I know this is an old thread, but I've been outta commission for a while. Had a stroke back in August, jest getting back into the forum. As a long tine BM owner I have a few questions. What speakers are ya using? Which preamp tubes are ya running? Have you adjusted the HRM stack? Are you using the PAB when using the OD? If not, you are going through two tonestacks, which results in mud.
I can tell you that switching the slope resistor is easy, I even have the parts to make an adjustable slope resistor. Just have gotten around to it. Hope this helps!

EL34s won't make the BM sound Marshally. The OTS series gets most of its tone from the Preamp circuit.

depends? what kinda tone ya lookin for?

Gregg

I use two with paper cones and pre rola doping in my BM50 and love em. Every thing else I try sounds bland by comparison

I'd try different speakers, along with the mods mentioned by TennAmp, espcially the slope resisitor. I have had the parts sitting around to modify mine for like two years and keep forgetting to do it.  The low value stock value really allows alot of low to get through there. Personally, i like the low end, amd run the deep switch on mine which tightens it up quite a bit. i run my bass somewhat higher than most folks do, but, i also run an open back 2x12 and that might make a difference. I run through two Weber AlNiCo 1265's and they sound perfect with the BM.

my BM50 is loud as hell. Surely, the loudest 50 watt tube amp i have ever owned, and i play mostly on the clean side. Does it have as much headroom as the 100 watt? No, of course not, silly! Does it have more headroom than most 50 watt amps clean "channel" absolutely! Can i make it dirty in a hurry with a boost, or the modified tone stack lift (PAB). Hell yes!!!! That's the point of the thing though.

Basically, to the OP, the BM 50 will prolly give you more clean headroom than you need, unless you want Twin levels, then go with the BM 100

Gregg

Thanks, man. I woulda responded faster, but i kinda forgot about the forums 

On the truss rod issue, i have had a DC 59 since 1998 and live in FL with temp and humidity swings and my Dano has never needed adjustment. they put good necks on those buggers 

The answer to your question is here: 

http://ceriatoneforum.com/index.php?topic=1117.0

hope this helps!

Gregg

I play a big fat esquire a lot of the time, and the BM is great when you push the clean side to the edge with a nice clean boost or modify the PAB to the original value or both It's probably just what you're after

Gregg

Any new run of cabs, Henry?

Gregg

It can also depend on the speaker choice as well. I find the BM to be warm but really more of a full range, due to the bottoms end that it has. I run mine thru two Weber 1265 Alnico with the "pre rola" treatment, and they are well broken in by weber and myself. They are 16 ohms run in parallel, so I run at 8 ohms. This seems to bring balance to the amp. Since the speakers are a bit tight, I can run the bass a lil higher around 6 of so, and with the deep switch on, it tightens things up even more.

The slope resistor value is also lower than the rest of the OTS series, which allows for more low end, and also changes the entire curve of the eq to be more  "full range" as well, a bit more raw, but yet a bit more musical than others; there's a lot of low end and high end harmonics there just waiting to be found.

A lot of guys change out the slope resistor to a higher value to change the eq curve and basically make the amp a tad brighter. I have all the parts to make the slope resistor variable, from the stock value all the way to 120, just haven't found the time to do it.

Basically, the amp isn't really dark, it just has a ton of low end due to the slope resistor, and the way the PI is setup as well. It just takes some dialing in and speaker swapping to find what you like. The EVM 12L is a good choice, or it's eminence clones the Delta 12a and the Delta 12 pro A. Both are very close to the EV and half the price, they just need a good heavy break in. I used the 20 year old equivalent of the Delta 12a that I had in my 4x12 for a while til age and dry rot took their toll.

I hope this helps!

I have all the parts and advice from Nik to do the slope mod, just have to find the time to do it.

As for tubes, I generally run late 50's/early 60's Long Plate GE tubes in V1 and V2, and a telefunken ribbed plate in V3 and in the c-lator. The Telefunkens are known for their toughness and long life, so I think they are perfect for the PI and the small space in the c-lator.Sometimes i run a JAN GE 5751 in V2 for a different flavor.

For output tubes I run either the Tung Sol "reissue" 6L6GC which offers a nice 5881 sound without worrying about redplating, or JAN Phillips 6L6WGB. The 6L6WGB is a small bottle tube, which is rated at a lower wattage (23-25) compared to a typical 6L6. It is a sweet sounding tube, I think mainly because it is on the razors edge as far as plate voltage and current is concerned. In the BM it really brings out it's raw tweedy side. the OTS the B+ voltage is just outside the range of the tube, so use with caution. I have redplated one once, but was able to shut her down before it went into full melt down.

Sorry for the long post again, but I hope this helps!

Gregg

. As jeffhamula stated, On the majority of the OTS amps, the PAB lifts the tonestack and removes it from the signal chain to a varying degree, depending on the model. In studying the layouts, each model seems to employ this lift a little differently, depending on the design of the stack and if the circuit has a mid boost or deep boost, etc and these little differences seem to allow for either more mids or high mids to get thru, depending on how it is employed. It seems only the BM does a full across the board lift, and, in the originals, employed a higher value resistor (22M vs 68k) resulting in even more boost. I have my PAB wired on a switch with 22M and 68k, and there is a huge difference.
In your case, I'd try a clean boost pedal IN FRONT OF the amp, not in the loop. I was using a Boosta Grande for a long time, and switched to the BYOC Tri boost. They both work very well, just different flavors

Sorry for the long winded explanation, and I hope this helps!

Gregg

Have you tried new output tubes? Checked to see what the bias is set at? When the volume jumps and it starts to feedback are you able to walk over and check to see if the output tubes are red plating? That's a few things you can check pretty easily.

Gregg

I think his was an older model that had a certain type of buffer in it, or better control of signal in and out of the unit, if I recall. That's why it would work fairly well without the c/k-lator

Gregg