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

Discussion in 'Amps/Cabs Tech Corner: Amplifier, Cab & Speakers' started by Blueswede, Feb 12, 2005.


  1. Blueswede

    Blueswede Gold Supporting Member

    Messages:
    2,406
    Joined:
    Nov 29, 2003
    Location:
    Sunny So Cal
    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
     
  2. TheAmpNerd

    TheAmpNerd Member

    Messages:
    1,063
    Joined:
    Sep 23, 2004
    Location:
    Tejas
    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.
     
  3. Blueswede

    Blueswede Gold Supporting Member

    Messages:
    2,406
    Joined:
    Nov 29, 2003
    Location:
    Sunny So Cal
    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
     
  4. BPlexico

    BPlexico Member

    Messages:
    529
    Joined:
    Mar 23, 2002
    Location:
    Northern California
    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
     
  5. spyeman

    spyeman Supporting Member

    Messages:
    3,448
    Joined:
    Feb 18, 2005
    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.
     
  6. Blueswede

    Blueswede Gold Supporting Member

    Messages:
    2,406
    Joined:
    Nov 29, 2003
    Location:
    Sunny So Cal
    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.
     
  7. spyeman

    spyeman Supporting Member

    Messages:
    3,448
    Joined:
    Feb 18, 2005
    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
     
  8. BPlexico

    BPlexico Member

    Messages:
    529
    Joined:
    Mar 23, 2002
    Location:
    Northern California
  9. Curt

    Curt Member

    Messages:
    6,995
    Joined:
    Nov 3, 2003
    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
     

Share This Page