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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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Tube DIY Asylum Do It Yourself (DIY) paradise for tube and SET project builders. |
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In Reply to: VT-25/10 SE Circuits posted by Cpwill on December 29, 2005 at 08:48:38:
Hi,Some general 10Y notes....
1) The high gain means there is less strain on the driver stage when operating in class A1, a single driverstage of even a 56/76 can work well, using the 425V/18mA datasheet operating point a 76 with inductive or CCS load can drive the 10Y from a standard CD Player, halve a 6SN7 etc might be used, this may be likely the only place in an audio circuit where I can see a use for a 6SN7. Downside, your lot of power is < 2W, so even a 45 outruns it in power terms.
2) Use Class A2 and you can push 3-4W from the 10Y and it gets VERY interesting.
The easiest circuit for Class A1 would be a 2K2 cathode resistor (bypass with 33uF MKT/MKP Capacitor) on the 10Y and a 10K primary impedance output transformer, gridleak resistor 220K and 0.1...0.22uF coupling Cap to taste, +B is around 470V @ 18mA for the output stage. Heater best 7.2V DC, probably regulated.
Input/Driver stage could be a 6SN7 (or relations like 6J5, ECC82 et al) with 1K (bypass with 33uF MKT/MKP Capacitor) cathode resistor and 27K anode load resistor and a 4K7 +B decoupling resistor with 10uF MKP decoupling Capacitor. This will give full Class A1 output with a 2V RMS input (standard CD Player output).
Driver stage consumes around 7mA, so for a monoblock you would need 470V/25mA or 50mA for stereo, almost any valve rectifier will handle that, so choose one you like. With near choke input (meaning very small value first capacitor after rectifier) a 400V-0-400V transformer at 50mA DC rating should be fine.
You need a pair of 6.3V heater at 3A or so each to heat the 10Y's with DC, you can tap the 6.3V for the 6SN7(s) off that and one 5V winding for the rectifier.
That should get you going with a nice small Amp.
Ciao T
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- Re: VT-25/10 SE Circuits - Thorsten 06:38:31 12/30/05 (0)
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