- Posted by bcherry (M) on May 26, 2008 at 01:28:13
picture as shown. Each module is slightly bigger than a credit card, and two modules are needed for a stereo push pull amplifier (one module for each push pull pair of power tubes)
installation is pretty simple:
the module circuit is driven by an AC voltage of between 6.3 to 15 V which can be taken from the AC heater supply of the power tube. current draw is about 60 to 100 milliamps. Connect to 4/5 of terminal block
Then the negative DC bias supply voltage is disconnected from the bias pot and reconnected to the indicated position 1.
position 3 connects to ground between the two cathode resistors.
Position 2 is unused and reserved for a future function.
Cathode 1 and cathode 2 connect to their respective power tube cathodes (typically pin 8)
bias 1 and bias 2 connect to where the bias pot used to output bias voltage.
Bias pot is disconnected.Eliminates need for constant re-adjustment of Bias to compensate for mains variations and valve aging
Regulation of cathode current of tubes from around 1mA to 250mA with10R cathode resistor current match between halves depends on cathode resistor tolerance ± 1% due to circuit (typical mismatch << 0.1mA). Perfect current balance produces better bass
Current regulation is not influenced by music signal
Current set by standard 1/4W leaded resistor (exchangeable)
Current can be adjusted from 0mA to 90mA per tube if a 10K Pot is connected instead of the resistor
reduces noise on bias supply by at least 40db (100 times) so even the most basic bias supplies sound good. Lower noise improves resolution and imaging
Turn on Delay of 45 Seconds
Slow ramp up of current over a further 45 Second
Fault Indication via LED's (Red) on PCB; they can be re-mounted on the Amplifier chassis
Fault Indication via TTL compatible open collector output (can be used for additional protection circuitry or for our upcoming electronic choke PSU PCB)
multiple mounting holes for easy mounting
Can be fitted to any existing fixed bias equipped Amplifier without changing the original circuit and with absolutely minimal modifications, except bias potentiometers (and possibly cathode resistor changes)
Small size due to use of existing supplies already present in your amplifier
No high voltage connections are requiredwill post prices and availability within the next couple of days.
Regards
Brian
Take control! DIY.
Edits: 06/02/08
