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Post by mickey on Jul 7, 2018 6:32:45 GMT -7
I've used an NOS Mullard rectifier in my Maz Sr for nearly 10 years now, bought it off eBay and it's still going strong. I'm thinking of getting one for my Maz Jr, but does it make any difference whether I get one with a 4 notch plate, or copper lined anode etc. etc.? I have no real knowledge of the different types which come up for sale, I just want it to work and be totally reliable. There's also one described as a Mullard "E" and another is a "B"; I have no idea again!
Thanks!
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Post by perryr on Jul 7, 2018 9:38:18 GMT -7
4 notch rattle less (than the 7 notch ime) and are more or less the benchmark IMO. The earlier “fat base” where the base is larger than the glass are very nice and rattle even less. The fat base started in late 50’s with smooth plates and later around 1960 went to 4-notch plates before the bases went smaller. Problem with fat base is they won’t work with claw retainers, you gotta either remove the claw (heads), or change to a spring type retainer (if in a combo).
not sure about the E or B, all Mullards gz34 from the 60’s should have a B in the etched code indicating ‘Blackburn’ production plant.
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Post by mickey on Jul 8, 2018 0:27:32 GMT -7
4 notch rattle less and are more or less the benchmark IMO. The earlier “fat base” where the base is larger than the glass are very nice and rattle even less. The fat base started in late 50’s with smooth plates and later around 1960 went to 4-notch plates before the bases went smaller. Problem with fat base is they won’t work with claw retainers, you gotta either remove the claw (heads), or change to a spring type retainer (if in a combo). not sure about the E or B, all Mullards gz34 from the 60’s should have a B in the etched code indicating ‘Blackburn’ production plant. Helpful info which I didn't know, many thanks for this. It's particularly useful to know the fat base ones won't fit the claw retainers. There's a 4 notch one available if I want it, but it's expensive, so decision time, that or a Sovtek at a fifth of the price! Update....I just ordered an early 60's Mullard NOS GZ34, Blackburn factory, double ring getter, 4 notch plates, base looks the right size, hope my money is well spent!
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Post by bigben55 on Jul 9, 2018 7:14:36 GMT -7
Mind divulging the current going rate for Mullards? While I use Dr Zs recommended tube compliment in my Z28(new tubes) I use all NOS in my 1966 Super Reverb.....except a Sovtek 5AR4. I'd love to score a NOS rectifier, if for nothing else, to put my OCD to rest!
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Post by mickey on Jul 9, 2018 12:30:11 GMT -7
Mind divulging the current going rate for Mullards? While I use Dr Zs recommended tube compliment in my Z28(new tubes) I use all NOS in my 1966 Super Reverb.....except a Sovtek 5AR4. I'd love to score a NOS rectifier, if for nothing else, to put my OCD to rest! Just check eBay, that's where I got both mine, but check the sellers carefully first.
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Post by zpilot on Jul 9, 2018 16:56:12 GMT -7
I had no idea there were so many different variations. I own three Mullards and one is different from the other two. As far as sound goes I can not tell any difference between the three and the B+ from all are within 10 volts. I wouldn't overthink this.
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Post by mickey on Jul 10, 2018 0:11:31 GMT -7
I wouldn't overthink this. Good advice!
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Post by mickey on Aug 3, 2018 1:47:31 GMT -7
Another question....the GZ34 I bought is installed and working great. It was advertised as an NOS Mullard GZ34, fully tested, and D1: 89 D2: 90. Any idea what these figures refer to?
When it arrived it looked great...original box and wrapping paper! It was expensive, but came from a reputable seller based not far from me.
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Post by zpilot on Aug 3, 2018 6:22:04 GMT -7
I don't know what that number means other than maybe this. A GZ34 is a full wave rectifier. That means there is an output from both sides of the sine wave. So since those numbers are so close the output is "balanced". Also the "D" probably refers to it being a diode which is another term for rectifier. I've never seen this "D" on a spec sheet. Or at least if it is there I missed it.
After thinking about this for a moment I wonder if that number refers to the loss due to internal resistance of the tube expressed as a percentage, with 100 meaning no loss at all.
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Post by mickey on Aug 3, 2018 8:22:31 GMT -7
I don't know what that number means other than maybe this. A GZ34 is a full wave rectifier. That means there is an output from both sides of the sine wave. So since those numbers are so close the output is "balanced". Also the "D" probably refers to it being a diode which is another term for rectifier. I've never seen this "D" on a spec sheet. Or at least if it is there I missed it. After thinking about this for a moment I wonder if that number refers to the loss due to internal resistance of the tube expressed as a percentage, with 100 meaning no loss at all. Thanks for this, food for thought. Actually I also emailed the seller, who has just replied "The D1 D2 figures are the test results on the AVO VCM163 tester. They are the typical test figures of a new valve. They are within the test specification." So that doesn't really clarify what the numbers mean, only that they are ok.
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Post by greenblues58 on Aug 3, 2018 9:52:08 GMT -7
Mick the numbers and letters etched in the glass, if that is what you are referring to, are date and manufacturing facility codes. There are plenty of websites that explain the various codes from early days upto the 70's if you google it. I have a Blackburn Mullard GZ34 (though it's poor) and a handful of Dutch Mullard EF86 which are all good .
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Post by mickey on Aug 3, 2018 10:34:35 GMT -7
Mick the numbers and letters etched in the glass, if that is what you are referring to, are date and manufacturing facility codes. There are plenty of websites that explain the various codes from early days upto the 70's if you google it. I have a Blackburn Mullard GZ34 (though it's poor) and a handful of Dutch Mullard EF86 which are all good . Thanks Bob, though the figures are I believe test results. The valve has f32 etc etched on the glass, (can't remember exactly), but I identified it as a Blackburn GZ34 from around '67. Seems to work fine, hope it lasts! Interesting that your Blackburn one is poor, how can you tell? I thought a rectifier either works or it doesn't.....?
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Post by greenblues58 on Aug 3, 2018 10:51:54 GMT -7
Mick the numbers and letters etched in the glass, if that is what you are referring to, are date and manufacturing facility codes. There are plenty of websites that explain the various codes from early days upto the 70's if you google it. I have a Blackburn Mullard GZ34 (though it's poor) and a handful of Dutch Mullard EF86 which are all good . Thanks Bob, though the figures are I believe test results. The valve has f32 etc etched on the glass, (can't remember exactly), but I identified it as a Blackburn GZ34 from around '67. Seems to work fine, hope it lasts! Interesting that your Blackburn one is poor, how can you tell? I thought a rectifier either works or it doesn't.....? Well it works that's for sure. l put it in my Maz and the tone went very thin and harsh to the point l thought something was wrong with the amp. l put the original sovtek back in and all back to normal and has been in the Maz ever since. l have tried it in my deluxe reverb and it seemed okay though l didn't leave it in. it apparently tested good but l only parted with current production money for it. on a similar note my vibrolux had all its original RCA valves when l bought it . l purchased a NOS National 5U4GB to preserve the original and there is a definite pronounced difference in feel and tone and a change,though minor , in the bias reading.
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Post by mickey on Aug 4, 2018 2:23:08 GMT -7
Thanks Bob, though the figures are I believe test results. The valve has f32 etc etched on the glass, (can't remember exactly), but I identified it as a Blackburn GZ34 from around '67. Seems to work fine, hope it lasts! Interesting that your Blackburn one is poor, how can you tell? I thought a rectifier either works or it doesn't.....? Well it works that's for sure. l put it in my Maz and the tone went very thin and harsh to the point l thought something was wrong with the amp. l put the original sovtek back in and all back to normal and has been in the Maz ever since. l have tried it in my deluxe reverb and it seemed okay though l didn't leave it in. it apparently tested good but l only parted with current production money for it. on a similar note my vibrolux had all its original RCA valves when l bought it . l purchased a NOS National 5U4GB to preserve the original and there is a definite pronounced difference in feel and tone and a change,though minor , in the bias reading. Hmm....thing is, the amps were presumably designed to work with the Sovtek rectifier. I remember when I bought an NOS Mullard for my Maz 38 some years back, and I went back and forth between rectifiers thinking I could hear or feel a difference. Eventually I left the Mullard in the amp and it's been fine, or maybe I've just got used to it. Same thing now with my Maz Jr, yes the Mullard should be reliable, and I thought at first the amp doesn't seem to sound or feel any different, but now I'm not sure, and at last night's gig the amp seemed to lack its usual chime and guts. That could have been the small venue though, and I was standing very close to the cab which is never good in my book. I'll just have to experiment some more. I just plugged in at home and it sounded great, so who knows.
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