# So i just removed the tone stack from my bassmate



## analogteletube (Jan 26, 2011)

At gigs and in the studio i always run my bassmate dimed, everything on ten. I had been wondering for awhile about removing the tone stack and the proper way to go about it but i couldnt really find any info specifically on the bassmate. Mine is a Yba2-a/b 2-12ax7 2-el84. So i went for it. I Cut the lead from the slope resistor to the bass pot, and the one from the tropical fish to the treble pot and soldered them both to the hot side of the volume pot. Pretty hefty boost in volume and gain, im just wondering if anyone out there knows if its safe to run my bassmate this way?


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## washburned (Oct 13, 2006)

My new Valve Train has a switch that bypasses the tone stack and does the same thing...lots more volume and gain. And power amps for years have not used tone stacks.


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## analogteletube (Jan 26, 2011)

Hey thanks for the reply! I know there are lots of amps that have tonestack bypass switches, but they have been engineered to work by professionals. While doing research to figure out how i might go about removing my tonestack i had read that some types of amps would need to add another coupling cap to join the stages, while others could just have the tonestack cut right out. I'm looking for info related to my amp specifically.


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## parkhead (Aug 14, 2009)

If you got a healthy boost in volume and gain you did it right. If you needed a coupling cap you would have put DC on the next stage and have a bad distorted sound. 

If you want to tune what you,ve just done you might want to insert a cap try .002 .01 .02 values to get a tight guitar tone. 

P


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## analogteletube (Jan 26, 2011)

Thanks parkhead!, The distorted sound is heavenly so i guess i did it right!


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## nivek (May 17, 2011)

Question... what does it mean to remove the tonestack? Despite playing for many years, I guess I always just plug in, fiddle and go. Never got into changing stuff around with my gear (well, not true because I did shield and 5 wire ground my old strat). So, would you mind maybe explaining a bit? I suppose googling would have been faster .


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## keeperofthegood (Apr 30, 2008)

Typically tone stacks site between a pair of triodes. You can cut the stack out and put a 0.022 to 0.047UF cap in the stacks place.

The reason why is fairly simple. There is no "gain" in a stack. It sits in the center of half power. Turning the treble UP brings the power of the treble towards 100%, or down lowers it below 50%. Same for bass. Take it out, and you have essentially the same as all controls to full plus some because there are no side paths to bleed through.


Compare with Fender:

PRE:










POST:


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## nivek (May 17, 2011)

Ahhhhhh...

So... you're bypassing the EQ section so everything runs wide open in it's natural state, basically? Why not just add an extra 1 so you can turn it up to 11?

Is it the avoidance of bleeding side paths that is the main goal?

Why does it sound different to bypass with a cap instead of just cranking everything up full on?


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## keeperofthegood (Apr 30, 2008)

If you look at that second schematic, you still have the 100K and 0.047uf cap going either through the 10K pot or direct to ground and that is one where the signal will path away. The other pathway is the 260pf and 250K pot at the top, the next two pots down can be either 0 ohms direct to ground OR their max values direct to ground and so that is another. There is no time where these parts are lifted from ground. What I should google for is the schematic showing the switchable bypass for the tone stack

Here should have done this too. On yours you can follow where the signal goes to ground and how. Here too there is no pathway that is "out" of the ground of the signal through the tone stack:


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## JDW3 (Sep 23, 2009)

Slightly off topic, but looking at this schematic, can you tell me why I can't put a cap across the V1 5.6K cathode resistors? I have tried this, and it just creates high pitched squealing/feedback. I can lower one cathode resistor and it works fine, from 5.6K to 1.5K. But not both, and no bypass caps.

This is the amp/schematic I have been puzzling over this month. (And last year...) My thought is that the 2 triodes are cascaded, like a one wire mod. It's creating a lot of gain, but Marshall for example, uses this design and has much smaller cathodes, and they are bypassed.

Any thoughts?



keeperofthegood said:


> If you look at that second schematic, you still have the 100K and 0.047uf cap going either through the 10K pot or direct to ground and that is one where the signal will path away. The other pathway is the 260pf and 250K pot at the top, the next two pots down can be either 0 ohms direct to ground OR their max values direct to ground and so that is another. There is no time where these parts are lifted from ground. What I should google for is the schematic showing the switchable bypass for the tone stack
> 
> Here should have done this too. On yours you can follow where the signal goes to ground and how. Here too there is no pathway that is "out" of the ground of the signal through the tone stack:


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