USAPatriot
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- Joined
- Mar 22, 2014
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I couldn't pass this up at $279! I keep an eye of the CL ads here in Texas and it's virtually impossible to get even a used tube amp for under $300, so at $120 off, this was a steal, brand new from Musician's Friend as one of their "Stupid Deal of the Day" sales.
I cracked it open, replaced the chinese tubes in V1 and V2 with Marshall branded 12AX7's then rigged up a speaker cable so I could hook up my loose 70/80 to check the PV and bias. The PV was settled in at 340V after 30 minutes while the bias was a very chilly 16.6mv, which I boosted up to 24.1mv. Jet City changed the vertical variable resistor design so it can only be adjusted from inside the device versus the old style where you could move it with a thumbnail. The tolex is also black, which surprised me. My original JCA22H from late 2011 or early 2012 was blue. I think the black suits it better. Also, in the original version, I could check the bias by putting my probes on the solder joints where the 2 purple wires attach to the PCB (and labeled "bias"). Or I could use the TP (test point) below and between V6 and V7. Neither method works anymore. I had to put my probes on R52 to get a direct reading in mV. According to the Weber Bias Calculator, I'm getting 7W per tube, which are chinese EL84's. I have a spare set of EH's but they won't be much better.
These amps aren't the bee's knees, but they aren't awful either, in fact, they are quite good. With no reverb on board they can sound a little sterile and the chinese preamp tubes aren't the best choice. Had I thought about it I would have added another Marshall tube in the PI slot, or maybe a JJ or Tungsol. I spaced it and closed it up with the chinese tubes still populating V3, 4 and 5.
I don't have a cab to run this through so will have to piggyback it on top of my DSL40C and use it's speaker, which is on the agenda for tomorrow.
Question! Can I simply attach a second set of leads to the terminals on the V-30 in my 40C's cab and just switch back and forth as needed? Or leave them both plugged in? I obviously won't try to run them both at once! -Rod-
Check the bias at the pink resistor!
Porno!
I cracked it open, replaced the chinese tubes in V1 and V2 with Marshall branded 12AX7's then rigged up a speaker cable so I could hook up my loose 70/80 to check the PV and bias. The PV was settled in at 340V after 30 minutes while the bias was a very chilly 16.6mv, which I boosted up to 24.1mv. Jet City changed the vertical variable resistor design so it can only be adjusted from inside the device versus the old style where you could move it with a thumbnail. The tolex is also black, which surprised me. My original JCA22H from late 2011 or early 2012 was blue. I think the black suits it better. Also, in the original version, I could check the bias by putting my probes on the solder joints where the 2 purple wires attach to the PCB (and labeled "bias"). Or I could use the TP (test point) below and between V6 and V7. Neither method works anymore. I had to put my probes on R52 to get a direct reading in mV. According to the Weber Bias Calculator, I'm getting 7W per tube, which are chinese EL84's. I have a spare set of EH's but they won't be much better.
These amps aren't the bee's knees, but they aren't awful either, in fact, they are quite good. With no reverb on board they can sound a little sterile and the chinese preamp tubes aren't the best choice. Had I thought about it I would have added another Marshall tube in the PI slot, or maybe a JJ or Tungsol. I spaced it and closed it up with the chinese tubes still populating V3, 4 and 5.
I don't have a cab to run this through so will have to piggyback it on top of my DSL40C and use it's speaker, which is on the agenda for tomorrow.
Question! Can I simply attach a second set of leads to the terminals on the V-30 in my 40C's cab and just switch back and forth as needed? Or leave them both plugged in? I obviously won't try to run them both at once! -Rod-

Check the bias at the pink resistor!

Porno!
