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Post by premiumplus (Dave) on Jan 2, 2015 4:51:19 GMT -7
Hey all, My Maz 8 is a 2014 build, and it shipped with a 12AU7 reverb driver tube. I've seen other guys say that theirs uses a 12AT7, and there was a thread about changing the 12AT7 over to a 12AX7A to give the amp more balls. So I'm curious as to what your amps use for V3. The reason I'm asking is that yesterday I was thinking about selling my Maz 8. As much as I wanted to, I've never really connected with that amp. I didn't smile when I turned it off like my other Z amps. I've tried new tubes, NOS stuff, and it just wasn't happening. Then I saw the thread about V3 in the Answers (Resolved) section of Z-Talk, and I changed V3 to a 12AX7A. Holy Amplifiers, Z-Man! The heavens opened, the angels sang, and I got a big grin on my face...it completely changed the character of the amp. So try this out if you've got some tubes laying around and you're bored. Different 12Axxx7 tubes have different levels of gain, and here's a list showing the gain factor of different tubes if you're interested. Think of it in terms of percent of gain with the good 'ol 12AX7A at 100%. 12AX7 100 12AT7 60 12AY7 45 12AV7 41 12AU7 20 So we can see what a huge jump in gain it is from 20 to 100. The amp sounds incredible now, and I'm curious as to why Doc went with such a low gain tube. Maybe the reverb was too swampy with the higher gain tube; I don't know. I don't personally use reverb, and I have not done a before and after comparison about the effect of the tube swap, but the reverb is really wet by 10:30 or so! And by the way, my Maz 8 isn't for sale. It's a great thing when you can turn off your amp and feel great, isn't it?
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Post by premiumplus (Dave) on Jan 2, 2015 17:35:48 GMT -7
Anybody out there?
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Post by Jaguarguy (Mike) on Jan 2, 2015 17:43:46 GMT -7
I think everyone is still recovering from the holidays!
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Post by digs57 on Jan 2, 2015 17:45:23 GMT -7
im using the nos jan at7...quieter reverb...it is a 18 but yeah I like less noise.
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Post by Eddie on Jan 2, 2015 17:52:38 GMT -7
I believe the V3 tube has an effect on the tone and feel of the MAZ even when the reverb is fully off. I have a MAZ 18 and mine seems to change tonally when the V3 tube is messed with. I have tried a few in that spot for fun, but I always end up back at a 12AT7, which is what I have in mine now.
Glad you are digging the amp! Ed
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Post by BritInvasion on Jan 2, 2015 18:07:09 GMT -7
NOS 12AT7 in mine. I briefly tried a AX7 but it was too microphonic. I think it may be a sensitive position. In some reverb circuits a 12AT7 is needed , as it puts out much more current than the AX7. But if it works for ya , I say go for it.
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Post by doctorice on Jan 3, 2015 8:35:51 GMT -7
Tube chart in my 8 shows 12AT7, and that's what it's got.
My 8 is -- so far, knock wood -- very quiet with the stock AT7. Put a NOS AT7 in the MAZ 18 to replace a current-production tube that had gone bad. Made an audible difference.
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Post by Jaguarguy (Mike) on Jan 3, 2015 8:47:11 GMT -7
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Post by premiumplus (Dave) on Jan 3, 2015 11:08:53 GMT -7
Thanks, I'm going to try a variety of different tubes. It seems like the Maz is quite sensitive to tube changes. Looks like everyone else is using AT7's...I wonder when Doc made the change to AU7, and why....the diff is night and day.
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Post by BritInvasion on Jan 3, 2015 11:14:53 GMT -7
Thanks, I'm going to try a variety of different tubes. It seems like the Maz is quite sensitive to tube changes. Looks like everyone else is using AT7's...I wonder when Doc made the change to AU7, and why....the diff is night and day. I seem to remember reading somewhere it was changed in an effort to reduce noise in the reverb.
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Post by doctorice on Jan 3, 2015 11:31:46 GMT -7
Thanks, I'm going to try a variety of different tubes. It seems like the Maz is quite sensitive to tube changes. Looks like everyone else is using AT7's...I wonder when Doc made the change to AU7, and why....the diff is night and day. I seem to remember reading somewhere it was changed in an effort to reduce noise in the reverb. So if you like the push from the 12AX7, then a decent NOS 12AT7 may be a good midpoint between the gain of the AX and the noise reduction of the AU.
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Post by Dan F"i"fe on Jan 3, 2015 15:36:52 GMT -7
Mine has the AT7 as well. It's a JJ, the power tube is a Russian and the rest are Sovteks. It's probably getting time to replace them...
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Post by premiumplus (Dave) on Jan 3, 2015 16:03:34 GMT -7
I tried a bunch of 12AT7 tubes I have on hand, and settled on a nice sounding RCA. Sounds great. It makes a big difference between that one and the 12AU7 that came with the amp. It sounds bigger, more authoritative. Me likes!
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Post by premiumplus (Dave) on Jan 4, 2015 6:27:40 GMT -7
NOS 12AT7 in mine. I briefly tried a AX7 but it was too microphonic. I think it may be a sensitive position. In some reverb circuits a 12AT7 is needed , as it puts out much more current than the AX7. But if it works for ya , I say go for it. Exactly right. The 12AT7 has 60% of the gain a 12AX7A has, but it has way more current in milliamps. I'm going to put some on my tube curve tracer and compare against one another. The curve tracer is a great tool that traces the actual tube's Transfer Function (and other characteristics) at different grid and plate voltages...where my Hickok 536 tests at one voltage 'setup' on the tube, the curve tracer sweeps the voltages (user specified, very cool) that the tube functions with and gives a set of curves on a graph that is comparable to the data sheets that tube manufacturers publish. If anyone's interested, the one that I have was built from a kit produced by a Phillips engineer and university professor in the Netherlands. It's called the uTracer (Microtracer) and it's computer driven and very, very cool. Here's a link to his website: www.dos4ever.com/uTracer3/uTracer3.html No affiliation here, I'm just a satisfied nerd that has always wanted a tube tracer, but they haven't been made in years and the ones that are out there are very expensive. Plus, they usually need repair and or calibration. I did a lot of research and went with this kit, which is very well done. It definitely is not for a beginner, but if you know electronics it's a great alternative to a vintage unit. I've not completed the project yet, but the board is up and functional for a few tubes that I hard wired sockets for...
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Post by Stephen on Feb 8, 2016 21:39:50 GMT -7
I've got a 12AU7 on the way.
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Post by Stephen on Feb 10, 2016 21:24:55 GMT -7
The 12AU7 is definitely quieter.
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Post by purpletele on Feb 10, 2016 23:19:58 GMT -7
NOS 12AT7 in mine. I briefly tried a AX7 but it was too microphonic. I think it may be a sensitive position. In some reverb circuits a 12AT7 is needed , as it puts out much more current than the AX7. But if it works for ya , I say go for it. Exactly right. The 12AT7 has 60% of the gain a 12AX7A has, but it has way more current in milliamps. I'm going to put some on my tube curve tracer and compare against one another. The curve tracer is a great tool that traces the actual tube's Transfer Function (and other characteristics) at different grid and plate voltages...where my Hickok 536 tests at one voltage 'setup' on the tube, the curve tracer sweeps the voltages (user specified, very cool) that the tube functions with and gives a set of curves on a graph that is comparable to the data sheets that tube manufacturers publish. If anyone's interested, the one that I have was built from a kit produced by a Phillips engineer and university professor in the Netherlands. It's called the uTracer (Microtracer) and it's computer driven and very, very cool. Here's a link to his website: www.dos4ever.com/uTracer3/uTracer3.html No affiliation here, I'm just a satisfied nerd that has always wanted a tube tracer, but they haven't been made in years and the ones that are out there are very expensive. Plus, they usually need repair and or calibration. I did a lot of research and went with this kit, which is very well done. It definitely is not for a beginner, but if you know electronics it's a great alternative to a vintage unit. I've not completed the project yet, but the board is up and functional for a few tubes that I hard wired sockets for... Dave, I hope your feeling ok. The link for the U tracer didn't work. I am geeky enough to be interested, can you PM a fresh link
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Post by dergit (Markus) on Feb 15, 2016 9:53:49 GMT -7
Good to know... I barely use the reverb (it's set to 8:30 ish) and mine came with an AT7. Maybe AU7 would be a good idea.
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