Ceriatone Forum

Hi guys,

I have an HRM BM100. I really like the clean channel but I am still struggling with getting enough mids out of the OD channel. I am getting lost in the mix at gigs. I have adjusted the internal HRM trimmers and I have the mid control maxed, the bass around noon and the treble very low, almost off but it still sounds mid scooped to me. I have the OD trimmer at like 9' o clock and the Drive knob never past 6. I want to change the OD voicing of the amp so it is less mid-scooped, more Marshall-y like a '74 JMP that I have. What would I need to change component-wise to do this? I have modded amps before so I'll make sure I drain the caps. Thanks!

Don't mess with component values just yet.

Try the following settings instead :

Bass down to 73k from 500k (you are at noon)
Treble about 40% up. (around 11 o'clock)
mids on 4.45k (thats 1/4 of what you have now)

(OD gain trim) at 20k to ground.

These settings works excellent on my 100 w bluesmaster.

The bass/mid relationship is the key to great sounds on a BM,  IMO

Or you could use another relay board and use it to switch mid boost along with the OD... perhaps

Thanks for the ideas. My HRM trimmers were originally set the way you describe. Sounds good here at the house but not enough mids to cut through for me in live situations.

Could you describe this in more detail? This could work....

Well first of all you have to determine that mid boost works for you on OD channel.
If that works,... you could add another relay board and use it instead of the manual mid switch. You could add another switch on your foot switch or wire that relay in a way that it goes on only when you switch to OD... something like that.

you could try my custom HRM design (warning very midrangy)

250K treble pot (stock)
100K mid pot (original is 25K)
500k bass (stock)

lower the value of the treble cap (i use 200-330pf- depends on guitar/style)
Lower the value of the mid cap (i use 4n- down from 22n. This give huge sounding thick low mids)
Lower bass cap (10n-down from 22n. Keeps OD from getting muddy, compensates for  increased mids.)

On my personal amp i have a switch that changes the mid and bass caps. 4n/8n (mids) 8n/20n(bass) simultaniously

Thanks for more ideas guys, very helpful. I have been using my Boss EQ with the OD channel and the stuff I want to hear more of is in the 400-800K range. When I boost up that section of the EQ, the OD channel is perfect.

JD, would the mods you stated hit the midrange around that area? Thanks!

Can I ask what speakers you're using?
You may find that would solve it. Some speakers are very scooped. Perhaps you have ones very suited to the clean tone but not the OD tone

A few ideas:
I also find that the OD character changes a lot with different settings.
Try the OD trim on much higher and back off the front panel OD knobs.
Also, on the front  I find the left OD control adds more darkness than the right hand one, try a diff balance there

Before reworking the amp. first try whacking the OD trim up with the other settings the way you like them. It sounds like you may have the master vol low, and the OD trimmed low to match. I think the preamp needs more scooping when run clean with low master vol. If you run master vol at 3 o'clock, it runs brighter in clean mode (on mine).

btw, I can't tell for certain which set of trimmers/pots are being mentioned in some of these posts,

Yes about 400-1000hz lots and lots of low mids. The "scoop" in the HRM is moved to around 2K-3K and can be flattened out to sound more like a non-hrm EQ with the right settings