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Post by bellycaster on Nov 28, 2017 11:14:24 GMT -7
Hi All, I'm a new member on here today (UK Member), looking forward to receiving wisdom about these lovely amps. I had my Maz 18 die on me at rehearsal. I suspect the power valves as they don't last forever and one was glowing quite brightly, another place mentioned that it likely Red Plated. I didn't want to leave the amp turned on long enough to scrutinise everything as you will understand.
I've ordered my new set of matched JJ EL84's from Karltone in the UK, very good reputable dealer. The guy recommended that he sent a matching pair of low current draw valves as he understood these amps run very hot. There is information on the Valves boxes pertaining to Plate Current and Transconductance, which is 30 and 7.7 respectively.
This sound in the right ball park to you?
Anyway, the main point is, what else should I check on my amp. I notice that all my other amps have two Fuses on the back panel, a Mains Fuse and a HT Fuse. I can only see 1 Fuse on the back panel of my Maz 18? Is there another Fuse.
I did check the fuse near the mains socket and it hadn't blown. Also the Rectifier Valve I am assuming is still OK. I've been recommended a better R.V but don't want to swap that just yet. Is it OK to put in the new Power Valves with the original R.V still in place? Assuming it is OK.
The EL84s that died were the stock ones. I reckon I might have had 150 - 175 hours out of them.
Thanks for any help.
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Post by Jaguarguy (Mike) on Nov 28, 2017 11:28:46 GMT -7
Welcome to the Forum! A lot of good information and people here. Doc's link on the website above also has some great info! Here are two links from the site - the first is which tubes he is presently using in the amps drzamps.com/support/tube-info/and the second is a link to his troubleshooting page. drzamps.com/info/faq-troubleshoot/The Maz doesn't need to be biased so you can just drop in the tubes (be careful not to bend the pins however). As long as they matched the tubes you should be good to go. If not, just follow the troubleshooting link to figure out if something else is needed.
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Post by headshrinker (Marc) on Nov 28, 2017 12:27:01 GMT -7
Doc also recommends tubes in the medium range rather than high or low. Sounds like your supplier might be recommending low. Might want to check with them.
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Post by BritInvasion on Nov 28, 2017 12:53:30 GMT -7
Welcome to the forum. Adding to the above , the rectifier can continue to be used.
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Post by bellycaster on Nov 28, 2017 13:14:26 GMT -7
Thanks guys, all good info on those pages, but, could you please enlighten me regarding the Fuses, I can't get an answer to this question (below) and can't see it on those pages.
How many Fuses on the Maz 18? I can only see one on the back panel, whereas all my other amps have 2 on the back panel.
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Post by Chilly Gibbons (Todd T.) on Nov 28, 2017 17:58:21 GMT -7
Only a mains fuse, nothing else on the board. Many UK designs have multiple fuses, these have one. I suspect the fuse is fine if you turned the amp’s power off yourself instead of the fuse doing it for you.
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Post by Chilly Gibbons (Todd T.) on Nov 28, 2017 18:02:22 GMT -7
Also consider the Russian 6n14n el84 equivalents. Doc is now shipping amps with those with great results. Rugged, long lasting, and great sounding. Not expensive either, not yet anyway...
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Post by bellycaster on Nov 29, 2017 12:48:42 GMT -7
Thanks Chilly Gibbons (Todd T.) Yeah, that Fuse was good, so should be OK. I've heard good things about those Russian Valves, but it's not easy to get those over here in the UK.
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Post by premiumplus (Dave) on Nov 29, 2017 15:28:07 GMT -7
Forum member perryr sells the tubes that Doc uses in the ZWreck amps. I've ordered from him and he's great. He might be willing to ship internationally, I don't know. Send him a PM and see.
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Post by bellycaster on Dec 3, 2017 15:05:32 GMT -7
New valves are in and a good couple of hours out of them today, so hopefully that was the only problem. Thanks.
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