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Top ebayer, good communication, fast shipping, good products. A+++ | May-02-11 01:13 | |
| NOS 6X4 EZ90 CV493 RECTIFIER 1960s for Audio Note |
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Historic TubeMuseum, Tuxedo Park, New York Established in 1928 as a premier research facility in Tuxedo Park, New York, that attracted such brilliant and most visionary minds of the twentieth century - Albert Einstein, Werner Heisenberg, James Franck, Niels Bohr and Enrico Fermi to name a few. The Tuxedo Park lab attracted these top-flight scientists who experimented with audio, sound, time measurement, and radar (first klystron tube). Welcome to the ...
Historic TubeMuseum, Tuxedo Park, New York
TubeMuseum
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fast shipping and greatest care packing ++ | Buyer: | Jun-15-09 10:25 |
) GET RID OF THAT CHINESE TUBE IN YOUR NEW AMP AND UPGRADE TO VINTAGE 1950's RCA!
THIS IS A SELECTED LOW NOISE TUBE SUITABLE FOR INTENSE AUDIOPHILE and MUSICAL INSTRUMENT AMPLIFIER APPLICATIONS
Beautiful 1950's NOS RCA 5R4-GY RECTIFIER tubes are out-of-production and very rare & high quality
NOS RCA USA 5R4-GY
Made in 1950's in the UNITED STATES
RARE HANGING-FILIMENT SQUARE-GETTER!
NOS TUBE MUSEUM QUALITY
Made in 1951 decades ago!
STAPLED BLACK PLATES
NOS RCA 5R4-GY "D"-Getter Rectifier
NOS 1950's RCA RECTIFIER TUBE
100% NOS in ORIGINAL BOX
CODE 1-48 for 1951 (see main pictures)
GET RID OF THOSE CHINESE tin-pin TUBES IN YOUR NEW AMP AND UPGRADE TO A RCA FROM 1951!
TEST BETTER THAN 100% NOS specs
Picture of the Actual Tube # 1 being tested with 412/412 matched voltage
RECTIFIERS ARE TESTED BY V (VOLTAGE) AND NOT BY GM OR mA, if you see a seller providing micro-mhos (GM) then stay away because that's NOT how rectifiers are tested! We see too much of these mistaken inaccurate test-claims on eBay!
Tested on the State-of-the-Art AMPLITREX AT-1000 Electron Tube Test System
The rectifier is not in the signal chain portion of the amp, and your guitar signal does not pass through the rectifier at any time. But this doesn’t mean that the rectifier has no impact on the sound of your amp. Preamp and output tubes perform differently at various voltage levels, so a rectifier that converts your power transformer’s 330 volts to 400 volts DC will result in your amp sounding a little different than it would with a rectifier that converts it to 350 volts. Rectifiers also have frequency sensitive internal impedances that cause voltage loss or “sag” when power demands are high. This affects the attack, compression, dynamics, and touch-sensitivity that any tube amp gives you, and is something players tend to notice most about how their rectifiers are performing—whether they know it or not. Tube rectifiers are four-pin devices that typically fit into octal (eight-pin) sockets. However, only four pins are connected internally— two that take in five volts AC from the power transformer to heat the filaments so the tube can function, and two that take in the high-voltage AC current for conversion. So where does our DC come out? Through one of the pins that is taking in the filament supply. Sounds impossible, I know, but one pole of the AC (which is bipolar, alternating current) can enter while the lonesome DC exits. Some nine-pin tube rectifiers also exist, such as the EZ81 that was used in the early Vox AC15 and Marshall 18-watter of the mid ’60s. Recently back in fashion, the EZ81 looks a little like an EL84 output tube, and fits into the same type of socket, although only four of its pins are connected internally. Some small early guitar amps also used sevenpin- socket rectifiers such as the 6X4 or 6X5 (again, with only four pins “live”), but these tubes aren’t very common today.
TUBE RECTIFIER TYPES
Different types of rectifier tubes provide different levels of AC-to-DC conversion. The most common small-amp rectifier tube is the 5Y3, as found in old Champs, tweed Deluxes, and many vintage Gibson amps. This tube works fine in small combos that put out anything up to about 15 watts, but when pushed hard it can start to sag noticeably— cool, in the right place, but potentially frustrating when you’re looking for punch and clarity. At the other end of the scale, the GZ34 (equivalent to the 5AR4 in the USA) has long been considered the king of the rectifier tubes. This powerful, sturdy rectifier tube makes more DC out of the AC it’s fed, and does so very elegantly and with great efficiency, while still inducing many of the most-loved characteristics of tube rectification into an amplifier’s performance. Show a tube amp freak a European-made Mullard GZ34 from the ’60s and watch ’em go weak in the knees and start scrounging around for the $150 or more to pay for it.
In between the 5Y3 and GZ34 are a number of rectifier tubes—such as the 5R4, 5U4GB, 5U4, and 5V4—which yield AC/DC conversion with ascending efficiency, and are generally found in mid-sized amps. Rectifier tubes can sometimes be swapped for a different type in cases when you find it preferable to run your tubes at slightly higher or lower voltages. Such a change should only be made, however, after consulting with your amp’s manufacturer or a qualified tech.
As with preamp and output tubes, different makes of the same type of rectifier tube—and even different examples that came off the line from the same factory on the same day—can perform their duties a little differently. By this I mean that if you obtained three NOS Mullard GZ34s or three Sovtek 5Y3GTs from the same year of manufacture, popped them into an appropriate amp one after another, and measured the DC voltages that each put out, you would find slight variances. Tube amp fanatics understand the need to obtain a range of good rectifier tubes and test them all in an amp to see which one makes it tick most sweetly. If you go to these lengths yourself and find a particular rectifier that your amplifier seems to groove on, it might even be worth “blueprinting” that stage of your amp by measuring the DC voltage coming out of the rectifier (often referred to as B+) and note it down for posterity. Just remember that a tube amp’s power supply voltages are potentially lethal, so have a qualified tech do this for you if you’re unfamiliar with the procedure and related safety issues!
Next time you need to change rectifiers, try a few until you find one that gets your amp sounding its best. Be aware, however, that even our more reliable domestic power today will vary from town to town, or even from one side of town to the other, or according to time of day, demands of the season, and other factors. Plugging the same amp, with the same rectifier, into a socket giving off 118 volts in Cleveland then another providing 124 volts in Cincinnati will result in different voltage levels within the amp. Finally, if you do swap your rectifier for one that produces a different DC voltage level within the amp, be aware that many fixedbias amps will need to have their output tubes rebiased, another job for a professional. Digest, tweak, and enjoy—the tonal rewards are worth it.
RECTIFIERS ARE TESTED BY V (VOLTAGE) AND NOT BY GM OR mA, if you see a seller providing micro-mhos (GM) then stay away because that's NOT how rectifiers are tested! We see too much of these mistaken inaccurate test-claims on eBay!
CERTIFIED ULTRA-LOW-NOISE SPECIMEN
THESE ARE THE "TOP USA MADE 5R4-GY TUBES"
TubeMuseum tested tubes takes the guesswork out of the process of selection delivering you the best Audio tubes that there possibly can be.
Top ebayer, good communication, fast shipping, good products. A+++
May-02-11 01:13
NOS 6X4 EZ90 CV493 RECTIFIER 1960s for Audio Note
Terms of Auction
Buyer pays all shipping, Item must be in original condition including cosmetic lettering on tubes so handle with white-glove care, un-used with all original boxes, packing material, environmentally safe cornstarch pellets, and shipping box. ALL RETURNS subject to a 10% handling charge. Absolutely NO RETURNS on special orders. All exchanges must be pre-paid and returned in original packing, complete with no sign of wear or abuse, exactly the same condition as it was when you received it. In the event that the product is not in the same condition as you received it, you may be subject to a refusal and return, a determined restocking fee, repair charge, or disqualification. RETURN AUTHORIZATION (RA) number and instructions is required before sending any items. Shipping and handling charges are non-refundable.
Visit this seller's eBay Store!
TubeMuseum
TubeMuseum tested tubes takes the guesswork out of the process of selection delivering you the best Audio tubes that there possibly can be.
Top ebayer, good communication, fast shipping, good products. A+++
May-02-11 01:13
NOS 6X4 EZ90 CV493 RECTIFIER 1960s for Audio Note
Terms of Auction
Buyer pays all shipping, Item must be in original condition including cosmetic lettering on tubes so handle with white-glove care, un-used with all original boxes, packing material, environmentally safe cornstarch pellets, and shipping box. ALL RETURNS subject to a 10% handling charge. Absolutely NO RETURNS on special orders. All exchanges must be pre-paid and returned in original packing, complete with no sign of wear or abuse, exactly the same condition as it was when you received it. In the event that the product is not in the same condition as you received it, you may be subject to a refusal and return, a determined restocking fee, repair charge, or disqualification. RETURN AUTHORIZATION (RA) number and instructions is required before sending any items. Shipping and handling charges are non-refundable.
Visit this seller's eBay Store!
TubeMuseum
TubeMuseum