Polk audio tweeter “spitty “

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
6,781
Location
Connecticut
Tagline
BOT
#1
My precious monitors, that cost no less than $9 (for the pair) sound fine for the most part. But I noticed recently on some material the left tweeter seems a bit sibilant compared to the other.

Anyone have an idea? I thought perhaps the ferrofluid needs to be replaced perhaps? I’ve never done that before, but that doesn’t usually stop me…

Let’s hear your thoughts. F4E2D7D6-2439-4CD9-B868-DD2E68118A36.jpeg
 

Lazarus Short

Veteran and General Yakker
Joined
Mar 10, 2012
Messages
14,049
Location
Independence, MO
Tagline
I'm the Red Knight, by grant of the Black
#2
First, of course, switch the speakers and hear if the problem is in the amp or in the speaker.

Second, determine if the problem could be a bad crossover cap. I always suspect caps. Caps are evil.

Third, if it really bothers you, shop for a replacement tweeter.
 

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
6,781
Location
Connecticut
Tagline
BOT
#7
Ha!

I saw it on the internet, so…

They pulled the dome off, cleaned the gap, squirted new stuff in, put it back together. But I’ve not done it, and I’ve no idea if that would change things with the sound. I assume so. I was kinda hoping someone else would have experience doing it I could draw on theirs.
 
Joined
Nov 15, 2021
Messages
482
Location
near Liverpool, NY
Tagline
Lifelong student / listening = bliss
#12
Hi J!m,

Although I haven't personally disassembled/degunked any of these drivers, or even own any ferrofluid-enhanced drivers...once upon a time when I lived in southern NH I used to walk by/study the Ferrofluid display in the Manchester airport** ...so I guess that allows me to annoint myself as a subject-matter-expert? ;0)

Disclaimer: Since this is your tweeter, and I will stop on a dime in order to watch anyone operating on a piece of audio gear, my initial response is to want to talk you into doing the Dr. Kildriver quick-lube thing.

On the other hand, if this speaker was mine I'd want to first prove to myself that tweeter oil is the actual solution to this intermittent problem. If we do this right, it will be both fun & instructive, while at the same time avoid the frustration of fixing down the garden path, to mix metaphors a bit.

(Important: Please read the following as I am writing this primarily for people new to the vintage audio hobby and have stumbled across this thread...and not that I am talking down to you. It's just that your original query is something that I've been asked many a time by normal, well-adjusted folks, and what follows is a time-honored path from here to re-establishing sonic bliss. :0)

****

OK, in my humble opinion the first rule of troubleshooting an intermittent is "You can't fix something until you can first break it at will." This can be the hardest part of the entire repair effort, but by doing this you front load all the inevitable frustration into the beginning of the process. I know this sounds simplistic, but before I internalized this as a troubleshooter I suffered through countless episodes where I proved the maxim that "Nothing takes longer to fix than something that is not broken." And worst-case, during the attempted repair where none was needed, I would inadvertantly insert *another* fault. Fudge!

NOTE: Of course you can fix anything using the pure 'swaptronics' method, but that's a 0% learning, 100% spending model -- there's no sport in that.

Step 1:

Let the speakers play, and the very next time you hear the 'spittiness' write down the source, (FM radio station, CD, digital feed, etc) plus song with time stamp where it happens. Now, once you corral the first failure, and you can stimulate the fault at will, you have enough info to proceed.

However, in order to build confidence in our troubleshooting theory that will guide our repair, can you stimulate the fault at will with a 2nd song, 3rd song, etc? (It may sound like unnecessary effort, but oftentimes gathering additional data points can really help sharpen our focus later on.)

Can you can further define the failure? Is it primarily frequency-dependent (ie: you hit the right freq and the problem presents, whether it is loud or quiet?) Or, does the problem occur with differing frequencies/notes/harmonics for that driver -- that is, the problem can be stimulated at will simply by upping the volume setting?

Step 2:

OK, assuming that you now have the knowledge needed to stimulate the fault at will, it's time to switch to 'geographical fault isolation'.
Let's focus on physically narrowing down the failing component:

* Is the failure from a single specific source? (CD player, iPod, iPhone, online streaming, FM, vinyl, cassette, Edison cylinder, etc.)
or
* source doesn't matter -- all sources can/will stimulate the fault?

NOTE: If problem occurs only with a single source, then we need to (temporarily) shelve the bad tweeter theory, and fix the failing source first before proceeding. On the other hand, IF you can stimulate the failure with any/all sources, then proceed to the next step.

Step 3:

Swap the speakers between the L & R channels & stimulate the fault.

* Does the problem move with the speaker, or does it stay with 1 preamp/amp channel?

Obviously, if the problem moves, we're going down the speaker rabbit hole. On the other hand, if the problem presents on the LEFT channel with either speaker, then we're looking at the left signal chain. (preamp/amp and/or interconnections between amp & speaker)

For the sake of argument, let's say that the problem moves with the speaker. (ie: Problem moved to right channel.)

Step 4:

* IF the problem moves with the speaker, then if you swap the tweeters between the speakers...does the problem follow the suspect tweeter, or does it stay with the crossover network / wiring harness in the 'bad' speaker?

At this point, depending on if the problem moves with the suspect tweeter or stays with the suspect speaker cabinet we will have enough information to decide if you have a bad driver (that needs the oil change?) ...or is it a capacitor that's either dried up (and altering the frequency crossover point & sending excess (low freq) power to the tweeter...or the dielectric is breaking down during larger voltage swings & that is what's causing the spittiness you are hearing? Or is the tweeter's voice-coil dragging, and can only be heard during clean, quiet passages -- and loud music actually camouflages the failure?

****

Apologies for the length, but I just wanted to provide a rational troubleshooting roadmap for some of the good info I found in this thread.

****

I (and others?) eagerly await your next status update. Right now it could literally be anything from a single song to a single source, to a single channel in the amp, to a single speaker, to a single tweeter. Who knows? We may very well end up watching you Dr. Kildare the driver & giving it the million-mile lube job. I, for one, am headed to Wegman's for another pound bag of popcorn kernels... :0)

Happy Hunting --

3D

**You know, I never fully trusted my recollection, even when I was half my current age -- but this time I didn't hallucinate this particular memory, for if you look at post #9 in this thread, some dude that goes by the name "Nakdoc" referenced the same display in the same airport. (Granted, this was awhile ago...but the interwebs never forgets. :0)
 
Last edited:

J!m

Veteran and General Yakker
Joined
Dec 24, 2019
Messages
6,781
Location
Connecticut
Tagline
BOT
#13
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.
 
Joined
Nov 15, 2021
Messages
482
Location
near Liverpool, NY
Tagline
Lifelong student / listening = bliss
#14
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...
J!m,

While researching your problem, the ferrofluid/no ferrofluid question came up in my mind as well. If you can locate the speaker model # then we should be able to answer that in short order. It's possible that it's just a conventional driver, and that we're barking up the wrong twee-ter?

Keeping that $9 price of admission in mind, we can try 3 things for free before considering any crossover rework:

1) Swap speakers between channels & observe. (ie: Help decide is it speaker as victim vs speaker as perpetrator?)

2) Make sure all 3 tweeter fasteners are holding the tweeter tight to the front baffle. (Simple audible vibration of loose driver against baffle?)

3) Swap tweeters between speakers & listen. (Tweeter as victim vs tweeter as perpetrator.)

****

At this point, with no money out of pocket, you have enough info to figure out what needs replacement, followed by how much the replacement will cost you, and finally, does the cost/benefit ratio lead you to fix vs. decommission?

Note: When performing the cost/benefit analysis, you have to include the following:

a) The cost of these speakers was a cool $9. But the real question is, what is the 'cost-avoidance' of not buying suitable replacements? (ie: If the new speakers you want will set you back $99, then this is the figure of financial merit when deciding to fix vs replace.)
b) Are you working on this with a young apprentice? If so, then what is the value of the shared victory? Or instilling the value of fixing vs just throwing it away?
c) Personally, I am using my excuse of reviving all my old audio junque to (re)learn a bunch of analog electronic theory...and honing my troubleshooting chops. If I went to the local college & finally finished a EE degree (with a minor in Computer Science) ...it would cost a lot more money...and besides, at this point in life having a pedigree hanging on the wall isn't going to help me upgrade the coffee I drink. :0)

****

Who knows? All you may be hearing is either a loose tweeter rattling on the baffle, or even something as simple as a loose Faston connector. Possibly a cold-solder joint in the crossover network that is stimulated by all the vibration that surrounds it?

And last but not least, with the model number we can also figure out the ferro/no ferro question for free.

Go, Ninja. Given all of the above, there is no shame in fixing cheap speakers -- blame it on cost-avoidance. Blame it on continuing education/skill honing. Blame it on training your replacement in the hobby. I do it all the time...works for me! :0)

Cheers --

3D
 
Last edited:

laatsch55

Administrator,
Staff member
Joined
Jan 14, 2011
Messages
72,803
Location
Gillette, Wyo.
Tagline
Halfbiass...Electron Herder and Backass Woof
#15
Once again D3 you have given folks a lot to think about....appreciate it...

Having at least 2 bad 2" mid drivers I have been trying o decide how to duplicate the "scratchiness" I have heard at certain volumes and frequencies...you've given me some ideas....
 
Joined
Nov 15, 2021
Messages
482
Location
near Liverpool, NY
Tagline
Lifelong student / listening = bliss
#19
Once again D3 you have given folks a lot to think about....appreciate it...

Having at least 2 bad 2" mid drivers I have been trying o decide how to duplicate the "scratchiness" I have heard at certain volumes and frequencies...you've given me some ideas....
Lee,

Thanks to the very nature of our hobby, we tend to first trip over sonic anomalies using the most complex analog signals out there. (ie: music) Since our brains are internally wired to be good at pattern recognition, most of the time we figure out the specific music pattern that stimulates the fault & we're off to the repair races.

On the other hand, when it comes to diagnosing complicated loudspeakers with complicated signals it can quickly get really counterintuitive? (As a side note, I think that trying to get loudspeakers to do what *I* want {instead of whatever they feel like serving up} has served me way more humble pie than everything else put together over the years... :0)

****

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
HP 200CD as received.JPG
" It goes to 11 " (Hz)

NOTE: You guys running them new-fangled smartphones probably have an app to output a sweeping sine wave as an input to your amp. But for me, there's an ineffable something about grabbing a knob and having complete control over how fast/how slow/warble/linger/freeze the way I sweep through the audible range...

Anyway, no doubt I'm preaching to the choir, but for others reading this thread who are trying to figure out a way to take a maddening transient (peek-a-boo) intermittent in a speaker and turn it into a solid go/no-go fault, sometimes the purer/simpler the stimulus the better.

Happy Hunting!

Cheers --

3D
 
Last edited:
Top