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Post by Pete aka shouldb on Apr 28, 2016 5:17:33 GMT -7
Man, this Rectifier tube issue has opened a can of worms!!
I am being told on many amp / electronic forums that one of the main killers of tube rectifiers in the Stand By switch, which isn't needed anyway on any amp under 100W.......?
Further, to preserve my Rectifier tube, just disconnect / bypass the Stand By switch - it will do the amp no harm whatsoever, and will protect my Rectifier from a damaging surge when the Stand By is flipped on...........
Now this resonates historically with me, as I seem to remember a similar debate happening at the time I had my Ghia (with no Stand By switch).........
Any thoughts / opinions / experience / advice?
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Post by Rockerfeller on Apr 28, 2016 5:39:44 GMT -7
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Post by Pete aka shouldb on Apr 28, 2016 6:49:22 GMT -7
That's great, but I'm still confused a bit........it says always use the Stand By switch when using SS rectifiers, which I don't, so it doesn't matter when using tube rectifiers?
As I say above, many forums say that using a SB switch actually shortens the life of a tube rectifier..........?
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Post by Rockerfeller on Apr 28, 2016 7:12:24 GMT -7
Perhaps someone who builds high quality amps will chime in with the definitive answer and settle this once for all?
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Post by Lefty on Apr 28, 2016 8:21:11 GMT -7
If it wasn't needed, Doc wouldn't have included it.
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Post by BritInvasion on Apr 28, 2016 10:06:10 GMT -7
I don't think using a standby switch hurts the rectifier. I could be wrong about this , if I am someone please correct me... but I think the switch is "after" the rectifier in the circuit. When it's switched into play position it lets the full voltage/current from the rectifier thru to the rest of the tubes. But the main reason I don't think it's the switch is when I got my first Maz 18 in 2006 , I straight away put in an NOS GE rectifier. When I sold the 18 after gigging / rehearsing for 7 years , I kept the rectifier and installed it in my Maz 8. It stayed in there for 2 years , and when I sold that I again kept the rectifier and it now resides in my new 18NR. So 10 years of use ( with using the standby switch) and it's still going strong. I think the real problem is they don't make rectifiers like they used to. Just my 2 cents.
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Post by Lefty on Apr 28, 2016 11:23:33 GMT -7
+1 on the NOS Rectifier, well worth the money as they last for years. The one that came in my Super was probably original...still kicking.
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Post by benttop (Steve) on Apr 28, 2016 11:42:50 GMT -7
I have only NOS rectifiers in my amps that need a tube rectifier. The ones I've tried that are new manufacture have lasted anywhere from ten minutes to a year, but not usually much beyond that. For a guy who is gigging, that is an unacceptable risk to have the amp possibly go down at exactly the wrong moment.
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Post by Pete aka shouldb on Apr 28, 2016 15:41:36 GMT -7
I have only NOS rectifiers in my amps that need a tube rectifier. The ones I've tried that are new manufacture have lasted anywhere from ten minutes to a year, but not usually much beyond that. For a guy who is gigging, that is an unacceptable risk to have the amp possibly go down at exactly the wrong moment. Which is exactly what happened last Sat Well I have a couple of Sovtek ones coming (new) which buys me time to source a couple of decent NOS ones. Good advice........again
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Post by nmz on Apr 28, 2016 16:14:22 GMT -7
I have only NOS rectifiers in my amps that need a tube rectifier. The ones I've tried that are new manufacture have lasted anywhere from ten minutes to a year, but not usually much beyond that. For a guy who is gigging, that is an unacceptable risk to have the amp possibly go down at exactly the wrong moment. Which is exactly what happened last Sat Well I have a couple of Sovtek ones coming (new) which buys me time to source a couple of decent NOS ones. Good advice........again Wow, that sucks Pete. So far I have not had any issues with the origional in my Therapy but it makes me think about having a reliable stand by.
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Post by zpilot on Apr 29, 2016 5:42:36 GMT -7
I don't think using a standby switch hurts the rectifier. I could be wrong about this , if I am someone please correct me... but I think the switch is "after" the rectifier in the circuit. When it's switched into play position it lets the full voltage/current from the rectifier thru to the rest of the tubes. But the main reason I don't think it's the switch is when I got my first Maz 18 in 2006 , I straight away put in an NOS GE rectifier. When I sold the 18 after gigging / rehearsing for 7 years , I kept the rectifier and installed it in my Maz 8. It stayed in there for 2 years , and when I sold that I again kept the rectifier and it now resides in my new 18NR. So 10 years of use ( with using the standby switch) and it's still going strong. I think the real problem is they don't make rectifiers like they used to. Just my 2 cents. I have had a similar experience with a Mullard that I've had for about 20 years.
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Post by jimiata on Apr 29, 2016 7:08:06 GMT -7
I played my old '70's Ampeg B15N, bought used in 1976, pretty much 'till sold this past January. The only tubes changed were the 6L6 power tubes. I think the rectifier was/is a Sylvania or RCA.
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Post by Pete aka shouldb on May 11, 2016 0:19:26 GMT -7
If it wasn't needed, Doc wouldn't have included it. Not sure about that..........Ghia? I seem to remember another discussion somewhere else where he basically said that the SB switch is there because customers expect it to be, but with low wattage amps (<100 Watts) it's not needed electronically.........it's a just a great convenience for players to mute their amps. Now, I remember the content of that discussion, but it may have been another amp builder on another forum who said it, so forgive me Doc if I misquote you............... No matter, really, I was just curious.......it is a very convenient way to mute an amp for sure, so is useful for that , if nothing else
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Post by Mark (Basement Enthusiast) on May 11, 2016 9:05:26 GMT -7
I seem to remember it that way, too, Pete... really just a "mute" switch for all intents and purposes.
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Post by zpilot on May 11, 2016 11:21:16 GMT -7
It's always bugged me that my 20 watt 1964 Gemini 1 doesn't have a standby switch. It has a SS rectifier so the B+ is hitting the tubes before they have a chance to warm up. But consider this. It still has the original tubes and they test and sound good. Now I don't know how much time is actually on the amp because when I bought it it was inop. The power transformer was shorted and the rectifier had burned-out. I'm not sure which caused the other to happen. Anyway the amp had been down for a long time and I have not put more than 100 hours on it since I repaired it. Ampeg was a first class manufacturer back then and did not skimp on things and their decision to not include a standby switch seems to have panned out. But still I have considered installing one. I just don't want to drill an extra hole in a mint chassis.
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Post by bgkyt1 on Jun 8, 2016 7:20:39 GMT -7
According to the valve wizard website (google "valve wizard"), the cathode stripping problem due to B+ hitting tubes before they warm up is not relevant to tubes in a guitar amp and seems to say that standby switches are not necessary. I wouldn't add one to an amp that didn't have one, especially a collectible one.
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