high gain lee jackson gp 1000

[Cameron]

no luck for me either....the "noiseless" pickup helped a total 0%...

because of this im thinking its an issues with the mm04 booster having all unshielded wires. i have the control cavity shielded but then the wires have to run through the pickup cavity and then all the way up to the upper horn of the jackson rr24 to get to the jack. maybe im picking up emi after the pickup?

do you think shielding the entire inside of the guitar will have an effect? maybe i could wrap wire runs with aluminum foil and ground it? im really at a loss for what to do. the buzz/hum makes me not want to play at all, and definitely not make vids for youtube.

the wires for the battery also run right next to the wires for the output jack. could this be part of the issue?

Its the preamp...don't bother with any of that... Go read (again I'm saying) on how the umbles are grounded.... your master problem is a clue....just because you don't hear it.... does not mean the problem is gone.

[Cameron]

So I've tried installing a grid stopper and rewiring C4 between the two masters instead at 2 EQ switch, and nothing got better or worse. Still same old story. There must be some issue with the overall design... and yes possiby a ground issue. It is like the signal is partly being fed to ground, thats what it sounds like...the little signal that comes through gets all buzzed.

I guess I'll wait for a new PCB which I'm promised....and hope he'll figure it out with a oscilloscope and testing...

It will help but..he shouldn't need a scope and he should know by now whats wrong ...if he was selling these
Just post a pic of it...it might help. There are no secrets in this preamp..or on that junk board that was made or copied......

[Gorhrut]

Its the preamp...don't bother with any of that... Go read (again I'm saying) on how the dumbles are grounded.... your master problem is a clue....just because you don't hear it.... does not mean the problem is gone.

ill give it another look and try the layout like those. i just dont get how it could be the preamp. with the guitar unplugged (chord still attached to preamp) the amp is dead silent. the hum/buzz also rolls off with the guitar volume control.

i hope im not coming off as dismissive, i am going to try more with the preamp. its just, all the research ive done points to the pickup and emi.

[Cameron]

Its the preamp...don't bother with any of that... Go read (again I'm saying) on how the dumbles are grounded.... your master problem is a clue....just because you don't hear it.... does not mean the problem is gone.

ill give it another look and try the layout like those. i just dont get how it could be the preamp. with the guitar unplugged (chord still attached to preamp) the amp is dead silent. the hum/buzz also rolls off with the guitar volume control.

i hope im not coming off as dismissive, i am going to try more with the preamp. its just, all the research ive done points to the pickup and emi.

For me as a tech thats worked on these before...it tells me preamp. You need to understand grounds and what should be grounded to what ... Rune also.

[Gorhrut]

so its looking like i should move the ground for the rectifier and (reservoir?) cap onto a different chassis ground point than the others(originals had it on same lug as the power chord ground). does this seem correct? i dont mind trying it out i just want to make sure this is what you are thinking too....

also, i dont see the cathode follower on the dumbles. does my grounding for that seem ok?

[Rune]

It could generate hum, but I've never experimented that it has too much hum to handle, and at least not with EMG mics.
You could try to sheild everything better, but my guess is that this is an amp issue. I mean does other amps sound the same with the guitar?
Are all grids sheilded? Are any V1,2 and 3 cables running too close? Are both ground points secure and grounded to all the same points as the original?

[Gorhrut]

It could generate hum, but I've never experimented that it has too much hum to handle, and at least not with EMG mics.
You could try to sheild everything better, but my guess is that this is an amp issue. I mean does other amps sound the same with the guitar?
Are all grids sheilded? Are any V1,2 and 3 cables running too close? Are both ground points secure and grounded to all the same points as the original?

unfortunately i only have this 1 guitar and 1 amp. so i cant really try any others. i can bring my guitar/amp to guitar center and try them there to see if maybe its just an environmental issue but....idk

i tried grounding the rectifier bridge and all 3 filter caps(in all possible combinations) at another ground point to no avail. i also tried referencing the heaters to dc(off of pin 8 of the cathode follower. reads at 65v dc) and all that did was give me some crazy squeeling sounds.

might have to take it back to my tech and see if he can figure something out.

[Cameron]

so its looking like i should move the ground for the rectifier and (reservoir?) cap onto a different chassis ground point than the others(originals had it on same lug as the power chord ground). does this seem correct? i dont mind trying it out i just want to make sure this is what you are thinking too....

also, i dont see the cathode follower on the dumbles. does my grounding for that seem ok?

Thats a better idea to get it fixed. I don't know how you have it grounded ...so I cant tell you if thats IT. You cant just tie all the grounds together....... also look at the input, the cathodes and how that stuff is grounded. If you are talking about the layout you posted .....I said it probably would not work.

Try to bypass a gain stage to test the guitar....I bet it will work fine.

[Cameron]

i also tried referencing the heaters to dc(off of pin 8 of the cathode follower. reads at 65v dc) and all that did was give me some crazy squeeling sounds.

might have to take it back to my tech and see if he can figure something out.

That shows its unstable or you did it wrong.....Its something I have to do in every amp.....I know it makes the tubes pick up less hum.

[Rune]

My 88 behaves exactly the same way as the clone. The more I turn up the level trimpot the more noise. I think it is linear in my clone thought, because the noise is present on every setting except the very minimal one (still there but bearly audible). Now gorhruts original was noise free on that concept from the beginning right? And really the only difference is tube PCB..... sheilded cable dressing is very good on the original and comparing it to my 87 and my clone it really looks professional and very tidy. Almost exactly like the pictures I posted early in this thread, only differences are added lower C1 and R1 myself. And two of the power driver capacitors are different model and have to lay on their side because of their hight. So from the really quality pic I posted of the whole layout (decided to repost), can you spot any obvious ground issue?

[Cameron]

My 88 behaves exactly the same way as the clone. The more I turn up the level trimpot the more noise. I think it is linear in my clone thought, because the noise is present on every setting except the very minimal one (still there but bearly audible). Now gorhruts original was noise free on that concept from the beginning right? And really the only difference is tube PCB..... sheilded cable dressing is very good on the original and comparing it to my 87 and my clone it really looks professional and very tidy. Almost exactly like the pictures I posted early in this thread, only differences are added lower C1 and R1 myself. And two of the power driver capacitors are different model and have to lay on their side because of their hight. So from the really quality pic I posted of the whole layout (decided to repost), can you spot any obvious ground issue?

If you don't add gain ...it will work. When you add gain to this circuit board ..it will become unstable. I explained earlier in this thread why. If you don't show a pic ...I cant help you.....as far as what to change or fix in your's.

[Cameron]

My 88 behaves exactly the same way as the clone. The more I turn up the level trimpot the more noise. I think it is linear in my clone thought, because the noise is present on every setting except the very minimal one (still there but bearly audible). Now gorhruts original was noise free on that concept from the beginning right? And really the only difference is tube PCB..... sheilded cable dressing is very good on the original and comparing it to my 87 and my clone it really looks professional and very tidy. Almost exactly like the pictures I posted early in this thread, only differences are added lower C1 and R1 myself. And two of the power driver capacitors are different model and have to lay on their side because of their hight. So from the really quality pic I posted of the whole layout (decided to repost), can you spot any obvious ground issue?

Also the grid stopper in this one... is on the input jack.....your's may have it there also.

[Gorhrut]

so i tried grounding all three filter caps and rectifier to seperate location. didnt work. also tried redoing everything on bus ground system, that didnt do anything either.

randomly tried pulling out preamp tubes to see if that did anything, quiet when i pull second preamp tube. dont know if thats the actual problem area or if i just cant turn it up loud enough now to hear?....

also, i walked around the house with a cable plugged into the amp(with amp on and hum up loud) i turned off everything in the house except the outlet i was plugged into. when i point the cable in the direction of the powered outlet the hum/buzz gets BAD. when i point it at the unpowered outlets for some reason it actually makes it quiet.....

i dont know what any of these tests prove but they were interesting....

anyways, point to all this, i think ill admit that im out of my league for now and just take it to a real tech....

[Rune]

Yeah, all originals has their at the input socket.My clone didn't have any at all, but adding didn't do any. So the amp is broken stock then? Must be some of the worst mistakes a company can do. Anyways, what do you want picture of? There is large full amp pictures of original and clone in this thread.... Anything specific area to focous/zoom on?

All issues on my clone exist on every 88 model as well...

[Gorhrut]

was able to get ahold of another amp. same hum/buzz on that one too even on clean. tells me the preamp wasnt the cause of that problem.

im going to take the preamp to another location to verify. im thinking that my house is just in a bad location with TONS of emi.