|
Post by franksb on Nov 9, 2011 12:21:55 GMT -7
Hi Everybody! Today I discovered some strange things with my EZG Head! It is very similar to the problem baddaddy posted here (Title: Screaming over 2 o'clock). When i set the Post around 12 o'clock (or higher) and the Pre over 3 o'clock i get a super loud and high whistle. It's really loud!! Like a super high, loud feedback. It stops immediately as i turn it down a bit. It's like pushing a button, on off on off... (over 3, under 3...) When i have tha post way down, i can turn the pre more up without having the whistle. Sorry, i try my best to describe it... This is what i tried to do: Ich pulled all the preamp tubes and changed one after another. Switched the amp on with every new tube, problem still there. I put in all new preamp tubes, problem still there. I changed the rectifier tube, problem still there. The only thing i didn't change are the 6L6's, cause i didn't have any new ones around. The amp is 3 years old, still all stock tubes (Svetlana winged C's 6L6). I noticed one thing: When you take a close look at the powertubes (amp ready to play) you see a very light blueish glow (which is normal). When I turn the pre over 3 o'clock and that awful whistle starts you see this blue-glow start to flicker. So you think it's a problem with the 6L6's? I don't have any other problems with the amp - i love it. Never play that loud so i never noticed this weird thing before. You guys think i need new power tubes? As is said, the amp still sounds ok to my ears... I don't want to take it to the german dealer, had some bad experiences there... Thanks a lot!! Frankie
|
|
|
Post by bluegroove99 on Nov 12, 2011 8:48:20 GMT -7
I'd get a new pair of matched 6L6's and get the amp biased with the new tubes in place.
|
|
|
Post by hywelg on Aug 25, 2012 14:53:02 GMT -7
Did you get this resolved Frankie? I discovered mine does the same. I normally run pre at 1:00 and post around 9:00 to 11:00 and i was experimenting with pre at max and post at max (but not at the same time ) and with the pre at max when i turn the post up to about 9:00 i get the feedback/oscillation. Turn the pre down a bit and it goes away, turn the post back up and its there again. Tested the tubes to see if any were microphonic, they weren't. 6L6's are fairly new =C='s. I went out to buy some new preamp valves but it being Saturday and a Bank Holiday weekend here in the UK, www.hotroxuk.comhad closed early, so no joy. Will try again next week. I very rarely get chance to turn the volume up so loud that this feedback starts, and it can be prevented by backing off a little, but I'd like to get to the bottom of it none the less.
|
|
|
Post by franksb on Aug 26, 2012 5:22:50 GMT -7
hi!
thanks for your comment! good to know that someone has the same problem!
in fact i didn't solve it. like i wrote on the top of teh page, i tried everything that came to my mind. except taking it to a repair shop! like you said, i don't play the amp completely cranked up, except for recording maybe. so i have to admit i just kept it like it is... and i have some other amps that i use...
would love to hear from you if you somehow find out whats wrong!
thanks!
frankie
|
|
|
Post by Frankie Starr on Aug 26, 2012 23:52:59 GMT -7
I had something like this for a while....I used to give it a little (hard) tap on top and it would go away ! I would try to re-seat the reverb cables, maybe spray them with contact cleaner.....does it make any difference if the verb is up or off? I'm sure the boys at the shop will fix ya up.....
|
|
|
Post by franksb on Aug 29, 2012 13:35:28 GMT -7
Thanks guys!
Yes, i'm pretty sure it's not a tube issue! I think the best is to take it to a repairman... but right now i don't use it that much. i guess thats why i didn't do ii already!
thanks for your held frankie! i will try the tap on op and the reverb cables for sure! i don't think it makes any difference if the reverb is up or off, but i will check that!
|
|
|
Post by poipounder57 on Aug 30, 2012 1:10:29 GMT -7
My EZ had the same problems as yours. It turned out to be issues with the grounding. You should email the friendly folks at Z Amps...Don was very helpful. I'm no amp tech but I did some easy mods and repairs to some of my amps. Don was able to help me do the repairs needed. Now I can crank the volume on my EZ and no feedback problems.
|
|
|
Post by thecryingstrat on Oct 23, 2012 9:16:13 GMT -7
I have the exact same problem. It seems it´s a common ezg50 bug. I have the high pitched sound, and the sub sonic low noise. Someone around here, named the two, also. I wonder if it´s something that happened on the first run amps. Mine is a 2009 build.
|
|
|
Post by franksb on Oct 28, 2012 5:29:39 GMT -7
Thanks for the comment!
Seems like a common problem then! Weird, because it wasn't there when i bought the amp! The problem came recently! I'll bring it to a tech next week...
|
|
|
Post by ncguy66 on Oct 28, 2012 13:58:10 GMT -7
I also had this same problem with my EZG-50 head. I spoke on the phone with Dr.Z (himself) about a year ago, he told me it was probably a grounding issue. I can't remember every detail of the conversation, but basically he told me.... it's an alumium chasis and once the amp heats up and expands if there is any break or separation in the grounding it could cause this issue to happen. Everything is grounded to the chasis. He told me before I replace the tubes, try tighten all the screws and nuts. Remove the knobs and snug up all the nuts behind the knobs. I had a few that were not completely snug. Takes about 10 minutes, my amp as never squealed again. I guess thats why they call the man the DOCTOR,,,, he knows his stuff!
|
|
|
Post by hywelg on Nov 25, 2012 15:43:01 GMT -7
I emailed and Don got back to me with some very detailed instructions including annotated photos on how to cure it. If you can handle a soldering iron its about 10 minutes work.
Mine is completely sqeal free now.
Thanks Don.
|
|
|
Post by franksb on Nov 26, 2012 4:14:39 GMT -7
Thanks alot for the comment! The amp has been repaired, seemed like something was not soldered properly (the Tech said, it was simply forgotten when the amp was build...).
Really sad to tell, but the amp is sold! Was a great one, though... Replacement: TwoRock Studio Pro 100
Still got the MAZ38, which i'll probably never sell...
Thanks for all the help! Frank
|
|
|
Post by robertlucas on Jan 20, 2013 9:51:55 GMT -7
I used to have the high frequent squeeling noise with post at 9 o'clock and pre at 1 o'clock which suddenly stopped. Yesterday my EZG started to make the subsonic low noise at same settings. This afternoon the amp started 'growling' with pre & post at 9 o'clock. It freaked my bands soundtechs out! I live in Holland so sending it to Dr Z isn't an option. Any instruction out there to solve the problem myself or with my amptech? Thanks in advance for your comments.
|
|
|
Post by robertlucas on Jan 20, 2013 9:57:24 GMT -7
By the way, my EZG is a 2008 build
|
|
|
Post by jlc on Jan 22, 2013 9:51:56 GMT -7
I also had this same problem with my EZG-50 head. I spoke on the phone with Dr.Z (himself) about a year ago, he told me it was probably a grounding issue. I can't remember every detail of the conversation, but basically he told me.... it's an alumium chasis and once the amp heats up and expands if there is any break or separation in the grounding it could cause this issue to happen. Everything is grounded to the chasis. He told me before I replace the tubes, try tighten all the screws and nuts. Remove the knobs and snug up all the nuts behind the knobs. I had a few that were not completely snug. Takes about 10 minutes, my amp as never squealed again. I guess thats why they call the man the DOCTOR,,,, he knows his stuff! Also: Posted by hywelg on Nov 25, 2012, 5:43pm I emailed and Don got back to me with some very detailed instructions including annotated photos on how to cure it. If you can handle a soldering iron its about 10 minutes work. Mine is completely sqeal free now. Thanks Don. Hi, between you and your Tech, I would start here ^^^^
|
|
|
Post by pearl76 on Jun 6, 2018 12:51:20 GMT -7
I have the same problem. can someone please send me Don's instructions? thank you in advanced. Sorry for my bad english
|
|
|
Post by Maddog on Jun 6, 2018 13:22:40 GMT -7
I have the same problem. can someone please send me Don's instructions? thank you in advanced. Sorry for my bad english It's doubtful any active members that would see your message have this info. This thread is 7 years old, and none of the original contributors are very active on this forum today.
Probably best to contact: drzamps.com/
|
|