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Post by maz8believer on Feb 5, 2022 21:53:52 GMT -7
I purchased a 2012 Maz8 that looks new. Been playing a couple of months through an Air brake with the amp cranked. Great amp. Recently the amp cuts out when volume is up and master volume is over half; and sometimes squels before it cuts out. I tapped all the tubes with a pencil. The V7 Rectifier tube pops when tapped with pencil. Could this tube need replaced, should all tubes be replaced, should I take the amp to Dr Z Cleveland is only two hours away. This amp was shipped from Washington to Ohio. Thanks
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Post by purpletele on Feb 5, 2022 22:06:04 GMT -7
I purchased a 2012 Maz8 that looks new. Been playing a couple of months through an Air brake with the amp cranked. Great amp. Recently the amp cuts out when volume is up and master volume is over half; and sometimes squels before it cuts out. I tapped all the tubes with a pencil. The V7 Rectifier tube pops when tapped with pencil. Could this tube need replaced, should all tubes be replaced, should I take the amp to Dr Z Cleveland is only two hours away. This amp was shipped from Washington to Ohio. Thanks I would replace all of the tubes, and follow the Dr. Z recommendations, especially the rectifier. Changing tubes is really easy on that amp. I bet it will sound better, and 90 % that the squeal was the Power tube especially if it's cutting out. Let us know how it goes
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Post by maz8believer on Feb 6, 2022 6:46:33 GMT -7
Thanks will go to the tube shop and get the recomended tubes
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Post by LT on Feb 6, 2022 7:53:39 GMT -7
Welcome to the forum! Lots of very knowledgeable folks here. Purpletele who answered your question builds amps, so he knows his stuff!
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Post by headshrinker (Marc) on Feb 6, 2022 11:31:45 GMT -7
I'm going to give you a different opinion. Don't change them all at once. Do buy a rectifier, a power tube and two 12AX7s or one 12AX7 and a 12AT7. Then, put in the new rectifier, with crackling and popping I would not trust it. Then put in a new power tube and see if it sounds any better. If not, put the old one back and keep the new as a spare for when it does go. If it's better leave it in and keep the old as an emergency spare and mark it as old. Maybe get another power tube as a good backup. Then start with the 12AX7 and replace the first one and see if it sounds better. if yes it stays if not, old one back in. Continue down the line. Likely all of your preamp tubes are fine. They generally last for years and years. If you sub the 12AX7 for your 12AT7 it's fine, won't hurt anything. Some folks prefer that tube in that position. The idea here is sometimes you get a magical mix of preamp tubes that sound wonderful together. If you change all of the tubes out at once and things go south sound-wise. You don't know how to get it back at that point.
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Post by maz8believer on Feb 8, 2022 20:52:42 GMT -7
Thanks everyone got the tubes in 2 days from the tube shop replaced the originals. Played for four hours love this little amp. So thanks everyone that replied wish I knew about Dr Z years ago. Just wondering now if the MK II upgrade is worth it?
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Post by purpletele on Feb 8, 2022 22:25:55 GMT -7
Thanks everyone got the tubes in 2 days from the tube shop replaced the originals. Played for four hours love this little amp. So thanks everyone that replied wish I knew about Dr Z years ago. Just wondering now if the MK II upgrade is worth it? I believe that the Mk II Upgrades on the Maz 8 improved on the Reverb circuit and lowered the Noise Floor a bit. Based upon the testimonies from this forum, I would definitely get the upgrades. Make what is cool even more cool.
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Post by maz8believer on Feb 9, 2022 20:35:58 GMT -7
Well new tubes went in yesterday played for hours had a great distortion with some nice chime and seperation of notes when playing even bar chords. Tonight started her up let her get to operating temp and hit the standby played perhaps an hour and the amp went completely dead no sound at all. No smoke no smell light is still on fuse is good. The tubes ate all lit and seated. I play this amp cranked on both volume and master through a dr z airbrake and bedroom level. So it is played hard. Any thoughts 😕
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Post by headshrinker (Marc) on Feb 9, 2022 21:29:47 GMT -7
Lit tubes don't necessarily mean they are good. Did you check the fuse with a meter? Sometimes they can look good to the eye but be blown. Once you know the fuse is good and assuming you have your old tubes, put the old rectifier in and see if that fixes things. I know that was the suspect tube in the beginning, but I would try it if I didn't have another. If you have another in another amp, use it. For testing it's okay if it isn't a 5AR4. A 5Y3 or 5U4 will work for testing. If that doesn't solve it, try the old power tubes. If nothing, start with the preamp tube farthest from the power tube and start subbing from there. It's most likely a tube problem. Running the tubes hard shouldn't make any real difference. Some new tubes (and old ones) go quickly. They are sort of like light bulbs, you never know when they will go.
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Post by maz8believer on Feb 10, 2022 8:47:53 GMT -7
Thank you will start substituting tubes tonight
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Post by davebo on Feb 10, 2022 10:39:30 GMT -7
Hi Recently my Maz 8 went silent too. Fortunately it was just a speaker connection that popped loose at the spade.
I had the mod done about 2 months ago. It was great for my amp because currently I play at home lower volumes and the master volume mod allowed me to get much better tone at low volume. Also I requested more gain from the Volume knob which was giving me mostly clean. That was also a success. I’m very satisfied with it.
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Post by purpletele on Feb 10, 2022 12:05:20 GMT -7
Well new tubes went in yesterday played for hours had a great distortion with some nice chime and seperation of notes when playing even bar chords. Tonight started her up let her get to operating temp and hit the standby played perhaps an hour and the amp went completely dead no sound at all. No smoke no smell light is still on fuse is good. The tubes ate all lit and seated. I play this amp cranked on both volume and master through a dr z airbrake and bedroom level. So it is played hard. Any thoughts 😕 Take a look at the speaker wire to make sure it hasn't been burned by a tube. I doubt that is the issue, but you never know. I would clean the input jacks and the Send and return jacks with Deoxit to eliminate that from the possibilities. You should actually scrub the jacks with a light abrasive sandpaper. If I were to take a guess, I would think it could be a loose wire connection, or solder joint in the pre-amp section that is preventing the signal from going forward. That could also be an input jack connection issue.
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Post by Chilly Gibbons (Todd T.) on Feb 10, 2022 13:50:46 GMT -7
Well new tubes went in yesterday played for hours had a great distortion with some nice chime and seperation of notes when playing even bar chords. Tonight started her up let her get to operating temp and hit the standby played perhaps an hour and the amp went completely dead no sound at all. No smoke no smell light is still on fuse is good. The tubes ate all lit and seated. I play this amp cranked on both volume and master through a dr z airbrake and bedroom level. So it is played hard. Any thoughts 😕 Take a look at the speaker wire to make sure it hasn't been burned by a tube. I doubt that is the issue, but you never know. I would clean the input jacks and the Send and return jacks with Deoxit to eliminate that from the possibilities. You should actually scrub the jacks with a light abrasive sandpaper. If I were to take a guess, I would think it could be a loose wire connection, or solder joint in the pre-amp section that is preventing the signal from going forward. That could also be an input jack connection issue. When it comes to cleaning jacks, Dave has a great method using what I believe is a .22 caliber barrel cleaner and deoxit of course.
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Post by daddyelmis (Greg) on Feb 10, 2022 14:11:00 GMT -7
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Post by maz8believer on Feb 10, 2022 16:56:10 GMT -7
Thanks everyone you were correct headshrinker I put the old rectifier tube in and the amp worked. I put the new one in and it didnt. So it was the rectifier tube. Hopefully the tube shop will send me another. Since it says matched on the rectifier does that mean i am going to need two tubes replaced? Would these tubes be the rectifier and an El84?
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Post by Chilly Gibbons (Todd T.) on Feb 10, 2022 17:08:04 GMT -7
Thanks everyone you were correct headshrinker I put the old rectifier tube in and the amp worked. I put the new one in and it didnt. So it was the rectifier tube. Hopefully the tube shop will send me another. Since it says matched on the rectifier does that mean i am going to need two tubes replaced? Would these tubes be the rectifier and an El84? No, it would not be possible to match a recto and a power tube, very different characteristics. Hopefully they will send you another.
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Post by purpletele on Feb 10, 2022 17:52:48 GMT -7
Thanks everyone you were correct headshrinker I put the old rectifier tube in and the amp worked. I put the new one in and it didnt. So it was the rectifier tube. Hopefully the tube shop will send me another. Since it says matched on the rectifier does that mean i am going to need two tubes replaced? Would these tubes be the rectifier and an El84? I have learned that it is best to use the Rectifier recommended by Z, or use an NOS Rectifier. The Maz series of amps have jolt, for the lack of a better description, that requires a beefy Rectifier.
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Post by maz8believer on Feb 21, 2022 20:39:28 GMT -7
Well she is going to the repair shop waiting on the RA from dan from Dr Z. The amp is still cutting out. Thanks for all of the insight
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Post by maz8believer on Feb 21, 2022 20:41:56 GMT -7
This is what the amp is doing
If u care to listen
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Post by premiumplus (Dave) on Feb 23, 2022 5:23:38 GMT -7
Obviously it has an intermittent connection somewhere. Could be a jack, a tube socket, a pot, or a broken solder connection somewhere. Don will get it right, and it'll come back better than new.
The interesting part is that you say it sometimes squeals before it cuts out. I'm real curious as to what the root cause is, please let us know.
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