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Post by Deleted on Apr 17, 2006 22:02:18 GMT -7
Hi guys, I am new to the board. Last week I purchased a Maz Jr. combo with reverb. I had been playing it at my parents house for a few days and it was great, no problems at all. Tonight I played it at my apartment and all was well untill I cranked the reverb. At around the 12 o'clock position, any sound made from the guitar would initiate a strange feedback that started as a pulsing feedback and eventually settled into a steady hum that gradually grew in volume. Concerned, I began experimenting. With the guitar unplugged and the reverb fully cranked, the afformentioned feedback would begin all by itself, with no guitar signal to provoke it. Interestingly enough, when I picked the amp up and held it in the air, it would cease, and input from the guitar would no longer initiate the feedback. Having the reverb fully cranked would not start it either. As soon as it was back on the ground again the problem reared it's head. So what do you guys think? Could this be related to the apartment below me? I turned off all electronic equipment in my room to see if any of it was causing the problem and the problem still occured. This problem never happened at my parents home. So what do you guys think? Oh yea, btw, the feedback occured with both the master volume and volume controls at zero, and when the reverb was fully cranked there was a noticeable hiss. Thanks guys!
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Post by JASON (aka jgleaton) on Apr 17, 2006 22:33:24 GMT -7
Hey Mattman,
Welcome to the forum, Sorry it had to be over a problem though... Don't know if I'm the one that can really help you with this but their ARE some guy's that can... I guaruntee it! So hang in there... Questions:
Did you buy it New or Used? Is the Reverb working AT ALL under 12:00... and without feeding back? Is the Reverb (if working) a real deep and strong reverb early OR is it a light verb/ slowly gaining depth and still not real strong at 12:00 just before feedback...
You may need to start by checking the Reverb driver tube to see if it's microphonic/ bad? Also check the reverb cables (probably rca) and may need to check the pan check ALL the tubes... ESPECIALLY if you bought it USED!!
Well thats a start... some others more knowledgable than I may chime in with better and more specific ideas about what your problem is...But
To ease your mind... I had a problem with my verb on my MAZ 38 too... I bought it used and I ended up after trying everything I could just sending it back to DRZ and he fixed it right up, didn't charge me much at all and even CALLED me about it!! it WAS NOT UNDER WARRANTY and he didn't have to do that...
guess what I'm trying to relay to ya is to try some of the advice you'll get on the forum or from Doc if you contact him 1st... and then, worst comes to worst..send it back to Doc and he'll fix it...
if you bought it NEW then you need to let your DEALER know for the Warranty... if used... you'll have to pay, but mine wasn't much at all and has worked fine ever since...sounds great. good luck and hang in there...
Z-BEST CuSTOMER SERVICE.... ;D
Jason
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Post by Deleted on Apr 18, 2006 11:09:58 GMT -7
Thank you for replying jgleaton. I bought the amp brand new from MAE music in Davie, FL. The amp had only been there a day or two, and had only been play tested once by the sales manager. The reverb does indeed work under 12:00 AND without feeding back. The reverb is a real deep and strong reverb. I've been in contact with the doc and he said to try changing out the #3 and #4 tubes. My concern is replacing them with the correct tubes. I will try to check the reverb cables. Where are they located? Also, any explanation for the lack of feedback when the amp is not touching the ground (suspended by my arm)? I really am dying to start recording with this baby as soon as I get this stuff straightened out!
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Post by billyguitar on Apr 18, 2006 11:34:29 GMT -7
If the reverb works don't worry about the cables. If they were a problem you'd hear buzzing or no reverb at all. Change out the tubes, that's the first thing to try. It just sounds like one is microphonic.
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Post by Deleted on Apr 18, 2006 17:55:09 GMT -7
Thanks guys, at the suggestion of the doc I checked all the cables to make sure they were all connected properly, and they were. I took them out and put them back in (im a little OCD sometimes). Oddly enough, when I turned the amp back on and tried it out the feedback ceased. Cranked the reverb all the way up, nailed some open chords and no feedback! tried every possible scenario to get it to happen again, and it did not show up again. Could it be that the cables were the problem, or should I change out the #3 and #4 tube anyways as the doc suggested? If so, what are a good set of replacement tubes to go with? I believe the Maz Jr. is "self biasing", so I do not think that will be an issue. Thank you so much guys!
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Post by JASON (aka jgleaton) on Apr 18, 2006 23:58:02 GMT -7
Mattman,
Hey that sounds great maybe they just got knocked around a little and were loose?? One more thing just in case... when you have played it.... how long did you play it.... just to make sure (I'm OCD too) try this,
turn it on and let it get good and hot, and not just on standby but play it for a while also... then try turning the reverb up and see after it warms up and gets hot that one of the tubes is not warming up and ringing still?? just to double check and make sure your outta the woods....
if it's not ringing then your probably OK... maybe just the cables? but if it starts ringing again now or on down the line... check the tubes first. it IS self biasing/ cathode biased... the el-84 power tubes just need to be a matched pair/ set and you don't have to worry about the pre amp tubes/ 12AX7's cause you don't bias them anyway...
just to check if it ever does start ringing it's MOST likely a tube.. just change out with a 12AX7 you KNOW is good and see if it stops ... if it doesn't, try the good one in another position and so forth (being that you were having the problem with the reverb you would start by changing the reverb tubes, I'm thinkin theres 2.. driver and recovery?) **Don't worry about the proper replacement tube to do the check with just make sure it's the same KIND of tube (12AX7 or EL-84)and it's a good one....find the problem tube, THEN replace the problematic one with the one that suits your style for that particular tube position... really just simple trouble shooting...
ALSO, and this is important... Myles in the experts section on this forum is with the SAG group at Groove Tubes and you can ask him ANY tube related question in his section and he will answer you and you can take it to the BANK!! he KNOWs what he's talkin about (unlike myself). If you order from Groove Tubes you can add a note to Myles in the note section, tell him your from the Z forum and he'll hand pick the tubes for YOUR MAZ 18 cause he's familiar with and has EVERY Z amp himself... he may have EVERY AMP?
anyway, he can hook you up, and if your looking for NOS tubes like old Mullards and such... you can ask MIKE from KCA on the forum also in the experts section... he deals in NOS tubes and can help you with those when your ready to try the NOS stuff (great in DR Z amps btw)...
if you find a set of tubes that you like through Myles or elsewhere, go ahead and get a spare set of them after you make sure you like all of them and how they affect the sound of your amp (can REALLY shape YOUR tone with different TUBES and Speakers also) AND it's always good to have spares handy and then if one goes bad (at a gig!! worst possible moment..) you can immediatley replace with the exact same tube...and if you get it from myles it'll really be close to the exact same tube! good luck and I hope we helped... I'd see Myles for my tubes if I were in doubt... he's the man!! ;D
Jason
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