HRM Trimmers

[burntfingers]

Hi All,

Newbie here...thanks for all the knowledge sharing!

I've got C-tone HRM inbound and I'm trying to figure the best way to put the HRM trimmers on the outsite. I was wondering if concentric pots would work or if I should just bite the bullet and pop some holes in the front and add some pots?

Does anyone have experience with this?

Thanks!

[norburybrook]

personally. I don't like putting those controls on the outside.....for me, and I'll stress that it's for me, the temptation to be constantly fiddling is bad so I like to set and forget the HRM and learn to work with it.

too much choice isn't always a good thing, IMHO. I've made 3 HRM amps and not once have I had the temptation to put the pot's anywhere I could fiddle with them.

YMMV


Marcus

[Colossal]

personally. I don't like putting those controls on the outside.....for me, and I'll stress that it's for me, the temptation to be constantly fiddling is bad so I like to set and forget the HRM and learn to work with it.

too much choice isn't always a good thing, IMHO. I've made 3 HRM amps and not once have I had the temptation to put the pot's anywhere I could fiddle with them.

I just finished a 183 plus front panel HRM controls on the OD channel. Too much fiddly for me, but what the customer wanted.

[burntfingers]

Thanks for the reply...I’m going to tweak the values in these. What wattage trimmer should be used here?

[fred.violleau]

Hey burntfingers,

I did this year a build with the HRM controls in the front of my amp.
I also added a defeat switch to lift the HRM ground.

HRM_Front.jpg

I realized I usually prefer the sound without the HRM tonestack in the signal path.
It really damps down the sound. As some of the signal is being sent to ground with the HRM tonestack, you also loose a few dbs.
There is so much more bloom without the HRM tonestack that it is hard to get back to it.

I am actually considering converting my HRM an removing these from the signal path (and the front of the amp) for good !

All in all, it takes a lot of space on the front of the amp, plus you don't get to change the OD settings that much once you have found the sweet spot.

My 2cents here

Fred.

[fred.violleau]

Thanks for the reply...I’m going to tweak the values in these. What wattage trimmer should be used here?

These are the same as any pot in the signal path so probably 1/2 watt.

Fred.

[burntfingers]

Hey burntfingers,

I did this year a build with the HRM controls in the front of my amp.
I also added a defeat switch to lift the HRM ground.

HRM_Front.jpg

I realized I usually prefer the sound without the HRM tonestack in the signal path.
It really damps down the sound. As some of the signal is being sent to ground with the HRM tonestack, you also loose a few dbs.
There is so much more bloom without the HRM tonestack that it is hard to get back to it.

I am actually considering converting my HRM an removing these from the signal path (and the front of the amp) for good !

All in all, it takes a lot of space on the front of the amp, plus you don't get to change the OD settings that much once you have found the sweet spot.

My 2cents here

Fred.

Now this is interesting...how difficult is the HRM defeat switch to incorporate?

[M Fowler]

Henry's Redplate Amps Magic Dust Dual (MDD) has the HRM pots on the front panel and I played one at Henry's home in his work shop garage before he moved to another place to build his amps. Killer tones and a lot of fun to play. He gave me a tele and I wished I had brought my LP with.

Old post from TAG member to Henry:
I played a Redplate Magic Dust Duo at a friend’s house the other day.

As per forum rules here is a breakdown of the amp (to the best of my knowledge). I included a clip, which may be a somewhat poor representation of what this circuit is capable of but I included it anyways

The amp has HRM and NON-HRm Overdrive, Single control clean tone stack with a Rotary Knob to switch different voices (Tweed, Brown, Blackface) and a Buffered effects loop (D-lator).

To my knowledge (please correct me if I'm wrong Henry ) the HRM tone stack has the OD trimmer (AKA Trigger), OD Gain, and OD Volume as well as Treble, Middle, and Bass Controls with MID and Preamp Boost. All on the front panel

The NON-HRM has the same OD trimmer (AKA trigger), OD Gain, and OD Level controls but with no tone stack.

As well as being able to use both Overdrives (1 & 2) cascaded into each other.

The Clean has One Tone stack control, and the Rotary knob with 6 positions of Tweed, Brown, and black face voicing’s.

The Buffered effects loop does not have send/return controls but is set so that you can throw whatever you want in the loop with no need to muck around with levels to balance everything out, just grab and go.

Pretty accurate description - the front end is tweed based with a way to cut mids and preamp output to get the black and brown modes. The overall preamp output has to be reduced to feed the overdrives. There is no traditional master, in fact one of the mods on the RedPlate site (Mod#2) is to add a couple of resistors to simulate a 1MA set at noon for a pseudo master. The loop does have an internal trimmer for a send (factory set like a 250kA pot at noon) and the return is the front panel control labeled Master.
Here's a gut shot of a CosmicDust (same amp with 6V6 outputs): Henry H.

[AtomCap]

It would be an expensive project to do, but I've been contemplating using CTS Concentric pots and re-wafering them to the correct values to add HRM Controlls to the front panel without drilling additional holes, keep the look relatively clean as well..

[burntfingers]

It would be an expensive project to do, but I've been contemplating using CTS Concentric pots and re-wafering them to the correct values to add HRM Controlls to the front panel without drilling additional holes, keep the look relatively clean as well..

This is what I’ve been thinking about!

[AtomCap]

https://www.studioelectronics.biz/sunsh ... ail&p=3743
big bucks for a stacked knob, but would somewhat keep the look right

[stelligan]

Henry's Redplate Amps Magic Dust Dual (MDD) has the HRM pots on the front panel and I played one at Henry's home in his work shop garage before he moved to another place to build his amps. Killer tones and a lot of fun to play. He gave me a tele and I wished I had brought my LP with.

I own one of these. A desert island amp, really. Even though the HRM tones are on the front, I don't mess with them much since dialing it in. They are there if I need them though! Much easier to adjust and less "twitchy" than trimmers. Really dig the tweed front end....

md.jpg