Thanks for the detailed reply and the pic - awesome helpful

author=plasticvonaband link=topic=1541.msg16592#msg16592 date=1299906498
i've attached a pic of the slop resistor for you, but i have a few suggestions/questions

First of all as T Wilcox suggested, you may want to experiment with the OD trim. By adjusting it you can go from slight overdrive to all out chaos, but it starts to get fizzy as you turn it up.
What kind of preamp/power tubes are you running? Different tubes can yield different results

Experimenting with the OD trim sounds like a good idea.
I am currently running  these tubes:
v1 = RCA black plate 5751     
v2 = Brimar 12AT7WA / CV4024
v3 = GT SAG-AX7-MPI-1104092   
output = TAD 6L6WGC-STR
but I have some more 12ax7's on the way on the way that I want to try out in v1 & v2.

What kind of speakers are you running? The OTS series is kinda picky when it comes to speakers.

I've got a Celestion gold and a Electrovoice EVM-12S in a pair of thiele-style cabs.  Also tried a Celestion G12T-75.  The gold and evm12s are both fairly bright sounding.  I am happy with them, but I wouldn't mind hearing other speaker suggestions though if there is something particularly well suited to the OTS.

Are you running OD and PAB at the same time? If you aren't you may want to try it. Without the PAB on (which in my opinion should be renamed Tone Stack Lift, since that is what it does) in OD mode on an HRM amp you are sending you signal through two tone stacks which can make your town sound either muddy or harsh depending on your settings.

I have tried it this way, but I find the voicing between clean/od channels is too different, with the od channel being much duller/darker.  The previous owner disconnected the OD channel tone trim pots and replaced them with a cap.  I think I should try the amp with this mod reversed to see if it helps.


Also, the Preamp (clean) volume will effect the overall gain as well, as V1 cascades into V2. In otherwords if you crank the clean gain and use your guitar volume to get some nice dirt when pushed, when you kick in the OD channel your OD can be very gainy and fizzy as well.

I typically have the preamp volume at noon (5)

A C-Lator helps alot, but isn't technically necessary although, mine really woke up and sounded awesome with it

I ordered a C-lator, but it is taking a really long time to arrive.  I am really quite curious to see how the amp responds with it.


As far as the slope resistor goes, the common mod is to switch it to 68k or 100k and to switch the main tonestack bass pot from 500k to 250k, and i even considered doing it until the amp got nicely broken in, got some great speakers, played around with different tubes, and adjusted the OD tonestack with the PAB engaged, adjusted the OD trim, and got a c-lator.

I will give the 68k/100k a try.  What effect does 250k bass pot have? Less bass output?

Hope this helps, and let us know the answers to the questions if ya can; AND above all, remember all that matters is that you find YOUR tone and YOU like the way your amp sounds

Gregg

Again, a very helpful reply, thank you.

I suppose I should have stated my question a little bit more clearly.  I am new to the bluesmaster, but it is not a new amp.  I bought it used, it should be plenty broken in by now.

I am going to give the components a look over even if I do not change anything . . . just like to know what I have in there.  Slope resistor anyone?

I am also a new bluesmaster owner with a fizzy gain channel.  I think I will go through and check component values also.  Can anyone tell me which resistor is the slope resistor is?  I feel a little silly asking, but I am not an electronics whiz.  Also, I am assuming that there is no way to measure actual values of the components without removing them from the board?