How to set your OD In trimmer on HRM/BM

[mdroberts1243]

What philosophy/approach do you use to set the OD In trimmer?

Do you set it to keep OD1 clean with maximum clean volume (and let OD2 give you your distortion)? Or do you set it for some compression/distortion out of OD1?

I've played around with the input network/etc and found that there is always a pretty sensitive set-point where OD1 goes from clean to compressed/distorted (with maximum clean output from CL1 & CL2)... this has varied from 15k to 24k depending on the network.

Thanks,

[Fischerman]

I don't think I can answer your question (I just do it by ear pretty much..then measure it just for the info) but I have a couple questions that others may also have:
Is PAB on?
When you say 'with maximum clean output from CL1 & CL2'...what exactly do you mean here? I ask because obv PAB being on or off makes a big difference but also because when the grid of OD1 starts to get clipped...it shows up as 'distortion/compression' on the plate of CL2 when in OD mode (I assume due to grid current at OD1's grid). You could always check it in clean mode but the loading on CL2's output is slightly different and of course you have to set the PAB to the same state as when in OD mode.

The input network makes a big difference...I've tried a few variations and have gone as low as around 12k and as high as 32k.

[mdroberts1243]

I don't think I can answer your question (I just do it by ear pretty much..then measure it just for the info) but I have a couple questions that others may also have:
Is PAB on?
When you say 'with maximum clean output from CL1 & CL2'...what exactly do you mean here?

Hi Fischerman,

I am setting up the OD In trimmer with PAB on. Maximum output from CL1 and CL2 means that the input signal is set very high but doesn't compress/distort out of CL1 and the volume control is set as high as it can go without compressing/distorting the output of CL2... the important thing is that I adjust the volume so that the output of CL2 is very clean.

[mdroberts1243]

Poking around with the search tool I found these two quotes from Odourboy and Normster... anybody care to expand or comment on their philosophy for setting this?

Normster,

Where to you usually set the internal trimmer on your ready built D'Lites? I asked Chuck how his was set up and he suggested I ask you.

Thanks! OB.

I set it up by ear. With the Vol at 2:00 and OD Gain at 9:00, I turn the trimmer until I get just a touch of bluesy breakup (and clean with a releatively light touch). The sweet spot for me is ususally between 10:00 and 11:00 on the trimmer. Scott has suggested that with Chuck's touch, I should have bumped it closer to 11:00 but I think it's about 10:30.

In response to another poster's question...

[SNIP] It may be that you've simply got too much going into the OD1. That's going to make your tone harsh and grainy. I try to keep OD1 running in the compression zone - just shy of clipping - with max input. (For me, that's usually voluime at about 1:00, 6 on the dial). Let OD2 do the work.

[Fischerman]

I had posted a similar comment to odourboy's shortly after I first scoped my amp. I seemed to get better OD if I left OD1 pretty clean...but about as high as you can get it before it compresses/distorts. Like you said...there seems to be a sweet spot right around there...whether it's 'right on the verge' or just past it I'm still not sure.

[mdroberts1243]

I had posted a similar comment to odourboy's shortly after I first scoped my amp. I seemed to get better OD if I left OD1 pretty clean...but about as high as you can get it before it compresses/distorts. Like you said...there seems to be a sweet spot right around there...whether it's 'right on the verge' or just past it I'm still not sure.

Thanks again, Fischerman,

Thought I'd give one try at a friendly bump on this post... I was hoping to have a few wade in with their opinions... everybody has to set this somewhere!

I've been back and forth on this, trying it clean and then slightly dirty and haven't got a preference yet. I was wondering what people think Dumble's intent was and what might have been observed from the real thing.