Bright Cap Mod

MA Heads and Combos

Moderator: longfxukxnhair


Phano36
<100 Posts
<100 Posts
User avatar
Posts: 52
Joined: 03 Oct 2010, 06:46
Has Liked: 0
Been liked: 0
Contact:

Bright Cap Mod

Postby Phano36 » 20 Nov 2011, 17:36

Hello MA Lovers.

I just had the Fat lady (MA100C) opened to replaced a suspect JFET (board ID TR45) That could have been the cause of a load popping noise when switching from OD channel the Clean ... And I said to myself... why not get that Bright Cap remove or changed ... See, I play a Strat and for my personnal taste, I found the Clean channel way to bright... So someone out there know what is the bright cap capacitors board ID number ?
Maybe Mr Steeve D could share this with me, I wont tell anayone :dunno and since my amp is still opened and accessable ... Look like "C5" to me but anayway What is the actual value of the Cap ? Look like a 220 pf ?

By the way .. changing the JFET (J174) Board ID TR45 partialy fixed the channel switching loud popping issue ... Now It's only pop's when the reverb pot is turned on. If the reverb pot in turn off it doesn't pop at all strange no ! :doh

-- Mon Nov 21, 2011 4:30 pm --

Finaly ... I decided to perform the surgery anaway :yea !

I first pulled away the 220Pf Bright Cap on the clean channel and replaced it with a 47Pf. It did the job The clean channel is much more mellow and less crispy but maybe a bit too much ... An planning next to try a 100Pf insted of the 47Pf but first I want to try this set up(47Pf) during a life gig !

I Also made a few changes on the preamp on OD side . I replaced the 470Pf cap on the top of the treble control for a 220Pf I also changed the Bass circuit resistor by replacing the 33k by a 100k.
Outstanding results :jam :clap :headbanger !!!! I felt down my chair ! After that change ... I think I'm going to sell all of my over-drive and distortions pedals ... I just love that way my MA100C sound now..

The only negative observation that I saw, was a bit less Headroom on the OD side but still with the OD volume at 12 ,it played loud as hell !

Ciao

sandin
<25
<25
Posts: 1
Joined: 15 May 2013, 12:29
Has Liked: 0
Been liked: 0
Contact:

Re: Bright Cap Mod

Postby sandin » 15 May 2013, 12:33

Hello!
What can you tell me about the clean channel?
How did it work?
Im looking for a mod for this amp to improve the tone.
I don't use at all the OD channel so i don't mind about that.

Thanks!

thephantum
<100 Posts
<100 Posts
User avatar
Posts: 69
Joined: 04 Feb 2012, 12:49
Location: The backwoods of Virginia
Has Liked: 0
Been liked: 33 times
Contact:

Re: Bright Cap Mod

Postby thephantum » 16 May 2013, 17:07

There are couple of things I would try before opening up the amp and doing surgery. You'll be amazed at the difference in tone from the MA (clean or OD) by running it wide open with a volume pedal in front and a clean boost in the effects loop. If you have not already, definitely try a clean boost in the loop before doing any mods. It brings the MA to life.

The thing with the bright cap mod is that it will only have an effect at lower volumes. As you turn up the amp volume, the cap has less effect. Once the amp is wide open, the cap has no effect at all. So you can achieve the same result of removing the cap by running the amp wide open with a volume pedal in front of it to control dB level.

I've actually found it useful to have the bright cap in there. When I'm playing a brighter sounding guitar (the Strat or one of my Ibanez's), I can crank the amp volume, effectively eliminating the bright cap. Conversely, with a darker sounding guitar (like the SG), I can roll the amp volume down a little to brighten up the tone more. In both cases, I use the volume pedal to actually control dB levels. So the amp volume has become a type of tone control for me, allowing me to "dial in" whatever guitar I am playing at the time.

If you do decide to change the bright cap for a different value: keep in mind that caps made from different materials will have slightly different sounds well. In other words a 47pF poly film cap will sound slightly different than a 47pF ceramic disc cap.

Rock On.

Phano36
<100 Posts
<100 Posts
User avatar
Posts: 52
Joined: 03 Oct 2010, 06:46
Has Liked: 0
Been liked: 0
Contact:

Re: Bright Cap Mod

Postby Phano36 » 01 Jun 2013, 05:35

Hello SANDIN

I performed that Bright Cap mod a couple of years ago on the Clean channel.
Still have the 47pf cap install. Work great for my personnal taste. Like I've said in my oringinal post I didn't
liked that bright crisppy sound of the original. Some like it some dont, it's a matter of personnal taste ! :)

I re-modified the OD channel. I've went back to some of the original values. Specialy on the Bass circuit went back to the 33K resistor. I also replaced the cathode Cap originaly a 100 uf for a .68uf. Sound much more better like that
For my personnal taste like I've said :)
Ciao !

Return to “Marshall MA”

Who is online

Users browsing this forum: No registered users and 2 guests