School me on the JVM410 and JVM205 heads

[jchrisf]

I also felt like it sounded very close to my old DSL100. I checked the bias on mine with a Eurotubes probe, and it was ast 26 mA for both sets of EL34s. I left it alone because Marshall used to set the bias way too high and 26 is much safer. It's a little low, yes, but it's a safe bias. Anyway, maybe give it some more time? If it's not for you, at least you now know.

What's the bias supposed to be?

 

[BABMusic]

What's the bias supposed to be?

You know, Google AI says 30-35 mA. I wouldn't put up higher than 32 because Marshall PCB has shown to have problems with hotter bias. Definitely do not want 38 with this amp.

 

[angelspade]

Obviously the DSL and JVM share certain Marshall DNA...But having owned both, I don't find them to be very similar. I can dial the JVM OD1 in close to the DSL...But the DSL cannot do most of the tones available on the JVM spectrum as the DSL doesn't come close on gain, aggression or versatility. Just my ears and hands...Opinions will vary.

 

[jchrisf]

You know, Google AI says 30-35 mA. I wouldn't put up higher than 32 because Marshall PCB has shown to have problems with hotter bias. Definitely do not want 38 with this amp.

Did you get the 50 watt? I have the 100 and everything I'm seeing is saying to make it 70 mA.

 

[BABMusic]

Did you get the 50 watt? I have the 100 and everything I'm seeing is saying to make it 70 mA.

No, mine is a 100 watt like yours. I think that 70mA is equivalent to 2 power tubes. So I believe that would mean that you would want it set at 35 mA. 35 is on the warmer side, but probably safe. I would personally feel safer at 32 or less.

 

[jabps]

Obviously the DSL and JVM share certain Marshall DNA...But having owned both, I don't find them to be very similar. I can dial the JVM OD1 in close to the DSL...But the DSL cannot do most of the tones available on the JVM spectrum as the DSL doesn't come close on gain, aggression or versatility. Just my ears and hands...Opinions will vary.

Yep, the JVM's base platform was the 800, not the DSL as some assume.

Bias, both of mine are between 32 - 35ma. For those that want a little more try KT77's. Had one of my original two JVM's loaded with 77's, little difference, little more low end. Unfortunately they were JJ's and I had several issue's with bad tubes. Currently my two JVM's are loaded with an original set of Wing C's and the other, TAD's Redbase Premiums (I think their Mullards) both have been in there since the pandemic. No need to replace anytime soon either. I use all 9th gen Chinese 12's as well. The original Svet Winged C's sounded fantastic though, luckily I had an extra set that I took out of one of my original JVM's and loaded those up in my main JVM when the original set started to fade.

Btw/ my main amp has only had two sets of tubes in it during it's life of close to 20 years and that amp saw tons of gigs, roadwork, rehearsals and recording.

 

[ChuggNorris]

Obviously the DSL and JVM share certain Marshall DNA...But having owned both, I don't find them to be very similar. I can dial the JVM OD1 in close to the DSL...But the DSL cannot do most of the tones available on the JVM spectrum as the DSL doesn't come close on gain, aggression or versatility. Just my ears and hands...Opinions will vary.

The JVM410 was designed based on Marshall wanting a TSL100 with a more modern heavy channel added to it. (Yeah the amp people claim sucks but actually sounds incredible when the bias issue is fixed and the amp is dialed)

Thats why they gave Santiago a TSL100 for reference and told him to design the future version of that and add more tones. And why a properly working TSL100 can sound so similar when dialed right on the heavy channels.

The first JVM circuits were born on a 2203 chassis using the TSL 100 as the original starting reference. They also had a slo100, and a Bogner Exstacy in the room during this process.

 

[ChuggNorris]

Yep, the JVM's base platform was the 800, not the DSL as some assume.

Bias, both of mine are between 32 - 35ma. For those that want a little more try KT77's. Had one of my original two JVM's loaded with 77's, little difference, little more low end. Unfortunately they were JJ's and I had several issue's with bad tubes. Currently my two JVM's are loaded with an original set of Wing C's and the other, TAD's Redbase Premiums (I think their Mullards) both have been in there since the pandemic. No need to replace anytime soon either. I use all 9th gen Chinese 12's as well. The original Svet Winged C's sounded fantastic though, luckily I had an extra set that I took out of one of my original JVM's and loaded those up in my main JVM when the original set started to fade.

Btw/ my main amp has only had two sets of tubes in it during it's life of close to 20 years and that amp saw tons of gigs, roadwork, rehearsals and recording.

It was built off a 2203 chassis but the TSL100 was tonally the starting point and main reference used when he was designing and building the prototype JVM. But the DSL had a cult following so they continued that onto a budget friendly line and the JVM became the new king of heavy.

Unfortunately the jcm2000 TSL100 sounded amazing but had even more bias issues than 2000 DSL due to the bad design heating up the board then the board becoming conductive so people trashed them & talked alotta shit. A properly working one in the room hangs with a JVM but I give the edge to the JVM for being able to just do a little more, without reliability issues.

 

[ChuggNorris]

I also felt like it sounded very close to my old DSL100. I checked the bias on mine with a Eurotubes probe, and it was ast 26 mA for both sets of EL34s. I left it alone because Marshall used to set the bias way too high and 26 is much safer. It's a little low, yes, but it's a safe bias. Anyway, maybe give it some more time? If it's not for you, at least you now know.

In these amps you need to be around 36 honestly. 45 was warm and Marshall recommended but 26 is low in my opinion. I preferred some amps colder (diezel herbert) but a marshall? Nah son. Pump that bias up

 

[ChuggNorris]

You know, Google AI says 30-35 mA. I wouldn't put up higher than 32 because Marshall PCB has shown to have problems with hotter bias. Definitely do not want 38 with this amp.

Its not the PCBs fault at all.

Its the conditions under which the PCB is operating and its limited to the jcm2000 models and some 900s. Bad bias circuit design with less than a millimeter of space between grounds and high voltage.... generating too much heat in bias circuit.... board becomes conductive after cooking under stress of bad design... shit starts arcing. Running that low of bias doesnt solve the problem and if you play a long time youll have the same issue. A few lucky ones were in the mix.

But it was the design itself. The PCB wasnt itself the problem.

Saying "marshall pcb has shown to have problem with hotter bias" is way too generalized and false.


And he definitrly wants 38 with that amp

 

[jchrisf]

Its not the PCBs fault at all.

Its the conditions under which the PCB is operating and its limited to the jcm2000 models and some 900s. Bad bias circuit design with less than a millimeter of space between grounds and high voltage.... generating too much heat in sais circuit.... board becomes conductive after cooking under stress of bad design... shit starts arcing.

But it was the design itself. The PCB wasnt itself the problem.

Saying "marshall pcb has shown to have problem with hotter bias" is way too generalized and false.

In my research on biasing the JVM I'm seeing bias drift issues? Any idea what this is about?

 

[ChuggNorris]

In my research on biasing the JVM I'm seeing bias drift issues? Any idea what this is about?

I said its limited to the jcm2000 series and some 900s. There are no drift with the JVM. And often times the "bias drift" wasnt even bias drift people were just using the term everytime shit went wrong. It was a bad bias design none the less.

Jvm took all that was wrong with a TSL100, fixed it, made it reliable, and added more options to get even more heavy tones pretty much.

Claims of bias drift on a JVM is made by clueless morons. Its a bad power tube in their cases.... JVMs dont drift

 

[BABMusic]

In my research on biasing the JVM I'm seeing bias drift issues? Any idea what this is about?

I think that's exactly what he was referring to. I think most of what he said is true, but I wouldn't recommend 38 or higher. I think my old DSL100 was actually at around 42 for many years, but that's the way it came from the factory. You'll get more life out of your tubes if you bias at 32, and there's not always a better tone at hotter bias. Biasing at 38 is not the best idea if you turn it up loud. If you play at bedroom volumes only, it's fine. I keep my Friedman at 35-36, and I've tried 28, 32, 38. 35-36 changes the feel slightly without worrying if you turn up the amp.

 

[jchrisf]

I'm going to try 36 and see if it gives it any mojo.

 

[ChuggNorris]

I think that's exactly what he was referring to. I think most of what he said is true, but I wouldn't recommend 38 or higher. I think my old DSL100 was actually at around 42 for many years, but that's the way it came from the factory. You'll get more life out of your tubes if you bias at 32, and there's not always a better tone at hotter bias. Biasing at 38 is not the best idea if you turn it up loud. If you play at bedroom volumes only, it's fine. I keep my Friedman at 35-36, and I've tried 28, 32, 38. 35-36 changes the feel slightly without worrying if you turn up the amp.

He needs 35-40 range

I either run them at 36 or 39.

Same with SLX 100 And the old DSL100

JVM also has master volume. Turning up loud doesnt get weird with warmer bias unless its just flat out too hot. Which would be 45 and up in this case.

 

[ChuggNorris]

I got to spend a few minutes with it and to me it sounds like a DSL. I was not all that impressed. I'm wondering if I need to bias it? I did like the Crunch and OD1 channels the most.. the clean channel was awesome with an OD in front as was the Crunch. I did like the Plexi trick on OD2. The Reverb wasn't very good. It does sound great but nothing special so far.

I need to spend some more time with it and see what I can dial in but I think it is going back unless I can bias it and it comes alive.. the journey continues and I'll see what else I can dial in with it.

Unless the tubes are confirmed all working well. You need to try a new set. JVM does everything a DSL does.... and then goes beyond that.

You may just need time to get how it works when dialing..try weird shit and listen instead of look at the controls so much. Once you hear whats happening youll become more familiar.

Loved the DSL but thr JVM is absolutely its Daddy.

 

[jabps]

It was built off a 2203 chassis but the TSL100 was tonally the starting point and main reference used when he was designing and building the prototype JVM. But the DSL had a cult following so they continued that onto a budget friendly line and the JVM became the new king of heavy.

Unfortunately the jcm2000 TSL100 sounded amazing but had even more bias issues than 2000 DSL due to the bad design heating up the board then the board becoming conductive so people trashed them & talked alotta shit. A properly working one in the room hangs with a JVM but I give the edge to the JVM for being able to just do a little more, without reliability issues.

Actually bit of both... quoting Santiago below...

"When I joined M back in 2005 they already that a plan to upgrade the TSL and make it the new flagship. The starting point I was given to "take a TSL and add a 4th channel with more gain", so pretty much I took a TSL, put it on a shelf as reference and got a JCM800 2203 as starting point.

I always found the DSL a bit boomy/loose on the lower and scooped or perhaps fizzy. I understand that it records quite nicely and for some rock music is very good but it was just not my thing (apart then being an engineer it always bothered me the mess of wires inside...). Actually the DSL has 1 more gain stage than the JVM but I'd say the JVM is tighter, heavier than a DSL

It is actually a completely different amp to the DSL, there may be some similarities like the tone controls and cathode follower but I haven't used any DSL circuitry in the JVM, not even the transformers, we went back to JCM800 magnetics."

Also talking about the Satch Model...

"The HJS is, at end, quite different to the standard JVM. It has less gain, it is more open and less tight. A bit darker too. As Joe always says, he needs to play single notes for 2h every night and a more metal-style amp can get tiring. He also likes the amp to respond in a certain way to the way he picks and attacks the strings but, with a bit of boost you can get the amp quite tight and modern sounding too."

His thoughts on transformers and tubes for the JVM...

"The quick answer is no, you won't notice much. You may try the choke if you are inclined to modify something but I wouldn't change the transformers unless you have problems with them. The change in tone replacing the mains transformer with one designed for the amp (with the same voltages) won't accomplish anything, changing the output transformer may have some subtle differences but for the cost of changing all that I'd rather change pickups, speakers... I'd go for the 'feedback mod' rather than even considering to change the OT.
The 'best' modern EL34s were the old Svetlana, the winged C ones, but they don't make them anymore and since then it has been a bit of hit and miss. I'd probably go for JJs myself but I've also tried and used for quite some time the EHs."

 

[ChuggNorris]

Actually bit of both... quoting Santiago below...

"When I joined M back in 2005 they already that a plan to upgrade the TSL and make it the new flagship. The starting point I was given to "take a TSL and add a 4th channel with more gain", so pretty much I took a TSL, put it on a shelf as reference and got a JCM800 2203 as starting point.

I always found the DSL a bit boomy/loose on the lower and scooped or perhaps fizzy. I understand that it records quite nicely and for some rock music is very good but it was just not my thing (apart then being an engineer it always bothered me the mess of wires inside...). Actually the DSL has 1 more gain stage than the JVM but I'd say the JVM is tighter, heavier than a DSL

It is actually a completely different amp to the DSL, there may be some similarities like the tone controls and cathode follower but I haven't used any DSL circuitry in the JVM, not even the transformers, we went back to JCM800 magnetics."

Also talking about the Satch Model...

"The HJS is, at end, quite different to the standard JVM. It has less gain, it is more open and less tight. A bit darker too. As Joe always says, he needs to play single notes for 2h every night and a more metal-style amp can get tiring. He also likes the amp to respond in a certain way to the way he picks and attacks the strings but, with a bit of boost you can get the amp quite tight and modern sounding too."

His thoughts on transformers and tubes for the JVM...

"The quick answer is no, you won't notice much. You may try the choke if you are inclined to modify something but I wouldn't change the transformers unless you have problems with them. The change in tone replacing the mains transformer with one designed for the amp (with the same voltages) won't accomplish anything, changing the output transformer may have some subtle differences but for the cost of changing all that I'd rather change pickups, speakers... I'd go for the 'feedback mod' rather than even considering to change the OT.
The 'best' modern EL34s were the old Svetlana, the winged C ones, but they don't make them anymore and since then it has been a bit of hit and miss. I'd probably go for JJs myself but I've also tried and used for quite some time the EHs."

Absolutley.

His thread on "The Gear Forum" was a great read.

And the interviews with that queer Leon and the Aussie were nice.


And when you hear a dialed TSL100 next to a JVM this shit starts to make sense which is also hilarious based on how many absolute n00bs claim the TSL didnt sound good. Was either smoking crack or inhaling the fumes from the bias circuit arcing off the cooked PCB

 

[BABMusic]

Just curious, how does the tone/feel change if I set the bias at 37 vs. what I currently have at 26?

 

[ChuggNorris]

Just proves the point further here.

And shits on the TSL haters