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

santiall said:
at the end both controls are in series so you won't be driving the power amp higher if the MV is higher for example. The power amp "sees" whatever signal you put into its input and delivers power based on that. If this amp had a post phase inverter volume you could drive harder the phase splitter with a higher channel volume but it is not the case with the JVM and any amp with pre-PA master.

I know many people out there think that they are driving the power amp mpre having the MV high but sorry, that's just not the case in the JVM or in any amp with similar design (pretty much all the multi-channel amps out there).

Regarding noise, I'd suggest to have the channel volumes as high as you can, then set the overal listenning volume with the MV. The tone difference will be suble if you choose to have lower CV and higher MV. The general rule for maximizing noise performance in any circuit is to have as much gain as early as possible, this is the reason why you should have as much signal as you can into your audio interface and so on.

The way it was designed was to set the Clean Green to whatever gain/tone you like and then set the rest ov CV to match. They should be around noon.

The Satriani version has some frequency shaping around the channel volumes so the amp gets darker the lower the channel volume is. The standard one is pretty much flat, the frequency variations are subtle when using different volume settings
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Really interesting. When I owned the DSL, conventional wisdom on forums was the amp sounded best with the master volume cranked and then channel volumes dialed to whatever level your ears could withstand. (Generally pretty low since the master is cranked)

You seem to indicate it’s actually the reverse (at least with the JVM) that the best thing to do is crank the channel volume(s) and use the master to tame it down to “the police won’t get called tonight” levels.

Great feedback.
 
The original DSL had that power reduction thingy so in that case I can see why you would like to run the master and channels high.

Otherwise, there may be a subtle difference in tone when comparing channel high/master low, or perhaps those amps had a lot of channel crosstalk and by running the master high and channel low you minimized the "background fizz" if that makes sense... Those amps also had relatively low headroom fx loops, it could be that with channel volume high you overdrive the loop and started to distort.

Or it just was the usual hearsay that was repeated all over the place...

There are many caveats but let's say, that as starting point, I'd have the channel volume as high as I can and the adjust the master to desired playing level.
 
Hi Santiago, hope all is going well. This is not big M related but I wanted to know what is your opinion on the Bugera 6262 Infinium? I know you have a backgtound with big B and that amp has caught my eye.

Thank you again for the time you take for answer all our questions.

Pablo González Kettenhofen
 
Hi, all good thanks, hope you too!. Finally a non big M related post! :D.
As far as I am aware those amps were clones of the 5150/6505 circuits to which they added the autobiasing and output current protection. I haven't seen the schematics but what I heard sounded pretty much the same to me. I worked a little bit on those first Bugera amps and drew some initial schematics, prepared transformers and so on but left before any prototypes were made.

I'm sure sound-wise they are fine, probably more "econimcally made" than more expensive brands so the question would be whether you prefer something cheap that you don't mind if it breaks or you prefer something more expensive but easier to service, perhaps more reliable and so on.

Mind you, most of the problems with tube amps are the tubes, and those come from the same place for all the brands so the risk is pretty much the same, but perhaps finding someone that is willing to fix the autobiasing of those Bugera amps will be difficult and you will get the usual "for the price this costs it is not worth to fix"
 
santiall said:
Hi, all good thanks, hope you too!. Finally a non big M related post! :D.
As far as I am aware those amps were clones of the 5150/6505 circuits to which they added the autobiasing and output current protection. I haven't seen the schematics but what I heard sounded pretty much the same to me. I worked a little bit on those first Bugera amps and drew some initial schematics, prepared transformers and so on but left before any prototypes were made.

I'm sure sound-wise they are fine, probably more "econimcally made" than more expensive brands so the question would be whether you prefer something cheap that you don't mind if it breaks or you prefer something more expensive but easier to service, perhaps more reliable and so on.

Mind you, most of the problems with tube amps are the tubes, and those come from the same place for all the brands so the risk is pretty much the same, but perhaps finding someone that is willing to fix the autobiasing of those Bugera amps will be difficult and you will get the usual "for the price this costs it is not worth to fix"
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Thanks Santiago, that really helps to know possible scenarios. :)
 
@santiall I've been wanting to try a JVM for years and it turns out someone who watches my YT channel and lives 5 minutes from me has these.

About to blast them!

Screenshot 2023-03-15 at 10.23.25 pm.png
 
2112 said:
Far out I didn't expect the JVM to be able to do the 5150 style "crush, kill, destroy" style metal tones.

The switching is VERY intuitive and for such a complex amp it's really easy to use. Like so many things I'm a little late to the party. Respect @santiall !
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when designing the JVM we had a 5150, a Dual Rectifier, an Ecstasy and perhaps an SLO100 as references. I already had a 5150 myself and that was the level of gain I tried to reach, which is also similar to something like a 2203 with an SD-1 Overdrive for example (that I was also quite familiar with). I wanted it to be a bit more "Marshally" than the 5150 though, and believe it or not, the 5150 was noisier than the JVM.

Actually in absolute gain terms, probably the JVM is gainier than the 5150, but in 'useable' settings there are both rather similar.
The switching wasn't planned, just evelved that way. They were having a lot of trouble with multi-pin connectors for the footswitch so the whole idea of an intelligent footcontroller came to my mind and the system pretty much evolved by itself. Then, since there were so many interesting sounds available everything fell in place pretty much by itself.

Definitely the JVM has aged quite well... glad you have enjoyed it but, as said before, you can play so it is 'easy' for you to make things sound good ;) ( 'easy' in quotes because I'm not trying to take any merits away from you but highlighting your talent to do so!)
 
paisleywookiee said:
The JVM is a killer amp. A little on the noisy side, but sounds fantastic.
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yes, but when choosing between noise or gain we all went for gain. Back in the day, and with the original intention of the amplifier, noise wasn't that much of an issue. It was a pity that the Kerry King gate was designed just after the JVM was starting production, otherwise we should have put it in. Always so easy to look backwards and say "i should have done this or that' :D
 
Hi Santiago! I hope all is going good.

I have 3 questions that I'd like to consult with the master mind if I may.

1.- I have the cable atrached in the picture showing the actual specs on it (sorry for the bad camera focus) and I would like to know if that can work to conectado my JVM head to my cab?

I've had that cable for a long time and I just relized that it says "speaker cable". I've dumped this cable as I was using it as a regular instrument cable and it was noisy.

2.- If we could select diferent types of tubes how would it sound the JVM with 6L6?


3.- We've been talking a lot about overdrive but do you have any predilect circuit for clean tones? You also mentimed that the clean channel was your take on the big F circuit. However, Is there any special big F circuit (DR, TR, SR, HRD) that the JVM is based on?

Thank you :)
 

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Pablo González Kettenhofe said:
Hi Santiago! I hope all is going good.

I have 3 questions that I'd like to consult with the master mind if I may.

1.- I have the cable atrached in the picture showing the actual specs on it (sorry for the bad camera focus) and I would like to know if that can work to conectado my JVM head to my cab?

I've had that cable for a long time and I just relized that it says "speaker cable". I've dumped this cable as I was using it as a regular instrument cable and it was noisy.

2.- If we could select diferent types of tubes how would it sound the JVM with 6L6?


3.- We've been talking a lot about overdrive but do you have any predilect circuit for clean tones? You also mentimed that the clean channel was your take on the big F circuit. However, Is there any special big F circuit (DR, TR, SR, HRD) that the JVM is based on?

Thank you :)
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Hi, thanks for the questions

No problem with the cable, it's thick enough for the job..the worst case would be 100W@4ohm and that cable can carry much more than that amount of current.
My only comment with speaker cables is to make them as short as possible. If there was any power dissipated by the cable, it'll be proportional to the cable length so you would like it to be short.

6L6s work perfectly, I think the bias range was good enough to have them installed straight away too. Difficult though to explain the sound difference, I'd say just try them if you have a set to test :)

I like the black/silver face style Fender circuits for a clean channel. DT, TR, SR and they likes prey much share the same circuit and they are all nice. I'd go for a TR myself but all are ok. The HRD circuits are a bit different with extra gain here and there, not as "raw" as the others but quite nice for cleans I have to say.

The JVM is based on the DR/TR... with a tad more gain, it isn't as clean and has more harmonics but I like the extra "hair" that those bring without getting crunchy already. The 6100 30th anniversary has also a similar circuit but cleaner and perhaps a bit too "sterile" or flat compared to the standard JVM
 
santiall said:
Hi, thanks for the questions

No problem with the cable, it's thick enough for the job..the worst case would be 100W@4ohm and that cable can carry much more than that amount of current.
My only comment with speaker cables is to make them as short as possible. If there was any power dissipated by the cable, it'll be proportional to the cable length so you would like it to be short.

6L6s work perfectly, I think the bias range was good enough to have them installed straight away too. Difficult though to explain the sound difference, I'd say just try them if you have a set to test :)

I like the black/silver face style Fender circuits for a clean channel. DT, TR, SR and they likes prey much share the same circuit and they are all nice. I'd go for a TR myself but all are ok. The HRD circuits are a bit different with extra gain here and there, not as "raw" as the others but quite nice for cleans I have to say.

The JVM is based on the DR/TR... with a tad more gain, it isn't as clean and has more harmonics but I like the extra "hair" that those bring without getting crunchy already. The 6100 30th anniversary has also a similar circuit but cleaner and perhaps a bit too "sterile" or flat compared to the standard JVM
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Hi Santiago,

Thank you very much for your reply and guidance. I've had a very busy week and I totally forgot to say thank you. :)

I'm quite surprised that there is a posibility to use the 6L6 without any mod besides the biasing. Do you think it could sound something like the 5150?

Have a nice weekend!
 
Pablo González Kettenhofe said:
Hi Santiago,

Thank you very much for your reply and guidance. I've had a very busy week and I totally forgot to say thank you. :)

I'm quite surprised that there is a posibility to use the 6L6 without any mod besides the biasing. Do you think it could sound something like the 5150?

Have a nice weekend!
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6L6s will change the character of the amp but it won't make it a 5150, the preamps are quite different
 
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