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Post subject: Blues Deluxe Reissue Bias Settings
Posted: Tue Jul 13, 2010 11:07 am
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Has anyone changed the bias settings on a stock Fender Blues Deluxe Reissue? If so, what bias setting did you use and how did it affect the sound? TIA.

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Posted: Tue Jul 13, 2010 1:05 pm
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The setting is 60mA (60mV on 1 Ohm). I've measured 50 mV at cold and 58mA at hot (after 20mn). According to datasheet of 6L6GC (often Russian 5881WXT) used as push pull it is very cold, but the life time should be extended. 8)

Regarding sound, it's difficult to say, even at cold bias, I like the sound.

If you change the bias, take care of max power, check with datasheet:

http://www.drtube.com/datasheets/6l6gc-sed1996.pdf
http://www.mif.pg.gda.pl/homepages/fran ... /6L6GC.pdf
http://www.nj7p.org/Tube4.php?tube=6l6gc
http://www.drtube.com/datasheets/6l6gc-sed2001.pdf
http://www.drtube.com/datasheets/6l6gc-jj2003.pdf
http://www.eierc.com/rc/6L6GC.htm

By the way, I never found the SOVTEK Datasheet, if you have other datasheet, let me know.
:)

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Posted: Tue Jul 13, 2010 1:35 pm
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Thanks. Tissan.

So the factory setting is 60mA/60mV? I was looking at the Eurotubes website and they recommend not going above 70 mA/70 mV on the factory Groove Tubes. I will probably upgrade tubes in a few months, but I was curious about what one can get out ot the factory tubes with a simple bias adjustment.

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Posted: Tue Jul 13, 2010 1:51 pm
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i had 6l6ge groove tubes in mine with a 52mV setting and one tube fizzled out after 5 months. no warning. p.o.s.. i put in the gt 6l6r that was in it rebiased the amp then changed them to sovtek 6l6wxt+ i had bought a while back. i checed the bias and it now read 72mV(it had been set to factory 60mV with stock tubes) curious i wrote tube depot about the reading at bthe bias point in the amp. they said 50% disapation is usualy factory and that reading of 72mV was ok and was closer to 60% but it could go as much as 90mV but the tubes wouln't last, so i left it at 72mV and couldn't be happier. lesson well learned with gt. if that is their "flagship" tube it sunk. i also have gt soft touch kit in the pre amp and have had no problems with them.i love the way the amp sounds now.


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Posted: Tue Jul 13, 2010 1:52 pm
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i had 6l6ge groove tubes in mine with a 52mV setting and one tube fizzled out after 5 months. no warning. p.o.s.. i put in the gt 6l6r that was in it rebiased the amp then changed them to sovtek 6l6wxt+ i had bought a while back. i checed the bias and it now read 72mV(it had been set to factory 60mV with stock tubes) curious i wrote tube depot about the reading at bthe bias point in the amp. they said 50% disapation is usualy factory and that reading of 72mV was ok and was closer to 60% but it could go as much as 90mV but the tubes wouln't last, so i left it at 72mV and couldn't be happier. lesson well learned with gt. if that is their "flagship" tube it sunk. i also have gt soft touch kit in the pre amp and have had no problems with them.i love the way the amp sounds now.


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Posted: Tue Jul 13, 2010 2:16 pm
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Take care with russian equivalent:

http://www.jayskyler.com/guitar-gear-gu ... guide.html

I don't know 6L6ge (May be general Electric )?

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Posted: Tue Jul 13, 2010 2:29 pm
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killer topic & responses
thanks for the data sheets

my Twin~Amp calls for 60mV- i go 66mV

?
REMEMBER:

For this amp it says to

OUTPUT TUBE BIAS & BALANCE ADJUSTMENTS.
1. Warm up the Pro-Tubeamp for 2 minutes with STAND
BYswitch DOWN and OUTPUT POWER set to FULL.
Set SPEED and INTENSITYto “1“ and toggle TREMOLO
OFF. Put the STANDBYswitch in the UP position.
2. Remove the bias controls cover box.
3. Set BIAS: With a DC voltmeter, measure VDC between
the “GND”and “V9,V10”test points. Adjust BIASfor .06
VDC (60mVDC).
4. Set BALANCE: With a DC voltmeter, measure VDC
between the “V9,V10”and “V11,V12”test points. Adjust
BALANCEfor zero (0) VDC.
5. Replace the bias controls cover box.

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Posted: Tue Jul 13, 2010 3:20 pm
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With JJ's 6L6's in my HRDlx, I biased at 82mv. The plate voltage on my amp was about 455 volts so for a tube rated at 25 watts and 70% dissipation I was in the warmer end of the ballpark. You should actually check your plate voltage. I never messed with a Blues Deluxe, so I can't tell you for sure. Eurotubes suggests between 70-95mv on their JJ's. My amp was breaking up a little too early at 90-92mv that's why I backed it off a bit. The 5881's that were originally in my HRDlx were biased at 60mv sounded like arse and gave up the ghost in a month and a half. I never had any luck with GT's. I wonder what tubes Fender would use if they didn't own Groove Tubes? I'd never bias any GT 6L6 past 70 mv.

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Post subject:
Posted: Tue Jul 13, 2010 5:01 pm
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when those gt 6l6ge tubes went by-by i thought about getting some jjs but i had those sovteks and went ahead with them and was realy surprised with their performance. i can get the bdri to break up nicely with my strat. i have 57/62 pups in it. with my e.c. strat it absolutly roars. the 6l6wxt+ is the same as the eh6l6 ,just a little cheaper, and its from the same company,new sensor. one of those "conglomerate" companies. that stuff gives me a headache. all i can say is don't cook your tubes. its a balancing act. i won't run mine past 60% disapation on any tube. the stock tubes do just fine at 60mV. try 2 12ax7c and a 12at7 in the pi don't spend extra for the fender soft touch kit. you will like the results. it makes the amp very responsive to volume and touch.


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Posted: Tue Jul 13, 2010 8:05 pm
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I adjusted mine up to 40mA a tube and the amp started to cut out. Guess it can't handle it or maybe the tubes couldn't. Really didn't fuss over it much. I backed it down to 32-33 and it sounds better. Got rid of some of the shrilly highs and flabby lows.


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Posted: Tue Jul 13, 2010 8:09 pm
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32-34 ma is where they really sing.

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Posted: Tue Jul 13, 2010 9:27 pm
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Hey, thanks for all the great info and comments, folks. I've been reading the Eurotubes website and they seem to have a lot of good information. The video on biasing the HRD is really good. Right now I just want to see where my BDRI is sitting, and maybe up the bias a smidge to 70 mV.

I was thinking about getting the GT Soft Touch kit, but for the price of the kit (3 preamp tubes) from Guitar Center, I can get a complete retube kit with matched 6l6s from Eurotubes. I have been asking them (Eurotubes) some questions about their tubes and they are really fast in responding.

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Posted: Tue Jul 13, 2010 10:04 pm
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63supro wrote:
32-34 ma is where they really sing.


That's right in the same neighborhood where I bias all of my blackface 6L6 platforms as well, +/- around 1.0 mA depending upon whether they're NOS blackplate RCA's or mil-spec JAN's.

Arjay

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Posted: Wed Jul 14, 2010 6:13 am
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bluesky636 wrote:
Hey, thanks for all the great info and comments, folks. I've been reading the Eurotubes website and they seem to have a lot of good information. The video on biasing the HRD is really good. Right now I just want to see where my BDRI is sitting, and maybe up the bias a smidge to 70 mV.

I was thinking about getting the GT Soft Touch kit, but for the price of the kit (3 preamp tubes) from Guitar Center, I can get a complete retube kit with matched 6l6s from Eurotubes. I have been asking them (Eurotubes) some questions about their tubes and they are really fast in responding.


I wouldn't waste my money on GT's. :wink: Eurotubes sells full retubing kits depending on what you want. Clean, Blues, Gain etc. GT's are seriously overpriced.

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Posted: Wed Jul 14, 2010 8:21 am
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Retroverbial wrote:
63supro wrote:
32-34 ma is where they really sing.


That's right in the same neighborhood where I bias all of my blackface 6L6 platforms as well, +/- around 1.0 mA depending upon whether they're NOS blackplate RCA's or mil-spec JAN's.

Arjay
I biased some JAN Philips 6L6s to 35ma in my BF Pro Reverb,so I'm glad that's good to hear from y'all....and it sounds really good.
I would freak biasing tubes into the 60ma range. :shock:
I'm usually a 6V6 tubie...28ma oooohhh. :wink:


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