My second experience with an Orange amp and a red-plating EL34
Or in this case an EL34B
I turned the amp on yesterday and crackle crackle - funny noise - and looked inside to see one of the output valves red-plating and turned the amp off immediately
I didnt notice this before so I think it could be a new issue. Though I bought the amp second hand so I cant say with 100% percent certainty.
I've just ordered a matched pair of JJ EL34's and some new 12ax7's and will do a full re-valve as soon as they arrive but dang I didn't think this was gonna happen!?
I thought that the R30 was cathode biased and so it wouldnt be possible for valves to draw too much current? I saw another thread on here that suggests the valve
may be damaged and this is the reason that it is drawing too much current. Anyone have any experience with this ??
B
Red Plating
Moderator: bclaire
Red Plating
Orange AD30
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Re: Red Plating
It might be that there is damage. If so, you would expect a decent tech to be able to diagnose and resolve it. If it's just a single valve red plating then replacing the pair of power valves should fix it. If you replace them yourself, look carefully as they come up to temperature to make sure the pair are even and that neither appear to be wanting to red plate. You could also try just swapping the pair as seeing if the red plating follows the tube...
If you're worried - take it to a tech.
If you're worried - take it to a tech.
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- Duke of Orange
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Re: Red Plating
Cathode biasing isn't the 'automatic' biasing many people believe. It does 'self adjust' to an extent giving a certain amount of leeway for slightly different spec valves, but valves which are way off normal spec (for whatever reason) may still lead to problems.
I have a slight memeory at the back of my mind of hearing of EL34Bs having had rather different current draw from normal. Or one may may just have gone faulty.
To be honest I'd get a good amp tech to check things with the new valves. I'd actually recommend having ANY second hand amp properly checked over anyway...
Andy.
I have a slight memeory at the back of my mind of hearing of EL34Bs having had rather different current draw from normal. Or one may may just have gone faulty.
To be honest I'd get a good amp tech to check things with the new valves. I'd actually recommend having ANY second hand amp properly checked over anyway...
Andy.
aNDyH.
Ever tried to outstare a mirror?
In the bathtub of history the truth is harder to hold than the soap, and much more difficult to find!
Ever tried to outstare a mirror?
In the bathtub of history the truth is harder to hold than the soap, and much more difficult to find!
Re: Red Plating
I think you're right about the EL34B. I recall hearing them not even being able to be biased in some adjustable fixed bias amps without the bias circuit being modified.a.hun wrote: ↑Sat Aug 19, 2017 6:54 pmCathode biasing isn't the 'automatic' biasing many people believe. It does 'self adjust' to an extent giving a certain amount of leeway for slightly different spec valves, but valves which are way off normal spec (for whatever reason) may still lead to problems.
I have a slight memeory at the back of my mind of hearing of EL34Bs having had rather different current draw from normal. Or one may may just have gone faulty.
To be honest I'd get a good amp tech to check things with the new valves. I'd actually recommend having ANY second hand amp properly checked over anyway...
Andy.
Re: Red Plating
I got a set of JJ EL34's and some pre-amp tubes and popped them in on Sunday morning
Lets just say it was a good good day....Amp is sounding miles better, no red plating and
tone for days.
Lets just say it was a good good day....Amp is sounding miles better, no red plating and
tone for days.
Orange AD30
Groove Tubes Soul-O 75
Orange PPC 212 OB
Boss Nextone 40
Fender CIJ Pink Paisley Tele
Fender Classic Player Strat 50s
Yamaha SA1200s
Gibson Les Paul Standard
Gibson SG Jnr
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- Duke of Orange
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- Joined: Tue Aug 18, 2009 9:08 am
- Location: Derby, England
Re: Red Plating
Excellent! I love happy (noisy) endings!!!
Ant
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
Orange Gear: RV50 MKI, R30, AD15, PPC212
And.... Genz Benz Black Pearl 30
Past Orange: AD30TC Combo, TT, AD5
Guitars: Gibson Les Paul Standard Faded, Vigier Expert Retro 54, Gibson SG 70s Tribute, Aria Pro II RS X80, G&L ASAT Special Tribute
-
- Duke of Orange
- Posts: 9765
- Joined: Sat Jun 15, 2002 1:05 am
- Location: Amsterdam, Hollandland.nl
Re: Red Plating
Andy.
aNDyH.
Ever tried to outstare a mirror?
In the bathtub of history the truth is harder to hold than the soap, and much more difficult to find!
Ever tried to outstare a mirror?
In the bathtub of history the truth is harder to hold than the soap, and much more difficult to find!
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