Einstein -High end fizziness issue

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All of a sudden my Einstein has developed this high end fizziness, very light but there nonetheless (very high frequency, like a light sizzle-11k-13K ish?) that I have never noticed before. It bugs the crap out of me since this is what I hate about most other amps I have tried (almost all Mesa's have this) and what I love about my Diezel, clean sweet and rip your face off but no fizz. I've been having fluctuating bias problems, could this be related (underbias type of sound?) I'v installed new pre tubes in the first 3 positions and also plugged and unplugged the loop to see if this made any difference...nope. Possible phase inverter tube, should I try to change that one out too? Any thoughts would be helpful.
 
It may in fact be the phase inverter tube. I have noticed on mine that when using the loop, I have an almost noticeable sizzle when using some time delay effects. I've tried a couple of different delays in the loop to verify it wasn't the pedal. My amp is 2 years old now so I'm thinking that it may be time soon for me to replace my tubes in general. However, it can't hurt to experiment with that one socket and see if it fixes it.

What pre-amp tubes did you end up using?
 
I've tried about every preamp tube available, but I just bought a couple of AC7HG+ from Cryoset and they are high gain but very low noise and have a nice sweet sound. I have also used GT Chinese (cheap silver box ones) with great success as well as a NOS philips and the newer Tungsol as well.
 
Check you preamp & power amp tubes first. If your problem doesn't get fixed, check the caps next.
 
I have eliminated first 3 main preamp tubes and the 2 loop tubes. I also put brand new power tubes in too, no change. The only unchanged tube is the phase inverter so I guess I'll try that one next.
 
Try a 12AT7 with balanced halves in the phase inverter slot. The tubes are not that expensive, but I recommend the best quality tube you can afford.
 
Amp schematic shows a 12ax7 in the phase inverter. I know you want balanced halves but why the best quality tube and what will 12at7 do vs the supplied 12ax7? Thanks
 
To explain better, this high end fizz is like that of tearing paper, low in level but high enough in frequency to make the sound just a touch unpleasant, especially when playing alone sans band. It has not been present before. I will try different phase inverter tube tonight. I must have changed every tube in this thing at least twice except the PI...
 
I learned from Peter and Olaf that a slightly weaker phase inverter tube gave a bit more headroom to that V slot for the phase inverter.
I paid about $20 for a balanced 12AT7. I may be off here, but I believe that it may last longer.
I put one in my Einstein, when I got it three years ago, and it has never given me any problems. Before that, when I had a VH4, and a Herbert, they both got the same type tubes for their phase inverter positions. No problems with any of them.

I am not a tube expert, but their advice has always served me very well. To have a balanced one was only a couple of dollars more then just a regular one, so it was not a big deal, money-wise. I cannot remember if that tube has to be balanced or not, however.

I am however finding that my tubes are lasting a long time and I have no problems with any tubes. Whether this is "luck" or related to getting balanced tubes, I could not tell you. :dunno: But it works for me. :confused:
 
Still searching for the cause of this. Anyone have any other ideas on what to check next or might be causing this? Can anyone recommend a real good amp tech in the NW Chicago burb area? I don't want any butchers playing with my baby.
 
Funny, that was Peter's 2nd suggestion on the e-mail I just received. I'll check them, but I know they were replaced once already by Salwender the old US distributer or their tech. Just the timing is so funny because I had a mode switching issue and Peter graciously sent me new chips and indeed it fixed the mode switching issue but now I have this which I never had before. I did ask Peter and as I thought the chips are not in the audio path, they handle the switching logic only. Thanks for the tip, I'll keep trying. Thanks everyone who has tried to help. Please feel free to keep the ideas coming.
 
I am sorry to hear that you are still having problems. :aww:
I hope you can have these corrected to your satisfaction soon. :yes:
Stephen
 
Seems one of the smaller caps (are these the 22uf/500v?) where there's a pair of them on the side of the guitar input seems to be leaking where the wire goes into the cap....kind of tan foamy looking, just a little ball around where the wire exits. Funning thing is this amp aready has had several of these caps replaced, inclunding this one. Why would these fail so fast and or frequently? Don't get me wrong, I love this amp but it's starting to feel like I own a ferrari or something ,very fragile and needs a ton of maintenence (not something you want from an amp). I have 20 year old amps that have never had the caps replaced and sound fantastic. Now this is on it's second set? I love the way this thing sounds, better than anything else I own but I guess between all the tube issues, red plating tubes, the bias current fluctuations, the mode switching chips that went bad, and now this I'm getting frustrated. Add to this no certified US techs or I have to ship it somewhere and it's questionable whether I'd ever be comfortable gigging with this amp. I just want to be able to play my damn guitar ya know? Thanks, I feel better now. ;)
 
Are you sure those where the ones that were replaced? Can you take a closeup pic?
Any local tech can do this for you, it takes not more than 10 minutes.
 
Yes, different type (marking) and no retaining zip tie which the one right next to it has. They replaced 2 of them previously and this is one of the replacements. I know it's an easy fix, sort of, if you don't zap and kill yourself ;)
 
It's weird. I guess it would be a good idea to check the voltage in that capacitor after replacing to a new one. I would order the cap myself I take it to the tech with the amp. I'm not a tech, email Peter & ask what to check & what the values should be. If it's not just a faulty cap, then the readings should not be what they should be, the way I understand it.

As for the tubes, I guess it's pretty clear that Diezel amps put more pressure on tubes then others & I don't know what technical explanation is, but I'm sure there is one. I've been through quite a number of sets myself, but once you find a quality set they last for a while. The only way to have less tube failure is to bias colder.
 
Thanks nbarts, hey I notice you're in Chicago too, anyone really good here west of the city for amp tech stuff? Some of the guitar techs I've seen their work have been a little scary and I can't take a chance with an unknown. Anybody you would recommend? I'm in Rolling meadows for work and live in Algonquin. Thanks very much! Bob
 
I don't know how far you are willing to drive for a cap change. I have a tech here in Niles, he is fine, but still not that great. I mean most of the time I just go there with parts & already knowing what needs to be done & have him do it. They have known me for a while, so they kinda take care of my stuff momentarily, so I don't have to wait. I know they have fixed my mesa pre a while ago, this one I didn't know what the problem was & it took them a month! The only high praised tech I know around here is the guy who works next door to makenmusic, had no experience with this guy myself, but the word is he's the best in town. Then again, driving that far for something you already know makes not much sense I guess.
 
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