Amp_chaser
Active member
I've always had in my head an amp that could reproduce the sound of VH1 and VH2. We will never know if it was the studio, josé or something else going on that's for sure... I've tried some brown sound amps and the closest was my bray 4550 deluxe. However i felt that there was this little sound like the speakers were going to blow that was always lacking. Because of that i decided to learn how to build amps and to give a try at it. After a lot of years learning how to build and amps I believe that i've perhaps been able to make an amp sounding closer than the bray 4550 deluxe for VH1 and VH2.
Some months ago i began modding a tubetown px18 with Eddie's van halen's preamp board values leaked by Dave Friedman and with josé arredondo mods and values found threw deep net research.
After 4 months of intense research, modding and a lot of spent money, I came across some special values by josé used in an unusual amp. the josé amp with special values had cathode values for the extra gain stage of 3.3k bypassed by a non polarized 1uf and a transistor which when wired in the correct way produces a special sound. The amp i used as a modding platform has been butchered since it has been modded to death.
The story in short : It had a josé master volume, clipping transistors and the extra gain stage. Things were getting closer but it was still not the brown sound. I decided then to try to mod the phase inverter. By accident i forgot to rewire the 82k resistor and turned the amp on. I played a chord and was like WTFFFFFFFFFFF. the sound was dimed but the distortion and the compression increased by a lot. It was like i've jumped from 60% close to the brown sound to 90%. Another error happenned to me while i was trying clipping transistors models on the josé master volume. I wired the collectors together instead of the emitters. The voltage was way higher but unexpectedly there i could hear the brown sound. I then remembered that the old schematic of josé showed transistors linked together but he never stated if it was the collectors of the emittors.
Statement : i'm not saying i discovered how it was done. I'm saying it works on this el84 px18 plexi.
My mod 7 removes the 82k of the phase inverter changing the way distortion behave and turning the amp into a class AB amp. As a result your amp will lose a lot of output but distorsion and compression will be increased a lot.
I continued modding the px18 with those values during 4 months and found a way to get closer than any amp you could get for the brown sound. However don't worry if you don't like van halen but like the sound of Randy Rhoads, Warren de Martini, Schenker, Steve Stevens, George Lynch, Steve Vai, James Hetfield, and melty hot tones you'll appreciate to build this amp.
I own a sv20 and it will be on sale soon as i totally doesn't use it anymore. This 18w amp has replaced my fav amps. And i believe it sounds even better than my previous owned bray 4550 deluxe for Vh1 and Vh2 only.
Unfortunately i always fail at recording how it really sounds because i lack knowledge about recording and don't have the adequate gear however i promise that you wont be disappointed if you like the 80's hard rock / metal and Van Halen's tone.
the mods of this amp make it a low output amp but it's thanks to the low output and dimed amp that the brown sound can appear. The perfect way to play this amp live would be to use a power amp like the fryette power amp station and to boost its output like eddie used to slave his main amp with other amps.
here is the complete share of the Mod 7. There are some special values of the mod which are not given, but i give you close sounding alternatives. Some online people (techs mainly) which helped me to come with the mod recieved the original values.
Here you have some pictures of the mod 7 transposed to a 50w plexi with eddie's preamp board values amd 6ca7 : it works but still needs a lot of tweaking to reach the px18 sound. So don't mod you 50w or 100w yet with this mod. But build a px18 with mod 7 instead it will be worth it.
This Mod is free to use and you can even sell it for your own profit the only thing i ask you to do is to write on the backplate of the amp you're selling Mod 7 or Inspired by Mod 7.
Use this layout : https://www.mediafire.com/file/d902tfm62cj5k57/px18_Mod_7.pdf/file
You should read this PDF but only use this pdf link for the values of the clipping components and for the advices (however it's the previous file that dictates the mod) : https://www.mediafire.com/file/wqn2msfx2uf53mk/MOD_7_PX_18_and_Plexi_Prototype.pdf/file
those are the original layouts and schematic (without mods) : https://media.tubetown.net/cms/userfiles/downloads/px18-layout.pdf / https://media.tubetown.net/cms/userfiles/downloads/px18-schem.pdf
please don't use this mod on your 50w and 100w heads because the transposition of the mods on big heads is still a work in progress. It works but it still needs some modding on the bias section which means that the 50w and 100w still don't sound as good or better than the px18 but it will come as soon as the bias section values will be found.
for those wanting to build the amp i strongly recommend you to buy the transformers on the website GDS amps. Their Radiospares replica of the Marshall 1974x made by heyboer is one of the keys to this exceptionnal sound.
GDS Amplification » Parts
another thing to take into consideration : this amp sounds fatter with PAF style humbuckers and a less fat and more clean with high output humbuckers. 8k-9k with alnico V, 2 or 8 works very well. I tested it with the 78 model, Ibanez super 70's and the frankenstein humbucker.
I hope you'll enjoy this amp and I can't wait for your feedback.
if you want this amp but cannot build it ask perhaps for someone in the comment section or ask for a local tech to use the layout.
i forgot to specify bias is 34,2 mV at the 1ohm resistor when the 82k is disengaged which means with the brown switch ON and plexi dimed.
new clips coming. I had issues with my 2i2 drivers with audacity that's why i had muddy tone in my recordings. I'm now using cakewalk and it solved the issue. here are a new clip more are coming :
Some months ago i began modding a tubetown px18 with Eddie's van halen's preamp board values leaked by Dave Friedman and with josé arredondo mods and values found threw deep net research.
After 4 months of intense research, modding and a lot of spent money, I came across some special values by josé used in an unusual amp. the josé amp with special values had cathode values for the extra gain stage of 3.3k bypassed by a non polarized 1uf and a transistor which when wired in the correct way produces a special sound. The amp i used as a modding platform has been butchered since it has been modded to death.
The story in short : It had a josé master volume, clipping transistors and the extra gain stage. Things were getting closer but it was still not the brown sound. I decided then to try to mod the phase inverter. By accident i forgot to rewire the 82k resistor and turned the amp on. I played a chord and was like WTFFFFFFFFFFF. the sound was dimed but the distortion and the compression increased by a lot. It was like i've jumped from 60% close to the brown sound to 90%. Another error happenned to me while i was trying clipping transistors models on the josé master volume. I wired the collectors together instead of the emitters. The voltage was way higher but unexpectedly there i could hear the brown sound. I then remembered that the old schematic of josé showed transistors linked together but he never stated if it was the collectors of the emittors.
Statement : i'm not saying i discovered how it was done. I'm saying it works on this el84 px18 plexi.
My mod 7 removes the 82k of the phase inverter changing the way distortion behave and turning the amp into a class AB amp. As a result your amp will lose a lot of output but distorsion and compression will be increased a lot.
I continued modding the px18 with those values during 4 months and found a way to get closer than any amp you could get for the brown sound. However don't worry if you don't like van halen but like the sound of Randy Rhoads, Warren de Martini, Schenker, Steve Stevens, George Lynch, Steve Vai, James Hetfield, and melty hot tones you'll appreciate to build this amp.
I own a sv20 and it will be on sale soon as i totally doesn't use it anymore. This 18w amp has replaced my fav amps. And i believe it sounds even better than my previous owned bray 4550 deluxe for Vh1 and Vh2 only.
Unfortunately i always fail at recording how it really sounds because i lack knowledge about recording and don't have the adequate gear however i promise that you wont be disappointed if you like the 80's hard rock / metal and Van Halen's tone.
the mods of this amp make it a low output amp but it's thanks to the low output and dimed amp that the brown sound can appear. The perfect way to play this amp live would be to use a power amp like the fryette power amp station and to boost its output like eddie used to slave his main amp with other amps.
here is the complete share of the Mod 7. There are some special values of the mod which are not given, but i give you close sounding alternatives. Some online people (techs mainly) which helped me to come with the mod recieved the original values.
Here you have some pictures of the mod 7 transposed to a 50w plexi with eddie's preamp board values amd 6ca7 : it works but still needs a lot of tweaking to reach the px18 sound. So don't mod you 50w or 100w yet with this mod. But build a px18 with mod 7 instead it will be worth it.
This Mod is free to use and you can even sell it for your own profit the only thing i ask you to do is to write on the backplate of the amp you're selling Mod 7 or Inspired by Mod 7.
Use this layout : https://www.mediafire.com/file/d902tfm62cj5k57/px18_Mod_7.pdf/file
You should read this PDF but only use this pdf link for the values of the clipping components and for the advices (however it's the previous file that dictates the mod) : https://www.mediafire.com/file/wqn2msfx2uf53mk/MOD_7_PX_18_and_Plexi_Prototype.pdf/file
those are the original layouts and schematic (without mods) : https://media.tubetown.net/cms/userfiles/downloads/px18-layout.pdf / https://media.tubetown.net/cms/userfiles/downloads/px18-schem.pdf
please don't use this mod on your 50w and 100w heads because the transposition of the mods on big heads is still a work in progress. It works but it still needs some modding on the bias section which means that the 50w and 100w still don't sound as good or better than the px18 but it will come as soon as the bias section values will be found.
for those wanting to build the amp i strongly recommend you to buy the transformers on the website GDS amps. Their Radiospares replica of the Marshall 1974x made by heyboer is one of the keys to this exceptionnal sound.
GDS Amplification » Parts
another thing to take into consideration : this amp sounds fatter with PAF style humbuckers and a less fat and more clean with high output humbuckers. 8k-9k with alnico V, 2 or 8 works very well. I tested it with the 78 model, Ibanez super 70's and the frankenstein humbucker.
I hope you'll enjoy this amp and I can't wait for your feedback.
if you want this amp but cannot build it ask perhaps for someone in the comment section or ask for a local tech to use the layout.
i forgot to specify bias is 34,2 mV at the 1ohm resistor when the 82k is disengaged which means with the brown switch ON and plexi dimed.
new clips coming. I had issues with my 2i2 drivers with audacity that's why i had muddy tone in my recordings. I'm now using cakewalk and it solved the issue. here are a new clip more are coming :
Last edited:
