Make Bluesmaster OD Channel sound more like regular HRM

[The_Nuge]

Hi!
Is there a reasonably easy way of making the OD channel of a Ceriatone HRM Bluesmaster sound more like the OD channel of a regular Ceriatone HRM? All while not changing the sound of the clean channel!

Cheers

Es

[M Fowler]

Some advice I have gotten from guys working on these BM HRM amps.

The HRM trimmers in the BM are finicky to say the least (much like all HRM's in nature) , if I were you I'd get in there and try theses settings,

Bass: 200k
Middle: 9K
Treble: 125k

Then, adjust the PI with a matched 12ax7 ( I dig Long plates )
And a short plate in V1 & V2 (Mullard or Amperex short plates sound killer)

And set the OD Trigger at around 27.4k

Add a switch to defeat the HRM stack. I also sometimes do a 3 way mid boost. Now, the midboost, which is just essentially changing the treble cap value, is understated in its importance, I think. A lot of it depends on the guitar, and speaker used. Install a 6 way selector treble bleed.

Mark

[The_Nuge]

Thanks!
We'll try those settings next week and see how far we come. Do you adjust the PI voltage by ear, or use some set values?

Does the NF circuit, which the BM doesn't have, make a difference?

We have a regular HRM to compare with, both amps have EV12L speakers.

Cheers

Es

[norburybrook]

The bluesmaster DOES have negative feedback, it goes from the presence pot via 100k resistor at the PI end of the board to the 4 ohm tap on the output.




Marcus

[M Fowler]

You can used a matched 12AX7 PI tube and then adjust the voltage in the PI using the 10K trimmer pot to balance the PI voltage.

I personally don't think balancing the PI is all that great. It is totally subjective to the player to try achieve a balanced PI.

Like already stated: NFB is 100k 2w resistor off impedance tap.

Mark

[The_Nuge]

The bluesmaster DOES have negative feedback, it goes from the presence pot via 100k resistor at the PI end of the board to the 4 ohm tap on the output.




Marcus

Hi Marcus,

Sorry, I meant the switchable bit of the circuit between V1 and V2. My amp, the regular HRM, has this, and while I can hear a subtle difference with it on or off, I'm not entirely sure which position sounds best.
If someone can explain what it's supposed to do (in layman's terms), I'd be very grateful. I've built two amp kits, but my knowledge of their workings is extremely limited!

Cheers

Es

[norburybrook]

not sure what you mean by the switchable bit between V1 and V2?


only switches are

1: jazz rock.....IMHO a waste of time everyone uses the rock

2: PAB which bypasses the tone stack giving you a good clean boost( if your tone controls aren't all at 10)

3: OD channel, which speaks for its self.



Marcus

[brewdude]

I suspect he is asking about local negative feedback used in many Dumble circuits.

[M Fowler]

The BM is already clean so you don't need a LNFB circuit between the grid and plate of second stage. Most make it switchable if it is installed.

[chris_sanford]

Hi!
Is there a reasonably easy way of making the OD channel of a Ceriatone HRM Bluesmaster sound more like the OD channel of a regular Ceriatone HRM? All while not changing the sound of the clean channel!

Cheers

Es

What I do is change the boost so that it is of the old "treble-lift" type (which is more midrangey sounding), and then I use the OD with the boost engaged exclusively (I do not care for the sound of two tone stacks used together).

Another small, easy tweak is to change the power-amp feedback ratio to be more like the regular ODS: 12/1. The tightens up the bottom end a bit.

HTH,

chris

[The_Nuge]

Hi!
Is there a reasonably easy way of making the OD channel of a Ceriatone HRM Bluesmaster sound more like the OD channel of a regular Ceriatone HRM? All while not changing the sound of the clean channel!

Cheers

Es

What I do is change the boost so that it is of the old "treble-lift" type (which is more midrangey sounding), and then I use the OD with the boost engaged exclusively (I do not care for the sound of two tone stacks used together).

Another small, easy tweak is to change the power-amp feedback ratio to be more like the regular ODS: 12/1. The tightens up the bottom end a bit.

HTH,

chris

Hi Chris,

could you be a bit more specific? What needs changing where?
Unfortunately, my knowledge of amp circuits is ~nill, although I'm quite comfortable building kits (the Ceriatone HRM and a Soldano SLO clone so far) and soldering inside amps without getting myself electrocuted!

Thnaks!

es

[jelle]

It is the skyline PAB.

[The_Nuge]

Hi!

We had both amps side-by-side last night, and did a lot of comparing and tweaking.
First, the obvious differences:

The "Regular" HRM is a head and cab build, the BM a combo. I built the cab for the regular HRM myself, using plans found here (I think), whereas the combo uses a Tube-Town cab. Same EV12L in both amps. The separate cab is a good bit deeper than the combo, which probably explains why it produces more bottom end! We also ran the BM into the separate cab, and got more bottom end.
The BM runs a Kleinulator, the regular HRM a C-Lator. Settings similar,

Soundwise, we found the BM clean channel to be absolutely amazing, like a really, really good Blackface Fender. It has an amazing shimmering quality, even without reverb!
However, the OD channel either doesn't have enough gain, or turns fizzy when you turn up the gain or OD-Trim. Using the OD in conjunction with PAB helps, as does setting the HRM trimmers as recommended by M Fowler, but the tone isn't fluid enough...

The regular HRM on the other hand, has a decent clean tone, but nothing amazing. The OD channel is really, really good however! Really fluid and creamy, and works with both Strats and Les Pauls.

Now, how do we modify the BM OD channel to get the fluid & creamy tone of the regular HRM - but without messing with the clean tone. Is it even possible?
More ideas please - but in layman's terms, please

Cheers

Es

[norburybrook]

A friend of mine has built a lot of dumble type amps and said to me the bluesmaster has the best clean tone but the non HRM amps #102 etc have the best OD tone and there's been nothing he's done to get the best of both in 1 amp.


His new live rig consists of a #102 for OD sounds and a train wreck for clean, after a few years of trying to get it all from one amp he's finally given up and accepted 2 amps.


I'm building a BM at the moment so expect to be experiencing the same thing in a months time



Marcus

[10thTx]

For discussion purposes ......................

Not totally sure these reflect the layouts that are being referred to?

But perhaps are a starting place for a conversation about modifying one of these to have the best "clean" of the BM and the best "OD" of the HRM.

Having the schematics side by side may help with recognizing the differences.

There are some editable SCH schematics attached that someone can use to edit to offer some ideas behind this goal.

With respect, 10thtx