roberto wrote:Can you post the internal photos of that unit?
I'm not strictly interested in the sound you are looking for, I'm just looking if some mods are feasable.
I personally don't care about the caps at the output.
As I already explained, poweramps have usually 1M input impedance, inparallel with the 1M output impedance we'll obtain a 3Hz high pass filter.
I'd go to remove the 470p across the triodes (why waste a clean when you can adjust the lead?) and separate the first two triodes' supply.
The led can create asymmetry, but I'd move it downstream, with a resistor in series (again, why waste a clean, blabla).
One hundred people will give you one hundred different solutions.
Try those ones and report your impressions.
No the GPSP's are not the same, not any of them, and of course I held back some info on things I could do myself. And if you did those mods on yours it would be nothing but squeeky noise when you wasn't playing.
Jon is an idiot for sharing it to you, but then again what he shared is useless without more info. First of the circuit are different and half of the parts diviate or combines stuff. No it was just guidelines I got from 4 different guys who worked on it, including Lee Jackson himself. And it is quite easy to test and figure out what is needed for THAT tone. None of them would give you the info and if they did give you some hint, it would never be the same info.
Matej the maker of GPSP are not happy with either of you two, but it dosen't matter, no one could make that any cheaper and better than him anyway.
attached a red led to r1
i could be wrong but it sounds to me like this added a bit of distortion/clipping(very slight change)
and attached a blue led to r3
huge increase in volume and some more distortion
also lights up brighter when u play. swapped the power light with this led so u can see it from the outside
both leds are attached by alligator clips right now. idk if thats dangerous but it works until i can make the mods permanent.
Hi!
I admit, I know very much about this amp, but I'm not very educated in how to perform all sorts of mods and understans circuit 100%. So is there any good amp wiz out there willing to help me and maybe others wishing to modify/clone this amp? Gorhrut included.
Now the Bodom forum techs failed to understand what needed to be done so there is no more protecting of mods and making money of it by anyone. And no more production.
The GP-1000 design is horribe, yeah I know lee jackson was a great modder in the 80s, but he didn't know how to design good amps. Basically stole a design flaw from fender and only covered it up with some blocking caps.
Okay the issue with the amp is crossover distortion, and it exist even at stock values. I know somebody talked about sperating diode supplies, but how do you perform that? Could also ground all the grids on the triodes to calm it. But the main flaw is that PCB traces between the clean and distorted are crosstalking due to being to close to each other. Two techs Ive spoke with about this issue says its due to a spider network of traces round the relay. I'll post some pictures of both the clone and an old 88' original so you get some insight in how it is. They both says to rewire, but not what traces and paths needed cutting rewiring because they simply don't remember what they did 10 years ago. So I got a multimeter for testing if somebody could help me where and how to search for crossover distortion. If this get sorted the amp could be moded with more distortion without a trail of buzz at decaying notes.
Maybe I had too much coffee today. Or maybe it was the chocolate.
But, whatever.
So, on April 6 you get all high and mighty and come off like god. You chew out the other poster for sharing info, posting pics and make it sound like you have the secrets that no one else has. And, it is only you who can use these secrets and if anyone else tried, it would be "nothing but squeeky [sic] noise".
Now you come back and admit you are "not very educated" (which was obvious in your other posts), and you want us mere mortals to modify and clone this for you.
We all do of course, no need for sandpaper, put it away! I was going to say something along the same lines, but getting myself ready for work at the time was more important.
I'm personally still interested in what these mystical top secret mods are. Yea, there's the schematic on the first page. What're the other stuffs behind curtains? Where's that schematic and or notes? You said stuff about different models with different mods, useless info without more info, etc etc.
Lay it all out on the table and we might be able to make heads or tails for what you're looking to make the thing do versus what's been done/needs to be undone or done different, and so fourth.
Well, I could just ship the amp off to Alexi's tech and get the amp sorted out for 400 Euros + taxes and shipping. He wouldn´t do a 100% clone, but Alexi'd guitar tech has been kind enough to give me info on the basics of what he had in his GP-1000, but I like to thinker inside amps and I love challenges. I can solder and wire, I just don't know a lot about the technical part of how tubes and PCBs work.
Dedication to make the amp sound like that: There isn't any amp out there that sounds just like it. I mean yes close to, but not close enough. ENGL preamps and Marshall JVM/2210/jubilee are the closest because they kind of use much of the same idea. Heck, modding a 2210/JVM could be easier (getting the midrange right and sharper treble attack), but I don't got any of those.
Now the oscillation that the amp produces can't take any more distortion what so ever. It was fine tuned to stay low on noise even with that crossover distortion. So without any rewiring (or new PCB) it would just be buzzy noise decays. Even when you put an OD in front with some drive it buzzes out. Original same as clone.
Now I ain't building no clone for anyone anymore, but what I wanted for the clone was to make everything switchable, in case something was a bit off in the sound. Might have a mod that wasn't needed for the sound I was after. A lot of the suggested mods wasn't giveing us direct values, but also some were. I have a lot of notes and some emails with a few hint and direct values.
Some of the mods are stated here already, but not accurate. Alexis amp didn't have any diodes on the input caps, that was just something we tested for the clone because I thought it might add more distortion, while it only added a tiny bit more gain (volume) in most cases. diodes are in the amp but always sounds best in paralell to an output resistor or a resistor in the distortion path near the pot. At least in the schematics Ive seen and amps I've played. Now C2 and C3 is still modified with higher capacitors as well as some of the output capacitors are added to. C1 is really a question mark if it should be stock or upgrade. But I wouldn't make it bigger for Bodom sound, I tried it and the amp started to remind me more of a Peavey style of amp in the way the highs (treble) acted. If you guys need spesifics and values/parts used I could recheck my amp and emails.
It isn't magical mods, quite common stuff, much used in fender/marshall/boogie amps. It is just that this amp got its low midrange preset (mid shift in addition to regular mid pot) so it sounds very good with not a lot of tweaking.
Last edited by Rune on Thu Nov 27, 2014 12:08 pm, edited 2 times in total.
matt h wrote:I think I'm going to start accepting donations just not to be a dick to n00bs.
Well, I've a proposal.
Get the money not to be a dick, then send 50% to me. I'll be that dick.
You gain 50% of the ticket to see a free movie, I gain 50% of the ticket to enjoy directing the movie.
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