I just got myself a 1969 Vibrolux Reverb and I was wondering if the two 47K plate load resistors on the phase inverter, (instead of the usual 82K/100K arrangement) is anything to concern myself with?
The amp sounds fine IMHO but I've heard some people comment that these lower value plate load resistors on the PI is a bad thing. I just put in a fresh GZ34 and the amp is pretty loud and clean when the volume is set at 5 or so but going beyond 6 you start to get more dirt, which sounds about right for a VR.
Also there's a pair of 100K bias feed resistors instead of the typical 220K/220K, these are fed by a bias balance circuit. I added an extra 20K of resistance in series with the stock 15K bias resistor because I needed to up the bias voltage, everything sounds great, I was just wondering about those two PI 47K plate load resistors though.
Q: Blackfacing a '69 SF Vibrolux Reverb?
I just got myself a 1969 Vibrolux Reverb and I was wondering if the two 47K plate load resistors on the phase inverter, (instead of the usual 82K/100K arrangement) is anything to concern myself with?
The amp sounds fine IMHO but I've heard some people comment that these lower value plate load resistors on the PI is a bad thing. I just put in a fresh GZ34 and the amp is pretty loud and clean when the volume is set at 5 or so but going beyond 6 you start to get more dirt, which sounds about right for a VR.
Also there's a pair of 100K bias feed resistors instead of the typical 220K/220K, these are fed by a bias balance circuit. I added an extra 20K of resistance in series with the stock 15K bias resistor because I needed to up the bias voltage, everything sounds great, I was just wondering about those two PI 47K plate load resistors though.