Bright caps

[ClassicRock88]

I am planning on taking my 800 in to have a few (small) mods done to it. One of the mods that I am considering while it is on the bench is clipping the bright cap. As I have said before I really like JTM 45/100 and Superbass sounds. (I am seriously considering a Ceriatone Superbass but that is another story entirely) I have tried to look up as much info on clipping bright caps as I can but I'm not finding much. Some people do it and love it and others say that it destroys the character of a 2203/2204. Does anybody have any sound clips of a MV amp without the bright cap? Right now I have the Presence totally off and the treble between 3 and 4. I like the sound but would like some of the extra clarity that can be had with the presence control up a bit. If I turn it up it gets ear piercingly bright. I have an extra 12ax7 in mine so I am sure that contributes. Could I possibly have the bright cap switched so that I could take it in and out of the circuit depending on venues, speakers, etc?

[jboyjams]

I have a 79 2204 and tried no caps vs. stock. Currently it's stock and sounds great - but I set it pretty clean and hit it with overdrives and it becomes trebly to where I have to turn the tone off on a pedal, but straight in the amp sounds just right - I may experiment more with this. (there are 2 caps - one is a 470 piggy backed on a resistor from the pre-amp pot to the input. The other is 1000 on the pre-amp pot). Some people make them switchable.

pic:
http://www.amparchives.com/album/Marsha ... _orig.html

[michael_dba]

It's an easy mod to to do/undo if you don't like it.

If you are inclined, you can clip it yourself and use some of those short jumper leads with alligator clips on each end to reconnect it temporarily to compare it with and without....for both caps if you want. Your tech can do this with you.

It's switchable if you want to drill a hole in the chassis for a switch (or use an existing hole).

My other 2204 came with both caps removed and it just lost too much high end. Treble dimed, presence half way and still no highs. I would say it changed the character of the amp too much.

With just the cap on the Pre-amp pot removed and changing the Middle pot to a 50k (original is 25k) made it near perfect for me. (actually I cheated and just added about 25k of resistors to it to test. Liked it and left it)

[ClassicRock88]

Michael,

Does changing the mid value have a big effect? I would probably have to add resistors as mine is a horizontal model. I don't really have the option of changing pots. Most of the people I have talked to said don't remove them both, just the one on the preamp pot. I understand WHY Marshall did it. At least I think I do... amp does not get muddy as you back the volume off to clean it up... but WOW it can get barky. Mine has an aftermarket effects loop and an extra preamp tube, so what are more holes in it? I am getting an external bias anyway so it wouldn't pain me any more to have more holes drilled in the top.

JBoy - What do you typically run yours at? I typically run mine with the preamp at 5 and the master to taste (preferably between 4 and 6). I actually never dime the amp because I don't like the sound of it. I think most amps' sweet spots are not at 10.

[michael_dba]

Michael,

Does changing the mid value have a big effect? I would probably have to add resistors as mine is a horizontal model. I don't really have the option of changing pots. Most of the people I have talked to said don't remove them both, just the one on the preamp pot. I understand WHY Marshall did it. At least I think I do... amp does not get muddy as you back the volume off to clean it up... but WOW it can get barky. Mine has an aftermarket effects loop and an extra preamp tube, so what are more holes in it? I am getting an external bias anyway so it wouldn't pain me any more to have more holes drilled in the top.

Yeah, it's like the treble bleed cap on a guitar...helps some treble bleed thru when you turn down the volume.

As for the Middle mod, I've only played it with my Gretsch, which really needed some help with its midrange and low-treble. It's not a night-and-day difference in my case, but definitely opened up the A-D-G strings. I might try 100k for the hell of it sometime. I could only guess how this would sound with an extra preamp tube in there. No useful info on that one.
I'm also using Celestion Classic Lead 80's which help the upper mids as well. They work great with this amp in my situation...kind of a cleaner G12-65, so I run the pre-gain around 6-7.

[jboyjams]

I was running mine pretty clean with the Volume around 4 or 5 and the Preamp around 2.5.
This gives me a good bluesy base tone and can add an overdrive as needed.
Other times if I need to keep the volume down I set it vice versa.

Changing preamp tubes helped mine somewhat when using the amps gain (it had some older jj's and v1 was an 803) - I now have a Tung-Sol reissue in V1 and Mullard reissues in V2 and V3.

I need to experiment with the bright caps and using overdrives because it changes so dramatically in the Treble - I'm wondering if the 470 cap or the 1000 cap has more affect on this happening....?

(with no pedals the treble is fine - hitting it with an overdrive increases treble too much)

[Herbvis]

I would keep the bright cap. I find no bright cap makes the amp seem kind of dull.

[JCarno]

I would keep the bright cap. I find no bright cap makes the amp seem kind of dull.

I agree. I did the alligator clip test and after switching back and forth twice, I decided to permanently solder it back on. YMMV.

[ClassicRock88]

I would keep the bright cap. I find no bright cap makes the amp seem kind of dull.

I agree. I did the alligator clip test and after switching back and forth twice, I decided to permanently solder it back on. YMMV.

So I have heard. One suggestion that I saw on another forum (I believe MyLesPaul) was to change the value of the cap so it retains a treble bleed function but it is not as pronounced. Has anybody tried that? Also, do you know of any YouTube vids or audio clips I could find of these amps with the bright caps clipped?

[jboyjams]

When I tested various bright caps for my 1987x I bought them from Small Bear Electronics.

(Ceramic disc and silver mica using 100, 250, 500, 1000 pf) - a lot of people say to use silver mica but ceramic disc is what the originals used most of the time.

Shipping costs more than the caps themselves - very inexpensive part.

[ClassicRock88]

JBoy was that you that did the bright cap comparison on YouTube??

[jboyjams]

No - wasn't me but I'm hittin youtube to check it out

It makes sense how it thins out when swapping 100, 120, 250, 500, etc. but I'm confused on why it sounded warm when using 5000. On my 1987x 4700 is off the chart trebly.

[Herbvis]

What is the value of the bright cap? Usually it is 1000pf. It is not uncommon to lower it. get a few caps and test it out. Youi could also lower your tonestack treble cap to 250 to reduce the high end a bit. Or lower your nfb resistor, that can make quite a bit of impact.