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#1
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6eu7 or 12ax7? what to to use...
Hi all -
I'm still trying to figure out what to build for a RIAA section, and, while some claim that 12ax7 is a non-starter, it seems like quite a starter to me. Here's a (possibly) stupid question - I've got a pile of mullard 6eu7's, and the specs look suspiciously like 12ax7, except for the pinout & a claim that the pinout (and presumably the twisted fils) make EU a better choice (GE data sheet). I know that 12ax7Axxx's have twisted fils, but does anyone have any experience with EU's? This is a really tight layout, and the pinout certainly works better for me (heater pins at 1&2 right next to each other, isolated by the empty pin 3, which could be used as a nice hanging point for either HT or ground... Any thoughts? -dim |
#2
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"shiva" said:
Hi all - I'm still trying to figure out what to build for a RIAA section, and, while some claim that 12ax7 is a non-starter, it seems like quite a starter to me. Here's a (possibly) stupid question - I've got a pile of mullard 6eu7's, and the specs look suspiciously like 12ax7, except for the pinout & a claim that the pinout (and presumably the twisted fils) make EU a better choice (GE data sheet). I know that 12ax7Axxx's have twisted fils, but does anyone have any experience with EU's? This is a really tight layout, and the pinout certainly works better for me (heater pins at 1&2 right next to each other, isolated by the empty pin 3, which could be used as a nice hanging point for either HT or ground... Any thoughts? Dunno about 6EU7, but I subbed the CV4004 (a 12AX variety) for 6072 and ended up with substantially less noise, slightly lower gain but far better sound overall. The design is CC, passive RIAA and again CC. BTW twisted filaments? Surely you do use DC on the heaters in this app, so that won't matter at all? -- Sander de Waal " SOA of a KT88? Sufficient. " |
#3
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"shiva" wrote in message news:6lnYd.752$db6.365@trndny02... Hi all - I'm still trying to figure out what to build for a RIAA section, and, while some claim that 12ax7 is a non-starter, it seems like quite a starter to me. Here's a (possibly) stupid question - I've got a pile of mullard 6eu7's, and the specs look suspiciously like 12ax7, except for the pinout & a claim that the pinout (and presumably the twisted fils) make EU a better choice (GE data sheet). I know that 12ax7Axxx's have twisted fils, but does anyone have any experience with EU's? This is a really tight layout, and the pinout certainly works better for me (heater pins at 1&2 right next to each other, isolated by the empty pin 3, which could be used as a nice hanging point for either HT or ground... Any thoughts? -dim Nearly the same (some say exactly) tube, so go ahead, and those Mullards can stop loafing in the tube caddy. The only disadvantage I can think of is that there is no sub for a 6EU7. If later you want to used something of the 12A?7 varitey, you'll need to rewire. The nice thing about the 12A?7 family is that you can experiment with relative gain and adjust to your ears. Sometimes going down a notch to a 12AT7 is just the right thing to do. Otherwise, not much difference between 12AX7A and 6EU7. Convenience is as good a reason as any to use the 6EU7. Having idle Mullards is another good reason. |
#4
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On Fri, 11 Mar 2005 20:38:26 +0000, shiva wrote:
Hi all - I'm still trying to figure out what to build for a RIAA section, and, while some claim that 12ax7 is a non-starter, it seems like quite a starter to me. Here's a (possibly) stupid question - I've got a pile of mullard 6eu7's, and the specs look suspiciously like 12ax7, except for the pinout & a claim that the pinout (and presumably the twisted fils) make EU a better choice (GE data sheet). I know that 12ax7Axxx's have twisted fils, but does anyone have any experience with EU's? Internally 6EU7 is the same as 12AX7 except for the filament connections. Externally, 6EU7 was pinned differently so it wouldn't pick up as much hum when it was run on AC filaments (that was the sales talking point of the whole exercise). Assuming you are running the tubes on DC filaments, you can use either one (taking the different pinout into account, of course), in the same circuit. -- Ned Carlson Triode Electronics Chicago,IL USA www.triodeelectronics.com |
#5
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"Ned Carlson" wrote in message news On Fri, 11 Mar 2005 20:38:26 +0000, shiva wrote: Hi all - I'm still trying to figure out what to build for a RIAA section, and, while some claim that 12ax7 is a non-starter, it seems like quite a starter to me. Here's a (possibly) stupid question - I've got a pile of mullard 6eu7's, and the specs look suspiciously like 12ax7, except for the pinout & a claim that the pinout (and presumably the twisted fils) make EU a better choice (GE data sheet). I know that 12ax7Axxx's have twisted fils, but does anyone have any experience with EU's? Internally 6EU7 is the same as 12AX7 except for the filament connections. Externally, 6EU7 was pinned differently so it wouldn't pick up as much hum when it was run on AC filaments (that was the sales talking point of the whole exercise). Assuming you are running the tubes on DC filaments, you can use either one (taking the different pinout into account, of course), in the same circuit. Thanks Ned. Haven't ordered from you in a while - do you have any recommendations (or have in stock) any odd (russian?) output tubes (triodes, pentodes, any plate dis. / any basing) which are cheap & fun to design around? (I've given up on 807 / 6bg6 /8068's etc - the whole top-hat thing is more of a pain at sub - 700V plate voltage). I don't care if it's not a replenishable batch - this is strictly for one-off hobby projects. BTW, ever heard of Oliver amps? I've got one for the tyranies & the GZ34, it's made in Westbury, NY, and mine looks like some "wizard" was at it - this thing's full of 6eu7's, too. I know you collect schematics - I've drawn out the 2 PC boards & the tone /vol circuits, didn't bother with the PS 'cos it looked like it was designed by an idiot, and added later. If you know where i can download the schematics - i'd love to. If they don't exist, I can send you my partials (everything but the PS, , I can even *draft* them out & send a layout / PC drawings... Also, was the Stancor A-8053 the original OT? Thanks. -dim (with too many questions) |
#6
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BTW there's a cheaper substitute for 6EU7, which is the Russian 6N2P, but if
You have some Mullards ... Ciao Fabio "shiva" ha scritto nel messaggio news:4MEZd.5414$b_6.2248@trnddc01... "Ned Carlson" wrote in message news On Fri, 11 Mar 2005 20:38:26 +0000, shiva wrote: Hi all - I'm still trying to figure out what to build for a RIAA section, and, while some claim that 12ax7 is a non-starter, it seems like quite a starter to me. Here's a (possibly) stupid question - I've got a pile of mullard 6eu7's, and the specs look suspiciously like 12ax7, except for the pinout & a claim that the pinout (and presumably the twisted fils) make EU a better choice (GE data sheet). I know that 12ax7Axxx's have twisted fils, but does anyone have any experience with EU's? Internally 6EU7 is the same as 12AX7 except for the filament connections. Externally, 6EU7 was pinned differently so it wouldn't pick up as much hum when it was run on AC filaments (that was the sales talking point of the whole exercise). Assuming you are running the tubes on DC filaments, you can use either one (taking the different pinout into account, of course), in the same circuit. Thanks Ned. Haven't ordered from you in a while - do you have any recommendations (or have in stock) any odd (russian?) output tubes (triodes, pentodes, any plate dis. / any basing) which are cheap & fun to design around? (I've given up on 807 / 6bg6 /8068's etc - the whole top-hat thing is more of a pain at sub - 700V plate voltage). I don't care if it's not a replenishable batch - this is strictly for one-off hobby projects. BTW, ever heard of Oliver amps? I've got one for the tyranies & the GZ34, it's made in Westbury, NY, and mine looks like some "wizard" was at it - this thing's full of 6eu7's, too. I know you collect schematics - I've drawn out the 2 PC boards & the tone /vol circuits, didn't bother with the PS 'cos it looked like it was designed by an idiot, and added later. If you know where i can download the schematics - i'd love to. If they don't exist, I can send you my partials (everything but the PS, , I can even *draft* them out & send a layout / PC drawings... Also, was the Stancor A-8053 the original OT? Thanks. -dim (with too many questions) |
#7
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"Fabio Berutti" wrote in message ... BTW there's a cheaper substitute for 6EU7, which is the Russian 6N2P, but if You have some Mullards ... Ciao Fabio I remember some company re-basing AX7's with a chunk of PC board & cut off pins... I think I still have one, along with a ugo 12AX7 which tests well & glows orange... -dim |
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