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Post subject: Re: 5AR4 "mislabeled" as 5V4GA
Posted: Thu Jul 07, 2011 11:58 am
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Thanks for the info BMW! The codes are f32 and B9L3. I'll let you know when I get it.


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Post subject: Re: 5AR4 "mislabeled" as 5V4GA
Posted: Tue Jul 12, 2011 7:10 am
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Hope they turn out good. Squat bottle shape and size is first giveaway with flat bottle top. Guts are another. There were at least 5 different anode plate types. GE made 5AR4 came closest in size to the original Philips/Mullard GZ34. Photos are from Tubemonger's site.

f32 = GZ34

B9L3 = Blackburn, UK. 9 = prolly 1969 or 79. L = December. 3 = xf3 (or third variety)


Note the two to four serations on one plate. Others are mostly solid anode plate:

http://www.tubemongerlib.com/gallery2/d ... ritain.jpg

Compared to Type 4 , multi serated smaller plates of different geometry:

http://www.tubemongerlib.com/gallery2/d ... ritain.jpg

Or multi-serated, larger plates (Type 5):

http://www.tubemongerlib.com/gallery2/d ... ritain.jpg

Compared to Japanese made Matsushita GZ34 (which used Mullard tooling). They always have cross-hatched tops.

http://www.tubemongerlib.com/gallery2/d ... +Japan.jpg

GE made (USA) 5AR4:

http://www.tubemongerlib.com/gallery2/d ... +-+USA.jpg


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Post subject: Re: 5AR4 "mislabeled" as 5V4GA
Posted: Tue Jul 12, 2011 11:22 am
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Joined: Sat May 22, 2010 10:53 pm
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Forgot to post pics... here it is

Image

Image

Image

Image

Not sure what type this is, maybe type 4? I tested it in my DRRI, no rattles, bias remained the same as with the JJ GZ34 in there. Didn't notice a change in tone.

Out of all the different JJ tubes I tried in my DRRI the GZ34 is the only one that's still in my amp. For about $15 it seems to do a great job and had no issues with it after a year. I don't see the reason to spend $100+ on a Mullard GZ34 if it doesn't really do anything for the tone and the JJ seems to be very reliable so far. Got this Sylvania GZ34 off ebay for $66, needed a spare...


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Post subject: Re: 5AR4 "mislabeled" as 5V4GA
Posted: Tue Jul 12, 2011 11:45 am
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Mullards need a bit of time to break-in. The best part is you shouldn't need to changed out rectifier (famous last words)---for a long time. Esp if you crank the beejers outta your amp a lot.

BTW... best to have the power tubes re-biased. Often Fender draws the bias power supply off the rectifier. Or at the least, the slight change in current draw between the JJ and the Mullard, may alter the idle bias point.


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Post subject: Re: 5AR4 "mislabeled" as 5V4GA
Posted: Tue Jul 12, 2011 11:55 am
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I did have my bias meter hooked up, before and after installing new tube, kept the amp running for about 30 mins and monitored the bias, it was pretty much unchanged.

This GZ34 was listed as used, so I don't think it needs any breaking-in... I'll install it back in my DRRI, but would like to test it in my SF SR first, just to see what it sounds like.


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