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

[santiall]

Loop switching not so much a problem for me as I tend to never do that haha. I have not run into any issues overdriving anything in there

The bottom row 3 pedals here are all I have running in the loop

,

I experimented pretty heavily with the mix knob, it seemed like two low and my delay sound I wanted was compromised and too high the tone of the amp was compromised. I kind of like the lack of a knob in the other loop as it seems to just work for me lol

The MIX control only works as expected if you kill the direct signal, otherwise you will have all sorts of phasing issues, specially with digital pedals. You'd need to set the effect to 100% or use the "kill dry", then let the MIX control do it's job.
Option B is to set the MIX to 90-100% and treat the loop as a series loop. If you aren't switching the loop, then MIX to 100% is the way to go.

 

[SillyOctpuss]

What are you trying to connect?

This pic was when I was just running into the front of the amp but I've been trying to run some analogue drive pedals into the front of an hx stomp and then use the stomp in 4cm with the jvm.

I'm getting quite a lot of signal loss and extra high end which became more apparent at volume vs low volume playing in the house. I've been running into the series/parallel loop with the mix control at 100%

The send of the hx stomp is set to instrument level into the input of the jvm, the return from the jvm to the stomp is set to line level and the output of the stomp to the return of the jvm is also line level. The effects loop is set to the +4 dB setting.

 

[santiall]

View attachment 9192

This pic was when I was just running into the front of the amp but I've been trying to run some analogue drive pedals into the front of an hx stomp and then use the stomp in 4cm with the jvm.

I'm getting quite a lot of signal loss and extra high end which became more apparent at volume vs low volume playing in the house. I've been running into the series/parallel loop with the mix control at 100%

The send of the hx stomp is set to instrument level into the input of the jvm, the return from the jvm to the stomp is set to line level and the output of the stomp to the return of the jvm is also line level. The effects loop is set to the +4 dB setting.

the settings look good. I'd try connecting the whole system step by step. First the effects in front of the amp only, then the effects in the loop only (with the guitar connected directly to the amp input), then everything together. You'll be able to know where the losses start to appear.

Also make sure that you don't have any strange/unwanted routing in the HX so the 'front' and 'rear' signals are completely isolated.

With your setup it should be pretty much the same to use either loop and, actually, you also could use the SEND from the programmable loop and then return into the Power amp IN return. You'll bypass the loops and the reverb, probably a little bit quieter.

 

[Jonttu]

Hello there!
First of all, THANKS for the best amp ever! JVM410h!

I've had problems with the amp and im pretty sure that you are the one who to ask!
Ok, here it goes:

My problems started about 6months ago, all for sudden amp went mute and sound came back when i changed channel. This happened few times and then channel change didn't bring the sound back anymore. I had to turn the amp off and then after few minutes, same thing again.
I was controlling the amp with Harley Benton MP-100 midi controller, delay in the series loop and boss sd-1 infront of the amp. Nothing special fx wise.

First i thought problem could be my midiboard, perhaps it sends something weird midi commands to the amp? Since with that particular brand it could be possible, right?
I disconnected my midiboard, took delay away from the loop and same thing.. amp went mute again after few minutes and all leds turned off in the front panel.

I looked the schematic and found out that the channel relays are controlled with few digital IC's... I don't have any kind of datalogger, so my next idea was to replace 7805 regulator... perhaps +5V line drops and messes up the digital circuitry.
Nope. Didn't change anything.

Then after some time, first channel jammed, it didn't change modes anymore when i pressed the button in the front panel.. I looked the manual and found out that you can do factory reset for the amp.

I did and the amp worked flawlessy next 6months! two long studio sessions, many rehearsals with high volume and not a single problem with it!
I was sure that there was some byte "upside-down" in the Atmega or something, since the reset worked.

Last week same old problems came back! I did factory reset again, but amp worked maybe two minutes after that and problems came back...

I ordered new main board for the amp, but im still very curious what could cause that problem?

-Heat? well... it worked fine after factory reset.. many hours straight in studio without any problems.
-bad solder somewhere? ...unlikely... as they don't usually work 6months and then go bad again.
- +12V voltage drop from the input of the 7805? Btw, I did change C26, C31 and C34 capacitors just in case.

But im running out of ideas now

 

[santiall]

Hello there!
First of all, THANKS for the best amp ever! JVM410h!

I've had problems with the amp and im pretty sure that you are the one who to ask!
Ok, here it goes:

My problems started about 6months ago, all for sudden amp went mute and sound came back when i changed channel. This happened few times and then channel change didn't bring the sound back anymore. I had to turn the amp off and then after few minutes, same thing again.
I was controlling the amp with Harley Benton MP-100 midi controller, delay in the series loop and boss sd-1 infront of the amp. Nothing special fx wise.

First i thought problem could be my midiboard, perhaps it sends something weird midi commands to the amp? Since with that particular brand it could be possible, right?
I disconnected my midiboard, took delay away from the loop and same thing.. amp went mute again after few minutes and all leds turned off in the front panel.

I looked the schematic and found out that the channel relays are controlled with few digital IC's... I don't have any kind of datalogger, so my next idea was to replace 7805 regulator... perhaps +5V line drops and messes up the digital circuitry.
Nope. Didn't change anything.

Then after some time, first channel jammed, it didn't change modes anymore when i pressed the button in the front panel.. I looked the manual and found out that you can do factory reset for the amp.

I did and the amp worked flawlessy next 6months! two long studio sessions, many rehearsals with high volume and not a single problem with it!
I was sure that there was some byte "upside-down" in the Atmega or something, since the reset worked.

Last week same old problems came back! I did factory reset again, but amp worked maybe two minutes after that and problems came back...

I ordered new main board for the amp, but im still very curious what could cause that problem?

-Heat? well... it worked fine after factory reset.. many hours straight in studio without any problems.
-bad solder somewhere? ...unlikely... as they don't usually work 6months and then go bad again.
- +12V voltage drop from the input of the 7805? Btw, I did change C26, C31 and C34 capacitors just in case.

But im running out of ideas now

Hi, I'd start with more simple things... if the whole panel goes off it probably indicates some issues with either the 5V supply or, most likely, a connectio issues. You may have an intermittent issue with the falt ribbon cable that connects the main board to the front panel, or perhaps one of the T1A fuses that supply the 12V and 5V could be loose inside and fail intermittenly.
Even you mentioned it, don't discard a solder issue as well, those are random and can disappear before reoccuring some time later on

 

[Orvillain]

I'd totally forgotten that the original JVM had a parallel loop whilst the Satch one has a serial loop. Another win for the Satch model!! Which IMHO, really should be a standard Marshall model nowadays.

 

[SillyOctpuss]

@Orvillain casually mentioning his JS JVM.

 

[HotRats]

I'd totally forgotten that the original JVM had a parallel loop whilst the Satch one has a serial loop. Another win for the Satch model!! Which IMHO, really should be a standard Marshall model nowadays.

While I think a JVM MKII should incorporate some of the features and upgrades of the JS model I don't think that the 2 twin channels idea is a strong selling point, neither is the absence of an on board reverb.

Just to be clear, I'd buy a JS over the standard JVM but the success of the JVM over the JS speaks for itslef.

I belive that a JVM MKII should be a mix of the JVM and JVM JS models.

 

[Orvillain]

I don't think that the 2 twin channels idea is a strong selling point, neither is the absence of an on board reverb.

The reverb would have to be a significant upgrade over the old one, coz it was pretty bad. (Sorry Santi!)

The 2 twin channels - aren't I right in thinking that if you engage the mid-cut switch, then that is the same as flipping between OD1/OD2 on the original amp?? That's what I'd always thought anyway.

I quite like the 2 twin channels thing. Not so I can have them sound the same but have one a bit louder... but so that the gain characteristics are very similar from my mid-gain rhythms to my high-gain rhythms and lead tones.

You know how when you buy a 5150III and the blue sounds epic as fuck, and you switch to red and it almost sounds and feels like a totally different amp?? I really hate that about those amps!

 

[SillyOctpuss]

You know how when you buy a 5150III and the blue sounds epic as fuck, and you switch to red and it almost sounds and feels like a totally different amp?? I really hate that about those amps!

That's what I didn't like about tbe two channel jvm and why I had the drive channel modded. Moving from crunch to od2 felt like a different amp due to the shift in the mids. Having it modded to Od1 made it feel like the same amp again.
And yeah the reverb is serviceable but not great. The Helix handles that bit just fine.

 

[HotRats]

The reverb would have to be a significant upgrade over the old one, coz it was pretty bad. (Sorry Santi!)

The 2 twin channels - aren't I right in thinking that if you engage the mid-cut switch, then that is the same as flipping between OD1/OD2 on the original amp?? That's what I'd always thought anyway.

I quite like the 2 twin channels thing. Not so I can have them sound the same but have one a bit louder... but so that the gain characteristics are very similar from my mid-gain rhythms to my high-gain rhythms and lead tones.

You know how when you buy a 5150III and the blue sounds epic as fuck, and you switch to red and it almost sounds and feels like a totally different amp?? I really hate that about those amps!

I actually agree on everything, I was commenting from a marketing perspective.
Most players out there like options and reverb on big amps with fx loops

 

[Jonttu]

Hi, I'd start with more simple things... if the whole panel goes off it probably indicates some issues with either the 5V supply or, most likely, a connectio issues. You may have an intermittent issue with the falt ribbon cable that connects the main board to the front panel, or perhaps one of the T1A fuses that supply the 12V and 5V could be loose inside and fail intermittenly.
Even you mentioned it, don't discard a solder issue as well, those are random and can disappear before reoccuring some time later on

Thanks for the answer! :)
I will check out the things you said.

I might be digging way too deep here... but the thing that Factory reset solved all problems for 6months and then all problems came back... but then again factory reset didn't help last time, so it might have been just a coincidence.

I've removed the mainboard two times from the amp casing and i have cleaned the pins and checked many times that connectors are as they're supposed to be. Of course i can't say that cables itself don't have issues... I will check out that the fuses stays in their place tight!
thanks for the tips! i really appreciate it!

We had rehearsals yesterday and the amp worked great without any problems...
Go Figure.

 

[santiall]

While I think a JVM MKII should incorporate some of the features and upgrades of the JS model I don't think that the 2 twin channels idea is a strong selling point, neither is the absence of an on board reverb.

Just to be clear, I'd buy a JS over the standard JVM but the success of the JVM over the JS speaks for itslef.

I belive that a JVM MKII should be a mix of the JVM and JVM JS models.

The reverb would have to be a significant upgrade over the old one, coz it was pretty bad. (Sorry Santi!)

The 2 twin channels - aren't I right in thinking that if you engage the mid-cut switch, then that is the same as flipping between OD1/OD2 on the original amp?? That's what I'd always thought anyway.

I quite like the 2 twin channels thing. Not so I can have them sound the same but have one a bit louder... but so that the gain characteristics are very similar from my mid-gain rhythms to my high-gain rhythms and lead tones.

You know how when you buy a 5150III and the blue sounds epic as fuck, and you switch to red and it almost sounds and feels like a totally different amp?? I really hate that about those amps!

That's what I didn't like about tbe two channel jvm and why I had the drive channel modded. Moving from crunch to od2 felt like a different amp due to the shift in the mids. Having it modded to Od1 made it feel like the same amp again.
And yeah the reverb is serviceable but not great. The Helix handles that bit just fine.

lol, 3 people and already can't agree on feature set haha

you should also put things in perspective. This amp was pretty much conceived 3 years ago as the next DSL/TSL. Those were two channel and three channel amps with reverb, and parallel loop in the TSL if I am not mistaken. The JVMs took from there so many of the features have their origin in those amps. Also, traditionally, 2 channels amps are always the ones who sell the most. One channel is too limiting, 4 is too many for the general customer.

I do agree that probably nobody won't buy the amp because it has reverb or not. And also that having four channels that sound like the same amp is probably important and that's why I tried in the JVM as it was intended mostly for live use. There was always the choise of making OD2 much more scooped/metal, but it didn't really felt balanced when playing the whole thing together. With two channels it is much easier as it is some distortion agains some clean . In a studio situation, having balanced channels it is not that important I guess, if you use the amp as a 'bank of sounds'.

 

[santiall]

Thanks for the answer! :)
I will check out the things you said.

I might be digging way too deep here... but the thing that Factory reset solved all problems for 6months and then all problems came back... but then again factory reset didn't help last time, so it might have been just a coincidence.

I've removed the mainboard two times from the amp casing and i have cleaned the pins and checked many times that connectors are as they're supposed to be. Of course i can't say that cables itself don't have issues... I will check out that the fuses stays in their place tight!
thanks for the tips! i really appreciate it!

We had rehearsals yesterday and the amp worked great without any problems...
Go Figure.

do you always have something in the serial loop?, that loop relies on the jack switch when it is engaged and that can lead to sound cuts once the jack get a bit rusty and so on. The usual issue with serial loops that we tried to solve by adding the bypass switch. If you aren't using it set it to OFF so it will be bypassed by the switch

 

[Jonttu]

do you always have something in the serial loop?, that loop relies on the jack switch when it is engaged and that can lead to sound cuts once the jack get a bit rusty and so on. The usual issue with serial loops that we tried to solve by adding the bypass switch. If you aren't using it set it to OFF so it will be bypassed by the switch

Yes i do, i have Line6 Stomp in the series loop all the time.

When problem came up first time i had my effects in the paraller loop.. i thought it was loop issue so i put all my effects in the series loop.
Didn't help.. so i removed all my effects from the loop (and fx loops turned off) and i also removed midiboard... so there was nothing extra on the amp. However it still muted all for sudden and sound came back when i changed channel from the front panel buttons.

Until it didn't help anymore, amp went mute, channel led was still on but the amp didn't respond to any buttons i pressed, it was totally jammed.
I turned power off and back on and then the amp was alive again.. maybe for one minute.

Next time i tried it after few days, everything worked fine except clean channel didn't change the modes. Then i did the factory reset and it worked flawlessy for six months...

We'll see what happens after i get the new mainboard for the amp :)

 

[santiall]

Yes i do, i have Line6 Stomp in the series loop all the time.

When problem came up first time i had my effects in the paraller loop.. i thought it was loop issue so i put all my effects in the series loop.
Didn't help.. so i removed all my effects from the loop (and fx loops turned off) and i also removed midiboard... so there was nothing extra on the amp. However it still muted all for sudden and sound came back when i changed channel from the front panel buttons.

Until it didn't help anymore, amp went mute, channel led was still on but the amp didn't respond to any buttons i pressed, it was totally jammed.
I turned power off and back on and then the amp was alive again.. maybe for one minute.

Next time i tried it after few days, everything worked fine except clean channel didn't change the modes. Then i did the factory reset and it worked flawlessy for six months...

We'll see what happens after i get the new mainboard for the amp :)

let me know how it goes, good luck!

 

[Jonttu]

let me know how it goes, good luck!

I will! Thank you! :)
If i can't fix it, i will buy another one. Simple as that.

 

[Pablo González Kettenhofe]

Hi @santiall

I've been following this for months. I'm glad to see new comments.

Really nice that you take the time to interact.

I've been playing the 2008 JVM410H and the 1960A for almost 15 years!

Couple of months ago I found a good deal for a JVM410C so I pulled the trigger and I can say I'm also enjoying the combo versión it is very diferent than the head. This a 2017 combo model.

I also decided to try the ISP Technologies Decimator G string II which I find really nice and it has opened up the amp for me as I wouldn't use red modes on the OD channels because of the noise.

A couple of questions to the master mind:

Do you know any change or upgrade between the 2008 and 2017 model beside the footswitch?

What is you opinión of the ISP Technologies Decimator G string II?

Now that I'm using the decimator (4CM) before the the HX stomp (only for delay and time based effects) on the parallel fx loop and mix set to 100% I noticed on OD red mode a squeal that is quickly controlled by the gate. This only happens on the JVM 410h 2008 model. Do you know if I could be doing wrong? Bad cable?

Thak you again Santiago!

 

[santiall]

Hi @santiall

I've been following this for months. I'm glad to see new comments.

Really nice that you take the time to interact.

I've been playing the 2008 JVM410H and the 1960A for almost 15 years!

Couple of months ago I found a good deal for a JVM410C so I pulled the trigger and I can say I'm also enjoying the combo versión it is very diferent than the head. This a 2017 combo model.

I also decided to try the ISP Technologies Decimator G string II which I find really nice and it has opened up the amp for me as I wouldn't use red modes on the OD channels because of the noise.

A couple of questions to the master mind:

Do you know any change or upgrade between the 2008 and 2017 model beside the footswitch?

What is you opinión of the ISP Technologies Decimator G string II?

Now that I'm using the decimator (4CM) before the the HX stomp (only for delay and time based effects) on the parallel fx loop and mix set to 100% I noticed on OD red mode a squeal that is quickly controlled by the gate. This only happens on the JVM 410h 2008 model. Do you know if I could be doing wrong? Bad cable?

Thak you again Santiago!

Hola Pablo, yes, it has been quite active in here. The usual up/down cycles but a "steady interest" in chatting here, which is fun!

The only difference, which is not a small one, are the speakers. Combos are always trickier to design than heads, and not easy to make them sound big. In the JVM combo we just went for the same speakers that were used in the JCM2000 combos. They sounded good and gave some continuity to the ranges.

As far as I am aware nothing tone-wise was changed. The first change was to bypass the heater fuses, first with wires, then with a new pcb. I think at some point the pots were changed to a variation with nuts and of course they used different tubes over the years but the circuit has stayed the same. If they changed anything, say after 2017 I don't really know but I doubt.

The footswitch has 3 iteration. The very first ones were made in England as an interim solution while the production overseas was arranged. Then we standardised the footswitch to be used with more models so the LEDs were moved to the top of the switches so it can be used with more amps. Functionality is the same, the last ones are more universal and were planned to be used in a few amps that were never released...

The 4CM can be tricky and maybe the squeal you are using is ground related. You can debug it by removing the cables going to the amp input for example. If you are going to compare the two amps with the 4CM you would need to sent them in the same location, with the same grounding scheme. It could well happen that one setup has more ground noise or whatever.

I don't have any experience with the Decimator, I am aware that many people use it and it has good reviews but that's where my experience ends...

 

[Pablo González Kettenhofe]

Hola Pablo, yes, it has been quite active in here. The usual up/down cycles but a "steady interest" in chatting here, which is fun!

The only difference, which is not a small one, are the speakers. Combos are always trickier to design than heads, and not easy to make them sound big. In the JVM combo we just went for the same speakers that were used in the JCM2000 combos. They sounded good and gave some continuity to the ranges.

As far as I am aware nothing tone-wise was changed. The first change was to bypass the heater fuses, first with wires, then with a new pcb. I think at some point the pots were changed to a variation with nuts and of course they used different tubes over the years but the circuit has stayed the same. If they changed anything, say after 2017 I don't really know but I doubt.

The footswitch has 3 iteration. The very first ones were made in England as an interim solution while the production overseas was arranged. Then we standardised the footswitch to be used with more models so the LEDs were moved to the top of the switches so it can be used with more amps. Functionality is the same, the last ones are more universal and were planned to be used in a few amps that were never released...

The 4CM can be tricky and maybe the squeal you are using is ground related. You can debug it by removing the cables going to the amp input for example. If you are going to compare the two amps with the 4CM you would need to sent them in the same location, with the same grounding scheme. It could well happen that one setup has more ground noise or whatever.

I don't have any experience with the Decimator, I am aware that many people use it and it has good reviews but that's where my experience ends...

Hola @santiall

Thank you very much for your reply.

I can imagine that it is hard to design a combo and make it sound big with adicional restrictions of the layout.

I can tell you that I really enjoy playing both the combo and the head.

I saw the video with León Todd and it was really interesting about how you started and also your dad supporting you.

Also the fact that the first JVM prototype had more gain!

I have 3 more questions if your don't mind:

How would you define the OD1 and OD2 orange and red? Maybe a JCM800 on esteroids?

You mentioned on the interview that you got a mark V and fixed. I currently live in México and it is not easy get one oor try one. How do you like it and how would you compare the sound to the JVM? I know these are different animals but I have to ask.

Which do you like the most Dual Rectifier or Mark V?

Muchas gracias Santiago!