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Dr. Z burning through tubes

Jess 1971

Silver Supporting Member
Messages
4,023
I have a Dr. Z Maz 18 NR 2x10 combo amp. I've had it for about 18 months now, and while I love the amp, it burns through tubes quickly. I've gone through four rectifier tubes now, and just today I had to replace the EL84s for the third time as well.

I don't play the amp an awful lot, but when I have used it I have cranked it up often, as I've used this mostly for recording. But not really a whole lot of hours on it, and it's just stayed at home in my clean studio.

Is this normal for this amp? I got in touch with Dr. Z, and they got kind of defensive, accusing me of using crappy tubes, gavin faulty electric in my home, not knowing what I'm doing, etc. I got kind of annoyed to be honest. I use good tubes, EHX tubes as per Dr. Z's recommendation.

Anyway, is this common with these amps? The money on new tubes is more of an annoyance than anything else, but I just want to make sure that something isn't wrong that's causing this thing to burn through tubes. I bought the amp brand new from Humbucker Music.
 
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PBC

Member
Messages
607
Are you using a matched set from the middle of the range? I know that Dr Z recommends using a 6 rating.
 

lostpoet2

Silver Supporting Member
Messages
3,291
There is no way you should have gone through 4 rectifier tubes. They typically last for years - for example I've had a MAZ18 since 2008 and only changed the rectifier once because I wanted to preemptively upgrade to an NOS tube for longevity.

You should take your amp to a tech.
 

Cirrus

Member
Messages
2,429
I don't know anything about the amp, but if it's burning through tubes the answer is simple - it's running them too hot, so you should get a tech to bias the power section a little cooler.

The rectifier tube going so often is a concern. That needs to be looked at. Could simply be the afforementioned bias issue, or there could be a problem with the power transformer or filter caps putting too high a load on the rectifier.
 

whoismarykelly

Oh look! This is a thing I can change!
Messages
8,124
You should not be going through rectifier tubes at all. Something is wrong there.
 

Jess 1971

Silver Supporting Member
Messages
4,023
It's frustrating because I reached out to Dr. Z when I first started having problems with the amp, when it was still under warranty. So now I'm going to bring it to a tech and it's going to cost me $100 just to have him take a look.
 

RGB

Silver Supporting Member
Messages
6,257
Mine wasn't quite that bad...and I did gig it...but that's why I gave up and sold it.

It sounded great when I did a re-tube, but that great tone only lasted a short time and then it was a bit disappointing until the next re-tube.
 

S. S. Bender

Member
Messages
2,473
It's frustrating because I reached out to Dr. Z when I first started having problems with the amp, when it was still under warranty. So now I'm going to bring it to a tech and it's going to cost me $100 just to have him take a look.
There is no way your amp should have gone through four rectifier tubes. That is not normal.

The EL84's in mine only sounded good for about six to nine months of regular gigging before becoming "tired" and needing to be changed. Unfortunately, that is fairly normal in a Maz18.

Before you take it to a local amp tech, take another shot at contacting DR Z for help with your situation, and "Kill them with kindness" (and respect) as my wise Grandparents used to say. You might get a better result the second time around.
 
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Peteyvee

Premium Platinum Member
Messages
56,014
Tell him Pete from LA sent you and ask him to send me and Ms Vee some real NYC cannoli. :D
 

jay42

Member
Messages
7,088
The only scenario that makes sense (to me) is that it's biased way hot. I don't know what the rectifier is on it, but as stated, the rectifier should last a long time. Heat and vibration tend to be the problem. There must be too much current somewhere. There may be a factory mis-wire or similar issue.

As an example, I opened a '66 Showman several years ago. There were a couple connections which had never been soldered and one of the totem pole electrolytics was in backwards...and it had been working fine for over 35 years.

Is this amp cathode biased or fixed?
 

GT100

Member
Messages
4,126
6 months for EL84s isn't out of question if the amp is being used for an hour or more every day.

Lloyd
 




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