Amp tech in Dublin?

Hendrix89

Hi,

I need to find an experienced tech who can perform a basic modification on a valve amp. I want to get a capacitor removed from my Marshall 1987x vintage
re-issue. The mod is called the 'bright cap' mod in case anyone is familiar with it.

So are there even any amp techs in Dublin? I'll need an experienced person to work on my amp as it's not cheap!

Thanks.

boycey

Hi-
I have the same amp as you, did that mod myself, its really not hard at all. BUT as with all valve amps you have to be careful not to fry yourself. It took me ten minutes to open it up, clip the cap (its marked at c5 on the board) and put the chassis back in again. Any tech (theres a few mentioned in the sticky) could do that in minutes 'while you wait'.

It is worth doing in my opinion- takes that insane treble off the hi input and makes it a much more usable amp.

Theres loads of info on this if you google 'bright cap mod'- but as I stated if your gonna do this be careful, there are lethal voltages floating around in valve amps and it wont sound good at all if you crispyfry yourself!!

Good luck-
Boycey.

nb: now that I think about it older 1987x's have that cap in a different spot so read plenty of info if you gonna try it yourself- the Plexi Palace is a good place to start.

Hendrix89

Would have replied sooner but I was having log in problems.

Thanks for the feedback boycey. I know it's supposed to be very easy but I really don't see it that way.. for me anyway. I have no experience with soldering/de-soldering and I wouldn't have a clue how to get the cap off by that method, which I believe is the only way?

I have checked out many amp forums before for guides but none of them seem outline (in detail) exactly how to remove the cap. I have zero knowledge on this. Unless you wouldn't mind describing the process to me?

If I can't find a tech, I do have a friend who has a bit of experience in soldering so I may ask him to help. A tech would be easier though so if someone could direct me to a good one that would be great.

Fingers Mcginty

I'm sure someone on this forum could help you out.
I would but I'm out in the Sticks *with a bogger accent*

boycey

I know what you mean Hendrix89, Im not tecchy minded or skilled at all- but I was careful, removed the chassis and made damn sure I didnt touch any innards and snipped that little capacitor out with a wire cutter- kept it in case I ever wanted to put it back in too!! No soldering/de-soldering required (unless you wanted to re-fit it).
alladinsamps@yahoo.co.uk- he's based in Dublin , i e-mailed him about fitting a master volume to mine and got a prompt reply. Never got round to getting one fitted though. I would offer to do this for you but would be afraid i'd muck something up- if you just wanna hear what difference it makes pm me- you're more than welcome to try mine out- Im out in Clonee D15.

Boycey.

Hendrix89

Oh okay well that sounds like a much simpler way of doing it. I was almost certain that it required some (de)soldering. Much easier if I can just clip it off that way. Might just give it a try myself then.

So basically I just need to cut the two metal legs is that right? And that will obviously leave straces of the clipped legs in the board, will that still allow a replacement cap if I decide to have one?

And thanks for informing me about that tech. If I can't do this myself I'll definately contact him.

boycey

Clipping just one leg would break the connection and would be easily fixed if you didnt like the result. Thats probably your best bet.
I'd be very surprised if you didnt like the result- i found the hi-treble input unusable by itself before I did mine and it was like a volume on/off switch- that changes to a much more balanced output between the two volumes with the cap gone and means you can turn up that treble volume without slicing your head off!!
Good luck with it anyways and let us know how you get on- I will stress again though to be careful- if your in anyway unsure leave it to a tech!! Read up on draining the capacitors before you try anything and dont touch anything else in there!! As I mentioned before go on The Plexi Palace and do some searches- a lot of good info on there.

Boycey.

Hendrix89

Okay so I'll just cut one leg then. Less likely to lose the cap if it's left in there.

And yeah I have always wanted to use the High Treble channel from the day I got the amp, but of course the bright cap just causes a horrible amount of treble and a lot of noise aswell. I'm hoping to achieve a more punchy, Hendrix like tone out of this mod.

And don't worry I'll be careful. I'm an overly paranoid person so I tend to be very cautious in these situations!

Thanks again for the excellent advise. I'll report back with how it went.

Paolo_M

Here's a safe and easy way to get rid of the lethal charges. This only requires a straight lead with crocodile clips on either end and doesn't require you to go near the filter caps:

1. Turn off your amp in the usual way
2. Unplug it completely
3. Attached one end of a crocodile clip lead to the chassis and the other to pin 1 of the first preamp tube (the one nearest the input jack)
4. Flick the stand-by back to the on position as if you were playing (remember you're still unplugged, right?)
5. Let the charge drain through the amp for about 30 seconds, preferably more to be sure to be sure as they say
6. You're now ready to start poking around looking for that bright cap

Removing the bright cap on my Marshall JCM 800 and it has made the world of difference.
I can't for the life of me understand why Marshall put these caps in their amps but I suspect it's back to the early days when they were they were probably trying to differentiate between the Bass for the Super Lead series which were basically identical otherwise.

Red Sleeping Beauty

Hendrix89 wrote: »

Hi,

I need to find an experienced tech who can perform a basic modification on a valve amp. I want to get a capacitor removed from my Marshall 1987x vintage
re-issue. The mod is called the 'bright cap' mod in case anyone is familiar with it.

So are there even any amp techs in Dublin? I'll need an experienced person to work on my amp as it's not cheap!

Thanks.

i hope you have deep pockets!

Hendrix89

alan dunne 27 wrote: »

i hope you have deep pockets!

I sure don't! That's why I'm considering doing this myself.

Paolo_M, Thanks for going into that for me. I wasn't too sure how to go about making it safe to work on and you've made the steps very clear. I feel more comfortable about doing this now. Much appreciated mate.

Red Sleeping Beauty

Hendrix89 wrote: »

I sure don't! That's why I'm considering doing this myself.

Paolo_M, Thanks for going into that for me. I wasn't too sure how to go about making it safe to work on and you've made the steps very clear. I feel more comfortable about doing this now. Much appreciated mate.

Mr alladin's amp is expensive. €100 to replace a speaker in a Marshall avt combo. €45 for true bypass mod to a crybaby wah

Eoin Madsen

If all of the components are in spec, the filter caps should actually discharge on their own. Just leave it an hour or so after the amp is powered down. Standby should be in playing position. If you don't have the knowledge or means to verify if the caps are happily discharged or not though, opening the amp up would be a really bad idea. Saving a hundred or so bucks is a pretty small thing in the grand scheme of things. Even when non-fatal, a 200v shock off a filter cap is not fun (take my word for it ).

As people have already said, you can just clip off the bright cap if you don't mind leaving a little clutter in the solder tags. Though you may as well clip it off entirely - because there's no way to reattach it without soldering. If you don't like what removing it does, you're going to have to get someone to fix it for you.

The purpose of the cap is to bleed high frequencies across the volume pot at lower volumes so the amp doesn't dull when the gain is low. When the gain pot is cranked, the cap makes absolutely no difference.

As for why it's there... high gain high treble pickups didn't exist when they designed the amp.