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Title: Prinzetone hum problem Post by: Sam Slick on September 01, 2014, 02:51:37 AM I built a Prizetone kit with Larger Classic Tone transformers. The PT is a 40-18016 and the OT is a 40-18090. The amp has a hum. The hum is always there and increases when I roll back the guitar volume. The volume of the hum also increases as I change the volume knob of the amp. The hum increases with the tweed switch on (as you would expect). So far I have tried swapping tubes, different speaker cabs, different guitars, different outlets, all with the same result. I also noticed that the indicator bulb fluctuates in brightness just a bit but is not related to playing the amp. None of the other controls affect the hum and it does not change with the vibrato on or off. I have the bias set as low as it will go and increasing it adds more hum. Output tranny specs are here: http://www.classictone.net/40-18090.pdf. Power tranny specs are here: http://www.classictone.net/40-18016.pdf.
Thanks in advance for any suggestions. Title: Re: Prinzetone hum problem Post by: Sam Slick on September 01, 2014, 03:06:59 AM More pics
Title: Re: Prinzetone hum problem Post by: Sam Slick on September 01, 2014, 03:08:11 AM More pics
Title: Re: Prinzetone hum problem Post by: Sam Slick on September 02, 2014, 01:48:16 AM Tube voltages Pin 1. Pin 2. Pin 3. Pin 4. Pin 5. Pin 6. Pin 7. Pin 8. Pin 9
V1 12ax7 182 1.4 191 1.3 V2 12ax7 260 1.0 310 96 V3 6v6 .01 439 432 -42 0 V4 6v6 .01 435 433 -42 0 V5 5U4GB 310 312 I used a 5U4 rectifier tube to try to get closer to the original voltage (see http://www.classictone.net/40-18016.pdf). The layout calls for a GZ34. Not sure if that could be causing the hum, but thought I would include that info. |