high gain lee jackson gp 1000

[Gorhrut]

ran some more tests.....

hum non-stop with guitar plugged in. kinda disappears in background when playing

unplugged guitar, left cable in the amp. cuts hum in half unless i touch the chord end then its back to full.

unplugged chord from amp. no hum unless i am touching pot shaft of treble or mid shift. when treble is on full its a loud hum. when treble is on minimum you get nearly perfectly clear radio....

radio and hum go down when turning volume knob and go down tiny bit on distortion knob.

no other pots affect the sound.

[Rune]

Jana, that sounds more like the recoeding device can't handle the volume input. But yeah some sort of buzz....

[Cameron]

Check to see if the treble pot is loose ...the body of the treble pot should get its ground through the faceplate.

none of the pots have any wiggle in them at all. i dont crank the nuts down or anything but i have them fairly secure.

Check it with a meter. On some..Lee used ..these black lock washers for the pots....these oxidize over time and lose there connection. You can also run a little wire from the back of the pot next to it...make sure its grounded too tho. Marshalls have this problem sometimes also.

[Jana]

The "Noise" was in reference to the person playing the guitar. Any hum in there is from the single coil pickups.

[Rune]

A friend of mine got the same buzz on the amp, and he's a proffesional with a lable deal. So not due to playing style. Besides not many ways to do palm mutes.

[Jana]

Cameron,
What did you use to record on the iPhone? I used the voice memo app.

[Gorhrut]

here's a recording of mine. again, no poweramp just monitors and trimpot set to min.

for some reason my recorder cut out some parts so the songs are jacked up.....idk


settings:

volume full
distortion full
treble noon
mid full
mid shift 3
bass noon
p100 min
trimmer in place of v2b cathode resistor almost min
master out 10 o'clock

[Gorhrut]

here's one with p100 on max. all other settings the same.

[Smokebreak]

Sounds good Jana. You're gettin a good range. I made some noise, as well.
I stuck it in a 6V6 organ amp and made a couple of changes to suit.
Slope 100K, 2nd stage coupler 1n. I had way too many low muddy mids.
I think this amp used to be an express, cause it's got 5 knobs. So, I fixed the interstage pot at 100K to the 220K to ground to the grid. That's like a 3M or 1M pot around 3 or 8oclock, depending on the taper ! I also needed a 1n across that plate. Treble cap is permanently 2n. I'm thinking I probably should have left it at 1n. Close enough.
330p across both upper split loads. For the 4th stage after the 22n coupler, I have a 220K/110K divider into the 1n PI cap.
470r/10K/5Kscratchy. 22n outputs and 27K 8ohm feedback. 12AT7 is polite but 12AXY is stereotypically rockin here.
This amp already had a PPIMV so I used it.
I used the soundcloud app recorder and put my phone on the floor in front of my speaker.
https://soundcloud.com/jeremyslemenda/s ... -evening-7

Edited with correct url

[Rune]

Sounds good Gorhrut. Must be some issue with my internal pot I guess.... Might route it to the back...

[Reeltarded]

iPhone sample.

Gnarly!!

That is solid awesome right there. I could play White Room and love that.

Here's Petey The Mule, hybrid JCM2204/JTM45 with 270k plate 1st stage.

https://soundcloud.com/miles-hendrix/guerrero

No hum, no buzz, no pedals.

[Jana]

Thank you, Miles.

No pedals on mine either--just straight into the amp with a 10 foot cord and the volume knob and pickup selector for "channel switching".

I love your songs! I could listen to that all day.

[Reeltarded]

I played on and produced that, but not my song. Thanks! It would have sounded average if I hadn't met all of you here.

[Cameron]

Sounds good Gorhrut. Must be some issue with my internal pot I guess.... Might route it to the back...

Those small trimpots can be trouble sometimes ..are kind of delicate and are easily F'ed up ..mostly if overheated or oversolderd.

I think you said .....as well as Gorhrut...you had the transitional one ..... it has parts on the socket already.....so..... to get the 10k-100k off the board ......... connect one end of the 10k (R4) to the socket with the coupling cap soldered to the point where the 10k and 100ks connect together ...( send the signal from here to the pot on the back ...or you could send it straight to the front masters )....... connect the other end of the 100k ...... to the red wire where the 47k(R205) and the .001(C202) cap are connected.

The cathodes 10k(R204) is also here on the socket already ...I think... connect the shield of the cable going to the pot on the back or Master ..to where the 10k is grounded.

!Keep all parts and wiring for V2 away from V1 parts and wiring
....!!!I would try this first if you have a stock one or clone that is a little unstable !!

Also...!!!!very important!!!!..... to help stabilize this preamp in general...add a 68k to 220k grid stopper to the input/grid of V1B.....and also add a 100pf to 470pf over the 100k(R5) !!!this with the top on...may stop/fix the problem Rune is having.... without disconnecting the switching and doing all these mods!!!
.....!! I would try this first ...also... if you have a stock one or clone that is a little unstable !!

Going straight to the front masters will get the 50k(if thats what you have)out of the way... and that will give us more bass at the output.

Also...I think Ive been calling this 100k..I forgot about the 10k when discussing getting this part of the signal off the board ...sorry if that confused anyone.

[Gorhrut]

here it is with all mods and vht 2/90/2 power amp

mods done: updated tone stack values, c1 resistor and bypass 820 and .68, c2 bypass 1uf, c3 bypass 1uf, v2b cathode resistor replaced with 10k trimmer set almost to min., and relay removed/rewired....

gear:

jackson rr24
emg hz h4
mm04 preamp booster gain on 80%

gp 1000
volume: full
distortion: full
treble: noon
mid: full
mid shift: 3
bass: noon
master out: 11 o'clock
p100: full

vht settings
low fan speed and half power mode
volume: barely on(wife was home)
presence: 11 o'clock
depth: 1 o'clock

marshall 1960b cabinet
celestion g12t-75


what do you guys think?
besides fixing the hum i think im finished modding this one....