coupling cap bass mod Mk iii

[HelpingFriendly]

So I've read around the Web that lowering the uf of the decoupling caps in an amp will reduce the bass some and can help with woofy issues. I was wondering if anyone has input on this type of cap adjustment on the mark series? Am I correct that these are the 3 big electrolytic 30 uf caps? I'm about to order new f&t caps for the filter section and I want to replace the decoupling caps as well. I think I would benefit from the mod because I spend most of the time on the neck pickup where it can get woofy at times for my style of music. I don't think I would go lower than 20 uf which is just a small adjustment. I'm curious on your thoughts from some of you guys who really know the curcuit well.

I'm also considering raising the uf on the filters just a tad to "tighten" up the bass. Again, not to far from the stock values of 4x220uf. Just a slight increase. What do you guys think of this on a Mk iii? I also read you can adjust the cathode caps to reduce bass. I'm trying not to get the cathode and decoupling mixed up. Lol. I think one of them will give more headroom?

Oh and I do have experience cap changing and understand amp safety. I'm just eager to learn more about how each component does what. Thanks

 

[Boogiebabies]

So I've read around the Web that lowering the uf of the decoupling caps in an amp will reduce the bass some and can help with woofy issues. I was wondering if anyone has input on this type of cap adjustment on the mark series? Am I correct that these are the 3 big electrolytic 30 uf caps? I'm about to order new f&t caps for the filter section and I want to replace the decoupling caps as well. I think I would benefit from the mod because I spend most of the time on the neck pickup where it can get woofy at times for my style of music. I don't think I would go lower than 20 uf which is just a small adjustment. I'm curious on your thoughts from some of you guys who really know the curcuit well.

I'm also considering raising the uf on the filters just a tad to "tighten" up the bass. Again, not to far from the stock values of 4x220uf. Just a slight increase. What do you guys think of this on a Mk iii? I also read you can adjust the cathode caps to reduce bass. I'm trying not to get the cathode and decoupling mixed up. Lol. I think one of them will give more headroom?

Oh and I do have experience cap changing and understand amp safety. I'm just eager to learn more about how each component does what. Thanks

Those amps have so much filtering I think they could let 30Hz of bass through. You better off looking at reducing the value of the cathode bypass caps in the preamp, that is where the woof is but I think the design is perfect.

 

[chipaudette]

If you're looking at the 30 uF caps and the 220 uF caps, I think that you're looking in the wrong place to tame your perception of too much bass.

As suggested above, look at reducing the value of the caps on the cathode of each pre-amp tube, or reducing the value of the caps between each pre-amp gain stage (usually 0.047 uF).

Before you do anything, try engaging the Graphic EQ and turning down the lowest bass slider. Or, put a 10-band graphic EQ in the effects loop. These will give you a sense of whether bass reduction is really what you seek.

Other options include trying a different speaker, a different guitar, or putting the amp in a different location in your room. Making changes to the circuit itself may be relatively easy, but your goal to affect the bass response will also have (probably unintended) effects on the perceived gain of the amp and its perceived touch sensitivity. You may lose some of the desirable characteristics of your amp along with removing the undesirable ones.

Good luck,

Chip