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Hi,
I built a set of the original Billie monos back in 2002. Haven't used them in a few years but just put them back in the system. The sound was pinched and not as good as I remembered them being so I opened them up for a look at what might be wrong.
I measured voltages and found...
Out of the wall: 126v AC
At GZ34: 447v AC (rectifier not in socket power transformer wired for 120v))
The AC side is a bit high, but not too bad.
On the DC side:
GZ34 output: 520v Dc
After 8h choke: 511v DC
After dropping resistor feeding 6SL7: 345v DC
At pin 2 of 300B: 505v DC
At front of cathode resistor: 85v DC
The 82 ohm resistor from the GZ34 to the first capacitor stage measures 84ohms.
The choke measures 78 ohms.
The power supply transformer measures around 85 ohms.
All measurements taken with the circuit around the part being measured open.
Anyone know what might be going on?
Thanks,
Maybe try trimming back voltages overall by 10%.
Maybe there is an extra tap on the primary.
Also we always find equipment that sits unused for a long time sounds thin when first used again. Especially if there are Blackgates somewhere in the ps or across the cathode.
regards
Brian
DIY - Done Right!
The DC was measured with all tubes in sockets and 8 ohm speakers connected.
Thanks,
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