It Has Arrived

[texhex]

The crazy thing is this amp was biased so low to begin with. All the tubes were at 26! and it sounded like total crap. If you bought a new JVM recently and didn't check the bias you really should. I use one of these $30 probes from Eurotubes and a Kaiweets 601 Multimeter, both good investments.

You searched for Bias Probes - Eurotubes

www.eurotubes.com

KAIWEETS KM601 True-RMS Smart Digital Multimeter

Accurately measure AC/DC voltage, AC/DC current, and 10A current, and can also be used to test continuity, capacitance, frequency, duty cycle, resistance, diode, temperature, NCV, and live wire.

kaiweets.com

I'm looking forward to spending some more time with this thing when I've had some sleep and am not so tired. It's a pretty wild amp. I can only imagine what this was like when it hit in 2006.

 

[Trollbait]

I use one of these $30 probes from Eurotubes and a Kaiweets 601 Multimeter, both good investments.

Thanks for that link. If you understand that capacitors can be deadly, is biasing a tube amp something a non pro can do?

 

[la szum]

The crazy thing is this amp was biased so low to begin with. All the tubes were at 26! and it sounded like total crap. If you bought a new JVM recently and didn't check the bias you really should. I use one of these $30 probes from Eurotubes and a Kaiweets 601 Multimeter, both good investments.

You searched for Bias Probes - Eurotubes

www.eurotubes.com

KAIWEETS KM601 True-RMS Smart Digital Multimeter

Accurately measure AC/DC voltage, AC/DC current, and 10A current, and can also be used to test continuity, capacitance, frequency, duty cycle, resistance, diode, temperature, NCV, and live wire.

kaiweets.com

I'm looking forward to spending some more time with this thing when I've had some sleep and am not so tired. It's a pretty wild amp. I can only imagine what this was like when it hit in 2006.

Per manufacturer recommendations I am guessing. Shipping them cold like that
seems like a safer bet for the manufacturer in the long run, but not the best
sonic experience for the user.

Congrats again!

 

[la szum]

Thanks for that link. If you understand that capacitors can be deadly, is biasing a tube amp something a non pro can do?

It is. Tie one hand behind your back.

Some of the newer amps even have bias ports where you can stick your thingies in
and get an instant reading.

 

[texhex]

Thanks for that link. If you understand that capacitors can be deadly, is biasing a tube amp something a non pro can do?

All amps are a little different. If you are careful there's no reason why you shouldn't be able to do it on your own.

This post was really helpful for this specific amp:

I need to check the bias on my JVM410H

Two entirely separate issues. I swapped the preamp tube to kill some of the fizz, and that was successful. But I also want to check the bias because of all the reports of them being biased cold from the factory. Okay, so what is the ECC83 that sits right next to the EL34's? Ah! - got it now...

www.marshallforum.com

 

[Achilles]

We have that same fan

Pretty sure everyone has the exact same one. We do.

 

[texhex]

This amp is a damn masterpiece of Marshall goodness! I'm only through OD1 and OD2, Green and Orange and they are both fantastic.

Green on OD1 or OD2, gain on about 4 with a boost (Maxon 808, or TS) is sublime. It has just enough gain with the boost pushing it and is absolutely sick Marshall rock. Hop over to Orange and turn off the boost and it's perfect raw, high gain but not muddy or fizzy. It's exactly what I wanted it to sound like.

I've played through the models in the AXE (HJS up until recently) enough to know it would sound good but man, I'm really diggin the real thing.

The only thing I'm not thrilled about is the amount of hiss on OD1/2 Orange. It's not horrible but it's definitely noticeable and a Gate takes care of it but you have to Gate it pretty hard. That's the one nice thing about the AXE is there isn't the same amount of hiss and you can set the Gates much lower. Kemper Profiles of this amp so far also lack the hiss. So whatever... it is what it is.

At first I was totally bummed and ready to ship this thing back. Like WTF, no way this amp can be this bad. It was flubby and muddy on the bottom, brittle fizz and spitty on the top and sounded like total crap. Every note I played I was getting more pissed and dejected, plus I was wiped tired. Cold bias was the culprit. Once the bias was sorted and I got some sleep, it's a totally different amp.

It also took me some back and fourth with the controls and my ears because I've been stuck in EVH/Badlander land so long I forgot what a damn Marshall sounds like. Fuck man, it's like a reset of my brain. So far the JVM OD1/2 won't do the resonant, low chug gank of a boosted blue EVH, Badlander Crush or boosted Recto. Maybe I can get into that territory but I haven't figured it out yet. Right now it's just a roaring jet of sweet Marshall gain.

The BE-100 is smoother, it's got it's own thing happening, higher gain on HBE, smoothed off. The Helios is darker and just way different. I think it's because the BE and Helios are maybe based off of a Plexi style circuit? The JVM OD1/2 is more raw, high gain Marshall which is exactly what I was hoping for.

@santiall huge thanks to you and Marshall for bringing this amp to life. It must have been a shockwave in 2006... it's still banging in 2023!

This is where I've ended up so far on the two OD channels, I haven't gotten into Red on either of these but Green and Orange are Looking forward to seeing what I can do with OD1/2 Red and the Clean and Crunch channels.

Why are DSL headshells so BIG? Friggin thing is like a truck grill!

 

[TheTrueZoltan!]

Yep, it's a beast, but a very noisy one.

 

[texhex]

Marshall JJ and Shuguang vs. Mesa JJ

The Marshall tubes are nosier and noticeably louder whereas the Mesa tubes are much quieter. Pretty interesting.

JVM410H Tube Layout:
V6: Gain stage (has a metal cover)
V7: Gain stage
V8: Cathode follower
V9: Effects loop and reverb mixer
V5: Phase inverter

Marshall Tube Positions:
V6 - Red
V7 - Red
V8 - Gold
V9 - Gold
V5 - Red

Mesa Tube Positions:
V6 - SPAX7-A
V7 - SPAX7-A
V8 - 12AX7-A
V9 - 12AX7-A
V5 - SPAX7-A


You can hear (and see) where the volume drops or increases based on the tube used. Reamp DI, all amp settings were the same between changes. OD1 Orange




Stock Marshall Tubes:
(Red) VLVE-00067 ECC83S JJ Low Microphony Red Logo
(Gold) VLVE-00049 12AX7B/ECC83 Shuguang High Microphony Gold Logo

Mesa SPAX7-A and 12AX7-A:

Notice the differences in the Marshall JJ vs. the Mesa JJ.

 

[spawnofthesith]

Congrats!!



This may sound a bit counter intuitive, but on the 210h I had, the hiss - I won't say went away, but stopped being noticeable at all to me once playing with the band practice levels or on stage

Playing at home though it was fairly annoying