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

[5150loveeddie]

The closest I got is 3.5v and still had the swrill but far away and it's decay is shorter (it seems), I played the amp cranked today and it was basicly not there... I just removed one side of the assemblies solder some small insulated alligator clips on the tips and will pop them in and out. Scope is not an option yet, have to know how to use it ..

I do hear it almost everywhere also, at least in most Marshalls!

[Ricky Lee]

In tracking Ruby's progress, for 18watters, seems like he's audibly noticed crossover in most new tranny's except Heybeor. Didn't hear it in most(but not all) old salvaged iron. So if you're building an 18 watter, take note... At least in his case, with that circuit, iron can make a difference. We've heard it with the old stuff though... And Dan has heard it with everything....(We should investigate iron, once we're sure we have a solution)

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.

[Froumy]

Yeah, these are the ones that drive you crazy. I actually don't hear it, but I'm dying to find the solution. Why are you suspect of newer components in the filter section? Just curious. Are you using stock JTM 45 spec's? If so, could be ghosting.. Although, wasn't there a bad batch of caps around recently? Can't remember....

Electrically, it seems the long tail pair is prone to annoying crossover. I'm thinking every single one has some crossover. Including the old ones, but it's not always heard. Other than that, the long tail pair sure does sound nice... I'd say, let's see what happens with the diodes, then find out why some guys hear it, and some don't. Don't forget that there are other ways to limit the drive from the PI....

[Ricky Lee]

I'm suspect of the tranny's we're getting now days as well. Example build two identical amps, with indentical pieces/parts, identical craftsmanship and one will have this issue and the other one won't. Now change everything in the amp with the problem, except the hardware, and you still have the problem. Next on my list is to change the hardware to see if problem follows the hradware. As for the filter caps, they don't seem to hold charge like the older ones. The most recent amps I've built when turning the amp off the filters drain to 0 almost immediately, unlike the older ones that seemed to hold charge for days. Good example of craftsmanship, especially with the new F&T's where their outside insulator is generally bubbled and peeled straight from the factory. If one doesn't take pride with the obvious exterior construction of their product what would make me beleive that the internal workings are any better?

[Froumy]

Good points on new caps. Ones I've used drain almost immediatly, too. I wouldn't think it would change the RC time constant, though. Not sure how it would help introduce audible crossover, either, but who knows. Ruby hasn't noticed it with the heybeor, with new 18W builds, so you'd think the tranny would be the obvious culprit. BUT, when he swapped his "bad" tranny with one that didn't do it, well, there it was again. Not pointing to the tranny. There's got to be some interaction going on there. Maybe there are frequencies coming back to the filters messing them up just enough? Beats me. Until/if we find out why, we're going to have to resort to a little trickery.

[Billy Batz]

You guys can easily hear it in clips of old amps if you listen close. Like new amps as much depends on how they record the amp and how its set up. I dnt doubt tranys could have a lot to do with it but that didnt help when I swaped tranys. I swaped in a completely different type (2" to 1.5") both were still heyboers tho.

[Flames1950]

You guys can easily hear it in clips of old amps if you listen close. Like new amps as much depends on how they record the amp and how its set up. I dnt doubt tranys could have a lot to do with it but that didnt help when I swaped tranys. I swaped in a completely different type (2" to 1.5") both were still heyboers tho.

No kidding, it's all over AC/DC classics and I can hear it in Metallica's older still-Marshall recordings. It's out there.

And as long as it's just a part of the design and the original sound, I'm OK with it..........

[Froumy]

Yeah I know. Curious as to why it's painfully obvious in some, and others you can't really hear it. Should be an answer other than the diode trick...

[Billy Batz]

Ill use the diode trick granted it doesnt change anything.

[Froumy]

Ricky Lee, Bill Batz, 5150lovedie,

Any updates?

How's it treating you cranked, Stephane? You mentioned it was basically not there. Any tone sacrifice?

Ricky Lee, I think you bought them. Have you tried it yet? What are your thoughts?

Dan, have you tried it, or are you just keeping it stock?


Just wondering if a different approach would be the best solution, or if this one is an acceptable fix. Thanks.

- Bob

[5150loveeddie]

I'm still with the same Zeners mentioned (33v) with a -29.5 bias voltage and it is better I beleive, will try some closer ones as soon as I get them, I don't think it effetcs the tone either except that a little swril might give you a little more depht/3Dish or just more dimension to the sound maybe...

I'd like to know what others is getting also!!??

[Ricky Lee]

My bias with 500 plate voltage is -46 so the 43v zeners I bought won't work. Like I said before I have the dual voltage 400v/500v tranny. The negative bias is -39 @ 400v plates and -46 @ 500v plate voltage. I'm thinking maybe a 50v Zener to accommodate both voltages. So far I haven't been able to locate a comparable value Zener for my bias. I do have a Zener 82v that might suffice but where in the grid do I wire it in?

[5150loveeddie]

My bias with 500 plate voltage is -46 so the 43v zeners I bought won't work. Like I said before I have the dual voltage 400v/500v tranny. The negative bias is -39 @ 400v plates and -46 @ 500v plate voltage. I'm thinking maybe a 50v Zener to accommodate both voltages. So far I haven't been able to locate a comparable value Zener for my bias. I do have a Zener 82v that might suffice but where in the grid do I wire it in?

Ricky you could go "in between" with your power tranny, use one low and one high tap so you get around 450 on the plates, that should bring you near your 42-43v, and just bias a little hotter to bring it below 43v on the bias voltage (if nessesary)........

[Billy Batz]

Dan, have you tried it, or are you just keeping it stock?

Oh Im trying it. But I have no time right now.

[5150loveeddie]

So what's up with everybody, any progress?? It sure did help for me the Zener clipper stuff!!