Rockman X100 - Make it a DIY Pedal

VivMeLol · Post by **VivMeLol** » 28 Apr 2021, 09:06

NOTES ON CHOOSING CORRECT COMPRESSION RATIO IN ROCKMAN X100

There are too many notes of people getting flummoxed on how to "Bias the FET" in the X100. Many have claimed that the FET is a booby trap. Few DIYers just got "some compression" rather than "correct compression" while many did not get any compression at all,

Here is a graph on effect of setting the compressor of an X100 in CLN mode. This is from the SPICE analysis of the X100, correlated to readings from a real X100.

Compression ratio too low:
In the graph labelled 4.44/6.46, the 100 X compressor has too low a compression ratio, hence the output is high.

With power supply of 6V, 0, -6V. the Opamp cannot output more than about 4.5 or 5V. The Opamp will clip for high input signals since more output is demanded but is not possible. This is shown at point where graph plateaus out for high signals. Clipping is not acceptable for a clean sound.

Compression ratio too high:
In the graph labelled 6.44/6.46, the compressor has too high a compression ratio. The compression is severe. The output is low. Some might like the sound of high ratio compression, almost like a limiter. However when the same compressor is shifted to EDGE and DIST modes, there will not be enough signal to drive these modes into severe clipping.

The Goldilocks setting range:
Somewhere in the middle is a whole range of acceptable compression ratios that neither distort nor give low output (estimated region in pastel green)

However only one of them is TOM's FACTORY SETTING.

That is why so many measurements were needed on a real X100 to determine what was the magic TOM'S FACTORY SETTING.

Unfortunately, we only measured one X100 so far. So we have only one reliable reading of TOM's FACTORY SETTING. However, I feel plus minus large range from that one reading is all within the acceptable green zone.

Meaning that suppose Tom wanted a compressor ratio of 4:1

Then maybe from 2.5:1 till 8:1 is all kinda good enough and satisfies the criteria of no clipping but high enough output

But low ratio like 1.2: 1 will clip and high ratio like 15:1 will give low output

It would be nice to get readings from other X100.

VivMeLol · Post by **VivMeLol** » 01 May 2021, 11:07

Pedro Yi's demo of the DIST mode on the SMD module he made

External Chorus and Reverb at the moment since Pedro concentrated on Compressor and Gain stage first. However the Chorus has already been tested by Josh in parallel and we will soon have soundcloud demos of our compressor>dist>EQ>chorus and also compressor>EQ>Chorus

and believe you me, it takes a whole bunch of Perseverance and Integrity to make 600+ measurements to be able to assertively state that the Compressor and Gain stage follows the standard we all love so much. Thank you, Pedro, for your immense effort !!!

PS: Please check the clarity and volume of high notes on high frets from 02:23

And check the Signal to noise ratio too !!

caspercody · Post by **caspercody** » 04 May 2021, 16:17

Here are vero layouts for input section, eq 1 and 2 section, and distortion section. I have verified all these boards work. I could not find a icon for a switch that has only (2) rows of (5) pins, but I connected to a slide switch similar to the original.

VivMeLol · Post by **VivMeLol** » 07 May 2021, 09:03

I had started looking into this project purely as an Electronics enthusiast, in awe at the great tricks Tom used to get his sound.

But then when we started to make progress and posted Soundclouds, others asked us to deliver them some actual pedal that would give them THAT SOUND plus some more options.

We now made a form to collect user inputs on a possible proposed future product. If this moves ahead, we will try to incorporate your suggestions.

Please be kind to give us your inputs

https://forms.gle/AqLdX7H91V9dZ46z9

JTEX · Post by **JTEX** » 07 Jun 2021, 21:04

I just joined this board specifically for this thread. My goodness, was it ever a chore to join! It took about 2 weeks before I got a validation email so I can log in. But that's a different story...

I've been working on a very similar project and I made good progress. I have a fully working board, functionally closest to the Rockman Soloist, but with many, many changes. Most notably, it runs on a single 9V battery, it's tiny, and it has a working analog stereo chorus/doubler that uses MN3207 (vs the original, extinct MN3007). If anybody from this project would like to compare notes etc, I'm here.

This is how it sounded before I got the chorus chip:

JTEX · Post by **JTEX** » 23 Jun 2021, 03:31

You may have noticed that 2N4339 is really pricey these days, US$12. Its surface mount cousin SMP4339 is much more reasonable though, at only a couple of $. Just saying.

VivMeLol · Post by **VivMeLol** » 09 Jul 2021, 20:13

I have been studying the AutoClean Patents

https://patents.google.com/patent/US4752960A/en

https://rockman-gearup.com/rockman.fr/Legal/4752960.pdf

Oh, It's a very smart way of trying to detect the peak level of guitar signal

Then on the assumption that lower peak levels mean that the guitar has low settings of volume control, the treble and volume are boosted,

and if the peak levels are high, it is assumed that the guitar volume control is high and then the treble and volume are reduced.

Nett result : when the guitar cleans up with lower volume settings, the normally expected lower final Amp volume and loss of treble do not happen !! You get fairly consistent volume levels and tonal characteristic even if you lower the guitar volume to get cleaner sounds !!!

Smart !!!

enterprice · Post by **enterprice** » 23 Sep 2021, 18:22

JTEX wrote: ↑23 Jun 2021, 03:31 You may have noticed that 2N4339 is really pricey these days, US$12. Its surface mount cousin SMP4339 is much more reasonable though, at only a couple of $. Just saying.

I also get good results for the compressor with the PN4117A FET .The 2N4339 is a bit too expensive in my opinion.

jrmont · Post by **jrmont** » 23 Oct 2021, 20:21

FeVeR2112 wrote: ↑01 Nov 2020, 16:49 In some reading at rockman.fr - It refers to the EQ section as an early concept of a cab-sim. This is the frequency response charted out - diagram credit to www.rockman.fr.

I built the compression, distortion and EQ sections per the "original" schematics but with the few component value changes documented in this thread. The response from the input to the output of the board when in the Dirty 1 position is shown below.

That response was measured with a free Android app from Sergio Gudhov called Audio Analyser. Get yourself a Camcorder TRRS to three RCA connectors and you have a useful spectrum analyser for projects like this one.

Images of PCB and schematic (switch in Dirty 1 position) at https://305keepers.com/rckman.

I am still working on getting the 2N4339 compressor to work. The detector is working but I do not see any effect on the gain so far. I used a 5M pot with a few fixed megs on each side to make the bias adjustable. I am about to dig into that problem thanks to a better understanding after reading http://www.rockman.fr/Reviews/GC.htm.

VivMeLol · Post by **VivMeLol** » 04 Mar 2022, 18:32

caspercody · Post by **caspercody** » 04 Mar 2022, 23:22

Looks nice, how does it sound

JTEX · Post by **JTEX** » 06 Mar 2022, 06:05

VivMeLol wrote: ↑04 Mar 2022, 18:32

Looking great!

I just finished my own version of a delay section for my Shockman. It has nothing in common with the X100 ECHO, and it only draws 3mA from 9V. I'm very cheap with my power budget

Carvindc125 · Post by **Carvindc125** » 09 Mar 2022, 02:52

JTEX wrote: ↑06 Mar 2022, 06:05
VivMeLol wrote: ↑04 Mar 2022, 18:32
Looking great!

I just finished my own version of a delay section for my Shockman. It has nothing in common with the X100 ECHO, and it only draws 3mA from 9V. I'm very cheap with my power budget

We are actually brainstorming on a new Echo section as well.
Good stuff!
Going to post a demo of our pedal soon

thpmink · Post by **thpmink** » 09 Mar 2022, 12:46

So, any thoughts on the frequency-selective compression that's in the patent and the Sustainor? I figure this would be an easy mod (+1 resistor and 2 caps). Mr. Scholz only applied this to the gain modes, so yet another complication in switching, but I guess a simple extra switch would do as well.

I am talking about this part (schem from the patent):

: FREQ-SELECTIVE-COMPRESSION.png (44.56 KiB) Viewed 2016 times

The purpose here is, if I understood it correctly, to lower the maximum gain of the compressor when in edge or distortion mode, but do so selectively. Here is what it looks like modelled:

In clean modes, the frequency response is essentially flat. Not so here. As you can see, the maximum gain of most of the frequency range is actually lowered compared to the clean modes. The patent claims this lowers noise, and gives a high-end boost.

I haven't built the comp yet, so I was wondering if someone has experience with it? Is it worth it?

Edit: Or is that what R174-R175-R176 (in the Schematic shared in this thread) are for in the X-100?

JTEX · Post by **JTEX** » 10 Mar 2022, 01:31

Aussiepom · Post by **Aussiepom** » 15 Jun 2022, 08:09

Hi All,

Recent sign up here, and a big enthusiast of the X100 (Def Leppard Hysteria got me playing the guitar 30 years ago). mods - sorry if this isn't the right thread, picking the best with the most recent activity. Based on all the great info on this forum I've decided to take the plunge and build an X100 from scratch. This is largely based on the info in this thread: viewtopic.php?t=25015

There are some great resources here, and following to high quality pics of "real" X100 boards I've created gerbers which are now in production (happy to share if anyone is interested - especially as I'm asking for help here). Between the layouts in the X100 Rev 10.pdf and reality there were a number of differences. Within the same thread there is a list of variations between the BOM in the PDF and the real components for the 100 board. I'm now creating my own BOM and am wondering the same about the 200 board... I've scoured this site and everywhere but cannot find anything. Picking this apart from pictures isn't viable. Question is, does anyone have an X100 rev 10 who can verify this or this info to hand that they would be willing to share? Cheers

Yazoo55 · Post by **Yazoo55** » 28 Jun 2022, 19:32

I went through the process of cloning an X100 and had the same problem regarding resistor and capacitor values. The values I settled on can be found in this thread. Another member, Fermusicman helped me by checking his X100:
viewtopic.php?t=25015

Aussiepom · Post by **Aussiepom** » 29 Jun 2022, 04:33

Yazoo55 wrote: ↑28 Jun 2022, 19:32 I went through the process of cloning an X100 and had the same problem regarding resistor and capacitor values. The values I settled on can be found in this thread. Another member, Fermusicman helped me by checking his X100:
viewtopic.php?t=25015

Hi Yazoo55,

Thanks for lthe response. I saw your post on that thread which is great, but as far as I could tell you only built the 100 board right? I've used those values to modify the BOM for that board, but I'm wondering about the 200 board. I sent Fermusicman a PM but it doesn't seem like he's been online in a while.

Yazoo55 · Post by **Yazoo55** » 29 Jun 2022, 20:10

If the 200 board is the the Echo board with the MN3011, I went back about a year or so ago (hard to tell with the Covid lockdown) and did the second board. What I found is that the values listed on the drawings which are available online are accurate whereas the schematic values in the X100 Rev 10 pdf are incorrect in some places. The drawings are available in several places including here:
https://www.scribd.com/doc/255015170/Ro ... Schematics

Aussiepom · Post by **Aussiepom** » 01 Jul 2022, 07:22

Yazoo55 wrote: ↑29 Jun 2022, 20:10 If the 200 board is the the Echo board with the MN3011, I went back about a year or so ago (hard to tell with the Covid lockdown) and did the second board. What I found is that the values listed on the drawings which are available online are accurate whereas the schematic values in the X100 Rev 10 pdf are incorrect in some places. The drawings are available in several places including here:
https://www.scribd.com/doc/255015170/Ro ... Schematics

Thanks so much for the info. Yeah, my terminology of "100 board" and "200 board" comes from the PDF schematics that refer to each of them as such. The MN3011 is indeed on the echo or "200" board. Great to hear that the parts list (values) for that board is correct. Now onto ordering the components and building it!

How do you find the sound of your Rockman clone? Happy with the overall results? I'm really looking for that Def Leppard Hysteria sound within reason of course - we all know how engineered it is beyond just an X100. Watching comparisons of the Boston 100 plugin against the actual X100 sold me on doing this build.