What's wrong with my Mk III???

[Vigo1999]

Hey guys!

suddenly my III started to make some funny noises, just like a string/fret buzz . . . it occurs mainly (should i say practically only?) on the G note above 500hz (1st string, 3rd fret / 2nd string, 8th fret and their octaves).

already have changed the power tubes and tried with another guitar, although didnt swap the pre tubes . . .

what's wrong with her???

thanks!!

 

[Boogiebabies]

Could be preamp tubes or ghost notes coming from the power supply.
It's more often (98%) the preamp tubes going bad.

Try a new V1 and then V3 and V4. The V1, all the way to th right looking from the back, it the one that amplifies all the signal to the rest of the amp. It you amp sounds bad in clean, R2 or Lead, I would replace it first.

 

[Vigo1999]

Could be preamp tubes or ghost notes coming from the power supply.
It's more often (98%) the preamp tubes going bad.

Try a new V1 and then V3 and V4. The V1, all the way to th right looking from the back, it the one that amplifies all the signal to the rest of the amp. It you amp sounds bad in clean, R2 or Lead, I would replace it first.

Thanks BB 8)

gonna check that later at night, although i have changed some of 'em a couple of months ago (not all of them) . . . i was afraid that could be something worst, like a bad power supply as you said, THAT will be bad

Ghost notes appears only when a bad power supply is happening or with bad pre tubes also??

 

[Boogiebabies]

Mostly with bad preamp tubes they are worse. A bad power supply may add some strange harmonics and diminish the amps bottom end.

 

[stokes]

If the preamp tubes dont solve it,it is likely time for a recap.If those caps are original,you cant go wrong changing them anyway,you will notice a tighter response from the amp.

 

[Vigo1999]

If the preamp tubes dont solve it,it is likely time for a recap.If those caps are original,you cant go wrong changing them anyway,you will notice a tighter response from the amp.

Hummm, that's a worst scenario for sure . . . but sooner or later this will happens, i'm almost sure this baby still have their original caps (im not the original owner) and this baby is from the class of 88' . . .

i've been using JJs for a long time . . . what you guys think that worth a try?? maybe some tungsols?? or the hype is bigger than the fact?? :?:

 

[stokes]

No reason to consider it a "worst case" kind of thing.It is something inherent in tube amps,just like tubes wear out so do the filter caps,its inevitable.I know there are some people who think it is not something needed unless there is some catastrophic failure,I can tell you I have never done a cap job on an amp that had caps that were around ten years old and sometimes less,that otherwise seemed fine,and didnt have the owner amazed at the improvement in the amps response.If your amp has its original caps,you will definately hear an improvement with fresh,good quality caps,and it just doesnt make sense to leave them until they fail.

 

[user 2126]

the tech that I know tell that he got amps from the '50 and never change a single caps in it and also said it not necessary in a maintains point of view to change these caps for nothing, you change them when they are not working anymore.

 

[Boogiebabies]

I am not a huge fan of cap changes for the sake of cap changes.
I understand at somepoint they should be changed, but if you use the amp the caps will operate properly for many years. I have three 22 year old IIC+'s and each one has every factory cap with not loss of bottom end, ghost notes or lack of definition. Add to that a 17 year old MK III, 15 year old DR and a 13 year old MK IV. All original.

Do I keep caps in stock? Yes I do. They can go out at anytime, but even new caps can suffer a quick mortality. I keep caps for Boogie's and Marshall's, although my 20 year old 2555 Silver Jubilee sound great, it's just a precuation to keep the down time to a minimum.

 

[Vigo1999]

thanks for all the replies guys! 8)

but yes, i was not thinking about a recap right now, i think this baby sure has plenty of life on 'em . . . although, like i said, im not the original owner, so i dont know how far this baby was pushed.

gonna take her to a tech and see what he says, it's time for a tube swap and annual cleaning already.

but, if needed, which brands for caps i should be looking??

 

[user 2126]

Sprague 30uf 500vdc (3 blue caps at the left)
Illinois (or better) 220uf 300vdc (2 or 4 long caps at the right)

 

[stokes]

I would suggest F&T's for the 220uf's.

 

[6L6C]

I just had a cap job done to my 1992 Mark IV. They where not leaking or anything like that. And the amp sounded great but I wanted to do a PM (preventive maintenance). I knew I would hear a difference (I have been told my ears are pretty good) but my god what a difference you would have to be deaf not to hear the difference. Basically:
For a high gain amp it is now very quiet.
Tone is better and much bolder (more harmonically rich)
The tone is also allot tighter with the high gain channels especially
Sustain seems to be better (maybe that’s just me)
I talked to “Stokes” several times and the work was done as to his specs, the caps where F&T's & Sprague. The caps where also “formed” before installation.
After the amp was done I wished I had done some “before clips” to late now and like I said I really didn’t expect that big a difference the amp had already sounded awesome. But I was certainly wrong.

 

[stokes]

6L6C-glad you are happy with the results of your cap change,I find it hard to believe that people with so much amp tech experience dont feel the need to change caps,or think it can be beneficial.I would certainly be suspicious of any tech who tells me an amp from the '50's would not be in need of a cap job,but hey,to each his own.

 

[Vigo1999]

I just had a cap job done to my 1992 Mark IV. They where not leaking or anything like that. And the amp sounded great but I wanted to do a PM (preventive maintenance). I knew I would hear a difference (I have been told my ears are pretty good) but my god what a difference you would have to be deaf not to hear the difference. Basically:
For a high gain amp it is now very quiet.
Tone is better and much bolder (more harmonically rich)
The tone is also allot tighter with the high gain channels especially
Sustain seems to be better (maybe that’s just me)
I talked to “Stokes” several times and the work was done as to his specs, the caps where F&T's & Sprague. The caps where also “formed” before installation.
After the amp was done I wished I had done some “before clips” to late now and like I said I really didn’t expect that big a difference the amp had already sounded awesome. But I was certainly wrong.

Hummm, great, good to know that, thanks 6L6 especially that, although i love her sound, i think the bass could be a lil more tight, not so loose . . . 8)

 

[user 2126]

6L6C-glad you are happy with the results of your cap change,I find it hard to believe that people with so much amp tech experience dont feel the need to change caps,or think it can be beneficial.

Just because people with GREAT experience tell me not do it.

 

[Vigo1999]

6L6C-glad you are happy with the results of your cap change,I find it hard to believe that people with so much amp tech experience dont feel the need to change caps,or think it can be beneficial.I would certainly be suspicious of any tech who tells me an amp from the '50's would not be in need of a cap job,but hey,to each his own.

Hey Stokes wondering if i cant find'em here if you have some for sale (and of course, willing to ship to me down here . . .) :wink:

 

[stokes]

Vigo,I dont sell parts,if you do a web search you can find suppliers here in the USA if you cant find any down there.I use a supplier named Newsensor,I have stated in other posts that they are not the cheapest,but I have my own personal reasons for using them.

 

[user 2126]

http://www.jmimusic.com/products.php?cat=97
http://www.tubedepot.com/cp-il-220-300v.html

 

[Vigo1999]

Vigo,I dont sell parts,if you do a web search you can find suppliers here in the USA if you cant find any down there.I use a supplier named Newsensor,I have stated in other posts that they are not the cheapest,but I have my own personal reasons for using them.

All cool Stokes, thanks a lot, gonna research for'em. 8)