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Post by larryz on Mar 27, 2020 14:56:54 GMT -7
Hi Ztalk -
I've had my Maz18NR back with the MV MarkII mod for a few months now and have FINALLY been able to tap into more of what the Maz has to offer at living room volumes. Yahoo!
But recently some of the "magic" seems to be missing. The power tubes are the new spec, but I'm still on the original (10 year old) pre-amp tubes. I'm thinking that the reason the tone sounds a bit harsh and seems to break up very early is that I've possibly worn out the pre-amp tubes?
Any ideas? Thanks!
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Post by pcns on Mar 27, 2020 15:08:54 GMT -7
10 years is a good long time but not unusual. Are any of them going microphonic?
V1 seems to get most of the work so you might start there. As long as you changing maybe pick up a couple of different brands and have a little shoot out between them.
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Post by larryz on Mar 27, 2020 15:31:21 GMT -7
Thanks for the suggestion! I can start with V1. Silly question, maybe, but how can I tell if it's going microphonic?
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Post by purpletele on Mar 27, 2020 15:39:53 GMT -7
Thanks for the suggestion! I can start with V1. Silly question, maybe, but how can I tell if it's going microphonic? You can tap the tube with a pencil when the amp is running. If the tap sounds like it extends through the amp circuit then that is sort of the description of Microphonic. Definitely pick up new tubes. I would look at the Z website and get the exact tubes recommended for your amp. Hope it works out
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Post by larryz on Mar 27, 2020 15:43:16 GMT -7
Thanks for the suggestion--looking it up now.
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Post by steiner on Mar 27, 2020 15:51:21 GMT -7
I've noticed non-harmonic distortion when digging in. V1 replacement has cured a good portion of the noise.
Rather than buying many different tubes, I buy multiples of the same and try them all across V1. I've also been testing 5751 and 12AT7 tubes to see how the amps respond.
With time on my hands, this has been a very informative exercise and helpful experiment.
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Post by purpletele on Mar 27, 2020 18:19:43 GMT -7
I've noticed non-harmonic distortion when digging in. V1 replacement has cured a good portion of the noise. Rather than buying many different tubes, I buy multiples of the same and try them all across V1. I've also been testing 5751 and 12AT7 tubes to see how the amps respond. With time on my hands, this has been a very informative exercise and helpful experiment. I have a Maz 38 Mark II and I'm not sure what I have in there but I remember the 5751 was real smooth in my Maz 18.
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Post by zpilot on Mar 27, 2020 21:10:17 GMT -7
The phase inverter is probably the hardest working tube in the amp, especially since it has a post phase-inverter master volume. Use a Sovtek 12AX7LPS as the replacement. I believe that is what Doc has used for quite some time. I would replace both that and V1.
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Post by walt on Mar 28, 2020 5:22:48 GMT -7
This thread is why this forum is great,I always read troubleshooting threads,even if I don't own that amp,because there is always bits of info to use.
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Post by easyed on Mar 30, 2020 16:15:47 GMT -7
V2, the cathode follower is another tube that runs voltage higher than any preamp tube other than the PI. Get a fresh 12AX7. JJ's are factory spec but I like the current production Svetlana for V1 and V2. Try the new tube in V1 first and then in V2. Replacing the PI with the factory spec Sovtek 12AX7 LPS with balanced halves is a good idea; recommended by several sources for replacement when power tubes are changed.
Do the changes one at a time. If you don't detect an improvement, then you'll have a spare. Always a good idea to have a spare set.
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Post by GuitarZ on Mar 30, 2020 18:34:55 GMT -7
Don't know if this is helpful, but every now and then I'll plug into my amps here at home, and it feels like I'm missing some magic. I'll typically then switch from my Maz Jr to Ghia or visa versa and be happy. I'll switch back a few days later and be happy.
I'm only sharing because my home setup really doesn't change. I have my IsoCab piped up to my studio into my headphones, my amp settings don't change much, volumes not changing, and I only have my Les Paul and Strat. So, nothings changing, everything is stable, but I feel something is missing.
So, another option is to give it a rest for a few days and see if the magic's there when you get back.
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Post by premiumplus (Dave) on Mar 31, 2020 17:35:58 GMT -7
Your power tubes are good? Then change the phase inverter first, then V1, V2 etc. If it's got reverb, the reverb driver tube works hard as well.
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Post by larryz on Apr 13, 2020 21:18:34 GMT -7
Thanks to everyone for sharing their experience and knowledge. I seem to be back in the magic with no tube changes--sometimes coming back after some time and a different instrument and the journey starts again--I'm now discovering the "CUT" knob in the 9 o'clock position! Who knew?!
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Post by John on Apr 15, 2020 3:42:06 GMT -7
Maybe you need a new guitar? Maybe you need 5 new guitars?
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Post by T-R☼CK ♫ on Apr 15, 2020 11:21:18 GMT -7
You'll know.
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