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

[Szlast]

Safety standards are the same for everybody, probably bigger companies take them more seriously as first, you want your products safe to begin with. then the fines can be huge if you are not responsible. For a small company you probably risk bankrupcy if they catch you not complying, you can face legal punishment as well. It is more serious than some people think.

What I was meaning with that is that some older effects also had that ground lifting circuit. You'll end isolating your ground more and more as they are technicall in series althoug most likely the ground will be shorted through the rest of the wiring. Still the principle is easy, try to keep one continuous ground, then act if there are problems

I have some cables made with the screen cut on one side, work good for things like FX loops. A 10-100Ω resistor instead of open probably is a better idea but you know... shoemaker's son goes barefoot haha. You couls add the capactiro and diodes across the resistor, if they fit in the jack, and you will have the full circuit in your cable,.

Transformers are OK as well but yes, you need to drive them properly to avoid loses or create resonances. I haven't had issues with the usual short cable between an FX loop and a rack for example

cheers!

Thanks a lot!

Regards!

 

[alenv3]

Hi Santiago!

I have also question about jvm410 fx loop ...

I'm trying to find ideal fx unit for jvm loop so I have MINIMAL tonal and dynamic loss.

Will use it probably only In "power amp" loop (no 4 cable method) for chorus, delay, reverb and master volume on expression pedal.

Thinking about g-system, hx effects, or something else If you have on mind?

Tnx!

 

[santiall]

Hi Santiago!

I have also question about jvm410 fx loop ...

I'm trying to find ideal fx unit for jvm loop so I have MINIMAL tonal and dynamic loss.

Will use it probably only In "power amp" loop (no 4 cable method) for chorus, delay, reverb and master volume on expression pedal.

Thinking about g-system, hx effects, or something else If you have on mind?

Tnx!

Hi,
I've mostly used the TC G-Major and G-Force and the the Yamaha SPX-2000 as multieffect in the FX loop of my amps, not only with a JVM, but you will need a MIDI controller with them.
If you want something with footcontroller you'll be fine with those you mention. There are some other options but make sure that they can take line level signals, not just guitar/instrument levels or you may have trouble when using the power amp loop

 

[T-Bone]

Hi, Santiago! Congrats on designing the very underrated JVM. I feel it's the greatest Marshall ever because of the wide range of drive levels while always sounding like a Marshall. I love that it's very tight with intense harmonic content. I recently picked up the 1 watt JVM. Using a reactive load box and impulse responses for speaker sim has shown me that little amps can sound as good as the big ones! What can you share about that amp? How could its OD channel be modded to be like OD1 instead of OD2 from the big ones? Also, what can you tell us about the reverb on the JVM? What hardware units would you compare it to? Thanks in advance!

1 watt JVM demo

 

[santiall]

Hi Todd, thanks for the message and compliments. Not sure about the underrating of the JVM but I'd think it's not bad for something that is going to be 20 years old soon :). Nice playing and tone in your videos!

JVM1... actually that amp is based on the OD1 RED mode of the standard JVM. It is a very similar circuit but with a bit less gain than the 100W preamp. In a normal use case the 1W amp will be distorting more often that the 100W so I lowered the gain to balance the total gain. What I mean is that, usually, the 100W power amp would be used in its linear zone but the 1W power will be used distorted so it was too much pre+power amp distortion. On top of that,Tte 1W also has the low power mode to be more room friendly when used fully overdriven, also to encourage people to drive the power amp harder.

The reverb of the JVMs... it is whatever effects card Marshall had at the time. We did put some work on it to make it sound balanced in the amp but it wasn't exclusively developed for this amp nor based in any particular hardware. We alreay knew that just having a knob called "reverb" some people would complain and say reverb this and reverb that. Still happens today so yeah, it is one of those haha. At the end people who really like reverb will use their preferred one in the loop, the ones who don't like reverb will turn it to zero (and maybe come to a forum to complain abouthow a bad idea it is to have reverb in an amp hahaha).

Those were also the times when a combo had to have reverb but a head must NOT have reverb... The JVM had to be the same amp for head or combo to streamline development and production so it is in all the series. I see the reverb more like a nice-to-have commodity, like if you go with the amp to play somewhere and that particular room is really dry, or you just want to play guitar but without having to connect everything, so you have it in there but probably you wouldn't use it to record the amp.

 

[T-Bone]

Hi Todd, thanks for the message and compliments. Not sure about the underrating of the JVM but I'd think it's not bad for something that is going to be 20 years old soon :). Nice playing and tone in your videos!

JVM1... actually that amp is based on the OD1 RED mode of the standard JVM. It is a very similar circuit but with a bit less gain than the 100W preamp. In a normal use case the 1W amp will be distorting more often that the 100W so I lowered the gain to balance the total gain. What I mean is that, usually, the 100W power amp would be used in its linear zone but the 1W power will be used distorted so it was too much pre+power amp distortion. On top of that,Tte 1W also has the low power mode to be more room friendly when used fully overdriven, also to encourage people to drive the power amp harder.

The reverb of the JVMs... it is whatever effects card Marshall had at the time. We did put some work on it to make it sound balanced in the amp but it wasn't exclusively developed for this amp nor based in any particular hardware. We alreay knew that just having a knob called "reverb" some people would complain and say reverb this and reverb that. Still happens today so yeah, it is one of those haha. At the end people who really like reverb will use their preferred one in the loop, the ones who don't like reverb will turn it to zero (and maybe come to a forum to complain abouthow a bad idea it is to have reverb in an amp hahaha).

Those were also the times when a combo had to have reverb but a head must NOT have reverb... The JVM had to be the same amp for head or combo to streamline development and production so it is in all the series. I see the reverb more like a nice-to-have commodity, like if you go with the amp to play somewhere and that particular room is really dry, or you just want to play guitar but without having to connect everything, so you have it in there but probably you wouldn't use it to record the amp.

Thanks so much for the reply and info! On the reverb...I'm an at-home studio enthusiast. I always use reverb, but I really don't like tweaking them or obsessing about which one sounds best. I guess I was just wanting you to tell me that the reverb on the JVM is exactly like a top-of-the-line Lexicon plate reverb or something similar. I really like the idea of a great reverb, already dialed-in, with just one simple knob for more or less.