Ceriatone Forum

Hi all,

The cleans of my HRM 100w amp are really nice, but I can't really dial out the high end fizzyness when I use a les paul. I tried the amps distortion, pretty fizzy. I tried pedals, and the more gain, the more fizzy it got.

I tried different settings (Lower preamp gain, higher output amp gain) but is really didn't make much of a difference.

So my question:

Is the HRM just (a bit) fizzy on the high end, or is there something wrong?

I tried the speakers with another top and I had no fizzynes, so it's not the speakers (g12 65)

Please let me know

Have you tried setting the gain knob on the back of the chassis at 10 O'clock or less? Adjusted the HRM trimpots inside? Set the PI trimmer?

Hi Sander,

Ask Frank to adjust the HRM tone stack. It's ultra sensitive for different guitars.
This is gotto be done while you play.

Groeten,

Erwin

jmernyk; I mainly use overdrive pedals for my distortion sound, I never liked using distortion from the amp itself. The gain knob on the back wouldn't help because I use pedals (am i right?). Haven't adjust the trimpots, don't know what a PI trimmer is (please explain!)

erwin_ve; That might be a good idea, I don't really know anything about the HRM tonestack. Do you really think it will make a difference? I want the fizzyness to be gone, with a strat AND with a les paul.
Can I adjust the tonestack myself or do you suggest going to Franc.


Thanks a lot for your comments guys!! :)

The HRM has a pretty fizzy OD high end. Most of us are attracted to the Dumble type amps because of Robben Fords cremy sounds. However, remember that Robben Ford use a a Dumbleator (in series mode) connected with long connection wires to/from his TC2290. This effectively trims offs OD highs.

Alternatively to a dumbleator (in series mode) I use a 1n capacitor in series with a 150k resistor soldered to OD master pot in and ground. This trims off the fizzy highs in my HRM amp.

Hi Claus, You're probably right. My HRM has a built in dumblelator. No fizzy sound with it. So you're basically have a fixed ground bleed?

I use a kleinulator...  It's not a dumbleator, I know, but i'm just saying.

erwin_ve how did you get a build in dumbleator?? And could you please answer my previous questions? I'd appreciate that!

My HRM is built in a old Peavey Classic VT chassis. Since there was plenty of room I built in a dumblelator too.

I don't know what Franc did to your circuit that your pedals also sound fizzy, really you better ask him. There are multiple things that can cause it; bright cap on the clean master, wrong position of signal wires in relation to the heater wires. Bright settings on the Klein. etc. Most of it is tech talk and would take a long time to explain.
The HRM tone stack are 3 trimpots that do the treble mid and bass for your overdrive channel. But it has no effect if you use the clean channel.

Yes, exactly

I use 1n + 150k in my HRM
and
1n + 180k in my high plate non-HRM

I have found the values by trial and error comparing with the sound of having the dumblelator in the circuit.

Would a modification like this also work for the clean channel? (to get rid  of the fizzyness with pedals?)

Yes it would. However, try a trimmer in series with a capacitor in order to find the sweet spot. When you have found a sound you like, simply measure the trimmer value and put a an ordinary resistor of same value in  the circuit.

If you amp is rather new. Have a little patience with the amp. It takes 50-100 hours to break in, which in effect will soften the tone. You can simulate this with the above mentioned trimmer. And adjust the trimmer on a weekly basis until the amp has settled in. Pretty smart huh?

Hi, we might try this mod to see if it helps in this amp. Do you mean the 'Level' pot?

The OD master pot

Okay, but that only works on the clean channel, so how will that help the OD channel?

Hi Franc,
Is it possible you have a marshall style heater wiring? If so; make sure all the wires to the tube(cathode and plate) have 1cm space related to the heater wires.

This really seems like a nice mod that might work for me..

I noticed there is more fizz when I plug my les paul into the 'high' input. When I plug into the 'low' input there's still a fizzy high end, but not as much as before. So what does this tell us?

I also noticed that the high end is pretty much controlled by the presence knob. When I turn it to 0 most of the fizz is gone. But than the overall tone of the amp is of course a bit "dull' or 'in a box". Can't it be that I just don't like "presence"? My previous amp didn't even had a presence control and maybe that's why i dídn't experienced fizzynes....????

Maybe it all sounds a bit weird, but these thoughts are just in my head;)

You should et out more  ;)

Just kidding.

You could try a different capacitor value in the presence circuit in order to change the frequency point of same.

Wow I'm learning more and more. 8)

I think 95% of the problem is actually in the presence control! I used to have it round 3. Now I put it at lets say 0.75 and the fizzynes is more or less gone...? I raised the treble a bit and its getting better!

But now I really miss a bit of, how should I say it, 'life' in the sound. It could be more present ;)! (like it's a bit caught in the speakers and not comming out all the way)

Is there a way to have some more presence, as in cutting through the mix, without adding the high end fizz (hair on the notes)...????

The problem isn't fizzyness. Setting the presence low is masking the problem.

I've modded 3 different OTS with marshall style heater wiring that had this problem.

Floating heater wires(like Fender) does not mess up your tone. Grid and cathode wires are sensitive to the magnetics produced by the heater wires.

It is possible to lift the cathode grid an plate wire a bit so don't touch the marshall style heater wire. But the Fender way is better IMO.