The Dynaco Tube Audio Forum

Dedicated to the restoration and preservation of all original Dynaco tube audio equipment - Customer support for Tubes4hifi VTA tube amp and preamp kits and all Dynakitparts.com products


    Mullard GZ33 NOS tube

    avatar
    ImFritz

    Posts : 48
    Join date : 2017-01-01
    Age : 60
    Location : Redford, Michigan

    Mullard GZ33 NOS tube  Empty Mullard GZ33 NOS tube

    Post by ImFritz on Wed Mar 20, 2019 4:59 pm

    Advice needed,
    Today I received a Mullard GZ33/CV5745 (says British made) rectifier tube for my VTA ST-120 via usps from Upscale audio in california.
    Paid a cool 100 bucks for it. When I carefully unpacked it out of the peanut foam it was in and then in another small box with bubble wrap around the tube. I gently move the tube around and its rattling like a baby's rattle. Is this cause to have any concern or is it normal for this tube.
    I really dont want to install the tube if its defective right off the bat and cause any other damage to the amp. confused

    Thanks
    Fritz
    Brap
    Brap

    Posts : 112
    Join date : 2013-11-28
    Age : 64
    Location : Lisle, Illinois

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by Brap on Wed Mar 20, 2019 5:21 pm

    If I was you, I would give them a call. Rattling does not sound good for a tube.
    cci1492
    cci1492

    Posts : 299
    Join date : 2016-05-09
    Age : 58
    Location : Bergen County NJ

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by cci1492 on Wed Mar 20, 2019 7:41 pm

    I purchased 4 gz33 from the same vendor. They had a nice coating of dust but no rattle. Also, he called me and explained no guarantee at all, even if they blow up upon initial power up. Hopefully you didn't get the same call. When ordering, the checkout process asks where you intend to use the tube, that's how he wound up calling me. He's obviously confused because Ive been using them for about a year without problems. I think he's thinking of those Philips 5R4GYS Holland made rectifiers he was selling a few years ago.
    avatar
    ImFritz

    Posts : 48
    Join date : 2017-01-01
    Age : 60
    Location : Redford, Michigan

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by ImFritz on Wed Mar 20, 2019 7:58 pm

    Thanks for the responses.
    I did call them and spoke with a guy named John. Guess he is their resident guru. He told me it could be a piece of glass. Suspect
    He was nice enough though. Told me to see if I could identify what is was in it. For the life of me I can hear the extremely loud rattle but cant see anything in the tube.
    He told me I could try it in the amp or if I wanted, send it back and he would get me another.
    So what did I do? Yep I rolled it in and tried it. What a Face Well its playing and sounding SWEET! I really dont think it sounds any better than the Gold Lion GZ34
    but...
    My inventory of tubes begins. Now im getting anxious cause Im going down Sat. to pick up my brand spanking new Magnepan 1.7i's. bounce
    Dave_in_Va
    Dave_in_Va

    Posts : 342
    Join date : 2013-04-02

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by Dave_in_Va on Wed Mar 20, 2019 10:30 pm

    Fritz, can you tell me the height of the GZ 33 from the bottom of the base to the top of the glass?
    I have a cover on my ST 70 and want to see if it'll fit.
    Thanks.
    avatar
    New2Tubez

    Posts : 66
    Join date : 2018-03-20
    Location : NY

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by New2Tubez on Wed Mar 20, 2019 10:45 pm

    cci1492 wrote:I purchased 4 gz33 from the same vendor. They had a nice coating of dust but no rattle. Also, he called me and explained no guarantee at all, even if they blow up upon initial power up. When ordering, the checkout process asks where you intend to use the tube, that's how he wound up calling me. He's obviously confused because Ive been using them for about a year without problems. I think he's thinking of those Philips 5R4GYS Holland made rectifiers he was selling a few years ago.

    FWIW, they called me when I ordered my TungSol 5AR4 for my ST120 just over a year ago. I explained that I had Bob's blessing and I did the "yellow sheet mod" which I also explained. It's still working fine a year later. I also passed the info on to Bob at that time. A couple months ago, I wrote a review of the rectifer on their site to try and help un-demonize these amps. At least they are as concerned with a $35 tube as with your GZ33 :P


    Last edited by New2Tubez on Thu Mar 21, 2019 6:31 pm; edited 1 time in total
    cci1492
    cci1492

    Posts : 299
    Join date : 2016-05-09
    Age : 58
    Location : Bergen County NJ

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by cci1492 on Thu Mar 21, 2019 8:49 am

    New2Tubez, when I spoke with kevin I provided links where Bob explained this was a known good fit. His response was he didn't want to be out the dough for the cost of the tubes. Fair enough, if they fail I'll throw them in the trash and call it a learning experience.
    Tubes4ever
    Tubes4ever

    Posts : 136
    Join date : 2015-07-14
    Location : Star, Idaho

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by Tubes4ever on Thu Mar 21, 2019 10:59 am

    Dave_in_Va wrote:Fritz, can you tell me the height of the GZ 33 from the bottom of the base to the top of the glass?
    I have a cover on my ST 70 and want to see if it'll fit.
    Thanks.

    The seated height of the GZ33 is 5 inches. I just measured mine.

    Tim
    slate1
    slate1

    Posts : 54
    Join date : 2017-07-26

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by slate1 on Thu Mar 21, 2019 2:02 pm

    Coincidentally, I also ordered one of these a week or so ago from Upscale.  No call, etc. even though I put that it was going in a VTA ST-120.  

    Unfortunately, I haven't been able to try it out as the matched quad of TAD KT88-STR's I also ordered arrived first and one of them had a dead short that resulted in blowing a 10 ohm 2 watt resistor on one of the sockets.   Sad

    Preparing to send the amp in for the install of the auto-bias board.  TAD KT88's are en route back to the vendor for replacement and we will try this all again!
    Peter W.
    Peter W.

    Posts : 1361
    Join date : 2016-08-07
    Location : Melrose Park, PA

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by Peter W. on Thu Mar 21, 2019 2:36 pm

    I find it rather artful that TAD does emphasize their German heritage, but nowhere mentions that their tubes are made in China by Shuguang. No comment on the tubes themselves - just the marketing.
    Dave_in_Va
    Dave_in_Va

    Posts : 342
    Join date : 2013-04-02

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by Dave_in_Va on Thu Mar 21, 2019 2:41 pm

    For the record, the 5"tall GZ 33 isn't going to fit with the cover installed.

    Thanks for the info.
    cci1492
    cci1492

    Posts : 299
    Join date : 2016-05-09
    Age : 58
    Location : Bergen County NJ

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by cci1492 on Thu Mar 21, 2019 2:47 pm

    I love this tube on the Bob's M125. It plays loud, and honestly, I can't hear a difference in bass or in slam when compared to the copper weber. Between the weber and the Gold Lion GZ34 and a PrimaLuna 5AR4 (Chinese something or other) you have to crank it up a good amount to hear it start compressing the sound a little. At lower volume they all sound about the same, really nice, just a wonderful reliable amp.
    avatar
    Jim McShane

    Posts : 214
    Join date : 2011-10-19
    Location : South Suburban Chicago

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by Jim McShane on Thu Mar 21, 2019 3:47 pm

    ImFritz wrote:Thanks for the responses.
    I did call them and spoke with a guy named John. Guess he is their resident guru. He told me it could be a piece of glass. Suspect
    He was nice enough though. Told me to see if I could identify what is was in it. For the life of me I can hear the extremely loud rattle but cant see anything in the tube.
    He told me I could try it in the amp or if I wanted, send it back and he would get me another.
    So what did I do?  Yep I rolled it in and tried it. What a Face  Well its playing and sounding SWEET! I really dont think it sounds any better than the Gold Lion GZ34
    but...
    My inventory of tubes begins. Now im getting anxious cause Im going down Sat. to pick up my brand spanking new Magnepan 1.7i's. bounce

    Sometimes a piece of cement will be loose inside the base. If that's the case you wouldn't be able to see it but you can probably localize the sound down to the base. If that's what is is there's no harm at all and nothing to worry about. That's fairly common in old stock octal tubes.
    slate1
    slate1

    Posts : 54
    Join date : 2017-07-26

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by slate1 on Thu Mar 21, 2019 4:08 pm

    Peter W. wrote:I find it rather artful that TAD does emphasize their German heritage, but nowhere mentions that their tubes are made in China by Shuguang. No comment on the tubes themselves - just the marketing.

    I just take for granted that any new tube on the market has to be Chinese or Russian.... don't really even think about it anymore. The Shuguang tubes have been especially reliable for me over the years and I like many of the varietals marketed under various brands. This is the first failure I've experienced in a brand new example - I suspect it was damaged in shipping.

    If NOS KT88 and 6550 tubes weren't so blasted expensive, I'd consider them but unfortunately it's just not possible for me.
    peterh
    peterh

    Posts : 1210
    Join date : 2012-12-25
    Location : gothenburg, sweden

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by peterh on Thu Mar 21, 2019 4:45 pm

    slate1 wrote:
    Peter W. wrote:I find it rather artful that TAD does emphasize their German heritage, but nowhere mentions that their tubes are made in China by Shuguang. No comment on the tubes themselves - just the marketing.

    I just take for granted that any new tube on the market has to be Chinese or Russian.... don't really even think about it anymore.  The Shuguang tubes have been especially reliable for me over the years and I like many of the varietals marketed under various brands.  This is the first failure I've experienced in a brand new example - I suspect it was damaged in shipping.

    If NOS KT88 and 6550 tubes weren't so blasted expensive, I'd consider them but unfortunately it's just not possible for me.

    Don't forget EU makers, JJ is one large, several other specialized exists in EU
    JJ has a representative in EUROTUBES.com, a US enterprise.

    avatar
    ImFritz

    Posts : 48
    Join date : 2017-01-01
    Age : 60
    Location : Redford, Michigan

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by ImFritz on Thu Mar 21, 2019 8:39 pm

    Dave_in_Va wrote:Fritz, can you tell me the height of the GZ 33 from the bottom of the base to the top of the glass?
    I have a cover on my ST 70 and want to see if it'll fit.
    Thanks.


    Dave,
    Sorry as I just saw your post. Yes indeed it is 5 inches tall.
    avatar
    ImFritz

    Posts : 48
    Join date : 2017-01-01
    Age : 60
    Location : Redford, Michigan

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by ImFritz on Thu Mar 21, 2019 8:42 pm

    Jim McShane wrote:
    ImFritz wrote:Thanks for the responses.
    I did call them and spoke with a guy named John. Guess he is their resident guru. He told me it could be a piece of glass. Suspect
    He was nice enough though. Told me to see if I could identify what is was in it. For the life of me I can hear the extremely loud rattle but cant see anything in the tube.
    He told me I could try it in the amp or if I wanted, send it back and he would get me another.
    So what did I do?  Yep I rolled it in and tried it. What a Face  Well its playing and sounding SWEET! I really dont think it sounds any better than the Gold Lion GZ34
    but...
    My inventory of tubes begins. Now im getting anxious cause Im going down Sat. to pick up my brand spanking new Magnepan 1.7i's. bounce

    Sometimes a piece of cement will be loose inside the base. If that's the case you wouldn't be able to see it but you can probably localize the sound down to the base. If that's what is is there's no harm at all and nothing to worry about. That's fairly common in old stock octal tubes.

    Jim,
    thanks for the response. I believe you are correct. The rattle sound is coming from the base. I've had it running periodically for two days now and no problems.

    Sponsored content

    Mullard GZ33 NOS tube  Empty Re: Mullard GZ33 NOS tube

    Post by Sponsored content


      Current date/time is Wed Oct 16, 2019 9:49 pm