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Dr. Z burning through tubes

Jess 1971

Silver Supporting Member
Messages
3,981
Except he did and they didn't help him.
Exactly. It was a pretty frustrating series of e-mails.

I haven't really put much mileage on this amp to be honest. I used it quite a bit when I was tracking our latest album, but there have also been several weeks when I didn't even turn it on at all. I have other amps too, which also get some use.
 

DR.Z

Double Platinum Member
Messages
350
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.
Jess if you bought it new like you stated and had it for 18 months
it's still under warranty. Not sure who you talked to that was defensive with you but tomorrow call me 216 475 1444 I can help.

Also there are more then 5000 MAZ 18's build and being used, your problem is not a typical if it was the world would know.
 

71strat

Member
Messages
9,577
6 Months is what is expected out of EL34's ??? EEKS!!! Hour a day. 180 days = 180 Hours ?? NOS Mullard EL34's are only just broken in at 180 hours.

I go for its either Biased to Hot or the Current At The Wall Is To High.

I just had this problem ( WALL CURRENT TO HIGH. and FRIED A $350 GEC NOS KT66. EEEKKSSSSSSSSSSS!

Wall current can Regularly exceed 125 and it did whaere I am and after repeated boughts the tube couldn't take it anymore and Failed. 1 is still good. I hoe. It doesn't rk. Im going to have it tested by Brenden at Tube World.

I just bought a Matched Pair to replace the others and they were $725 dollars.

So wall current is very important to look at. It will run your amp hotter than you realize. Especially if you have an Older Vintage amp as wall current back then was like 115. Now it can and Does Exceed 125v.

I think that is why many Modern tubes fail. They are already compromised in Construction and Materials from the Originals. So they fail MUCH FASTER.

I replaced the Original RCA Blackplates on my 69 Dual Showman 4 years ago because 1 was Mircophonic. I figure I got well over 10,000 hours out of them

Average of 1 hour per day x 365 days in a year x 40 years =14,600 hours.

My Mullard 10M that I have in the V3 of my Metro Amps GMP45 was Guarantted From The Factory for 2 Years or 10,000 HOurs. 24 hours per day for 60 weeks is 10,080 hours at full 100% output. Guaranteed !!!!!

Modern tubes can have as much as 50% Rejection Rate.

Notice I didn't say Failure. They work and that's about as far as it goes.

I would check the Wall Current though.

I also jst ordered a Parts Express 10A Variac with a meter. I will never run expensive tubes straight into the wall EVER AGAIN.




 

jay42

Member
Messages
7,084
Current At The Wall Is To High. [clip]

So wall current is very important to look at. It will run your amp hotter than you realize. Especially if you have an Older Vintage amp as wall current back then was like 115. Now it can and Does Exceed 125v.
PSA I guess. The issue is voltage at the wall, though I kind of doubt it's the problem with this amplifier. Current from the normal US wall socket is going to trip a circuit breaker at 15A or 20A, depending. A guitar amplifier does not draw that sort of current unless something is drastically wrong inside. If the wall Voltage is too high, internal voltages and currents may be too high for specific components. I would expect to see redplating output tubes in this scenario. See what the good Dr. has to say when you call him.

You could buy a Watt's Up from Amazon -- this one is overpriced, btw, so don't buy it
http://www.amazon.com/Watts-Pro-Electricity-Consumption-Meter/dp/B000CSWW92/ref=sr_1_5?ie=UTF8&qid=1412895695&sr=8-5&keywords=watt%27s+up

Otherwise, you can't tell how much current is being drawn.
 

DrainBamage

Member
Messages
2,407
Is the maz really biased with a 68ohm resistor? That thing must eat tubes and sound amazing at the same time.
 

DR.Z

Double Platinum Member
Messages
350
Is the maz really biased with a 68ohm resistor? That thing must eat tubes and sound amazing at the same time.
The four EL-84 MAZ -38 uses a 68 ohm bias resistor.
The two EL-84 MAZ -18 uses a 150 ohm bias resistor.
 
Messages
514
Jess if you bought it new like you stated and had it for 18 months
it's still under warranty. Not sure who you talked to that was defensive with you but tomorrow call me 216 475 1444 I can help.

Also there are more then 5000 MAZ 18's build and being used, your problem is not a typical if it was the world would know.
This is one of the reasons I own 2 Dr. Z amps and am looking for my third - He is fantastic at customer service and I regularly see him helping people on this and other forums. Plus his amps sound bad assed :rockin
 

S. S. Bender

Member
Messages
2,473
6 Months is what is expected out of EL34's ??? EEKS!!! Hour a day. 180 days = 180 Hours ?? NOS Mullard EL34's are only just broken in at 180 hours.

I go for its either Biased to Hot or the Current At The Wall Is To High.

I just had this problem ( WALL CURRENT TO HIGH. and FRIED A $350 GEC NOS KT66. EEEKKSSSSSSSSSSS!

Wall current can Regularly exceed 125 and it did whaere I am and after repeated boughts the tube couldn't take it anymore and Failed. 1 is still good. I hoe. It doesn't rk. Im going to have it tested by Brenden at Tube World.

I just bought a Matched Pair to replace the others and they were $725 dollars.

So wall current is very important to look at. It will run your amp hotter than you realize. Especially if you have an Older Vintage amp as wall current back then was like 115. Now it can and Does Exceed 125v.

I think that is why many Modern tubes fail. They are already compromised in Construction and Materials from the Originals. So they fail MUCH FASTER.

I replaced the Original RCA Blackplates on my 69 Dual Showman 4 years ago because 1 was Mircophonic. I figure I got well over 10,000 hours out of them

Average of 1 hour per day x 365 days in a year x 40 years =14,600 hours.

My Mullard 10M that I have in the V3 of my Metro Amps GMP45 was Guarantted From The Factory for 2 Years or 10,000 HOurs. 24 hours per day for 60 weeks is 10,080 hours at full 100% output. Guaranteed !!!!!

Modern tubes can have as much as 50% Rejection Rate.

Notice I didn't say Failure. They work and that's about as far as it goes.

I would check the Wall Current though.

I also jst ordered a Parts Express 10A Variac with a meter. I will never run expensive tubes straight into the wall EVER AGAIN.
We are discussing the rectifier and power tubes of a Maz18, the latter of which are EL84's, not EL34's. New production EL84 tubes sound great when used in the Maz18. They are not expensive, and supplies are plentiful, unlike most NOS tubes.
 
Last edited:

tubedude

Member
Messages
427
I have little confidence in new production rectifier tubes. Buy a Mullard rectifier and you may never replace it again
 

71strat

Member
Messages
9,577
My bad eyes saw EL34's sorry. EL84 should still last 1000's of hours.


Good NOS Tubes are Plentiful.

I have 00 confidence in any modern tube when it comes down to it.

For a Nice Amp like you have I wouldn't skimp on tubes. Ill never be convinced Modern Tubes are Any Good. Ive had Nothing but trouble with them. Ive had 0 problems with NOS.


Psvane in China has probably the best Modern Production Tubes.

For less than 200 dollars you can get what are arguable the best EL84 you can get at Any Price.

You can also get Great NOS EL84's for 80-100 dollars a Matched Pair.

You can get these at audiotubes.com.

This tube was Guaranteed 2 Years or 10,000 hours from the Factory when new. And that's Guaranteed 100% output and 24 hours a day. 60 weeks is 10,080 hours.





6BQ5/EL84 Mullard 10M Series gold pin, MATCHED PAIR
New old stock, in purple and gold matched pair box. Great 1960s vintage British tube sound, original 10Ms with Blackburn UK Mullard factory codes! The 10M series is noted for excellent sonics, gold pins, and 10,000 hour heater life. A rare pair, since these tubes are so hard to find. Tested and burned in at the factory, with dark marks visible on the inside glass from this. Excellent match confirmed by us.​
$190.00 per pair​
As you can see by my earlier post I use the Mullard 10M Gold Pin 12ax7.​
It was a 500 dollar tube.​
The above is the EL84 version.​
 

UncleLarry

Member
Messages
2,243
You can also get Great NOS EL84's for 80-100 dollars a Matched Pair.

You can get these at audiotubes.com.

This tube was Guaranteed 2 Years or 10,000 hours from the Factory when new. And that's Guaranteed 100% output and 24 hours a day. 60 weeks is 10,080 hours.


6BQ5/EL84 Mullard 10M Series gold pin, MATCHED PAIR
New old stock, in purple and gold matched pair box. Great 1960s vintage British tube sound, original 10Ms with Blackburn UK Mullard factory codes! The 10M series is noted for excellent sonics, gold pins, and 10,000 hour heater life. A rare pair, since these tubes are so hard to find. Tested and burned in at the factory, with dark marks visible on the inside glass from this. Excellent match confirmed by us.​
$190.00 per pair​
As you can see by my earlier post I use the Mullard 10M Gold Pin 12ax7.​
It was a 500 dollar tube.​
The above is the EL84 version.​
You don't have to spend big bank on good tubes. You can get good NOS Russian military tubes for less than $45/pair from Doug's Tubes. I use these in my Mesa Subway Rocket that runs the plates at almost 400 volts. They sound great and hold up really well: http://www.dougstubes.com/power-tubes/el84-6bq5/nos-6n14n-eb.html
 

TheoDog

Silver Supporting Member
Messages
20,108
It is somewhat known the Maz amps go through power tubes a bit quicker than other amps.
My Maz had slightly audible variations depending on wall voltage.

The reaching out comment from the company is all that we needed to see.
Perhaps 1 employee at the company (that fielded the original emails) is still learning the customer service culture.

I am looking forward to the OPs update.
 

Trotter

Member
Messages
6,679
I owned a Maz 18 2x10 and it went though tubes really quick... I even remember replacing the rectifier tube a couple times.

That amp really didn't work for me!
 

Jess 1971

Silver Supporting Member
Messages
3,981
To be clear, I did not post this to bitch about Dr. Z amps or their customer service. I think the products they make are good, and the general consensus is that they are decent, responsive folks. Fair enough. This was my experience when I first contacted them:

I e-mailed them months ago to ask about the problem I was having, as it seemed a little odd to burn through two rectifier tubes so quickly, especially when I didn't play the amp all that much. They responded with a series of questions--i.e., how long have I had the amp, what tubes was I using, did I have a receipt, and did I have the wall voltage in my house checked.

The first rectifier tube that blew was whatever came with the amp. I replaced it with a JJ and that blew about two months later. Dr. Z said that I was using bad tubes, that JJs are inferior. Ok, but what about the tube that came with the amp? Was that bad too? So I figured I'd try exactly what they said and use EHX tubes. Same problem, blew two more of those.

I then got a copy of my receipt and scanned it, and e-mailed it to them. The next series of e-mails I got from them insisted that the electricity in my house was likely the culprit. So I got my electrician to come take a look, but everything checked out fine.

Bear in mind that I've been playing guitar for about 30 years and I've owned a lot of other tube amps along the way, including some nice Riveras, Fenders, Marshalls, etc., and I've never had this type of problem So while I'm not an amp tech, I have an idea of what I'm doing and how to maintain these things. One of the reasons I bought the Maz 18 was that it self-biases, as long as you get a matching set of EL 84s. FWIW, I used the exact EL84s as recommended by Dr. Z: matched set of Electro Harmonix tubes, with a midrange output (I think 5.6 maybe).

Anyway, with all respect to Dr. Z, it just felt like they were doing everything they could to emphasize that the problem must somehow be with the user. The tone of the e-mails just seemed kind of accusatory, which I didn't really think was cool. That said, I do appreciate them coming on board here to offer to help, so I'm not going to fault an entire company for what may have been an issue with one guy. But I just wanted to clarify my experience.

At this stage, I think I'm likely to just bring this thing to my local amp tech rather than go through the hassle of packing up this monster and shipping it to Dr. Z headquarters.
 

Jess 1971

Silver Supporting Member
Messages
3,981
I owned a Maz 18 2x10 and it went though tubes really quick... I even remember replacing the rectifier tube a couple times.

That amp really didn't work for me!
Did you ever have a tech look at it, or did you just unload it and move on?
 

Trotter

Member
Messages
6,679
Did you ever have a tech look at it, or did you just unload it and move on?
I looked at it. It seemed fine other than the fact it ran hot. My BadCat did the same thing too. Some amp makers really push these EL84's... it makes them sound awesome, but as a result, tube life is pretty poor. Why I went through a couple rectifier tubes is still a mystery to me though. If I remember correctly, the 3rd one I installed lasted and was fine...
 

Blue Strat

Member
Messages
30,243
I looked at it. It seemed fine other than the fact it ran hot. My BadCat did the same thing too. Some amp makers really push these EL84's... it makes them sound awesome, but as a result, tube life is pretty poor. Why I went through a couple rectifier tubes is still a mystery to me though. If I remember correctly, the 3rd one I installed lasted and was fine...

If the power tubes are biased to meltdown, this can have a negative impact on the rectifier. When I hear about power tubes AND rectifiers dying this is the first thing that comes to mind.
 

DR.Z

Double Platinum Member
Messages
350
If the power tubes are biased to meltdown, this can have a negative impact on the rectifier. When I hear about power tubes AND rectifiers dying this is the first thing that comes to mind.

The amp is not biased to meltdown.
12.8 watts per tube at idle, a bit over spec but by no means MELTDOWN.
The total currant draw of the two EL 84's is appox. 72 mA , a 5AR4 is rated at 200 mA on the low currant production side, 250 mA if your talking Mullard GZ-34.
 

The Whiz

Member
Messages
6,098
I would like to interrupt this thread by thanking the good Doctor for the Z28 with 10" speakers. Ooh yeah. You may now return to the regular thread currently in progress. :band
 






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