Polk audio tweeter “spitty “

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#21
Cool! Reading around I was pretty sure that you possessed the really big guns in audio testing land. (!)

FWIW I've been watching for the right Keithley 2015 to come up for sale -- I'm ready & waiting!

And it seems that all paths in the land of audio troubleshooting eventually lead to the AP test suite. For me, the fact that supposedly a bunch of folks working there came from Tektronix just makes me want it all the more. Of course any discussion around Audio Precision quickly becomes an investment vs. purchase thing, so I'm trying to figure out how to get into a previously-enjoyed system...from here. :0)

EDIT: And to be perfectly candid, I really think I *need* to work with some vintage test gear first before I jump into a used AP setup. (In much the same way that all the time I spent rebuilding carbs, reading spark plugs, changing the distributor spark advance curves with springs & weights, cam swaps, etc., proved invaluable once we started messing around with EFI systems. That is, I already knew what I wanted from the engine bay, and just needed to figure out what software knobs to turn...instead of trying to figure out what the engine wants PLUS how to retune a EFI system simultaneously.)

The bottom line is that I am definitely headed in the direction of yourself , Grapplesaw, & Gepetto...but I gotta crawl B4 I walk B4 I run with the big dogs. :0)

Eagerly awaiting the blow-by-bow description of what you discover while sleuthing those midrange issues!

Good luck --

3D
 
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#22
Given this, sometimes when I can't figure out how to 'break it at will' using a complicated signal, then as a troubleshooter I'll go 100% in the opposite direction. In other words, sometimes a quick sweep of a pure tone from bottom to top will tease out the sonic speedbump you've been searching for:

Old school HP 200CD -- 5Hz to 600kHz
View attachment 62514
" It goes to 11 " (Hz)
Speaking of pure tone testing, at low levels it's no problem, but if I'm looking for failures that only present at higher volumes I literally get a headache just thinking about suffering through that test session. :0(

Luckily, the fix for me is simply using a pair of earplugs. A lot of times it is easier to discern the problem with plugs in as the volume levels go up.

And for truly life-size troubleshooting, I can personally vouch that a set of these in addition to a pair of well fitting earplugs allow me to easily work all day without headaches, level shifting, ringing/tinnitus, etc.

****

I write the above only because I got to thinking about sweeping for a midrange driver problem with 5-10 watts worth of test tones...non-musical test signals can take all the fun out a troubleshooting session PDQ. :0)

FWIW --

3D
 

NeverSatisfied

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#24
Lee and 3D, please post your test gear in the thread for vintage meters. That way any guys wanting to get into building, testing and troubleshooting will have a spot to look at various equipment they might want to start accumulating.
I agree with 3D that learning on analog stuff builds a better foundation than jumping straight into expensive digital gear. Obviously there are some exceptions but in general learn to use a wrench before you buy an air ratchet.
 

Gepetto

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#25
Well, if I swap cables and the problem follows the cable, and is not resident in the speaker, we then know it's not the speaker.

If it remains in the same speaker, regardless of connection to it, the problem is in the speaker.

Then we could dissect the crossover, and rebuild them both with fresh caps. Probably not a horrible idea anyway, but these are not that old, so not my first thought.

Do these tweeters even HAVE ferrofluid in them? That thought occurred to me today...

I have been ignoring this problem continuously since I noticed it.
It's probably your cable Jim :)

Prop the speaker cables off the floor with chopsticks and that usually mellows them out. Perry usually has some advice on this...
 

WOPL Sniffer

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#27
It's probably your cable Jim :)

Prop the speaker cables off the floor with chopsticks and that usually mellows them out. Perry usually has some advice on this...

Can't talk now.... Still giggling over the last "Slurp and Burp"

The bottom line is that I am definitely headed in the direction of yourself , Grapplesaw, & Gepetto...but I gotta crawl B4 I walk B4 I run with the big dogs. :0)
 
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#28
Lee and 3D, please post your test gear in the thread for vintage meters. That way any guys wanting to get into building, testing and troubleshooting will have a spot to look at various equipment they might want to start accumulating.
I agree with 3D that learning on analog stuff builds a better foundation than jumping straight into expensive digital gear. Obviously there are some exceptions but in general learn to use a wrench before you buy an air ratchet.
NeverSatisfied, I think that's a great idea. I think that the first things to be added should be from the talent in here that have multiple successful WOPL conversions out there earning their keep. Mr. WOPL Sniffer & his mil-spec soldering/wiring, Gepetto's SPICE space & his proto test mules, Lee & Glen's Audio Precision test stations, etc. (Glen showing us his new dummy load that he brewed up is a great example of something that's very helpful to me trying to come up with a reliable test environment where I can make repeatable measurements. (!)

****

No doubt the folks that have been here since the beginning take it for granted, but as a relative newbie with a fresh set of eyes I'd like to point out that this forum is different than the others.

The only way I can explain it...is that when I'm seriously interested in quality food, I'm looking for a farmer or a cook, not a food critic. I've learned over the years that when you talk to someone who has actually made something work with their own 2 hands, they can give you genuine insight on the stuff that really matters. Conversely, the most a food critic can give you is their opinion. (And anyone reading this knows that old saw by heart. :0)

In other forums that I searched for PL restoration info (but that I chose not to join) my hopes would go up when someone with first-hand experience with a PL amp would ask a question, and then almost immediately people would jump in & repeat 2nd-hand or 3rd-hand urban legends about the equipment. "Yeah, I was at Woodstock when a Flame Linear burned up one of the speaker towers while Jimi was playing the Star-Spangled Banner, my bloviation circuit is set on stun, blah blah blah..." :0)

You know what I mean. Meanwhile, in here Wattsabundant is sharing hard-won info, Gepetto is helping Glen debug his Dual 500 after WOPLing, George S is showing just how far he will go to eliminate 60hz interference from contaminating his test measurements, plus everyone from WOPL Sniffer to Nando to AngrySailor, the tape contingent, plus the vinyl devos, & the rest of the folks here. Restorations & hotrodding reports stream in from all over the world to boot - awesome!

****

So yeah, if we leave it up to the audio food critics in the other forums to help create The Next Generation of audio enthusiasts this hobby is as good as dead. But here you guys demonstrate that you don't have to be Bill Gates in order to surround yourself with world-class tunes. Just gotta dive in, and with the help of the talent here, see it through until you get it back up & running.

Apologies for the length. Earlier today the postman dropped off a 7.5 lb box of wire from Mr. NavLinear, and I'm still all hepped up over my good fortune. :)

3D

PS: Spence, I'll be happy to put up what I got & why I decided to go with what I did. (It might be of use to the 'bang for the buck' crowd. :0)
 
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nakdoc

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#31
The tweeter may be swapped easily. Tweeter terminals are plug in connectors. Crossover caps cannot cause "spitting" , only treble attenuation (horns are the exception). Ferrofluid gets thick with time causing treble attenuation, but not spitting, however it would be good to know if the spitting goes away when the volume is reduced 10%.
The woofer in this Polk also separates the rubber from the cone, so try to gently lift the surround where it is glued to the cone. Any loose rubber will rattle at certain frequencies.
 

J!m

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#32
I've had no time to look at this again. I will do this weekend and try to get more intel on this problem.

It's usually 10:30-11PM that I finally have time to do.. something. Trying to spin records 'til midnight or so but I'm pretty tired by then. (Can't make any noise with the little man sleeping)
 

WOPL Sniffer

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#33
I've had no time to look at this again. I will do this weekend and try to get more intel on this problem.

It's usually 10:30-11PM that I finally have time to do.. something. Trying to spin records 'til midnight or so but I'm pretty tired by then. (Can't make any noise with the little man sleeping)

You got Napoleon staying with you??? :)
 
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