The deep bass is killing the speakers!

rs159

My parents got a PSW202 and 2 R15s. They've just got a basic stereo receiver so the crossover must be set at the sub. So here's how it goes -
1. I set the Xover to 90 and adjust the sub volume.
2. I start playing some music to fine tune the Xover
3. I get to some music with some deep bass, and the 15s are flapping their asses off. I never hit Xmax, but you could tell they were in pain.
4. I adjust Xover
5. Same thing
6. I adjust Xover again
7. Same thing
8. I set Xover as high as it would go
9. Same thing
10. I plug the ports with athletic socks to keep the woofers from unloading below the tuning frequency
11. Same thing
12. I turn down the bass control on the receiver and turn sub volume higher
13. Same thing

I don't know what else to do without spending more money. Suggestions?

faster100

How high is the volume?? to make the R15's start flapping??
and at this point, did you already ruin the speaker?? when my psw404 starting flapping it was shot!! I to had it to high of volume.. It happens.. if i understand what "flapping" means when you say that... sounds like a bad thing

I personally had the R15's and hooked them to my old Onkyo amp i had and it took half volume with no problem.. so it might be the receiver that the problem lies. or something else.. specially if nothing you try changes the state they are in, either one its the receiver or something, or they are toast

rs159

No, they are fine. They just exert way more than they should and there is tons of port noise. They just don't know when to quit. It's fine at around regular conversation volume, but turn it up any higher and it gets real bad. I don't know why the sub amp doesn't filter the extreme lows?

brettw22

If you have a different receiver handy, hook the speaks up to that and see if the result is the same. Better to test it out that way to isolate the problem.

rs159

No, no extra receiver handy. Although this did happen with a pair of cheapo pioneer speakers, but turning up the xover helped w/ them. Personally, I don't see how a basic stereo receiver could cause problem since there is no internal filtering. My guess is that it's the sub amp, but then I don't know.

Dr. Spec

There is CLEARLY a wiring problem here. At 90 Hz, cone movement on the R15's should be almost nil.

Please explain EXACTLY how this subwoofer and the R15's are wired. Don't skip any steps.

Doc

rs159

Wow, now i feel stupid... i switched around the speaker outputs and the inputs on the sub

fireshoes

So it's sounding better now?

rs159

No, actually it sounds like a 1950 tv speaker with fuzzy reception and half dead tubes in the amp and with half the spider missing and the surround deteriorated away.

MxStYlEpOlKmAn

Ratshack sales tv speakers for 4 bucks.

rs159

Sweet... looks like I'll have to pick a couple up! I've been waiting to upgrade to better home theater sound.

rs159

I don't like to resurect things I put to death myself, but...
Even with the xover at around 110, (and with everything wired correctly), a few very deep test tones and rap and some rock can make the R15s work their asses off. Just exactly how steep is the filter on the 202? This doesn't seem right.

Dr. Spec

Filter rate should be between 12-24 db/octave. Maybe you fried the filter by connecting it backwards - it's hard to say.

Even at 12 dB/octave, at 110, the mains shouldn't be working too hard at all.

Regardless, was there a signifiant improvement after properly wiring the sub/speak connection?

rs159

No, I remember with the old cheapo pioneer speakers on the exact same tones and the exact same songs turning the xover up helped a lot. Those were 6.5" woofers, but that shouldn't matter too much. Maybe the xover was fried... I guess I could use external crossovers, but that'd just be more money.

RuSsMaN

rs, are you using any 'enhancement' on the receiver? Loudness, 3d bass, tone controls, etc.....

rs159

Now that you mention it, I think I did turn on the Onkyo "selective tone control" - which basically adds boom and sparkle. I'll see if I can't improve it by turning it off when I get home.

Dr. Spec

Originally posted by rs159
Maybe the xover was fried...

Does anyone with electronics knowledge want to chime in here? Could he have fried his filter by connecting to the sub backwards and feeding it a signal into the output?

RuSsMaN

I doubt it (no electronics knowledge brought into it).

The high pass is probably passive anyway. I don't know on the Polk subs, do they have a fixed high pass using the speaker level connections? I know a lot of subs do, and its usually 1st or 2nd order passive. (6 - 12db/oct @ a given freq)

Cheers,
Russ

HBombToo

Originally posted by Dr. Spec


Does anyone with electronics knowledge want to chime in here? Could he have fried his filter by connecting to the sub backwards and feeding it a signal into the output?

My first reaction to this would be if there was damage it would now be in an Open State; therefore, nothing would pass...

passive or active an open is an open if this makes sense.

HBomb

RuSsMaN

I read you Henry, but thinking along the passive lines, there would be no electricity connected to the circuit itself. Do caps and resistors care which way juice flows through them? At least as far as damaging them?

I'm an electrical moron, so enlighten me.

Jstas

Resistors are not polarized, in about 99% of the cases. There are resistors that are polarized but I have never seen them used in a cross-over. Cross-overs are pretty simple devices.

Capacitors on the other hand, it's the opposite. Only about 10% of the capacitors I have seen are not polarized. Every other capacitor has polarized leads. Those that don't are very specialized and will not be found in cross-overs either.

There is usually a switching diode in a cross-over or amplifier. If that is connected incorrectly, it WILL break.

Also, if something is friend it does not mean a connection has been broken necessarily. A ground could be fuses or a power lead could have been jumped by a fused ground. A partially damaged ground lead will cause all kinds of noise but still let the signal get through along with alot of other crap.

HBombToo

I agree with Jstas in all comments and add a few of my own thoughts.

From what I have seen in most audio equipment be it an amp, internal crossover or any other processor internal and before the output circuit a capacitor is the final component before the out connection. These capacitors are intentionally put there to prevent such an occurance from destroying the entire device.

If the capacitor is fried there is nothing that could pass either way and thats why I have my reservation as to something blown. Just to support my claims, alot of specialty upgrades to dacs, crossovers, amps and preamps will remove this final cap from the circuit in an attempt to remove as much as possible from altering the signal.

Resistors, Capacitors, inductors will Open in general when they blow. Capacitors on the other hand can short and this is 1 method for determining if a capacitor is bad. Simply take a volt/ohm meter across the cap and at first it will look conductive/a short then a voltage will develop as the cap charges under this dc condition. If the cap stays a short a voltage/potential will never develop. In my time as a tech I usually looked for the cap to open because a failure typically will blow the contact leads and always look like a voltage or no rise time.

I guess its possible that a crossover type circuit could have a failure and pass a signal but that signal would be so wacked I can't imagine it even being recognizable???

Its really tough troubleshooting these types of thigs with not being there but I will admit it is FUN.

HBomb

Dr. Spec

Excellent stuff guys - thanks.

So what other possible explanation is there for his woofers in the mains still jumping around after the signal is passed through a filter set at 110 Hz with what is probably at least a 12 dB/octave slope.

Even if he has a bunch of bass enhancement stuff activated on the receiver ("loudness" control or bass boost or whatever), that only affects signal amplitude; the filter should still knock it out if it's occurring way down low in the typical bass ranges of 35-50 Hz.

If his woofers are still having a coronary after being high passed at 110, it seems to me SOMETHING is wrong with the filter. Even at very high volumes, the woofers in my mains only move maybe 1/4" and they are high passed at 80 Hz.

I wonder, is there a filter bypass switch on this sub? I doubt it but it's worth asking.

RuSsMaN

From my experience, the 'loudness' control and bass tone controls on *most* receivers is around 80-100Hz, and can be as much as +10, +12db.

Something is still amiss, regardless.

rs159

The bass control on the receiver works at 100hz. I don't know much else about what it does to the signal. As for the selective tone control, i have no idea. All I know is that it adds boom and sparkle and I think I might have switched it on.

Something I was stupid enough not to mention before - adjusting the xover does make a very audible difference in what the sub does, it just always seems like all the bass gets through to the mains.

HBombToo

After my 2.5 year old trashed my 350 I had to tear it apart and SEE the Majic. What can I say! Behing the external portion of the plate amp and panel connections I did take a really close look at how everything was attached and is pretty slick. There is actually a circuit board on the inside where the connections from the outside world tie into the amp itself. I'm sitting here thinking at very high volumes/voltages from the speaker level imputs a breakdown of the dielectric across the board could be coupling low freq energy back out to the mains. If there is a deposit of some sort or perhaps even a ding not caught buy QA this could be causing the problem.

This is just a shot in the dark though....

HBomb

rs159

Well, I got work to do tonight, and tomorrow night, and the night after that... I probably won't get around to tearing apart the thing until the weekend. BTW, this thing was bought on one of my fun trips to circuit city, but i opted not to get the extended waranty. It was just purchased recently, and the thing weighs like 30 lbs. Would it be better to rip it apart or send it for service do you think? (Maybe this thread should be in troubleshooting by this point?)

Dr. Spec

Hell, it's a new subwoofer - Polk warranties it for at least a few years. Send the plate amp back for testing with a description of the filtering (or lack thereof) problem.

Good point on the loudness control, Russ - if it's too close to the filter point, some will still sneak through. The loudness boost on my older h/k pre-pro is at 50 Hz, though, although others will vary of course.

rs159

I think that might be the problem. The STC on the onkyo seems to deepen things a bit instead of fattening up the midrange like the typical "da big bass" kind of boost. I'll try it when I get home in about half an hour.

rs159

Well, I turned off STC and though the effect is not so pronounced, the 15s still flap their asses off starting at around 40hz. I strongly believe by now that the amp has malfunctioned. In my belief that I and anything I own is invincible, I didn't get the warranty at CC. Figures...

rs159

On a side note, I wonder how we can live with ourselves calling the 202 a SUBwoofer. The f3 on that thing is 45hz. A more fitting name would be "self-amplified bass booster" or something like that.