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HD 150 Bias and tube selection question

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Chip
Posted on Monday, August 26, 2002 - 07:06 pm:   

I have a 210 HD 150 bought in 1980. It has the solid state preamp I am sure...

My questions are: Is it self biasing?..........

And which 6L6 is the best choice out there for the high plate voltage these things run....I have heard the Svetlana due to the bottle size and the operational propeties....anything else?

Maybe Terry could comment on this for me please...

thanks !!
Terry
Posted on Monday, August 26, 2002 - 09:03 pm:   

Hi Chip, your amp is not self biasing!
The amp that is self biasing, is the RD50 with the 12AX7 tube.
For your amp, I like the 7581A. They are a military 6L6GC. They can take the voltage. You can find them on Ebay for about $50.00 a pair.
Next I like the Svetlana.I would like to see some of the new GT6L6GE made by Grove Tube. They may be a good choice, but I've not seen any. Reset your bias, and put some new tubes in and you should have no trouble. Terry
Terry
Posted on Monday, August 26, 2002 - 09:56 pm:   

KCA nos Tubes http://users.erols.com/bluestat/
Chip
Posted on Tuesday, August 27, 2002 - 09:25 pm:   

Wow Terry, quite a selection there....which ones would you go for? I am leaning towards the NOS JAN Philips 6L6GCs since they available in a matched quartet.... what do you think?

Whatever tube I decide on you can provide me with correct bias amperage correct?

This is so great....for a long time I was in the dark with my MM amp, except for the guy I know that used to carry them in the 70's.....seems no one gave them the time of day, but now they are coming on with a strong following and with the respect they deserve.

I have yet to find a louder, more powerful, and more durable amp. I never seemed to have the "sterile" sound that everyone stigmatized these amps as having.....might be the gain circut in the 150 that accounts for that though...

anyway thanks alot.
Terry
Posted on Wednesday, August 28, 2002 - 08:34 am:   

Chip, I would get the 7581A that is the tube I use
for 150 amps I repair. The JAN 6L6GC is a small
tube that works well in Fender. It is up to you.