Likewise, their tendency to get shrill at maximum volumes can alienate players who expect fatter, darker tones when they dime the volume. But their low end can be too loose and unfocused for contemporary tastes. It’s easy to love their airy highs, cracking presence, and magnificent dynamic response. Let’s face it: Fender’s 1950s tweed models can be problematic for modern guitarists. It’s easily one of the best-sounding tweed-influenced amps I’ve ever encountered. By the second or third time the problem disappears and, sometimes, the real cause is exposed.Let’s invert this review and put the conclusion up front: The California Tweed, Mesa’s new take on old Fender amp circuits, is simply stunning. Any fewer than three and I remain unconvinced. My new MO is to ask the person reporting the problem to eliminate all other variables (nothing plugged in between the guitar and amp), try different guitars and cables, and confirm the issue THREE TIMES. Last 14 out of 15 customer "issues" turned out to be user error in testing/troubleshooting. I go through this with customers quite often. More likely, you're changing more than one thing at a time and blaming the wrong thing. Regardless of matching, there's no tube related reason that a pair of tubes will work one time and never again.unless you destroyed them the first time. There are lots of Ebay sellers who are uninformed about proper matching. In order to be matched, he should be testing "plate or cathode current" at a plate voltage near 400Volts. Sounds like the seller is convinced that the tubes are matched, but there's not enough information for us to conclude that. I guess what I'm saying is, while on paper, the best performing/efficient amp will be with a perfectly matched output pair, but there is something to be said about the tone of a slightly mismatched pair. Tough to really say what was the difference - certainly, a 70s pair of GE 6CA7s are arguably "better" than new production tubes, but I would not discount the lack of character (dare I say, hifi-edness?) of the perfectly matched tubes or the lack of punch (read as efficient performance?) with a widely mismatched set. WOW, what a difference - they had much more character than the JJs that were perfectly matched, and more punch and clarity when pushed up the dial (later break up) than the Rubys. They were not perfect, but much closer than the originals, maybe 2-3ma apart. Then I had an old pair of GE 6CA7s and dropped them in. The amp sounded fine - but seemed to have less "character" or "body" - tough to describe. Dropped them in and they were EXACTLY matched. (So much for the Ruby Tubes matching system!) However, I had other tubes I could use. The other was running about 30ma - about 53% PD. One tube was running hotter than the other - I placed that at about 68% PD - which is about 39ma (at the 1 ohm cathode resistor I put in). The tubes in the amp were a "matched pair" of Ruby E元4s (supposedly pretty new). Just the other day, I installed an adjustable bias circuit on the amp. Regarding mismatch in fixed bias on a Traynor YBA-1 fixed bias (adjustable) E元4/6CA7 output tube pair: (Or maybe the stronger tube can just pull more away - not sure.) So it seems that a weaker tube in a shared cathode resistor pair will "leave more current available" to a stronger tube on the other side. The amp sounded "best" with the new pair. And when I paired the weaker of the originals with the new tube, the new tube was over 100% while the old one drew even less. The new tube drew more current (close to 100%) and the old tube (originally drawing 92%) was now below 90%. But for "fun" I left one in (the 93%) and put in the "higher drawing" original tube in the other slot. I got a new matched pair of JJs and dropped them in and they were drawing 93% and 95% (which is workable). Nevertheless I didn't want such a mismatch. But when checking the tubes individually at the plates based on checking the voltage drop across the output transformer windings divided by the resistance, one tube was drawing about 92% max plate and the other was drawing only 45%! However, it really didn't sound awful - maybe too early of a breakup, but no real horror. Regarding mismatch in shared cathode bias - Ampeg Gemini with a pair of 7591s sharing a 140ohm cathode resistor:īased on checking the voltage drop across the shared resistor, it looked like the pair were drawing about 70% max plate voltage. (And how do we define close enough, though?) Here's some anecdotal/real data I can share as an observation on two amps I just worked on in the last month: Click to expand.Well that depends on what you define a "matched".
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