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JohnGeneva 26th March 2012 07:10 PM

Aikido LV 48V ECC99 or 6N6p
Hi, I am going to build an Aikido LV line amp from John B's circuit board, 48v version, which is suggested in the manual to use ECC99 tubes or 12BH7. The russian 6n6p is similar except for heater pinout I have been told. Is this an ok replacement and has anyone used these tubes in an Aikido LV ? They seem to be a lot cheaper than the ECC99 tubes.

If so how did they wire up the 6n6p to make the pinout fit. I understand the ECC99 has pin 4 5 heater with pin 9 center tap on the heater for 12.3v, and 6n69 has 4 and 5 heater for 6.3v. Any ideas or recommendations appreciated.

Thanks, John

Triodethom 26th March 2012 07:49 PM

If you look at the manual it uses 9a and 9aj based tubes the 6n6p uses the 9 pin for an internal shield between the the two section so just hook up the heaters in series and a large wattage resistor to drop the voltage to 24 volts or supply the heater bu then selves. that what will work. If you use the 6n27p John suggest the a 24 volt supply works and no need for voltage dropping res.

JohnGeneva 16th April 2012 08:49 PM

Thanks the note Triodethom, I now have received the pcb board of the Aikido lv which came in the mail today and see that power supply + goes through a 1 ohm resistor which John suggests for ECC99/(same resistor suggested for the 6n27p) then to terminal 4 of tubes, and return is via terminal 5 via all the heater circuits of the 4 tubes then which returns to ground. pin 9 does not seem to be connected anywhere on John's circuit board.

By following the traces on the PCB board, it looks like the heaters are hooked up in series on the pcb board, positive to pin 4 on the first tube, then pin 5 to pin 4 of the second tube, and so on to the last tube where pin 5 returns to earth. Will the fact that pin 9 of the ECC99 pin center tap is not hooked up to anything cause any problems? The heater circuit does not appear on John's schematic.

Since I am a strict beginner on a learning curve, and this will be my first completed tube project, does this mean that the 6n6p will be a direct plug in replacement. I already have a 48 v power supply so the 6n27p is not an option.

I already erronously ordered the 6n6p tubes from Ebay (they were advertized as a ECC99 replacement) but if you suggest they won't fit appropriately should I just go ahead and buy real ECC99 tubes?

Thanks any help with this beginner question. John

Triodethom 17th April 2012 03:10 AM

the ecc99 is a 12volt tube with a center tap so 12 +12+12+12 get to 48 . Well it 6+6 (pin 4 to 9 to 5 ) in each tube . The 6n6p is 6 (pin 4 to pin 5) thus 6+6+6+6 to 24 volts if you hook up a 24volt regulator in place of the resistor with a heat sink you can use the 6n6p tubes . the regulator is a lot cheaper than 4 ecc99 tubes about 1,5 to 2 euros for the reg and heatsink I would say or 2dollars south of the Masion Dixion line.

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