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Post subject: DRRI Bias settings
Posted: Mon Oct 01, 2012 5:18 am
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Hey everyone.

Proud to say I am finally the owner of a new Deluxe Reverb RI, and it's amazing, however I have a feeling that the bias may be set too cold out of the factory. I have heard this is a common occurance. going to get a tech to stick a bias probe on it, (currently have factory standard groove tube GT6V6-S; white 6 equipped. and before anyone says chuck them which i know someone will, ill let them die and then change them) What should I have the bias adjusted too? someone said about 22mA is maximum headroom for these DRRI's?

anyone have any experience with bias adjustments on these amps or good replacement tube experience would be appreciated. Thanks!


Last edited by searchfortone on Wed Oct 24, 2012 4:54 am, edited 1 time in total.

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Post subject: Re: DRRI Bias settings
Posted: Mon Oct 01, 2012 7:54 am
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That sounds about right. You should consider the bias as a whole, which includes Plate volts and the output tube's max Plate watt rating. A good range for idle bias is between 50% and 70% of the tube's max Plate watt rating. Since idle Plate wattage is Plate volts times Plate current, 22 mA at approx 400 Plate volts is very close to 70% of a 14 watt tube.

GT tubes are the most thoroughly tested tubes on the planet, you can't get any better modern tubes. GT tests and relabels modern tubes such as Sovtek, EH, Chinese and others, and some tubes are made exclusively for GT like the ones that you have which are made in the JJ factory, not relabeled JJ's. I am a fan of GT tubes. Sound is subjective, so if you like the sound, keep them. Most people don't have a clue, and it seems popular to make excuses to participate in the trendy practice of installing new tubes. So, forget the nay-Sayers and enjoy. :wink:

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Post subject: Re: DRRI Bias settings
Posted: Sat Oct 13, 2012 7:54 am
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I have a DRRI with stock Groove Tubes which I've owned for around 6 months. In the 1st month had a power tube go microphonic after a month. Just had a 12at7 in the reverb go out a week ago. Now the rectifier tube is rattling. Needless to say I'm not to impressed with grove tube quality control. A set of JJ's from Eurotube will be going in as soon as I have the cash. I intend to rebias then to around 22-23ma at that time.

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Post subject: Re: DRRI Bias settings
Posted: Sat Oct 13, 2012 8:12 am
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I thought the standard DRRI tubes were rated at 12 watts?

viewtopic.php?f=13&t=72470

With JJ's rated at 14 watts I'm sitting at ~ 21 and 422 vdc.

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Post subject: Re: DRRI Bias settings
Posted: Sat Oct 13, 2012 9:25 am
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Hou-Tex wrote:
With JJ's rated at 14 watts I'm sitting at ~ 21 and 422 vdc.


That's just about optimum for your tube/amp combination.

Arjay

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Post subject: Re: DRRI Bias settings
Posted: Sat Oct 13, 2012 6:01 pm
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Retroverbial wrote:
Hou-Tex wrote:
With JJ's rated at 14 watts I'm sitting at ~ 21 and 422 vdc.


That's just about optimum for your tube/amp combination.

Arjay


Somebody taught me that.







:D

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