Homepage › Forums › Discussion › Accident & Emergency › Valve amps are better for your figure
- This topic has 12 replies, 3 voices, and was last updated 16 years, 1 month ago by 1bassleft.
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June 8, 2016 at 12:17 pm #246371bassleftParticipant
Conclusive proof comes from this auction for a solid-state AC30:
http://i11.ebayimg.com/02/i/000/d7/e6/fda7_1.JPG
http://cgi.ebay.co.uk/Vox-ac30-top-boost_W0QQitemZ130196009898QQihZ003QQcategoryZ10171QQssPageNameZWDVWQQrdZ1QQcmdZViewItemNow I don’t feel so bad about lugging my 4xEL34 heads around the place.
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February 19, 2008 at 11:02 pm #1286611bassleftParticipant
Yes, the standby is only for switch on. If you have a beer break, just turn down the vols and leave it running; don’t go into standby. I also switch off the mains (and strum a chord for that frazzle-azzle-pfft thing), then flick the standby back into position for when I’ll next use it.
The idea behind this is to drain the capacitors of their stored charge. Opinions are mixed on whether moving the amp while still warm is more likely to damage the valves, but it doesn’t hurt to get paid and finish your beer before tering down 🙂
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February 19, 2008 at 8:34 am #128659lee_UKParticipant
I also heard on a VOX amps website, the best way to preserve an amps valves is to put on the main swicch, leave for 1 minute before switching on the standby , but to switch off you turn the power off first to bleed the voltage for 30 secs then turn off the standby, one thing ive always done is after switching off not to move the amp til the last possible moment, the valves are very delicate when hot.
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February 18, 2008 at 10:42 pm #1286601bassleftParticipant
Now I think about it, none of my WEM Dominators has a standby, including the 30W and the RSC GP30 I’ve just sold (also cathode-biased, maybe Class A) didn’t have one either. Bit mystifying, because I can’t see any reason why cathode-biasing saves the valves from torture. EL84s were/are a lot cheaper than the EL34, but that doesn’t explain the absence on the RSC. I suppose that cathode-biasing means that, if a tube goes kaput, you simply buy a replacement and drop it in, whereas fixed-bias amps would require a new set and re-biasing. Expensive and tedious enough to warrant fitting a standby circuit.
Incidentally, all Doms I’ve bought still had their 70s Mullard EL84s in there so a standby isn’t the big deal you’d think. The only exception was that 30W version (parallel push-pull, still cathode biased), bought for 41 quid as a non-worker. It had three Hungarian Tungsrams and a nasty, dead, Chinese EL84 that can’t cope with the screen current of old amps. Replacing the Chinee with a Tungsram got it working fine.
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February 18, 2008 at 10:31 pm #1286571bassleftParticipant
I believe you’re right on the Vox but wrong about the theory. The original Voxes had no standby switch even with diode rectification, something the Korg reissues have rectified (ouch 😳 ). If a valve, like the GZ34 or EZ81, did the rectifying, then the power valves (the EL84s) don’t get an immediate blast of DC before they’ve warmed up. Diode rectifiers send it straight through, so a standby is a good idea to let the heaters warm up.
HST, my CMI-Marshall has no standby and the Mullard EL34s lasted for donkeys and the Svets put in around 2000 are still there (although the amp was gigged a lot less from then).
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February 18, 2008 at 1:18 am #128658lee_UKParticipant
I thought it was the other way around, valve rectifier = standby switch, im pretty sure that early 70’s one would be a Rose Morris which had SS rectification, and no standby, where as the later Korg Reissue had a standby and valve GZ34 rectification, ive not checked any of this out, its just from memory, i might have it all arse 😯 about face..
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February 17, 2008 at 11:40 pm #1286551bassleftParticipant
I’ve never really spent time on researching AC30s. I know there are plenty of sites that would make dating a relative breeze. Lacking a standby switch is often a sign of valve rectification. Because the valve takes time itself to warm up, no standby is necessary but a switch to SS diode rectification means that the power valves get the DC instantly, hence the standby. Hmmm, a valve-rectified AC30 would be highly prized and, although I’m not bothered myself, I know people who would happily pay me rather more than 500 quid for one. I’m feeling a bit of a chump now 😳
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February 17, 2008 at 6:22 am #128656lee_UKParticipant
No Standby swich usualy means SS, but i think the early 70’s Vox Valve AC30’s didn’t use a standby. But all the heat vents gives it away.
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February 16, 2008 at 8:17 am #1286531bassleftParticipant
Looking at the logo and everything else, Lee, I think you’re right. But too late 👿 😆 . I don’t really care about bidding serious money for them, but it looks like £475 was a serious steal. I just assumed it was the ’70s SS version after the Thomas Organ deal. Speaking of which, shall we run a sweepstake on when this seller last saw his “Thomas Organ”? 🙂
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February 15, 2008 at 7:11 am #128654lee_UKParticipant
It’s definatly a Valve amp…. sorry Bass.
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February 15, 2008 at 3:23 am #128651TimParticipant
[quote=”1bassleft”]…comes from this auction for a solid-state AC30[/quote]
I guess so. 😀
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February 14, 2008 at 4:45 pm #128652lee_UKParticipant
Is it a solid state? the amp that is, not the seller.
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February 12, 2008 at 2:08 am #128650TimParticipant
His spine is probably still ok tho….
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