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Post by eaglev on Oct 21, 2005 9:13:46 GMT -7
Hi, just picked up a used MAZ 18 JR 1 x 12. Everything sounds great, except I'm not getting much volume. Data: (using PRS CE22 with dragon IIs, neck PU on) With the amp volume up all the way and the master at 8 oclock, gutar volume at 4, the sound is clean but at voice level. The sound gradually breaks up when the guitar volume passes 4. At 10 on the guitar we have major breakup (think Van Halen II) but the sound level is low enough in the room I can talk to my wife over it.
Similar results with a Strat and LP.
Great bedroom amp at this point.
Is this normal, a tube replacement issue or something deeper?
thanks
Vin
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Post by Bill on Oct 21, 2005 9:45:10 GMT -7
A friend brought his Maz Jr over recently for the same problem...volume cranked and you could talk over it. Ended up being the 12AT7 pre-amp tube, had a hairline crack in the glass. Popped a new one in and back in bidness! Check all your tubes, most likely the culprit.
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Post by eaglev on Oct 21, 2005 10:48:13 GMT -7
OK,
I just replaced all the preamp tubes with brand new tubes I had on hand. Same volume results though the tone has shifted a bit.
I then swapped out the old EL-84s (GT #7s, one is unmarked) with two new ones (GT #6) I just purchased at GC. The new power tubes actually lowered the volume and produced more distortion. ??
I put the original EL-84s back in.
I'm ready to go buy another full set of tubes, but before this gets more expensive I was wondering if it could be something else??
thx
Vin
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Post by JChance on Oct 21, 2005 11:29:41 GMT -7
If your master is at 8'oclock, then the power amp is hardly on at all! The "volume" is more of a pre-amp gain type of thing, with the master being more of an "output." I would start in "reverse" order and set the amp clean by: 1) Turning the master wide open 2) Using the volume as your "VOLUME" ;-)
And if you want a dirtier sound, gradually turn the master down and the volume up until you reach the distortion and volume level you want.
If that doesn't work, and the MAZ Jr. sounds quiet even with the master dimed, then there is definitely an issue with the amp itself. I always run my master wide open, and use the volume between 12 o'clock and 2 o'clock depending on the room. I've never had a problem with the MAZ Jr being loud enough, and still sometimes have audio guys telling me to turn down! Good luck...
JC
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Post by eaglev on Oct 21, 2005 11:58:39 GMT -7
JC, Thanks for the advice. I did exactly as you suggested, master fully clockwise and started raising the volume from the completely off position while strumming the guitar. The sound became audible at about 9 oclock on the volume knob. The level then grew rapidly, loudest I've heard out of it, but still not what I would call loud. (my 1/2 watt homebuilt Gilmour is still way louder) Then the sound started to intermitently drop out, cutting in and out, as if you had an intermitent connection, but I wasn't moving anything, just strumming. I also detected a mild "phase shifter" type effect in the sound coming out. It was fuzy, then cleared, then fuzzed up again. I think this amp needs to go to a tech. Thx Vin
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rgb
Full Member
Posts: 158
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Post by rgb on Oct 21, 2005 12:26:55 GMT -7
Have you changed the rectifier tube? There have been some issues with them and maybe this is related?
Good luck!
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Post by JChance on Oct 21, 2005 13:04:55 GMT -7
Rectifier could be it....And as elementary as it sounds, the intermittent volume thing with the knob sounds like a dirty/damaged pot. Might be worth a try to completely turn all of the knobs back and forth (all the way off and on) vigorously about 30 or 40 times just to make sure those pots haven't somehow gotten dust/dirt/corrosion in them. Hopefully, there's a simple fix to this whole deal...
JC
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Post by DRZ on Oct 21, 2005 13:19:55 GMT -7
eaglev, does it have an Effects loop? If so jumper it with a short instrument cord, like a pedal board cord in send and return.
Z
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Post by eaglev on Oct 21, 2005 14:13:07 GMT -7
DR Z,
No effects loop on this unit. Just the reverb send and return off the chassis bottom, two inputs and two speaker outs.
Vin
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Post by DRZ on Oct 21, 2005 16:48:33 GMT -7
Well not sure you have a problem. Max the Master control, max your strat's vol. control, set amp Volume at say 11:00 aand it should be a pretty loud 18 watts all three EQ's straight up and cut straight up.
Z
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Post by eaglev on Oct 21, 2005 18:55:36 GMT -7
Tried what you suggested. The sound level is such that we could still have a conversation at normal voice levels in a 10' x 12' room. I could live with the volume like this except for two things; 1. it cuts in an out randomly, not just on off, but also, cleaner than more overdriven, without me doing anything to the guitar controls or the amp. 2. There is no clean headroom at all. If I move the guitar volume knob off the stop there's a small sliver of clean, beyond that it goes directly into heavy crunch. Tried this on a strat, and CE22, same result. Going to bring it to the local tech expert tomorrow. Thanks vin
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Post by billyguitar on Oct 22, 2005 8:19:59 GMT -7
Try it with another speaker?
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Post by squeallydan on Oct 31, 2005 10:37:19 GMT -7
I'm curious as to how this turned out? What was wrong with it?
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Post by eaglev on Nov 18, 2005 7:21:20 GMT -7
Just got it back from the local Tech (Boise Speaker Repair A++ highly recommended).
The amp had a bad Screen Grid Resistor in the power tube section. Bill replaced it and well now we have serious volume.
Thanks to all.
Vin
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