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  #11  
Old 07-20-2012, 08:57 AM
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Originally Posted by jdandy View Post
Ivan.......It is true that a 12AX7 has a published gain of 100, while the 12AT7 has a published gain of 60 to 70. Transconductance is quite a bit different between the two tubes, as well.

The 12AX7 has a transconductance spec of 1600 when new, where a 12AT7 has a transconductance spec of 5000 or more. Although the two different tubes will operate with the same pin configurations, they are quite different, ultimately impacting distortion specifications. Whether it is a driver circuit or an inverter circuit, I would only use the proper tube for the circuit in which it was designed to be operated.
Very good DAN w/2 comments. As detailed in the tube bible (Essential Characteristics , General Electric) the 12AT7 gain is 70 and the transconductance of the 12AT7 is 5,500 & 4,000; whereas the 12AX7's is 1,250 and 1,600.

Now, on the transconductance numbers, it really depends on the type of tube tester one uses & not sure what type the folks at GE who published the bible used to obtain those numbers.

When you & I (and Rodney) visited and we tested tubes, you probably recall my test set registered some high figures. Not that it was defective, but the test set manual even stated to expect a range from x-y as we recorded.

Probably a good thing about the bible is that it is consistant throughout in it's transconductance numbers of the various tubes.

Best

Bob
__________________
Amps:VAC 450iQ Monos in Silver Flake on HRS M3X2-1921's, HRS G7 Footers/G-Links & Sound Anchor Conecoasters.
Preamp:VAC Statement (on order) (Silver Flake)
Digital Source: dCS Rossini CD/SACD Transport, Vivaldi APEX DAC, Upsampler Plus & matching Clock (Silver)
Analogue Preamp:VAC Renaissance SE Phono stage in Silver Flake with XLR Output Option & with Nordost Valhalla XLR's.
Analogue Sources:SME 20/2 w/SME V arm & Nordost Odin 2 Tone Arm Cable, Palo Santos Presentation Cartridge & Akai GX-400D Reel-to-Reel w/relapped heads by JRF Magnetic Sciences. Akai RC-17 cabled remote (original owner since 1974).
Vibration Control:TT on HRS M3X2-1921 shelf.
Speakers:Wilson Audio Alexia V (on order in Ferrari Argento Silver/Parchment grills sitting on Acoustic Diode Kit).
Power Cables:4 Nordost Odin Supreme Reference on amps, preamp & DAC. Ansuz Acoustics C2 on Transport & Clock.
Power Distribution:Ansuz Mainz D3 Distributor & Ansuz Mainz C2 1M Power Cable
Power Outlets:Furutech GTX-D NCF (R) duplex outlet, GTX Wall Plate & Duplex Cover (x2) on dedicated, same panel phase, 20A breakers.
Speaker Cables:2M Nordost Odin 2 Supreme Reference on Nordost Sort Lifts.
Signal Cables:Nordost Odin XLR's on dCS DAC & Amps.
Digital Cables: Nordost Odin 2's, 110-ohm AES/EBU on dCS Transport to DAC.
Clock Cables:5 each 75 ohm 1.25M Nordost Valhalla BNC/BNC Digital
Ethernet Cable: WireWorld Platinum 1M Starlight® 8 Twinax
Headphones:Vintage Koss Pro IV AA.
RCM: Audio Desk PRO
Tube Test Gear:Mint late '60's/calibrated Heathkit TT-1A, MaxiMatcher Power Amp & Preamp & Space Tech Labs ATT-3.02 tube test sets.
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  #12  
Old 07-20-2012, 10:10 AM
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Bob.......Thanks for the additional information. I wish I had a tube tester like yours. either one of them.
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STUDIO - McIntosh C1000C/P, MC2301 (2), MR88, Aurender N10, Esoteric K-01X, Shunyata Sigma spdif digital cable, Sonos Connect, PurePower 2000, Stillpoints, Furutech Flux 50, Michell Gyro SE, Michell HR Power Supply, SME 309, Ortofon Cadenza Black, Wireworld, Sonus faber Amati Anniversario
LIVING ROOM - McIntosh C2300, MC75 (2), MR85, Magnum Dynalab 205, Simaudio MOON Neo 260D-T, Schiit Audio Yggdrasil, Aurender N100H, Shunyata Sigma USB cable, Micro Seiki DD40, Ortofon Cadenza Blue, Nakamichi BX-300, Sony 60ES DAT, PS Audio P10, Furutech Flux 50, Sonos Connect, Stillpoints, Wireworld, Kimber, PMC EB1i, JL Audio f113
VINTAGE - McIntosh MA230, Tandberg 3011A tuner, Olive 04HD, Sony DTC-59ES DAT, McIntosh 4300V, JBL 4312A
Last edited by jdandy; 07-20-2012 at 11:40 AM.
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  #13  
Old 07-20-2012, 02:46 PM
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Originally Posted by jdandy View Post
Bob.......Thanks for the additional information. I wish I had a tube tester like yours. either one of them.
I'm still looking for one for you Dan. Have been for quite some time.

Again, thanks for the memorable visit. It's still fresh.

Bob
__________________
Amps:VAC 450iQ Monos in Silver Flake on HRS M3X2-1921's, HRS G7 Footers/G-Links & Sound Anchor Conecoasters.
Preamp:VAC Statement (on order) (Silver Flake)
Digital Source: dCS Rossini CD/SACD Transport, Vivaldi APEX DAC, Upsampler Plus & matching Clock (Silver)
Analogue Preamp:VAC Renaissance SE Phono stage in Silver Flake with XLR Output Option & with Nordost Valhalla XLR's.
Analogue Sources:SME 20/2 w/SME V arm & Nordost Odin 2 Tone Arm Cable, Palo Santos Presentation Cartridge & Akai GX-400D Reel-to-Reel w/relapped heads by JRF Magnetic Sciences. Akai RC-17 cabled remote (original owner since 1974).
Vibration Control:TT on HRS M3X2-1921 shelf.
Speakers:Wilson Audio Alexia V (on order in Ferrari Argento Silver/Parchment grills sitting on Acoustic Diode Kit).
Power Cables:4 Nordost Odin Supreme Reference on amps, preamp & DAC. Ansuz Acoustics C2 on Transport & Clock.
Power Distribution:Ansuz Mainz D3 Distributor & Ansuz Mainz C2 1M Power Cable
Power Outlets:Furutech GTX-D NCF (R) duplex outlet, GTX Wall Plate & Duplex Cover (x2) on dedicated, same panel phase, 20A breakers.
Speaker Cables:2M Nordost Odin 2 Supreme Reference on Nordost Sort Lifts.
Signal Cables:Nordost Odin XLR's on dCS DAC & Amps.
Digital Cables: Nordost Odin 2's, 110-ohm AES/EBU on dCS Transport to DAC.
Clock Cables:5 each 75 ohm 1.25M Nordost Valhalla BNC/BNC Digital
Ethernet Cable: WireWorld Platinum 1M Starlight® 8 Twinax
Headphones:Vintage Koss Pro IV AA.
RCM: Audio Desk PRO
Tube Test Gear:Mint late '60's/calibrated Heathkit TT-1A, MaxiMatcher Power Amp & Preamp & Space Tech Labs ATT-3.02 tube test sets.
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  #14  
Old 07-20-2012, 03:39 PM
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Originally Posted by vintage_tube View Post
I'm still looking for one for you Dan. Have been for quite some time.

Again, thanks for the memorable visit. It's still fresh.
Bob.......I enjoyed your visit. You are welcome to stop by again if you find yourself in the area.
__________________
Dan



STUDIO - McIntosh C1000C/P, MC2301 (2), MR88, Aurender N10, Esoteric K-01X, Shunyata Sigma spdif digital cable, Sonos Connect, PurePower 2000, Stillpoints, Furutech Flux 50, Michell Gyro SE, Michell HR Power Supply, SME 309, Ortofon Cadenza Black, Wireworld, Sonus faber Amati Anniversario
LIVING ROOM - McIntosh C2300, MC75 (2), MR85, Magnum Dynalab 205, Simaudio MOON Neo 260D-T, Schiit Audio Yggdrasil, Aurender N100H, Shunyata Sigma USB cable, Micro Seiki DD40, Ortofon Cadenza Blue, Nakamichi BX-300, Sony 60ES DAT, PS Audio P10, Furutech Flux 50, Sonos Connect, Stillpoints, Wireworld, Kimber, PMC EB1i, JL Audio f113
VINTAGE - McIntosh MA230, Tandberg 3011A tuner, Olive 04HD, Sony DTC-59ES DAT, McIntosh 4300V, JBL 4312A
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