high gain lee jackson gp 1000

[Cameron]

oh, youre talking about the sansamp.....that makes more sense.

i think rune suggested that as a way to further adjust the tone. idk how well it would work because i dont own one to try it out.

An EQ would be a good way to adjust the tone. There is no reason to use a sansamp like this.. I don't see why he would want to do that ??

[Rune]

Because the sansamp has a blend mix 50/50 on it's loop return and can also add both EQ and overdrive to the overall sound. Now I know the Sansamp has it's issues with white noise and are all solid state, but it really has some great tones. Also explain why Bodom had it and the GP-1000 on at all times during gigs and studio in the years of 2005-2009? The sansamp was on and on preset 62 or 63 (cant quite remember). EQ settings are all over the web...
I've owned the unit for years, and I read this review on ultimate-guitar where this dude was combining his stock 88 GP-1000 with the sansamp and was quite impressed, he claimed he could get very close to Bodoms "Follow the Reaper" tone while doing this and uploaded some clips to show for.
So I decided to test it with my clone when I got it and with the RSP 2400 Enhancer/Hush/Exciter I got 99% 2005-2009 Bodom tone miced up with a SM57. Really nice low end, punchy mids and great distortion, but some noise of course.....

[Rune]

Make sure to add an effects loop if you plan to put RSP2000 and/or Samsamp in the circuit. Great job on the amp. I will straighten out the trimpot issues later on, TWCC has told me he could still make me a new problem free main PCB. Or at least give me the layout so I could order one myself.

No, well except the MID pot to 50K (20K would also do). But Bodom uses it at the lowest setting (1) so I guess it actually means it's on full anyways.
You could also add more bass by changing the coupling capacitor C9 to 4400p and if you would like even more you could add a small capacitor to R205. Other than that I think the amp have plenty of treble already, and the mid-shift is still set on the value you need for "that" tone. And increasing values of C203-204 will add tightness.

This amp would have been more issue free and easier to mod with point to point layout.

Why do you think the sansamp is in a loop? The output of the preamp is the send of a loop and the return is the poweramp... no need for a loop here....and adding the loop will change the tone of this preamp.

Why do you think 1 is "full on"?

Increasing c204 205 will make it ...darker ...less highs ...not tightness IMO..
R205 (47k) should have a .001 cap already there..... again increasing this will cut the high end ....not add bass.

The best way to add bass.. without changing the tone too much is ...change the 50k trim to 1meg

Why I think 1 is full on; I read that it gives you a fuller scale of whatever pot you are increasing. So I you double the pot at 5 times, then the value you had with thre previous pot would be 5 times less on the new pot. Or am I mistaken? So Bodom had it from 1 o clock to full on a 10K pot and if they added it to a 50K pot it would be 1-2 right?

C204/C205 are guides from the tech. And yes darker is something I would describe Bodoms modern tone as. That is a good thing in this case. I know adding to caps takes highs away, that's what they are for in these cases, shaping tone. If you cut treble, the other frequencies will shine through right?

But we want to change the tone, that's the whole thing. We're not searching for a now vintage sound, with too much crispy highs and little bass. And we don't want overdrive that could barely do Queen on very high preamp settings. This is a Jazz, blues and rock amp we want to turn into a metal amp. With just as much distortion as a 5150 (5150 just compress distortion if you put it over 1-2 o'clock, have that one too).

[Cameron]

Make sure to add an effects loop if you plan to put RSP2000 and/or Samsamp in the circuit. Great job on the amp. I will straighten out the trimpot issues later on, TWCC has told me he could still make me a new problem free main PCB. Or at least give me the layout so I could order one myself.

No, well except the MID pot to 50K (20K would also do). But Bodom uses it at the lowest setting (1) so I guess it actually means it's on full anyways.
You could also add more bass by changing the coupling capacitor C9 to 4400p and if you would like even more you could add a small capacitor to R205. Other than that I think the amp have plenty of treble already, and the mid-shift is still set on the value you need for "that" tone. And increasing values of C203-204 will add tightness.

This amp would have been more issue free and easier to mod with point to point layout.

Why do you think the sansamp is in a loop? The output of the preamp is the send of a loop and the return is the poweramp... no need for a loop here....and adding the loop will change the tone of this preamp.

Why do you think 1 is "full on"?

Increasing c204 205 will make it ...darker ...less highs ...not tightness IMO..
R205 (47k) should have a .001 cap already there..... again increasing this will cut the high end ....not add bass.

The best way to add bass.. without changing the tone too much is ...change the 50k trim to 1meg

Why I think 1 is full on; I read that it gives you a fuller scale of whatever pot you are increasing. So I you double the pot at 5 times, then the value you had with thre previous pot would be 5 times less on the new pot. Or am I mistaken? So Bodom had it from 1 o clock to full on a 10K pot and if they added it to a 50K pot it would be 1-2 right?

C204/C205 are guides from the tech. And yes darker is something I would describe Bodoms modern tone as. That is a good thing in this case. I know adding to caps takes highs away, that's what they are for in these cases, shaping tone. If you cut treble, the other frequencies will shine through right?

But we want to change the tone, that's the whole thing. We're not searching for a now vintage sound, with too much crispy highs and little bass. And we don't want overdrive that could barely do Queen on very high preamp settings. This is a Jazz, blues and rock amp we want to turn into a metal amp. With just as much distortion as a 5150 (5150 just compress distortion if you put it over 1-2 o'clock, have that one too).

1 is not full on ...turning the mid pot down ...1....sends the tone stack to ground ..so 1 is 1 whatever pot you use..also ...if you cut treble ..you just cut treble....you have ..as I said ...allot of this stuff wrong. Jazz ?? blues?? This preamp was doing this metal type tone... years ago ...when Alexi was in his baby diapers
My friend teched for him off and on through out the years ...he was also Kerry King's tech ... Its not as much gain as you are thinking.... and its mostly the way he plays ....no ...everybody does not palm mute the same way.

[Gorhrut]

maybe your buddy knows exactly what mods alexi had done, cameron(wink wink)

[Cameron]

maybe your buddy knows exactly what mods alexi had done, cameron(wink wink)

BCIII is not with us anymore..so I can't ask. Its for the most part ...the 10k in the last gain stage ....you can try the LEDs but 1k/1uf there will work also ..and I like the way it feels with the 1k. It is not as much gain as people think. The preamp in the guitar with the LJ preamp is what the gain is...nothing in the loop for gain......but sometimes a boss overdrive in front.
Sansamp can be used for in-ear monitors and other things that help the backline tech's and mix....you can also just use it as a back up into the PA if the rig goes down.

[Cameron]

Its in his hands ... not allot of gain. It really is just the pre in the guitar ...the LJ preamp with the 10k mod and fix the LJ preamp issues ...and you should be able to get that tone..the rest is how you play.

[Gorhrut]

yeah thats what i have done and it sounds spot on to me. i just wanted to check if there was any random thing i hadnt done yet....

[Gorhrut]

i think i may have figured out part of my hum problem....

there are two main ground points on the chassis. 1 near the input jack and one near the power cable.(there are also one or two near the tube bases also)

the one near the power cable should only have the middle lug of the power cable attached correct? my transformer is also connected here. am i correct in thinking, having the transformer and the rest of the circuit on separate grounds caused a ground loop? also, will i further eliminate trouble by removing the tube base ground points also?


edit: i got the cables mixed up. the one that connects to ground near the cable is the first filter cap

[martin manning]

Your ground scheme seems reasonable, except for some small details.

The safety ground (middle lug of power cable) should be on its own bolt near the AC inlet.

The first filter (or reservoir) ground should be near the AC inlet, and include the center taps from the HV secondary and the filament winding. The key point is that the reservoir cap ground and the HV center tap (or diode bridge ground) go directly to this ground point since there is a large ripple current flowing in this circuit.

Grounds near the tube sockets for the power tube cathodes are not a problem, and the screen filter, speaker jack, and PI grounds can go nearby.

The preamp grounds should be near the input jack.

[Gorhrut]

so having multiple ground points isnt the cause of the hum?

idk how to get rid of this hum. it is actually overpowering the guitar....

[martin manning]

Multiple ground points are not a problem if done correctly. Can you tell whether this hum is 60 Hz or 120 Hz?

Does your filament circuit have a center tap, either on the PT or an artificial CT (a 100 ohm resustor from each side to ground)? Without this you will get a lot of 60 Hz.

[Gorhrut]

it has the artificial center tap.

idk about the 60 or 120.....

[martin manning]

Got a tuner? B2 is 123.5 Hz; second fret on A string.

[Gorhrut]

actually i think i may have fixed it. i moved the 68k resistor from the input jack to the tube base. now i only have hum when the cord or guitar are plugged in. so i guess its time to shield the guitar.