nov 2023, 02:47
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)

What happened to the Super Clean and Super Sweet projects? Will you sell a PCB?

superlac · Post by **superlac** » 29 Jul 2024, 16:57

Hello!

I have built the Aion Sl Drive, but I have some problems with it and I cant't figure out what is wrong.

If I flip the Freq2 switch, the Vb voltage is go down to 0, of course in this case there are no volume at all, because it's missing the Vbias voltage. If I flip the switch, the overall 9V power is still present everywhere in the circuit, but the Vb is missing. No current draw or short or anything failure, just this.
I've checked all of the voltages and everything is looking good except one thing. On the R13 resistor leg, which is connected to the Vb via the switch, no matter where is the switch the Vb is always present. I've checked the switches and they are fine, all of the switching good, and make the contact. Ive tried to replace the DIP with normal SPDT switches and they working just like the DIP. If Freq2 is "active" the VB is missing, but the 9V is still present.
Can somebody help me? I've never seen anything like this before.

aion · Post by **aion** » 31 Jul 2024, 00:52

superlac wrote: ↑29 Jul 2024, 16:57 I have built the Aion Sl Drive, but I have some problems with it and I cant't figure out what is wrong.

If I flip the Freq2 switch, the Vb voltage is go down to 0, of course in this case there are no volume at all, because it's missing the Vbias voltage. If I flip the switch, the overall 9V power is still present everywhere in the circuit, but the Vb is missing. No current draw or short or anything failure, just this.
I've checked all of the voltages and everything is looking good except one thing. On the R13 resistor leg, which is connected to the Vb via the switch, no matter where is the switch the Vb is always present. I've checked the switches and they are fine, all of the switching good, and make the contact. Ive tried to replace the DIP with normal SPDT switches and they working just like the DIP. If Freq2 is "active" the VB is missing, but the 9V is still present.
Can somebody help me? I've never seen anything like this before.

Fortunately it's a specific enough problem that it should be easy to narrow down. It's probably not the switch itself, but the junction between R5 and the switch is shorting to ground. When you engage the switch, rather than connecting R5 to the bias voltage, it's instead grounding the bias voltage which impacts the rest of the circuit.

superlac · Post by **superlac** » 05 Aug 2024, 06:32

Dear Aion,

Thanks for the reply. R5 is the pulldown resistor in the input which is connected to ground of course, but if I engage Freq2 on the 2.2M resistor the bias voltage can drop current to go to ground in that high resistance? You sure thats the problem? I'm talking about R12. Maybe Im missing something?