Fuzz/Phase shifting effect (muskito flying by) in the mids

5150loveeddie · Post by **5150loveeddie** » Sat Jun 21, 2008 5:28 pm

I'm having a not so nice high mid fuzzing or fizzing note on top of the regular note, kinda like a guy shaving with an electric shaver in the back ground, not out of tune, it is there more when the note is fading out, there is like a phasing shifting effect at the same time, goes up and down kinda slowly, the sound has gain and in pitch. It is difficult to explain, some notes will do it more prononced then others, it is not ghosting (I think, it is note the regular ghosting here if it is...), it tend to go away when reducing mids or presence but still there far away, don't want to loose the mids so WFT??

It is on a 50w el34 type amp

Ricky Lee · Post by **Ricky Lee** » Sat Jun 21, 2008 5:48 pm

What model amp is it.

5150loveeddie · Post by **5150loveeddie** » Sat Jun 21, 2008 7:02 pm

Ricky Lee wrote:What model amp is it.

Marshall plexi type el34 head (1987)

Swap tubes still the same, swap speakers still the same (no speaker rob), think I might need a scope........

Any ideas? Larry, Flames, Dan, all of the old timer here??

Ricky Lee · Post by **Ricky Lee** » Sat Jun 21, 2008 9:50 pm

Is it a new build? Some of these new preamp tubes I've heard give that fuzz affect. Maybe puts some phot

Flames1950 · Post by **Flames1950** » Sat Jun 21, 2008 10:12 pm

5150loveeddie wrote:
Ricky Lee wrote:What model amp is it.

Marshall plexi type el34 head (1987)

Swap tubes still the same, swap speakers still the same (no speaker rob), think I might need a scope........

Any ideas? Larry, Flames, Dan, all of the old timer here??

Sounds like the noise problem Dan had in his amp that was driving him nuts. I think he was sending that one to Brian Wallace to try and isolate the noise and its cause. Many original Marshalls had the noise too.

5150loveeddie · Post by **5150loveeddie** » Sat Jun 21, 2008 11:14 pm

Yep it is a new build, 12ax7 are old stock and testing good.

Yeah, I think I saw Dan explaining it and had to put a 150pf for his fizz cap per Larry's suggestion?!!??! Or what it for that? Could try it and see, after that if no joy a scope will be needed unless someone knows what the hell... It drives me nuts also

Flames1950 · Post by **Flames1950** » Sat Jun 21, 2008 11:16 pm

I thought Dan just liked the sound of the 150pF fizz cap but still had the issue. I always use a 100pF personally.

5150loveeddie · Post by **5150loveeddie** » Sat Jun 21, 2008 11:22 pm

OK....damn, It's a 100pf also from day 1...... I think it might be a certain type of parasitic oscillation....maybe

5150loveeddie · Post by **5150loveeddie** » Fri Jun 27, 2008 3:52 pm

need some serious guru help

Still have my muskito buzzing in the upper mids, "zzzzzzziiiiouuuuu" in the signal..

Changed: tubes, choke is stronger, filtering higher (went lower, then back up), shielded part of the input, swap guitars, swap cabinets, no attenuation, swap screens from 1K5 to 1k Wylwin 1%, redid my ouput grids (5.6k AB CC), checked my lead dress (seems ok), etc...

Still does it

Anyone?

Ricky Lee · Post by **Ricky Lee** » Fri Jun 27, 2008 4:23 pm

These type problems are what drives one nuts, especially when you change everything in the amp and still have the problem. Your not the only one I'm hearing that has this buzzing issue which makes me suspicious of some of these modern day parts, especially in the filtering department.

novosibir · Post by **novosibir** » Fri Jun 27, 2008 4:30 pm

5150loveeddie wrote:Still have my muskito buzzing in the upper mids, "zzzzzzziiiiouuuuu" in the signal..

Difficult to say w/o a sound clip.

- couldt be a leaky coupling cap to the volumes
- couldt be cross talk between two wires, where one is the transmitter, the other the receiver
- couldt be the diode effect of a bad or too hot/too cold soldered solder joint
- couldt be a bad contact on a nearly broken off leg of a cap or resistor
- couldt be audible artifacts of RF oscillation
- couldt be ghosting
- couldt be .....

No sound clip, no photos --> no concrete advice

Larry

5150loveeddie · Post by **5150loveeddie** » Fri Jun 27, 2008 5:43 pm

novosibir wrote:couldt be the diode effect of a bad or too hot/too cold soldered solder joint

Diode effect?

Thx for the inputs here Larry, have some stuff to look at!!

Scope would find that easy I guess? A scope job here for fastest result findings??

Billy Batz · Post by **Billy Batz** » Fri Jun 27, 2008 6:16 pm

I still have a sound clip of it below. It comes off different in htat clip for some reason. Much more pronounced and separate then it usually is. Your description is dead on.

I never did nail it down and I never did send it to Brian to hook it up to all his gadgets.Tried tubes. Nope. I redid all the grounds. Not it. Changed the filtering. Not it. Changed the output trany. Not it. Changed the filter cap make. Not it. Messed with dress- no. Disconnected the NFB. No joy. I isolated it and found its NOT a preamp thing. So I shielded the grid wires thinking maybe its some kind of cross talk from the OT leads. Nope. Changed the bias filtering. No. I mean the list feels endless now.

I emailed Larry and Brian and other people about this for a long time. I was convinced it was a power supply anomaly. One of the reasons it recorded so well is taht I was using a MASS150 at the time and it had this wierd way of isolating or concentrating that noise. You cant hear it easily in any of my other clips. Now that I was tuned into that noise I notice it everywhere. Since I did the 67 Ive noticed it in all my builds to some degree- JTM45/100, 68, 67, Super Reverb, Princeton, amps Ive done for people, etc.. Also its in almost everyones clips.

But it doesnt just stop there. So many songs I can clearly pick it out. ACDC especially- check Walk All Over You and that whle HtH album and the rest of their albums- you can hear it well if you listen in the beginning of Do You Feel Like We Do, Aerosmith, Allmans, Metallica, Black Crows, Sabbath, Cream. I swear I was hearing it every time I turned the radio on. Its a buzz conspiracy. I think its intrinsic and most people just dont notice it but like ghosting some amps seem to do it way more then others and its most easily heard when using attenautors. The sheer volume covers it up. There may be a simple fix tho. Who knows? I gave up.

Billy Batz · Post by **Billy Batz** » Fri Jun 27, 2008 6:37 pm

BTW there is also a laundry list of things I can rule out by elimination because it appears in different amps and they arent all the same. SoZos arent to blame since I used mustards and Mallory ODs in others, Tube types, SS rectification, PT, its not something relating to high wattage/current, speaker type, speaker wire, impedance, jacks/switch/selectors/sockets, I highly doubt after a half dozen+ amps its a broken lead or cold solder joint. I was just disgusted and gave up. I learned to live with it like ghosting.

5150loveeddie · Post by **5150loveeddie** » Fri Jun 27, 2008 8:00 pm

My goodness your clip is the SAME EXACT buzz over the note I have to the hair, 99.99% same damn thing.....ok I'll go read your post now...

Now that you talk about it, I think I do ear it in lots of Marshall also, it is worse with an attenuator, was thinking it was because of th hotplate at very low volume settings that would do it but them without the hotplate I ear it also, it is kinda part of the sound but now that I noticed it I do ear it everywhere now

.

Metropoulos Forum

Fuzz/Phase shifting effect (muskito flying by) in the mids

Who has Aluminium OR Steal chassis OR both with the SNAG???

Fuzz/Phase shifting effect (muskito flying by) in the mids