Building high-end 'tables cheap at Home Despot II

Although it's OK to replace a 12AX7 with a 5751, the 5751 is electrically slightly different, mostly in that it has a lower mu and slightly lower plate resistance than a 12AX7. And I am not sure the 5751 is inherently a lower noise tube compared to any 12AX7 variant (e.g., ECC83, etc.). The slight reduction in gain could reduce amplification of other sources of circuit noise and thereby give an impression of overall lower noise. Sonic differences you hear could be due to the differences in electrical parameters between the two tube types. But that's perfectly fine, of course.

Thanks Lew - I looked at the spec sheet. Amplification factor of 70 as opposed to 100 for the 12AX7. You are right, GE's spec sheet doesnt say anything about low-noise, the 5751 is for "rigorous duty", i.e., a missle tube. Nevertheless, on first impression, it does sound good.

Mike

Hi all, really busy right now so consider this a guerilla hit and then I have to run. Be back later to elaborate. Yep, that 5751 makes a world of difference, in the EAR 834P anyway. Considered a lower-noise tube than the 12AX7 even the reduced gain aside, and more accurate to boot. I wanna try it in my too-much-gain CJ PV-8 too, though there are risks, I'll leave the cover off and observe for any out-of-the-ordinary events, smoke, fire.

Now to the real news: I've just come up with a near-free HUGE and important improvement for the Lenco, as events at Rick's place (the floppy/drunken idler-wheel arm post), experimenting with Reinderspeter's top-plate and a recent rebuild of a Lenco and preparation of a Technics SP10 MKII all conspired to Show me The Way. Haha a teaser :-)!! Still listening right now, so I'll keep it under my hat until I know for sure.

On the speaker side, there's nothing in this world will touch a BIG horn-loaded speaker, now I've got those incredible Electro-Voice SERIOUSLY blowing me away (for Mario if he's watching: a 12TRXB (two-way dual-concentric) crossing over to a T25A horn-loaded midrange, with two L-pads. These speakers need a truly well-damped (over-damped?) room in order to perform with no nasties, but once that's done, there's nothing I've ever heard which will touch these: talk about TECHNICOLOR. Makes everything else sound anemic and tired. The best and tightest bass I've ever heard (and I mean LOW reach, tightness and the SLAM of George Frasier, if anyone remembers); a detail-meister; even the highs are rich and glorious (if not ultra-extended like angels squeaking)!! And talk about seductive RICHNESS, like drowning in an ocean (and I mean ocean, the sound envelops you so) of dark chocolate, but with with razor-sharp candy (transients) and explosives (dynamics to level the Rockies) inside. Those looking for a "vintage" system which will duke it out with the best of modern/current, look for these, or for the big Klipsches: next stop the Battle Royal between the Cornwalls and these particular E-Vs (whatever they are). But think shag carpeting, big fluffy couches, tons of crap lining the walls, suspended ceilings. Or you'll know what your tooth enamel is made of, or was made of. Maybe a couch, some books and a rug will do, I'm working on it. At my buddy's place (you guessed it: big fluffy couches, shag carpeting, tons of crap on the walls, suspended ceilings), simply the best I've ever heard, anywhere, ever. At least it doesn't take a carpenter and a gazillion bucks, just some bad taste, and a trip to the used furniture shop ;-). Speakers plus these furnishings, much less than any speaker which can stand in their shade :-).

Gotta go pack my car, I'm off on a trip for a few days looking for Templars in the Northern forests ;-). Have fun all!!

Jean, As you fade off into the sunset, did I hear you intimate that you are building/have built a plinth for an SP10? While I am no lover of the Heil tweeter, I've had a longstanding curiosity re those big EV (and JBL) horn-loaded spkrs of the 50s. I bet they're great.

Hi Jean,
Those EV triaxials must sound great! Originally matched for Aristocat enclosures - guess about 8+ cubic feet? Saw another pair of EV-16s down at my municipal re-use center @ $5 for the pair. Once again, no foam, no grilles and, little doubt, in need of cross-over rebuilds.
Now the 12” EV-16s three-ways with Danish mids and paper tweeters, are nowhere in the same league as the 12TRX/12TRXB, but I was simply astounded when they left my Rectilinears sounding tepid when stacked for easy A/B comparison.
Then something happened… they fell off completely. Not sure whether I used a couple of bad capacitors from a defective batch (Dayton “audio” grade) or I did something ruinous to the voice coils – but they're “get up and go” has “got up and left”. Hmmmm. Sometimes I wonder if these old paper cones are environmentally sensitive – temperature/humidity etc. Maybe they’re winter performers. In the meantime, I think I’ll take a pass on those orphans at re-use and look to step up into the EV/Horn combo.
A stab at your tease…. Bearing capture into the plinth?
All best,
- Mario