JHS - AT (Andy Timmons) Signature Drive  [traced]

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bugg
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Post by roseblood11 »

The toggle is a on/off/on, so no clipping diodes in middle position?

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Hast du in deiner Finanzplanung ein Plug In für Drums mit drin? Hilft einem sehr beim Ideen sammeln... Ich nutze zB EZdrummer, weil man da schnell im Plug-In eine Songstruktur bauen kann und dann mit einem Click in die DAW übernehmen.

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Post by bugg »

roseblood11 wrote:The toggle is a on/off/on, so no clipping diodes in middle position?
I do believe that is correct. This should correspond to the 100W mode, described as "cleaner, loud".

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Post by Scruffie »

roseblood11 wrote:Hast du in deiner Finanzplanung ein Plug In für Drums mit drin? Hilft einem sehr beim Ideen sammeln... Ich nutze zB EZdrummer, weil man da schnell im Plug-In eine Songstruktur bauen kann und dann mit einem Click in die DAW übernehmen.
Mein Deutsch ist schlecht aber das ist nicht verwandt? :scratch: :mrgreen:

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Post by Groovenut »

bugg wrote:
roseblood11 wrote:The toggle is a on/off/on, so no clipping diodes in middle position?
I do believe that is correct. This should correspond to the 100W mode, described as "cleaner, loud".
I was under the impression that the louder setting were the LEDs , the lowest setting were the Schotky's and the middle setting were mosfets.

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Post by bugg »

Groovenut wrote:
bugg wrote:
roseblood11 wrote:The toggle is a on/off/on, so no clipping diodes in middle position?
I do believe that is correct. This should correspond to the 100W mode, described as "cleaner, loud".
I was under the impression that the louder setting were the LEDs , the lowest setting were the Schotky's and the middle setting were mosfets.
There are no mosfets in the thing. I know the Madbean Turnabout has them, but the AT doesn't.

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Post by Groovenut »

bugg wrote:
Groovenut wrote:
bugg wrote:
roseblood11 wrote:The toggle is a on/off/on, so no clipping diodes in middle position?
I do believe that is correct. This should correspond to the 100W mode, described as "cleaner, loud".
I was under the impression that the louder setting were the LEDs , the lowest setting were the Schotky's and the middle setting were mosfets.
There are no mosfets in the thing. I know the Madbean Turnabout has them, but the AT doesn't.
Ah I see. Very interesting. Thanks for the info!
There's an assembled board on ebay that claims to be JHS @ that seems to bear this out in the pics.

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Post by alexradium »

OMG its amazing,what a genius!

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Post by bugg »

I don't have the original in-hand anymore but this is a fairly good pic of the PCB.

The two components at the bottom (D201 and Q200) are part of the LED switching. There are no components on the other side of the board.
jhspedals_at_003.jpg

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Post by Manfred »

Scruffie wrote:
roseblood11 wrote:Hast du in deiner Finanzplanung ein Plug In für Drums mit drin? Hilft einem sehr beim Ideen sammeln... Ich nutze zB EZdrummer, weil man da schnell im Plug-In eine Songstruktur bauen kann und dann mit einem Click in die DAW übernehmen.
Mein Deutsch ist schlecht aber das ist nicht verwandt? :scratch: :mrgreen:
Miss the point, I guess text insert by mistake.

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Post by roseblood11 »

Ups, I wanted to post that to another forum. Crappy small smartphone display...

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Post by shredgd »

The EQ is a linear (B) pot like the Air pot. I am sure because after endless researches I found a picture of the top side of a AT pedal circuit board, showing the B10k pot.

Have a nice day!
Giulio

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Post by Adam_MD »

Has anyone done a vero layout for this yet? So far I've only seen the Madbean Turnabout.

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Post by Ben N »

Should be very easy to convert the one to the other.

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Post by Ichabod_Crane »

Comparing the schematic of the Madbean Turnabout and the Pedal PCB version of the JHS - AT the differences are minimal. In the Pedal PCB the coupling cap after the second opamp stage is 2.2uF and not 1uF, and the Volume pot is log and not linear.
And of course the clipping, the central position is with Mosfet in the Madbean Turnabout (a sort of OCD style, I guess). While in the Pedal PCB is with any diode or anything. I guess the original AT is like the Pedal PCB.
I would like to build a JHS AT, but I have some doubts about the schematic.

About the EQ pot: rev log vs linear. I can't say what original pedal mount.
shredgd wrote:The EQ is a linear (B) pot like the Air pot. I am sure because after endless researches I found a picture of the top side of a AT pedal circuit board, showing the B10k pot.
I'd like to see this picture, too. Anyway, with my emulator probably a reverse log as EQ should give a more balanced response.

There's a lot of discussions about the difference between the AT and the Crunch Box, and in some picture we can see in the AT pedal just a third extra 100nF cap, one after the gain pot, one in the power filter as in the Crunch Box. Everybody says that this extra 100nF cap is across the ground and in parallel to the 22nF in the tone section. But Pedal PCB and Madbean Turnabout doens't have it.

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Post by shredgd »

Ichabod_Crane wrote: About the EQ pot: rev log vs linear. I can't say what original pedal mount.
shredgd wrote:The EQ is a linear (B) pot like the Air pot. I am sure because after endless researches I found a picture of the top side of a AT pedal circuit board, showing the B10k pot.
I'd like to see this picture, too. Anyway, with my emulator probably a reverse log as EQ should give a more balanced response.
Here you have it!
Attachments
IMG_0762.JPG

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Post by shredgd »

Ichabod_Crane wrote: There's a lot of discussions about the difference between the AT and the Crunch Box, and in some picture we can see in the AT pedal just a third extra 100nF cap, one after the gain pot, one in the power filter as in the Crunch Box. Everybody says that this extra 100nF cap is across the ground and in parallel to the 22nF in the tone section. But Pedal PCB and Madbean Turnabout doens't have it.
I've already written in another forum that this "extra 100nf cap" is only a voltage stabilizer for the opamp, placed between V+ and ground, which is a good practice to have very close to the opamp. The cap in the tone section is really only the 22nf.

Giulio

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Post by Ichabod_Crane »

Thank shredgd for the picture. It's really clear that the EQ is a linear pot. I'm curious to try a rev log, too.

Thank you Giulio, I missed your information in this other forum. Then, this 100nF you mean is a bit like the other in the power filter? (C10 in the Pedal PCB schematic posted above).

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Post by shredgd »

Ichabod_Crane wrote:Then, this 100nF you mean is a bit like the other in the power filter? (C10 in the Pedal PCB schematic posted above).
Exactly. Compare this Angry Charlie guts picture (C9):
IMG_1064.JPG
with this Sweet Tea guts picture (Angry Charlie part of the circuit on the right), where you have an SMD cap in the same place, very close to the opamp. In both layouts that cap is far from the 22nf caps of the tone section.
IMG_0432.JPG

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