| Author | Message | ||
| Gary H. |
I just received my RP 112-sixty-five today. It appears to have a brand new set of EL34WXT's in it. The tube chart is missing, and there is no indication of tube type on the chassis. I have never seen one of the phas0r models that has EL34's, they all have been 6L6 models. This seems to be an earlier one though, because it doesn't have the pull-stop on the phasor. It has the darker logo. Does anybody know if these are correct? Thanks for the help! | ||
| Barry Marie |
I have an RD 112-100 with EL34 tubes. My logo also has the black background. According to other postings I have read on this site, the earlier model RD and RP's have EL34 tubes (approx pre 1979) with black logo background. The later models had 6L6 tubes (apparently EL34's were hard to get) and the the logo color was reversed. Hope this helps. Check some of the archive postings for more info. | ||
| Anonymous |
hi, please correct me, but I thought the amps with the black-background-logo are the newer models? I own an 212 HD One-thirty which I dated to 1976 by the date-codes on the speakers and the transformers. And it has got the black writing on bright background logo. The history on the main page doesn't bring clarity as it only says that the logo colors got inverted, but not what it was before. best regards, Vito. | ||
| Steve Kennedy |
The pre-1980 models have badges with a Silver background and the raised artwork/lettering is painted black. Those models made from 1980-84 had the reverse color scheme... black background with the raised art/lettering sanded/brushed to reveal the underlying aluminum that the badges were cast with. There is always the possibility of a few "stragglers" either way, where a 1979 model had the newer black badges or they hadn't yet run out of the old ones on certain models so the badge change didn't happen until later. These colors and dates are based on equipment that appears in Music Man catalogs. As we all know, some realities are a bit different! | ||
| J.D. |
I have a 74 212HD-130, recently a friend who has serviced my amps for years put in 4 6l6GC tubes when it came time for replacement, so far I've had no problems with it, what are some problems to look for, if these are not the right tubes? I just picked the amp up about a month ago for a great price, and I love the tone I'm getting, but the tubes are a concern. J.D. | ||
| Marc |
"...recently a FRIEND who has serviced my amps for YEARS put in 4 6l6GC tubes when it came time for replacement,..." WHAT a bone-smoker of a question. WHAT, you stiffed this guy $$$$ or boinked his wife and now you're paranoid?! When you sit to pee do visions of big snakes slithering up your wazoo come to that pin head of yours? Get back in the woodshed ya _____________. Ha ha. | ||
| J.D. |
Thank you for your reply, but you did not answer my question. Up until recently, I've only played through solid state amplifiers, this is my first tube amp. If modifications do need to be made to use 6l6 tubes, what are they? J.D. | ||
| Steve Kennedy |
If you look at the 6L6 and EL34 versions of the same basic amplifier designs from Music Man, you will notice one thing... the circuitry is virtually identical! The ONE thing that IS a potential concern is going the reverse direction...taking an amp designed for 6L6 types and substituting EL34s. The EL34 tubes require about TWICE the heater current, so you can burn up a marginal heater winding in a power transformer if it was originally only specified for a 6L6 output. Outside of some minor pinout difference (associated with pin 1 I seem to recall), a properly biased 6L6 should theoretically be happy in an amp originally designed for EL34s. This is my somewhat educated take on it unless someone else can quote technical specifics to the contrary. | ||
| J.D. |
Thank you for the info Steve, I really appreciate it, now I don't have to wonder if I'm gonna burn something up during a gig. I play 4-5 nights a week, and I really depend on my equiptment. I've got a peavey for a back up, but it doesn't compare. | ||
| Terry |
If you have the 12AX7 tube then you need 6CA7/EL34! If not then you will have to look is in side the amp at the resistors on the power tubes. | ||
| aussie |
i understand the 12ax7 is for the phase inverter but; 1) what is a phase invertor and; 2) can u use a 12aU7 to reduce gain? | ||
| langley. |
The phase inverter splits the pre-amped signal for the power tubes to act on. The phase inverter doesn't act on gain. Do not use a 12AU7 in place of the 12AX7. |
Tue, 03/25/2014 - 09:56
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