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Dr. Z burning through tubes

jay42

Member
Messages
7,084
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 current production side, 250 mA if your talking Mullard GZ-34.
Mike, this is why I told a story about an old Showman I worked on. It had factory equipped boo-boos and lasted decades that way. What if, for example, a 68 ohm resistor ended up in the 150 ohm bin and no one noticed it? On final test, the amp would have sounded great, so out the door it goes. It's a manufacturer's nightmare. No amount of process can really stop someone from a spaz moment where everything looks perfect.

From your point of view, I can't see asking the OP to open the amp up, poke around, and take pictures...too risky liability-wise. It has to happen somewhere though.
 

Peteyvee

Premium Platinum Member
Messages
56,014
I'm impressed that Dr Z stepped in to take care of it. Go see Blackie with your out of warranty amps... :p
 

JumpMarine

Member
Messages
492
First off I have owned and loved a Maz 18 NR. Second, new production rectifier tubes have been continually found to be mediocre at best for life span. Drop an NOS one and forget about it. The Maz does eat power tubes, it's the nature of the beast and it's worth it because of how cheap they are to replace.
 

Blue Strat

Member
Messages
30,243
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.

Yes, but all of your amps don't do what the OP's amp is doing, so I'm suggesting that something is probably wrong related to the bias (cap leaky, wrong resistor, etc). Otherwise this thread probably wouldn't exist. ;)
 

drpoyer

Silver Supporting Member
Messages
627
I don't have any Z's but I know many players here in cleveland that use the Maz and have tube issues (mostly power tube). i am not exactly sure what is going on but I have heard higher than average wall voltage, bad tube batches and premature failure of components in the power section. As this is not a not a completly uncommon problem I check the wall voltage and send the chasis to Z for a check up.
 

Jess 1971

Silver Supporting Member
Messages
3,981
Hi, I saw DrZ's last post and he was also kind enough to reach out to me directly. I'm going to remove the chassis from the cab and ship it back to him to take a look. Thanks again for the advice. And thank you to Dr. Z for going out of your way to resolve this directly. All good.

Cheers,
Jess
 

Jess 1971

Silver Supporting Member
Messages
3,981
I got a nice big package of complementary NOS tubes and fuses from Dr. Z last night. I really appreciate you doing that. Thanks a million.
 

Kiwi

Silver Supporting Member
Messages
4,086
I got a nice big package of complementary NOS tubes and fuses from Dr. Z last night. I really appreciate you doing that. Thanks a million.
That's the Dr Z kind of customer service we've known for decades! :beer
 






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