MP-1 tone section

[MarshallJMP]

What do you guys think of the MP-1 tonesection?What can be changed,what freq's do you like?I was maybe thinking of doing some mods on the tone section.Like the bass really could use some tuning.

So let's hear it !

[DorsetRatt]

How about the eq being adjustable in increments of 1, instead of 2?

[MarshallJMP]

Probleem here is that the tc9170 only has 13 steps, -6 - 0 - 6 so no change possible.

[tomy]

Is tc9170 à chipset ?

[MarshallJMP]

Is tc9170 à chipset ?

The TC9170 is an electronic pot.There are 2 of those with 2 pots in it,so 4 bands.

[tomy]

Make sense.
But I didn't get the 13 steps idea(you mean -6 to +6 is 12 and 0 is 13th step? ) and 2 by 2 changing paramètres ?

[tomy]

Make sense.
But I didn't get the 13 steps idea(you mean -6 to +6 is 12 and 0 is 13th step? ) and 2 by 2 changing paramètres ?

Hey MJ, nevermind... I trust you !

[MarshallJMP]

Yes zero is also a step.What do you mean by "2 by 2 changing paramètres "?

[tomy]

If you have 13 steps between -6 & +6, when you increment by 2, it become 7 steps(-6/-4/-2/0/+2/+4/+6)

Am I wrong ?

[MarshallJMP]

Mmmm what ADA did was going from -15,-12,-9,-6,-4,-2,0,2,4,6,9,12,15 dB so 13 steps.

[tomy]

Gotcha !
So the increment by 2 cannot be changed !

And what part of the tone can you mod ?

[MarshallJMP]

Well f0 or the center freq,Q factor (filter bandwith) and K factor (filter gain) on the mid and treble filters (these are VCVS type filters).Bass and presence are different,bass is a very simple first order low pass filter and presence a simple bandpass filter.
I was maybe thinking to make them all VCVS filters.Don't know if it will be possible on the mainboard.Else maybe design a small doughterboard that plugs into the quad opamp.

[tomy]

Some of mods you built are based on daughter board and now as i understand, you want to go far on the motherboard ???          Interesting !!

On other idea :

-ADA mp1 is pretty well known for high gain tone (thinking of 3tm/3.666 mod). Is there  any chance to get greatter cleans  ???

[MarshallJMP]

Well with the 3TM/3.666 you mod the tubeboard that share's the clean/distortion tube.And it's a ying yang thing,you always have to sacrifice something,and in most cases it's the clean sounds.And in the case of the 3TM there is no clean tube anymore.That has been turned into a "brown channel".
This is one of the reasons i use an MP-2 for cleans.It has better cleans,even compared to a stock mp-1.

[tomy]

ok ! So let's keep it that way... mp1 for high gain that's his job