Just a suggestion from a retired electronics guy: any time you remove screws, covers, etc. and replace a component, it's best practice to power it up and test it before replacing covers and screws. I learned this as a rookie technician over 40 years ago.
shuguang 12ax7b's will give you the most gain. touching preamp tubes isn't an issue. power tubes is what "they say" you shouldn't handle but i never had an issue in decades from touching my tubes
Which 12ax7s did you use? Nothing to do with tubes but As a long time JMP-1 owner I’d advise owners to keep note of there presets incase of the battery going flat . if anybody dose not know this, the battery sole purpose is to keep those presets stored .
Hi, Guerrilla Studios! Great video. Have you ever some trouble, with the internal 3v battery? I'm very worry about leakage and maybe, it causes serious damages to the pcb. Thanks! Excuse my sloppy english. Cheers from Viamao City - Brazil 👊😃🎸🇧🇷
Hello again! Thanks for reply! Bought my unit about 3 years ago, and unfortunately don't know if the 3v internal battery, was replaced or not... I'll take care with my JMP-1 and gonna put my eyes on it, just in case... hehe. Thank you so much. Your videos are great! Cheers from Viamao City - Brazil👊😃🎸🇧🇷
Hi mine today for the first time had a bit of crackly plus the low e string with lots of gain sounds fatty.. would you say I may need new valves. Was going to put it in the shop but I've had it for ages so the valves might be a cheaper option to check first . Where did you get yours from.. thanks. By the way the treble also had little effect when going up + and down -
I'd certainly try the valves first. If the output has inconsistent level and quality they're usually the culprit and the easiest thing to change. I've found the JMP to be a bit of a noisy unit anyway and always use a noise gate with it. The output pots can also get crackly. I order all my valves from Hotrox UK.
My one started to hum also, changed the valves and all good again
Just a suggestion from a retired electronics guy: any time you remove screws, covers, etc. and replace a component, it's best practice to power it up and test it before replacing covers and screws. I learned this as a rookie technician over 40 years ago.
shuguang 12ax7b's will give you the most gain. touching preamp tubes isn't an issue. power tubes is what "they say" you shouldn't handle but i never had an issue in decades from touching my tubes
Which 12ax7s did you use?
Nothing to do with tubes but As a long time JMP-1 owner I’d advise owners to keep note of there presets incase of the battery going flat .
if anybody dose not know this, the battery sole purpose is to keep those presets stored .
Hi, Guerrilla Studios! Great video. Have you ever some trouble, with the internal 3v battery? I'm very worry about leakage and maybe, it causes serious damages to the pcb. Thanks! Excuse my sloppy english. Cheers from Viamao City - Brazil 👊😃🎸🇧🇷
Thanks for your question. We've had this unit for ten years or so and not had a problem with the battery yet or even had to change it.
Hello again! Thanks for reply! Bought my unit about 3 years ago, and unfortunately don't know if the 3v internal battery, was replaced or not... I'll take care with my JMP-1 and gonna put my eyes on it, just in case... hehe. Thank you so much. Your videos are great! Cheers from Viamao City - Brazil👊😃🎸🇧🇷
Thankyou!
Hi mine today for the first time had a bit of crackly plus the low e string with lots of gain sounds fatty.. would you say I may need new valves. Was going to put it in the shop but I've had it for ages so the valves might be a cheaper option to check first . Where did you get yours from.. thanks. By the way the treble also had little effect when going up + and down -
I'd certainly try the valves first. If the output has inconsistent level and quality they're usually the culprit and the easiest thing to change. I've found the JMP to be a bit of a noisy unit anyway and always use a noise gate with it. The output pots can also get crackly. I order all my valves from Hotrox UK.
So no biasing on these?
You're all good to go with them no bias required with preamp tubes