TubeMeister 18 flat EQ

With the help of a spectrum analyzer, I was able to determine that the bands being manipulated with the Tubemeister 18 are:

Bass - 200 Hz
Mid - 2 kHz
Treble - 7.5 kHz

I haven't been able to figure out what settings would be considered flat.

Does anyone know?

I had assumed from the feel of the thing that it was similar to a Baxandall or James setup with 12:00 as the flat points and cut/lift from there.  It just doesn't have the feel of a simple tonestack design to me.  With the treble set at 7.5kHz that explains a lot!  That's very high for a guitar amp and really leaves the Mid as the control making the most audible difference.  If the Treble is set that high then I have to ask why have a Presence control as that should be even higher and would be getting to the point where it won't be heard much at all?

EDIT: Mind you I only have experience of the 36s, both TM and GM.

I originally got the TM18 to use with bass & guitar, but it's lousy for bass, other than Motorhead songs.
I am dubious that 12 o'clock is flat, based on my readings with an Android Spectrum Analyzer application.
It does show that Mid has the most cut/boost, but I can't get a flat line on the app, especially not with the controls at 12 o'clock.

Ah, you say it's a Android app, so your input is from the microphone on your phone or tablet?

Yes, which is why I couldn't get a flat line.

That was just what I was going to point out!

I've just picked up a piece of freeware for my PC which will do this so I will have to set the amp up to feed into that.  We should get a realistic picture of what is what then.  I'll keep you up to date here when I can get it working.

Thanks!

I was wrong about the tone controls, they're not a Baxandall/James approach, they are a simple Marshall style tonestack.  I have a software tonestack simulator and here is what it just spat out.

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Each control is set to display Red - 0%, Green - 50%, Orange - 100%.  The others are held at 50% while each one is simulating its range.

There is a fair bit of interplay in each others' ranges isn't there?  Of course the TM36 and the GMs may be different but it is a fair bet that they will be tonestack designs as well, maybe with slightly different values for their individual voicings.

Great work BB!

I did the easy bit, Bdw supplied the hard bit.

Thanks!

Based on those graphs, I'd say the Bass frequency being manipulated is 40 Hz,
Mid is 800 Hz, and Treble is 10 kHz, but maybe I'm just reading them wrong.

The Bass control seems to vary +/- 6 dB
Mid +/- 5 dB
Treble +/- 5 dB

Are these results from the GM36 or from the simulator stand-alone?

If they're from the GM36, can you get a flat line dialing in all the EQ knobs?

They're from the TM18 values Brad.  You can see them in the pic below.

And I have just learned something very interesting I never knew.  There is a flat point but not in the middle!  It is with the Bass around 2%, Treble around 7% and the Mid around 71%.  It turns out to be absolutely flat with a Bass 3dB point close to 600Hz.  I never knew that those extremes would flatten out the graph as well as it does.

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Well that is superb!



EDIT: Whoops, need to adjust my log and lin pot types but the principle still holds. I'll correct it later.

I don't know electronics from a hole in the ground but nonetheless I find this fascinating and I applaud you guys for your talent and for taking the time to work on it and explain it.

So if I'm interpreting this info correctly, putting the EQ knobs at noon actually results in slightly scooped mids and VERY slightly bumped bass and treble, right?

bordonbert wrote:They're from the TM18 values Brad.  You can see them in the pic below.

And I have just learned something very interesting I never knew.  There is a flat point but not in the middle!  It is with the Bass around 2%, Treble around 7% and the Mid around 71%.  It turns out to be absolutely flat with a Bass 3dB point close to 600Hz.  I never knew that those extremes would flatten out the graph as well as it does.

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Well that is superb!

Thanks for doing this. It verifies what I thought from the spectrum analyzer, than at noon they're not flat.
I'm going to go play mine now with the Bass & Treble at 9 o'clock, and the Mid to 3 o'clock.