I tried the changes, but we really didn't hear much difference

The thing is, the amp barely reacts to the (front panel) Mid knob?
I have a second HRM 50W which is exactly the same, but this one DOES react to the Mid and sounds much better.

I have checked components in the mid section, but nothing seems to be way off.... What else can I check?

Thanks for your insights! This is definately something I am going to try.
I tried to capture what you wrote in a pic:



What would be a recommended value for treble to try? Would 250p be a good idea? And to what value did you lower the bass cap?

Well, partly, thanks

The top half of your picture shows what you expect and I know it is working this way, but the layout obviously is wrong here.
What are the caops for, to avoid switching noise?

Can you explain why in manual position without pedal, the amp is on the clean channel? I know it doesn't REALLY matter but I wonder if I made a mistake somewhere...

Looking at the OD switch, the 0.1u cap doesn't appear to do anything, because the top left lug of the switch where one end of the cap is connected to, doesn't go anywhere.
When switched to manual, S is connected to ground and the cap (which does nothing as it is floating).
When switched to pedal, S is connected to the pedal and the cap is shorted out (but still floating).

So this must be a mistake in the layout?

When you look at the picture of the finished amp, you see the wire from the pedal is going to the left upper lug, always connected to the cap.
I wonder if both switches shouldn't be wired the same....

Okay, I just tried and without pedal attached, putting the PAB switch to manual engages the PAB and putting it to pedal disengages.
However, the switch for the OD works the other way around and I am not sure I understand?
Switching to manual without pedal disengages the OD channel and switching to pedal engages.
Did I miswire anything or is this the way it should be?

Just trying to understand what's going on with those 2 switches

Really? I never noticed that. I will try right now In any case, whether the pedal is connected or not should not make a difference as in the manual position the wires coming from the pedal are disconnected, but I get your point.



Look at the pic: the black wire from the pedal connector is wired differently.

I'm looking for some improvements to the tonestack of the HRM.
It seems to me the Treble Middle and Bass controls are interacting too much.
The Mid knob hardly works when Bass is down and sounds like it is operating more in Treble areas than it should.
Is this the 'fault' of the internal tonestack that replaces the 0.005u cap that is there in the normal OTS?
Would it make sense to get rid of it and replace it with a 0.005u cap altogether?
Or is there a sweet spot for the internal 3 pots?

It's bugging me that the TMB controls are not responding the way I want them to...

It's not clear exaclty which type of PPIMV you will be installing, but if you do it right, setting it to '10' will make it virtually out of the circuit, so why bother with trying to make it switchable (which I think is not a good idea, if possible at all - you would need relays).

Hi, I have built a couple of HRMs already but this amp still has a lot of mysteries to me.

For starters the 2 switches on the back.
From a user's point of view: what's the use of these switches? Why would anyone ever set them to manual as there's no way to manually switch the channels or the boost? What's the point?

Technically: I see a difference between the pics on Ceriatone's website (pics of completed amp) and the layout there. I am not sure if it is important as I don't know the reason for the caps that are mounted (differently) to the switches. What do they do?

I have more questions about this amp, but let's focus on these for now

Thanks in advance.

I removed one from an old PC power unit and it says 12VDC....

Maybe I should find another one then...

I want to put a 12Vcd computerfan inside the box of a Dizzy30 because it gets very hot.
Ayone has an elegant solution for getting 12Vcd from the amp without too much modification?

Thanks for your comments.

In a combo, there is of course a lot more room for the air to flow.....

I think I'll replace the backplate with an alu strip to cover the tubes and leave the rest open.

If it makes good contact, you close the cage and it should always be an improvement.

If it causes hum that means something is wrong .

I wonder why no-one has replied

Don't know if this is still interests you, but it shouldn't be a problem to install a half power switch that lifts the ground of 2 of the 4 EL43s.
You get half power without a problem.

Hi All,

I have built a DC30 for a customer. Made a nice headcabinet in Matchless style for it.
When he plays it for a longer period (he is a professional guitarist), the chassis gets really hot.
To the point that he can barely touch the ON/OFF and STDBY switches.

I have tested the chassis upsidedown out of the cabinet for a couple of hours and it doesn't get that hot at all.
The PT warms up a little, but nothing to worry about.
So my conclusion is that it's really the tubes producing the heat and because the chassis is hanging, the hot air can't go anywhere.

I was wondering if more people experience this and what there solution is. Probably the best solution would to replace the wooden front with something like a grill so air can flow freely, bu that would change the look of the amp. Besides, the real DC30s are built the same way.

Or am I looking at a different problem?

Thanks.