Santiago Alvarez (electronics engineer, JVM, YJM, AFD...)

SillyOctpuss said:
Thanks for that @santiall.

I'm very happy with my JVM and just wanted to see if it would be easy to do. if so I thought I'd pick up a second JVM as a project to mod. The HJS is pretty expensive over here now while the standard is cheap and plentiful to pick up used.
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you may say that it is "easy", but not flexible. You could mod here and there to have the tones, or one of the tones, but having all the features won't be an easy one unless you can write your new control firmware.
That's how actually the HJS was started, an standard JVM with the 2203KK noise gate hacked in, some extra relays in there and new firmware
 
santiall said:
you may say that it is "easy", but not flexible. You could mod here and there to have the tones, or one of the tones, but having all the features won't be an easy one unless you can write your new control firmware.
That's how actually the HJS was started, an standard JVM with the 2203KK noise gate hacked in, some extra relays in there and new firmware
Click to expand...

Thanks Santiall. I'd really just like to mod the OD channel from the JVM to match the tones of the HJS OD channel. I find the JVM has too much gain and wanted to know how different the HJS OD channels circuit was from the standard JVM. Is the differences in the OD circuits different values or is the circuit different?

I don't want to add a noise gate or any extra switching or anything like that.
 
Was wondering are not all amps some form or variation based on the Original RCA and Westinghouse designs ?
 
SillyOctpuss said:
Thanks Santiall. I'd really just like to mod the OD channel from the JVM to match the tones of the HJS OD channel. I find the JVM has too much gain and wanted to know how different the HJS OD channels circuit was from the standard JVM. Is the differences in the OD circuits different values or is the circuit different?

I don't want to add a noise gate or any extra switching or anything like that.
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That's easy to do but modifying the OD channels will change the clean and crunch channels too. It's pretty much changing some values and adding a coupe of additional parts
 
Stone said:
Was wondering are not all amps some form or variation based on the Original RCA and Westinghouse designs ?
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Yeah, in a way same as saying that every modern car is a variation of a Ford T.
Pretty much all amplifiers, not only guitar, started using the application schematics that were included in the tube books and datasheets. The manufacturers wanted to sell tubes and had all sorts of pre-designed application circuits with the tube data.
It evolved from there, in the guitar market to make them as cheap and loud as possible. I'd say, a bit of an stretch, that pretty much everything is a variation of Valco (Supro, Harmony...) and Fender
 
santiall said:
Yeah, in a way same as saying that every modern car is a variation of a Ford T.
Pretty much all amplifiers, not only guitar, started using the application schematics that were included in the tube books and datasheets. The manufacturers wanted to sell tubes and had all sorts of pre-designed application circuits with the tube data.
It evolved from there, in the guitar market to make them as cheap and loud as possible. I'd say, a bit of an stretch, that pretty much everything is a variation of Valco (Supro, Harmony...) and Fender
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Is there any new ground that can be covered, or will it all be minor variations or feature add-ons from here?
 


just stumbled on this video - is there any info on this amp? The comments say its a one off 15W class A combo with a greenback.

EDIT: the thought of Slash wandering round Bletchley makes me laugh. I think I heard some Marshall employee's talking about Jim taking Zakk Wylde out to a local (maybe Indian) restaurant for dinner and telling him off for swearing. Always makes me laugh thinking of these huge rockstars spending time in BLETCH.
 
MirrorProfiles said:


just stumbled on this video - is there any info on this amp? The comments say its a one off 15W class A combo with a greenback.

EDIT: the thought of Slash wandering round Bletchley makes me laugh. I think I heard some Marshall employee's talking about Jim taking Zakk Wylde out to a local (maybe Indian) restaurant for dinner and telling him off for swearing. Always makes me laugh thinking of these huge rockstars spending time in BLETCH.
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If I am not mistaken that was a one-off that was prepared for Slash as a present, probaby in 2008? I don't have any further info...

not sure if Jim would tell anyone not to swear but it is true that the F word can be quite offensive for the more traditional brits. But well, probably in Bletchley the waiter would come and ask "whoot the F you wont to munch todeay, mite?" :rofl
 
santiall said:
(...) it is true that the F word can be quite offensive for the more traditional brits. (...)
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This does not seem to apply to our @Orvillain :LOL:

BTW, that F***er stubbornly refuses to sell me his JVM410HJS. Could you have a serious word with him, @santiall ? ;)

Words Support GIF by @InvestInAccess
 
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MirrorProfiles said:
thats polite for Bletchley! (I was born 2 miles away from Marshall's factory)

The guy who told that story does the tours of the factory, he was saying that Zakk (regularly) called Jim "dad" and apologised and gave him one of his leather jackets. Loved hearing that story
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Sounds/Seems legit. In every interview ZW gives he's always like "Father X, Saint Y" and stuff. Dude lives in his own wordworld.
 
MirrorProfiles said:
thats polite for Bletchley! (I was born 2 miles away from Marshall's factory)

The guy who told that story does the tours of the factory, he was saying that Zakk (regularly) called Jim "dad" and apologised and gave him one of his leather jackets. Loved hearing that story
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When I moved to work in Bletchley, after 5 years living out of Spain and pretty much speaking only in English, I didn't understand anything..., well, I could transcribe most of it but no idea of the meaning :wat

Btw, there is indeed one of his leather vests framed in the museum in the factory. Not sure the story behind, probably true with some spice added
 
Hey Santiago!

I just bumped into the schematic of the JVM1 on my hard disc.
Its FX loop takes one unused triode stage as AC CF buffer for the send, return simply feeds the PI.
When implementing this in a "proper" amp (50W or 100W), of course you would need to take down the send level quite a bit, to feed stompboxes, but the gain of a typical PI should make up for this. I could even put a 1M pot after the return, before the PI, as global master (maybe linear instead of log). This would also prevent hiss/noise of the FX device being amplified by the gain of the PI, because it would be taken down by the global master first.
Also the input impedance of the PI should be high enough to compensate any long cable runs coming from the FX device output, which in turn usually is low impedance, so ...

Is there something I haven't taken into account yet...?


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santiall said:
When I moved to work in Bletchley, after 5 years living out of Spain and pretty much speaking only in English, I didn't understand anything..., well, I could transcribe most of it but no idea of the meaning :wat
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My brother in law is from Girona. Know him for 10+ years at this point??? I still don't know what he's saying. :rofl
 
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