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Post subject: 1976 DR Bias Settings
Posted: Thu Jun 14, 2018 9:04 pm
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Hi,

When I bias my 76 DR, I either get a good current draw (around 20 mA ) with low voltages everywhere (389 VDC on 6V6 plates) or I get 420 VDC on 6v6 pates with a mere 5 0r 6 mA current draw. I can't get it to sound as sweet as some other SFDR's I bias. I get the same results with my old RCA 6v6"s as well as a brand new matched set of TAD 6v6's. Any insight would be appreciated.

JMG1
Thanks


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Post subject: Re: 1976 DR Bias Settings
Posted: Mon Jun 18, 2018 1:33 am
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Joined: Fri Feb 05, 2010 4:31 am
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Location: Province de Québec, Canada
Give a link for diagram , Is it the one with volume boost ?

I did not say is not normal this voltage drop out, check ;

1- Did you test tubes rectifier with new good one ?
2- Filter caps are good ?
3- Did all tubes heater receive 6.3 volts ?
4- Speaker is a 8 ohms ?

IMO late '70 fender amps are not the best sounding amps

Post in the Vintage Guitars Amplifier for more answer, experts are there

https://forums.fender.com/viewforum.php?f=12


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Post subject: Re: 1976 DR Bias Settings
Posted: Tue Jun 19, 2018 6:49 am
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Hi stratele52,

I did swap out my rectifier tube since I posted the comment and got everything pretty close to spec, now the amp sounds great. It seems to be an issue with my JJ 5AR4. I put my old RCA 5AR4 back in and that solved the issues. Thanks for you input. Cheers !


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Post subject: Re: 1976 DR Bias Settings
Posted: Tue Jun 19, 2018 7:54 am
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JMG1 wrote:
Hi stratele52,

I did swap out my rectifier tube since I posted the comment and got everything pretty close to spec, now the amp sounds great. It seems to be an issue with my JJ 5AR4. I put my old RCA 5AR4 back in and that solved the issues. Thanks for you input. Cheers !


:)


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