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Old 2nd April 2008, 04:26 AM   #11
John L is offline John L  United States
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Thanks for the information.
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Old 13th April 2008, 07:57 PM   #12
coresta is offline coresta  France
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Hi ! A rainy day ... but not lost : i finished a pair of 307A SE ... wooww on my A5 VOTs . Stay tuned for more pics
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Old 14th April 2008, 09:43 AM   #13
coresta is offline coresta  France
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Hello , here is the first picture .
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File Type: jpg 307adnimg_0002 [640x480].jpg (74.0 KB, 1133 views)
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Old 14th April 2008, 09:44 AM   #14
coresta is offline coresta  France
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and from upper side
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File Type: jpg 307dowimg_0001 [640x480].jpg (49.3 KB, 1154 views)
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Old 14th April 2008, 01:36 PM   #15
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@coresta

nice

can you share schematic and more info ?

I'm really interested in your experience with that bottle ......
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Old 14th April 2008, 06:41 PM   #16
coresta is offline coresta  France
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Hello , yes , i'll scan the schematic in a few days : i still have a low hum (on 515 woofers ..) but would like to cancel it . I operate them with 300/0/300 PT / 5R4WG /2x2uF polypro /10Hys /32 uF . There is 325volts on the OT (3,3k primary ) and G2 is tied to A with 47ohms WW. G2 to the center of a 30ohms pot to 750ohms WW (+47uF 63volts) to GND. Heater is fed through 2 WW 0,39ohms resistors to the 6,3Vac . Grid leak res : 255k MF . The red block is a coupling silver mica capacitor 22nF /500v . The input tube : A 10k decoulping resistors goes to 32uF to feed a 6C6 with 80k MF in anode , g2 : 900K MF /0,22uF and Rk : 1,21k MF //47uF tantalum . The Ammeter in cathode goes to 45mA . Silver teflon wiring and iron plate Sound is astonishing for such a low power of 6 watts. Smoth and grainy . Bass is ... good , not so hard as with my 50W OTLs but they would perform for driving a 299/805 combo ! I've build a pair and will modify them for a 423C gas regulator in the 6C6 screen grid . As Tubelabe says , the 307As are worth the effort for the 15 Euros each i found them
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Old 14th April 2008, 10:31 PM   #17
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For those in the US, AES has them for $11.50.
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Old 14th April 2008, 10:35 PM   #18
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tubelad, do you know offhand, or have an estimate, what Rp and mu are for these when triode strapped?
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Old 14th April 2008, 10:36 PM   #19
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Just called AES... they do not have any in stock....
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Old 14th April 2008, 10:44 PM   #20
Zen Mod is offline Zen Mod  Serbia
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Quote:
Originally posted by dsavitsk
tubelad, do you know offhand, or have an estimate, what Rp and mu are for these when triode strapped?

look at graph in post No.3
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