I noticed the description at Overland Express for the orange suede,
This rare head was built in the mid 80’s. The amp is 100 watts with a 50 watt half power switch, Hot Rubber Monkey Blues Master Pre-Amp with 6L6 power tubes. Included with this gem is a letter from Dumble mentioning an update he offered called “The Fat-City” which the owner had Dumble add to the amp circa 1988, hence the extra, exceedingly rare Dumble footswitch.
I really like the BM PI changes. Anyone tried the BM preamp changes and how did you like it? And what's the Fat City reference?
Since I live in Overland Park, KS if you guys would send me $40-60k I could just swing by and probably talk Mr Shaefer into selling it to us. I'd of course share the gut shots and schematic with any contributors. We could then flip it to some "Dumble aficionado". Maybe it would be easier to find the amp tech instead.
Robert wrote:
I really like the BM PI changes. Anyone tried the BM preamp changes and how did you like it?
I've built the BM circuit, and thought it sounded great. Really nice clean tones, and unlike the HRM setup, normal OD mode (without the PAB engaged) was very usable, and reminded me how much I like having working tone controls on the outside of the amp. Also, the somewhat fatter preamp voice works well to tame the edginess of the Marshall PI. So much so, that I (personally) believe the two were made to go together.
Robert wrote:
I really like the BM PI changes. Anyone tried the BM preamp changes and how did you like it?
I've built the BM circuit, and thought it sounded great. Really nice clean tones, and unlike the HRM setup, normal OD mode (without the PAB engaged) was very usable, and reminded me how much I like having working tone controls on the outside of the amp. Also, the somewhat fatter preamp voice works well to tame the edginess of the Marshall PI. So much so, that I (personally) believe the two were made to go together.
Build it yourself and see what I mean!
chris
I keep forgetting, Chris. Are you referring to the actual schematic from EG, or taking liberties from there on? If the EG schem, how did you implement the PAB?
ayan wrote:
I keep forgetting, Chris. Are you referring to the actual schematic from EG, or taking liberties from there on? If the EG schem, how did you implement the PAB?
Thanks,
Gil
Hi Gil,
Not the EG schem, but rather one that was posted here briefly and then pulled. Values are very similar though. As far as PAB goes, I just wired it up like normal and it seems to work fine, however I've seen a few pics that show the 22M 'quieting' resistors as ground-referenced, so there might be something different going on. Since normal OD mode sounded so good, I didn't worry about that too much.
In looking at the pics, It would seem that only 1 22M actually lifts the tonestack from ground, it looks like the other 22M lifts the .0047 on the R/J Switch, any ideas of how this may work?
I know the easy answer is just to build one. I was considering altering my nonHRM amp to accomodate the BM preamp. However, I just love it so much after the BM PI mods I'm afraid if I mod it more and want to come back, I will lose something in the process since there are so many preamp changes. Therefore, knowing ahead of time if it would be worthwhile was my goal.
chris_sanford wrote:Sorry, I'm not at liberty to share that one.
I understand. Could you share your thoughts as to what makes the Bluesmaster work in OD mode without the PAB engaged (unlike the standard HRM), or is that also a secret?
chris_sanford wrote:Sorry, I'm not at liberty to share that one.
I understand. Could you share your thoughts as to what makes the Bluesmaster work in OD mode without the PAB engaged (unlike the standard HRM), or is that also a secret?
Certainly! It's just a different EQ curve. I find that HRM amps tend to be muddy/boomy sounding in OD mode (without PAB)... the net result of having two tone stacks essentially in series, both creating dips in the mid-range. The BM front end lets you dial up a different response... with more mids if you want them, so it can sound like you are in PAB mode already, only the tone controls on the front panel are still active.
Funkalicousgroove wrote:In looking at the pics, It would seem that only 1 22M actually lifts the tonestack from ground, it looks like the other 22M lifts the .0047 on the R/J Switch, any ideas of how this may work?
Funk,
In looking at the relay board on the 'LC' amp, it seems like only one pole is switching... cause the other is bridged by a ground wire. What do you make of that? Also, unless I'm seeing things, 'treble' side of the jazz/rock switch is wired differently.
We could then flip it to some "Dumble aficionado". Maybe it would be easier to find the amp tech instead.
Also, the somewhat fatter preamp voice works well to tame the edginess of the Marshall PI. So much so, that I (personally) believe the two were made to go together.