Search results

Bit of a blast from the past, but did Matt ever do a review of "The Cleaner". I'm still using the two original modules I built and still like them every time I play 'em.

How can you tell if they are Heyboer? My two RM80s have very little in the way of markings on the transformers. From memory the output has a sticker with OT-75 on it.

Thanks for pointing out the errors. All fixed now.

Very cool.

Interesting. They're great in my clean modules, but I've steered clear of them for high gain use because of the increased risk of microphonics. You haven't experienced any of that? I'll definitely give them a go in V1 on some high gain modules....

I've got one. It was my primary pre-amp before I got into the Randall MTS stuff. It's a "good" bit of gear but in stock form the sound falls a little short of being "great". Clean channel is OK but nothing special (yet to hear a Carvin clean channel that really does it for me). Channel 2 can...

This would suggest that the microcontroller programming on the RM22 version is different than the RM100 version.

On what do you base this? See circuit diagram below of RM20 input stage showing how the second half of V1 is switched into the circuit when the boost function is engaged. The boost gain pot (not shown) acts as half of a voltage divider on V1:

Did you try replacing V1?

You may well have a bad valve in V1 or dirty pins/socket. Try another 12AX7 in there. V1 is the tube closest to the input socket.

I don't think this is right. After looking at the schematic for the RM20, the boost function uses the second half of the first 12AX7 (V1) to provide a gain boost in the signal path after the first input stage (1st half of V1) but before the first gain stage of the module. The boost level...

Well I really like The Cleaner (but I'm biased ☺).

I've added some pictures here that should help out - http://faqload.com/faqs/music/randall-rm20-master-volume-mod

Have done a few mods to my RM20 combos and heads that others may be interested in. Master volume mod: - lift the right side (looking from the front) of C9 from the board; - solder to pin 1 of an A1M pot (1M log / audio taper) pot; - solder an 0.1uF cap from pin 2 of the pot back to the vacant...

What a great DIY project. Awesome stuff. Thanks so much for sharing this and documenting it so well.

I haven't drawn any MTS PCBs because they vary so much. I have done schematics for all of the modules I've modified using Eeschema. Take a look here for an example done for the Brahma module. PM me and I'll send you a file to.get you started.

For a high gain rhythm module I like 0.001 there, but for a lead module you need lots of frequencies right across the spectrum to thicken single notes out. For this reason a 0.022uF C3 is about as "tight" as I would go. It is after all, the input coupling cap for the module. Carve too much...

Unless the 12ax7s are bad you're not going to get much of a change swapping them out. For a solo module I like somewhere between a 0.022uf and 0.047uf cap in C3. This will be too loose for a tight rhythm module but gives the meat you need for a good solo tone.

See how you go. The holes in the PCB for C6, C7 and C13 are actually smaller than for the other components. You may have trouble getting the leads to go through. Don't force it if they're tight.

You can use a electrolytic capacitor in that position (make sure you get the polarity right). Use a 50v one. They are much smaller than a film capacitor but can only be used in certain parts of the preamp circuit (C6, C7 and C13 are such locations).