Hoffman Amplifiers Tube Amplifier Forum
Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: firemedic on March 12, 2013, 10:52:05 am
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New amp: Carvin XV-112E. 4-6L6GC output. The owner says some other amp guy told him it was OK to just pop in 4-EL34s. Which he did. Kind of a red flag.
He dropped off the amp 2 months ago or more & I don't remember off the top of my head what he said was the problem. The Delta Blues has kept me tied up for a couple of weeks....
My question is, does anyone here have experience with these Carvins? Can you do that with this iron?
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The answer is NO. I'm getting a heater voltage of 5.8VDC withe EL34s in. No bueno.
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I had a Carvin X100B head which I think is the same basic amplifier. It was biased from the factory for EL34 tubes but having said that I can't think of a single amp with fixed bias where 6L6 and EL34 would be a hot swap. Mine had no switch for multiple bias options. I would have had to swap a resistor to rebias for 6L6.
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For EL34 use, socket need a jumper between pins 1 and 8 Check that
6L6 have a internal jumper. Amp builder don't need to solder one on the socket if amp use only 6L6
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New amp: Carvin XV-112E. 4-6L6GC output. The owner says some other amp guy told him it was OK to just pop in 4-EL34s.
...
My question is, does anyone here have experience with these Carvins? Can you do that with this iron?
Ask Carvin.
I could only find a schematic for the XV-112 (not 112E). That schematic indicates 4x EL34's, but doesn't show connection for pin 1. It does indicate 6vac for the tube heaters. So even this doesn't seem to be a match.
... I don't remember off the top of my head what he said was the problem. ...
Might want to ask. And save yourself a headache by getting him to demonstrate the problem.
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XV112 ( not E ) here
www.el34world.com/charts/Schematics/files/carvin/CARVIN_X-AMP.pdf (http://www.el34world.com/charts/Schematics/files/carvin/CARVIN_X-AMP.pdf)
Manual ;
www.carvinguitars.com/manuals/X-AMP.pdf (http://www.carvinguitars.com/manuals/X-AMP.pdf)
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The head I had was an odd beast. The clean channel - which was almost entirely solid state - sounded really good. The OD channel - which was all tube - was only meh. I bought it for chump change on Craigslist and sold it for the same on CL a few months later.
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He says it stopped working altogether. It worked for me & sounded pretty good, albeit w/ scratchy pots. I cleaned & lubed the pots then checked the heater voltage, found it low. I pulled 2 output tubes and the voltage went back up to 6.5vac. The chassis is well labeled, and specifies 6L6GCs. Bada bing.
I told him to find 4 6L6s that he likes & get back with me-I don't have a matched quad laying around. Other than that, I think we're all done here.
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The early X amps were 6L6. They later switched to EL34. The transitional amps like the one I had were silk screened on the chassis for 6L6 but factory labeled for EL34. That's over 2 amps additional heater current. He's lucky he didn't pooch the 6.3VAC secondary.