Page 16 of Audio Catalog by Michael Percy Audio

tubes i carry a small selection of the most popular tubes in current manufacture from ram labs and a few n.o.s gold aero as well as an occasional other type or two neither of these companies are tube manufacturers as such both specialize in purchasing tubes in large quantities from various sources they believe to manufacture the best tube of a particular type then they test and match these tubes to a very high standard this process assures you of the lowest noise possible in their highest grade tubes as well as very close matching and extremely low gas for power tubes all backed by a 90 day warranty my primary stock is from ram labs as they offer the best pricing on graded tubes and gold aero is out of business a ram labs ln grade 6dj8 for example is typically the best one in ten a sln would perhaps be the best of a hundred tubes tested even their standard grade tubes are quieter than an average off the shelf tube you may find the same tube for less elsewhere but you have no guarantee as to its noise level and might have to purchase several to find a quiet one ram labs publishes a very informative white paper on the necessity of careful power tube matching even if you have individual bias for each tube copies on request triode ram labs twin triodes super low noise low noise standard 6dj8 50.00 25.00 16.95 10 20 db less microphonic than equivalent grade 6dj8 6922 59.00 34.00 16.95 12ax7 50.00 25.00 16.95 12au7 50.00 25.00 16.95 12at7 50.00 25.00 16.95 12bh7 41.95 33.50 25.00 5751 50.00 25.00 16.95 5965 50.00 25.00 16.95 6fq7 41.95 33.50 25.00 7044 33.50 25.00 5ar4 one grade $25.00 ram labs 6dj8 are being phased out so stock is limited replace with 6922 matched pair 6550 chinese ram 59.00 6550 sovtek gold aero 100.00 el-34 chinese ram 42.00 el-34 siemens ram 84.00 output tubes 5881 sylvania ram 78.00 6l6 chinese ram 50.00 6sn7 singles ram 21.50 6dj8 are mostly russian a few yugo all 6922 s are russian 12ax7/au7/at7 s are yugo other 7199 tubes that work in most dyna are hard to find specify instead the r-99 tube which is available with reusable adaptor for plug in replacement for the 7199 $50 w/adaptor $35 alone sln ln s grades reflect individual section grades of dual triodes the standard grade is a good choice for high level stages and cathode followers and is quieter than a typical ungraded tube if lowest possible noise is not required do not spend unecessarily on a higher grade tube ram matched pair power tubes are computer matched for bias current ±5 and transconductance ±10 to a very tight standard close matching under in circuit simulation at typical working voltages is essential for amplifiers even with ac balance and bias adjustment for each tube otherwise asymmetrical clipping and power loss may occur nos tubes philips usa 6922 industrial grade 6dj8 equivalent untested sold as is $6.95 ea amperex 6dj8 marked hewlett packard $6.95 each rca 7199 limited stock of hard to find tube markings on tube say made in germany while supplies last boxed untested sold as is $25.00 each tube sockets 9 pin miniature chassis mount figure #1 gold plated contacts in a white glazed ceramic base requires .725 chassis hole for top mounting with 1.125 spacing for mounting screws $5.95 each 10 deduct 10 25 deduct 25 9 9 9 7 pin pin pin pin miniature pc mount type gold plated contacts white glazed ceramic pins on .775 d hole pattern $5.95 each 10 less 10 25 less 25 miniature chassis mount unglazed ceramics with possibly silver plated eyelet lug contacts $2.95 10 less 10 25 less 25 shielded miniature chassis mount phenolic with tinned copper contacts and aluminum shield $3.50 each 10 less 10 25 less 25 miniature chassis mount top mount to fit 0.625 hole with 0.825 screw spacing silver plated contacts $4.95 each 10 less 10 25 less 25 #1 #2 5p uy 6p uz five pin and six chassis mount glazed ceramic sockets with silver plated contacts $6.50 each 10 less 10 25 less 25 octal chassis mount white glazed ceramic figure #2 with gold plated contacts mounts from underneath the chassis and requires 1.10 diameter chassis hole with mounting screw holes spaced on 1.5 centers $7.95 each 10 less 10 25 less 25 octal bottom mount high quality black celanex socket w/tinned phosphor bronze contacts $2.50 ea 10 less 10 25 less 25 300b sockets chassis mount white glazed ceramic ux4 bottom mount four pin ceramic figure #3 with gold plated contacts $8.95 each super premium tube sockets where only the very best in the world will do machined teflon or epoxy impregnated wood laminate 9 pin chassis mount octal ux4 and other types with removable gold plated machined phosphor bronze or silver plated brass contacts call for plate caps teflon insulated call for #3 a few other ceramic types with silver contacts available 7pmt 6puz 5puy ask for pearl tube coolers heat sinks for tubes in some circumstances particularly for amplifier power tubes these can greatly extend tube life along with the general destructive properties of high temperatures there is evidence that the tube glass envelope becomes somewhat porous at high temperatures allowing the penetration of air into the envelope which greatly hastens the tube deterioration coolers are available for a variety of octal and nine pin types the octal power tube coolers come in a standard psf and close spacing pcf type if your power tubes have less than 1.05 inch spacing between each glass envelope or less than .95 spacing between them and a nine pin type on which you have installed a cooler then specify the pcf close fitting style coolers the pcf close fitting coolers work with envelope spacing as close as .60 the 9 pin coolers will work with envelope spacing as close as .60 with the outer band removed or .85 with bands installed specify type carefully two bands are supplied for use with each standard fitting tube cooler they are not used with the close fitting types thereby allowing very tight spacing between tubes osf-8 msf/mpsf9 with carbon sleeve osf-8 fits octal small signal tubes 6sn7 6sl7 6bl7 6bx7 5691 5692 $5.95 ea psf-200 pcf-200 fits 2 d bottles $8.95 each psf-150 pcf-150 fits 1.5 d bottles $8.95 each psf-125 pcf-125 fits 1.25 bottles $8.95 each pcf-250 fits 2.5 d bottles 211 813 845 tubes $11.95 each msf-9 fits 9 pin small signal tubes 12ax7 12au7 12at7 6dj8 7199 $5.95 each mpsf-9 fits 9 pin power tubes 6bq5 6fq7 el84 7119 $5.95 each silicone tube dampers high temperature 450° f silicone rings which can be slipped over small triodes such as 6dj8 12ax7 etc to mitigate the microphonic properties of tubes these won t dry out and crack like the neoprene types two per tube will reduce vibrational feedback and reduce hysteresis distortion 60¢ each or ten pieces for $5.00 16

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