Rockman X100 - Make it a DIY Pedal

All about modern commercial stompbox circuits from Electro Harmonix over MXR, Boss and Ibanez into the nineties.
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FeVeR2112
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Post by FeVeR2112 »

I have been wanting to do this for decades.... Make a pedal that has the Rockman Distortion sound. The chorus and echo would be other pedals.

I would like to collaborate with those willing to on this forum in creating a circuit that can be used in a pedal format.

The compression and fixed EQ sections seem to have the greatest influence on how 'that' sound is produced. The pedal version would have controls for gain, level and perhaps some EQ tweaking control. A foot switch for Edge / Dist selection and, of course, true bypass.

The circuit is interesting and parts I am unsure what it it doing.

The original X100 schematic and my redrawn version (see latest version at the end of this thread) with just the gain and EQ section is attached.

Please let me know if you would like to participate.

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X100 Rev 10.pdf
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Last edited by FeVeR2112 on 01 Nov 2020, 03:38, edited 1 time in total.

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CheapPedalCollector
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Post by CheapPedalCollector »

Don't forget the treble booster on the front end.

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FeVeR2112
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Post by FeVeR2112 »

CheapPedalCollector wrote: 29 Oct 2020, 04:57 Don't forget the treble booster on the front end.
Do you mean putting one in the pedal or having a TB pedal in front of the Rockman pedal?

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Post by bmxguitarsbmx »

This is a great idea FeVer.

I'm skeptical that R169 is connected directly to D117 and the output of the op-amp. D117 should be connected to signal capacitively and have a -Vreference. I COULD BE WRONG! :)

I have breadboarded some of these circuits so I will try to help. I remember having a struggle with figuring out how to select the FET.

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Post by CheapPedalCollector »

FeVeR2112 wrote: 29 Oct 2020, 14:17
Do you mean putting one in the pedal or having a TB pedal in front of the Rockman pedal?
Separate pedal, I really liked that one. At least my X-100 had one in it as the first stage. Was a BC-108 single transistor circuit iirc.

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Post by ppluis0 »

Hi FeVeR,

Please note that C104 have a value of 1nF in the original diagrams.

Cheers,
Jose

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FeVeR2112
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Post by FeVeR2112 »

ppluis0 wrote: 29 Oct 2020, 22:52 Hi FeVeR,

Please note that C104 have a value of 1nF in the original diagrams.

Cheers,
Jose
Just checked the schematic (it is also attached to the start of this thread). It shows C104 as 10uF.
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c104.jpg
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Post by CheapPedalCollector »

Hrm interesting, that schematic doesn't have the boost circuit.

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FeVeR2112
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Post by FeVeR2112 »

bmxguitarsbmx wrote: 29 Oct 2020, 15:12 I'm skeptical that R169 is connected directly to D117 and the output of the op-amp. D117 should be connected to signal capacitively and have a -Vreference.
Perhaps I should include the power supply portion.... There is a V- reference.... I will add to the schematic.
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negref.jpg
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Post by FeVeR2112 »

updated schema (see latest version at end of the thread)
Last edited by FeVeR2112 on 01 Nov 2020, 03:39, edited 1 time in total.

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Post by Manfred »

Not sure what this does
Triangular-wave generator with about 11 cycles per second.

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Post by bmxguitarsbmx »

I think there are problems with the X100B schematic.

What is D117, R176, and R175 doing? Certainly they should not be connected to the output of the op-amp. Maybe someone knows? Let's delete them until they prove to be needed.

The attack time is determined by R169 and C106. (D117 screws the attack time up as far as I can see, which is why I think it should be deleted)

The decay time is determined by C106 having a discharge path, which I don't see. So, the R105 connection should be moved to the other side of C104 (Drain of Q101). As drawn, C104 is blocking a DC path to ground. If we move the R105 connection, the attack time will be C106 draining through R107 + R106 + R105.

The Soloist schematic has these connections that I am describing, which is the circuit that I have messed about on the breadboarded with.

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Post by FeVeR2112 »

Manfred wrote: 30 Oct 2020, 03:30
Not sure what this does
Triangular-wave generator with about 11 cycles per second.
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So to just flash the power LED? Yah... it does that ...

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Post by ppluis0 »

FeVeR2112 wrote: 30 Oct 2020, 18:14 So to just flash the power LED? Yah... it does that ...
Hi FeVeR,

Not only flash that led, but also modulate (via pin 5 of 555) the square wave train from pin 3 of the same IC to make the chorus effect.

Regarding the capacitor previously mentioned, I say C104 in your drawing that is marked as C111 in the factory diagram.

Cheers,
Jose

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Post by FeVeR2112 »

ppluis0 wrote: 30 Oct 2020, 18:56
FeVeR2112 wrote: 30 Oct 2020, 18:14 So to just flash the power LED? Yah... it does that ...
I say C104 in your drawing that is marked as C111 in the factory diagram.
.
yup.... that is what happens when cut and paste is used! Correct the id/value.

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Post by FeVeR2112 »

Updated Schema
Last edited by FeVeR2112 on 01 Nov 2020, 03:39, edited 1 time in total.

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Post by bmxguitarsbmx »

Recheck the edge/distortion switch. If we are only doing "Edge" and "Distortion", the switching is only involving the input.

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Post by FeVeR2112 »

Attached is the edit for the edge/dist switch. After re-reading the X100 schema, I can see how it actually connects.

Thanks to bmxguitarsbmx for pointing that out.

As a pedal, I would think to add controls for gain for both edge and dist modes, a control for compression and a control for output level.

For EQ.... well.... that would be either taking away from the key Rockman sound .... or.... it could be fine tuning it. Where to insert the controls can be a good discussion point.
Attachments
Rockman Schem4.JPG

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Post by FeVeR2112 »

I am outlining the blocks in the circuit.... Is this section marked ????? part of the compression stage?
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Post by Manfred »

No, the "????" part of the circuit does not belong to the compressor stage.
R112A, C108A, R112, C108 form the input filter of stage IC2-A.
R113 determines together with R114 the gain of stage IC2-A

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