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Post by scottunzicker on Jun 7, 2017 7:36:25 GMT -7
In short, I made the mistake of letting a guy sit in last night. He had some weird, cigar box type guitar with a really hot humbucker and some sort of pedal. He cranked the preamp up to about 3 o'clock (not quite all the way) and the master almost dimed. He played a few notes pretty hard, then *pzzzt*, silence and darkness. I checked the fuse and it was toast. Do we think this was unhappy coincidence (it was a total **** gig last night for reasons I shan't explore here), or do we think something may be amiss? I should note that the Z Lux is bone stock EXCEPT that I'm running 4xTung Sol 5881s.
Thanks, fellas.
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Post by benttop (Steve) on Jun 7, 2017 8:13:55 GMT -7
In short, I made the mistake of letting a guy sit in last night. He had some weird, cigar box type guitar with a really hot humbucker and some sort of pedal. He cranked the preamp up to about 3 o'clock (not quite all the way) and the master almost dimed. He played a few notes pretty hard, then *pzzzt*, silence and darkness. I checked the fuse and it was toast. Do we think this was unhappy coincidence (it was a total **** gig last night for reasons I shan't explore here), or do we think something may be amiss? I should note that the Z Lux is bone stock EXCEPT that I'm running 4xTung Sol 5881s. Thanks, fellas. It's coincidence. I bet you lost a power tube - do you have the originals to sub in and try?
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Post by premiumplus (Dave) on Jun 7, 2017 8:15:38 GMT -7
I'd be surprised if the amp blew a fuse only because of the input. But what may have happened is that you had an output tube go south on you, which would in turn blow the fuse. Check out Doc's troubleshooting page here . It'll lead you to the solution.
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Post by scottunzicker on Jun 7, 2017 8:29:43 GMT -7
In short, I made the mistake of letting a guy sit in last night. He had some weird, cigar box type guitar with a really hot humbucker and some sort of pedal. He cranked the preamp up to about 3 o'clock (not quite all the way) and the master almost dimed. He played a few notes pretty hard, then *pzzzt*, silence and darkness. I checked the fuse and it was toast. Do we think this was unhappy coincidence (it was a total **** gig last night for reasons I shan't explore here), or do we think something may be amiss? I should note that the Z Lux is bone stock EXCEPT that I'm running 4xTung Sol 5881s. Thanks, fellas. It's coincidence. I bet you lost a power tube - do you have the originals to sub in and try? Steve - Thanks for the response. I do, indeed, have a spare set of 6V6s I can pop back in to try. Thanks for the advice.
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Post by scottunzicker on Jun 7, 2017 8:30:45 GMT -7
I'd be surprised if the amp blew a fuse only because of the input. But what may have happened is that you had an output tube go south on you, which would in turn blow the fuse. Check out Doc's troubleshooting page here . It'll lead you to the solution. Dave - Thanks for your time and that link. I thought I knew the Doc's site pretty well, but hadn't seen that troubleshooting section. Cheers!
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Post by Deleted on Jun 7, 2017 9:43:03 GMT -7
Did you have somebody set up your amp for 5881's? 5881's are not a straight swap for 6V6 tubes.
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Post by scottunzicker on Jun 7, 2017 11:07:05 GMT -7
Did you have somebody set up your amp for 5881's? 5881's are not a straight swap for 6V6 tubes. Roscoe - Thanks for the reply. According to Dr. Z, himself, the Z Lux can take a set of "medium grade" Tung Sol 5881s as a direct swap, which is exactly what I did. To wit: I can't speak for all NOS 5881's, but I have installed a quad of medium range TungSol RI 5881, plug-n-play no bias adjust, and they sounded great. Much more Fender like in its tone, like a mini Fender Twin reverb ... sort of. A bit more bite, cleaner overall, and an increase in power. Z Read more: ztalk.proboards.com/thread/72751/5881s#ixzz4jLE1bKIa
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Post by Deleted on Jun 7, 2017 11:09:41 GMT -7
He's the Doctor!!!
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Post by scottunzicker on Jun 7, 2017 14:39:08 GMT -7
Afternoon Update: My amp tech opened up the Z Lux to make sure no damage was done, which there wasn't any (he was concerned about blown resistors). (As an aside, he was very complimentary about the quality of the construction, the neatness of the wire routing, and the overall impeccable quality of the amp. This was his first time under the hood.) He made sure all was in order before replacing the fuse and firing it up. All the power and preamp tubes were fine. He measured all values, and all seems well. At idle, the amp is drawing around 1.8 amps, and, when driven, spiking up to about 1.95 amps. His theory about why the fuse popped last night mirrors mine: When homedude plugged his jankyass guitar in along with a drive pedal and cranked the daylights out of it, it made the Z Lux draw more than 2 amps (the rating on the slo blo fuse) for too long, thus popping the fuse. What do y'all think?
If Mr. Zaite is reading: Would it be advisable or inadvisable to use a slightly higher rated fuse since I'm running 5881s instead of 6V6s? I presume they draw a bit more current.
Cheers!
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Post by Deleted on Jun 7, 2017 17:14:22 GMT -7
Afternoon Update: My amp tech opened up the Z Lux to make sure no damage was done, which there wasn't any (he was concerned about blown resistors). (As an aside, he was very complimentary about the quality of the construction, the neatness of the wire routing, and the overall impeccable quality of the amp. This was his first time under the hood.) He made sure all was in order before replacing the fuse and firing it up. All the power and preamp tubes were fine. He measured all values, and all seems well. At idle, the amp is drawing around 1.8 amps, and, when driven, spiking up to about 1.95 amps. His theory about why the fuse popped last night mirrors mine: When homedude plugged his jankyass guitar in along with a drive pedal and cranked the daylights out of it, it made the Z Lux draw more than 2 amps (the rating on the slo blo fuse) for too long, thus popping the fuse. What do y'all think? If Mr. Zaite is reading: Would it be advisable or inadvisable to use a slightly higher rated fuse since I'm running 5881s instead of 6V6s? I presume they draw a bit more current. Cheers! I would think that's a good thing to do! My JAZ is currently running the same Tung Sol 5881's as you are. BUT, I actually just noticed that the JAZ has a 3 amp fuse!
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Post by Deleted on Jun 7, 2017 17:20:11 GMT -7
This thread is also just a great reminder of why I never let people use my gear unless they're playing my guitar and pedals too.
You never know which guy is going to show up with his Alembic preamp and EMG pickups and start hitting your amp harder than you would normally do. Such delicate situations for us guitarists with nice amps! It can be hard to tell people know but there comes a point you realize the $2000 amp you sweated for to buy is yours and you have the right to tell people NO.
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Post by scottunzicker on Jun 8, 2017 7:28:08 GMT -7
Thanks for the feedback, gents! I'd love to hear from someone at Dr. Z if using a 2.5-3 amp fuse would be a good idea if I'm running the 5881s instead of the 6V6s.
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Post by mudman on Jun 8, 2017 10:52:40 GMT -7
Thanks for the feedback, gents! I'd love to hear from someone at Dr. Z if using a 2.5-3 amp fuse would be a good idea if I'm running the 5881s instead of the 6V6s. Email repairs. They'll let you know really quick
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Post by scottunzicker on Jun 8, 2017 10:59:02 GMT -7
Thanks for the feedback, gents! I'd love to hear from someone at Dr. Z if using a 2.5-3 amp fuse would be a good idea if I'm running the 5881s instead of the 6V6s. Email repairs. They'll let you know really quick Thanks!
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Post by thatstatuemoved on Jun 8, 2017 19:53:40 GMT -7
Lesson learned here--next time tell the guy that wants to sit in to bring his own amp or better yet, tell him no unless he is a friend or somebody you know and trust. I never let strangers sit in however good they say they are, they are usually not. Our drummer let a guy sit in once, and they guy ended up breaking two heads on his drums and split without making any remittance of any kind. Had a guy who I did not know plug into an amp of mine at church and proceeded to blow the speaker. He was there for a wedding and I was not there. I even took my power cord for the amp home with me to avoid such things. Well this guy scrounged around and found a computer cord and fired her up and played through it and blew the speaker. Never heard from him and never found out who it was. Arrrg!!!
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Post by scottunzicker on Jun 12, 2017 8:31:34 GMT -7
Thanks for the feedback, gents! I'd love to hear from someone at Dr. Z if using a 2.5-3 amp fuse would be a good idea if I'm running the 5881s instead of the 6V6s. Email repairs. They'll let you know really quick Well, I emailed them last Thursday, and still no word, unfortunately.
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Post by mudman on Jun 12, 2017 15:49:45 GMT -7
Strange. Maybe give them a call?
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Post by scottunzicker on Jun 13, 2017 7:49:34 GMT -7
Howdy, all. I got a response from the good Dr. Z, himself. He's a great guy that makes an even greater product. His tech lead had, apparently, responded to me last Thursday, but his email must've gotten filtered as spam and I never got it. So their customer service remains STELLAR. Here's the relevant part of his response re: running a higher rated fuse if you're using 5881s instead of 6V6s (in short, the stock 2 amp slo blo fuse remains the recommended part either way):
" 5881’s in a Z Lux with its split load cathode bias and its low plate voltage ( for a 5881 ) doesn’t put out very much more output than the JJ 6V6.
Also the Impedance of the OT is for 6V6’s so full power will not be achieved with the 5881 even if the plate voltage was higher as needed on the 5881.
I did measure 9 ma more per tube on my bench today. And the increase is determined by the gain of the 5881 quad for the most part. A 2 amp slo-blo would be the safest fuse to use.
So basically in the Z-Lux the 5881’s are not run at proper high voltage for them to develop full output. The split load bias is also lower than the bias value for the 5881. And the Plate Impedance of the Out Put Transformer is higher than a 5881 wants to see , again lowering its full output. " So, once again the Good Doctor and his crew come through with great service and great information. Thanks, guys!
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