Dr. Z tube layout.........

Blueswede

Platinum Supporting Member
Messages
2,644
I went on to the Dr Z site to get the tube layout for my Maz Jr. Am I correct in assuming that the tube list he gives is in the correct order from right to left as you look at the back of the amp? I just want to be correct in replacing some of the preamp tubes. Steve
 

TheAmpNerd

Member
Messages
1,056
When in doubt,
call them out.

(216) 475-1444

Do the email thing.
drz@drzamps.com

However, if I recall, don't they have tube
charts in them? Have you looked
inside the cab and found it?

The following:

Power Output: 18 Watts
Output Tubes: 2 - EL-84
Preamp Tubes: 4 - 12AX7, 1 - 12AT7
Rectifier: 1 - GZ34

If I recall are not all in one row.

So if you look at yours, stick the
12AT7 where it should go (thinking
to the left as you stated) with
the 12AX7s to the right.

Get a shapie and write it next to the
tube socket so you won't forget.

Good luck, you'll figure it out.
 

Blueswede

Platinum Supporting Member
Messages
2,644
My amp does not have a chart inside. I have other amps that do, but not this one. I did email Dr Z and the response was not very clear. How do I know which socket is V1, V2, etc? The tubes are all in a row, with the power tubes on the left as you look at the back of the amp. I think I'll just do some experimentation; I picked up a couple of 12at7s today to replace the one in the Z. I'm sure I'll figure it out at some point. Thanks for your help. Steve
 

BPlexico

Gold Supporting Member
Messages
813
I don't have a MAZ JR, but typically the V1 tube is the pre amp tube farthest from the power tubes. The 12AT7 is probably for the phase inverter and would be the fifth pre amp tube (v5).

Thus if the lay out is as you say, the pre amp tube to the far right is V1 and as you move left they increase in number (v2, v3, etc...)

-- Barr
 

spyeman

Senior Member
Messages
3,615
I just bought a mint but used Maz Jr. 18 head via Ebay. I love the clean sounds, but I'm not getting much drive when cranked. I got no tube layout or owners manual. I thought maybe the tubes were old, so I looked at the Dr. Z site and saw the tube specs. I sent them an e-mail, and they indicated that the phase inverter is the tube next to the power EL34's, and that V1 and V2 (the furthest away from the EL's) will give me the most sonic change if I want to experiment. What was interesting is that the Dr. Z guy who e-mailed me back (didn't give a name) said I should have a different tube in the phase inv. slot than appears on the web site. He recommended a Sovtek AX7 LPS versus the 12AT7 that appears on the site.

Anyhow, I'm interested in hearing if others have tried other tube types in their Dr. Z and how they have sounded. Like I said, I love the clean sounds but I play lead and I'm not getting enough bite or sustain for leads, so I'm looking into boost and OD pedals.
 

Blueswede

Platinum Supporting Member
Messages
2,644
According to a schematic that was emailed to me, the phase inverter is in the v5 slot, and it takes a 12ax7. The reverb driver is in v3 and it takes the 12at7. If anyone wants to chime in regarding changing some of the ax7 tubes for other preamp tubes and the results they have gotten, it would be appreciated.
 

spyeman

Senior Member
Messages
3,615
Blueswede, I've looked at your posts and other threads, seems like you are doing the same thing I am - trying to get the "facts" on the positioning of the Maz Jr. tubes and also to see if anyone has found better/different results from experimentation.

Interestingly, when I look at the back of my amp, the power tubes are on the right and the pre-amps are on the left. I have a reverb head. The e-mails I received from Dr. Z indicated that the phase inverter should be in V5, next to the EL34's, and should be a Sovtek 12AX7 LPS, which I have found to exist at a couple of tube sites. Strangely he said he did not recommend a 12AT7, that he had only used them in a MAZ 38, older versions. Your schematic indicated the 12AT7 goes in V3 for the reverb. Tough to know what the heck to believe.

Anyhow, I plan on researching and then shopping for some tubes to experiment. I'll let you know what I find out. I did see in an earlier thread that Tesla El34's provide a bit more bite and gain, which is what I'm looking for. As mentioned before, I play lead, and while the Jr. is currently great for our clean tunes or even rock chords (when cranked), I need more bite and sustain for leads, thus I'm investigating new tubes and also pedals and such.

If you wouldn't mind, would you e-mail me the schematic you received on the Maz Jr, at spyeman@yahoo.com? I'd really appreciate it, I find that exchanging this kind of info is what really makes progress in the search for that perfect tone! (which is pretty much already there in the Z!) Thanks, Steve
 

Curt

Member
Messages
6,974
Originally posted by Blueswede
According to a schematic that was emailed to me, the phase inverter is in the v5 slot, and it takes a 12ax7. The reverb driver is in v3 and it takes the 12at7. If anyone wants to chime in regarding changing some of the ax7 tubes for other preamp tubes and the results they have gotten, it would be appreciated. [



The layout that I E-mailed to you applied to a Maz 18 head.

I tried a new (unused) Telefunkin 2AX7 in V1 but I ended up using a new Mullard instead. The Tele was a tad too bright. It was beautiful sounding..but a little too bright for my taste. I also removed the sovtek (V5 PI) and replaced it with a GT 12AX7M. That made it sounds a lot better when driven hard.

Curt
 




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