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Title: 4 x 6V6 50Watt Dumble plate voltage too high Post by: petermerlot on November 06, 2012, 06:24:56 AM Hi All,
I have modded my 50 watt Dumble to a HRM and then gone further with adding 2 valve sockets and running 4 x 6V6 tubes. I have it Biased low as I am getting 480 Volts across pin 3 and earth (Tube installed). Can any one out there show me by way of illustration how to lower the plate voltage. I have thought of using a 5w 50v Zener but I am not sure if 5w is high enough or just where to connect it. I was thinking maybe connect it where the wire comes of the 22uf 500V cap that goes to pin 6. Any help is appreciated..... Title: Re: 4 x 6V6 50Watt Dumble plate voltage too high Post by: hywelg on November 06, 2012, 09:17:55 AM Better to ask on The Amp Garage.
http://ampgarage.com/forum/viewforum.php?f=4&sid=a5971c399f6b90430456199d74307c0d (http://ampgarage.com/forum/viewforum.php?f=4&sid=a5971c399f6b90430456199d74307c0d) Title: Re: 4 x 6V6 50Watt Dumble plate voltage too high Post by: petermerlot on November 06, 2012, 01:14:43 PM Thanks for the tip. I registered it on amp garage and I have a lead already,
Kind Regards Peter http://www.aikenamps.com/Zener2.pdf Title: Re: 4 x 6V6 50Watt Dumble plate voltage too high Post by: Bluestone on December 29, 2012, 01:32:06 AM It is essential the plate & screen voltage specs of a 6v6 will handle these D type amps.
TAD & JJ are both robust and will be fine. There are some good 6v6 reviews out there that cover this subject. TAD has a more traditional type 6v6 tone.. where the JJ seems to have a more aggressive tone from what i`ve read. Just make sure the amp is biased correctly for 6V6 tubes. Nik said biasing shouldn`t be a problem, although he did mention if bias adjuster can`t quite meet 6v6 requirements, a small resistor mod in the circuit will sort that. I haven`t installed a quad of 6v6 in my OTS yet, although it could well be worth it. |