I have a D'Lite build that I've modified heavily. It's running low plates, a PI that's somewhere closer to a Bluesmaster, KT-88s in the PA, and some other changes. I spent almost a year tweaking it to get it where I wanted it.
I was doing a gig recently at church and had been reading about standby, and how it may not be good to leave the amp powered up but on standby for long periods. Sometimes our pastor can get a little long-winded.
Anyway, I made the mistake of not letting the amp warm up enough before I took it off standby for the next set. I only had about 20 seconds before we started to play. There was an arcing noise when I first powered it up, but no other problems since then.
But I swear, ever since then, the responsiveness and sustain of this amp has noticeably improved. The amp just sings. Weird!
odourboy wrote:Well now that you've let the cat out of the bag, you're going to HAVE to get to the bottom of this so we can all apply the 'Arc Mod' to our builds.
Yeah, hardly replicable...especially if I don't know what caused the arcing noise or what tube it was in. But feel free to try it yourself, as it's an easy mod: turn on amp, wait 5-10 seconds, turn standby off. Finished!
I'm betting it is either
a) pure coincidence, or
b) my imagination
Whatever. I've played two gigs with the amp since then, and I really like it. It may just be that I'm really noticing the new Penta KT-88s I put in there, which had only been in it for two gigs prior to the standby incident.
greiswig wrote:I have a D'Lite build that I've modified heavily. It's running low plates, a PI that's somewhere closer to a Bluesmaster, KT-88s in the PA, and some other changes. I spent almost a year tweaking it to get it where I wanted it.
I was doing a gig recently at church and had been reading about standby, and how it may not be good to leave the amp powered up but on standby for long periods. Sometimes our pastor can get a little long-winded.
Anyway, I made the mistake of not letting the amp warm up enough before I took it off standby for the next set. I only had about 20 seconds before we started to play. There was an arcing noise when I first powered it up, but no other problems since then.
But I swear, ever since then, the responsiveness and sustain of this amp has noticeably improved. The amp just sings. Weird!
A couple of thoughts: I supect not letting the amp warm up enough had absolutely nothing to do with anything. Also, have you lost any volume since the incident? If yes, I suspect one or more of your power tubes are getting ready to take a dump on you. It's been my experience that, sometimes, when tubes are on their way out they tend to sound the best in terms of warmth, sustain, etc. -- but not volume.
Cathode stripping and anode poisoning of power tubes were theory's brought about back in the 60's and 70's as it related mainly to high powered radio transmitters which ran at much higher voltages.. My partner worked on quite a few down south through the mid 70's..As it applies to guitar amps running at 450v it's not a major concern leaving an amp on stby for an hour or so especially a set of decent KT-88's shouldn't contribute to shorter tube life or arching... I know several companies like Peavey have published info about the subject promoting a Stby feature that they designed to inhibit such anomalies from occurring... I believe these to be marketing schemes to promote their designs... If anyone else out there that has documented evidence from a reputable source other than another amp company's promoting a design enhancement I would love to see it.. Keep in mind it has to be related to guitar amp voltages...Until then I don't buy it.. I would recheck my bias maybe that one tube is running hotter higher bias which it will for a while then start to run away on you...What OPT transformer are you using..KT-88 dissipate around 40 watts each... I have 2 KT-88 Classic high plate I LOVE!!!
Tony VVT
Last edited by talbany on Mon Oct 19, 2009 8:45 pm, edited 3 times in total.
ayan wrote:
A couple of thoughts: I supect not letting the amp warm up enough had absolutely nothing to do with anything. Also, have you lost any volume since the incident? If yes, I suspect one or more of your power tubes are getting ready to take a dump on you. It's been my experience that, sometimes, when tubes are on their way out they tend to sound the best in terms of warmth, sustain, etc. -- but not volume.
Gil
Well, no noticeable change in volume. I'll keep my fingers crossed. It did dawn on me that I should probably check the bias: they were within 3ma of each other an hour after I first popped them in...I wonder if they still are.
