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Peter P.

Is My Subwoofer Adjusted Correctly?

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While waiting to find a Klipsch kg SW subwoofer locally, I'm considering reconnecting to my system the powered, ported Sony SAWM40 subwoofer I have. Don't laugh; I bought it used, and cheap!

 

Part of what annoys me about the Sony is, most of the time I listen to NPR/FM radio, and when voices pronounce words with the letter "B" or "P" I hear a slight booming "pop" clearly coming from the subwoofer. In phonetics it's called a Bilabial Stop, which pretty much means the lips come together at the end of the sound for that sharp consonant end.

 

I can turn the output level of the subwoofer down and eliminate the issue, but then the subwoofer adds nothing to music. It's either one or the other.

 

Is this common with subwoofers? With powered subwoofers? Is it the 12" size of my driver? I've monkeyed with the level and crossover and can't fix one without silencing the other.

 

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There is no actual standard for calibrating music in a room.  It's the source, the equipment and preference that determines it.  With that said, calibrating a sub with an AVR using Audyssey or MCACC or the like for home theater is a good starting point for music.  Typically music listeners if they change the settings, will increase the subwoofer by as much as 6db from a home theater calibration.

 

The problem is occuring with how the sub is blending with the mains.  What mains are you using, and are you using an AVR or something else?  Most likely the sound you hear is too much output within the crossover region, that's my first best guess.   By changing how the mains and subs are crossed, you should be able to eliminate the problem.  Let us know what you're running your system with and from there it can be solved.  My first guess without knowing what you're using it with would be that the slope of the crossover(s) is not steep enough.  

 

RK  

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Thanks for the reply.

 

The mains are 6.5" woofer bookshelf speakers with a low end of 55Hz. I've experimented with the crossover so it's varied; from the current position and scale on the crossover control, it's currently set to roughly 70-90Hz. I'm using a basic 2 channel receiver with the tone controls set flat. None of the specs I find tell me the slope of the subwoofer's crossover.

 

I would have to agree regarding your comment "...increase the subwoofer by as much as 6dB from a home theater calibration." I could understand a difference between music and movie effects.

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It sounds like you hearing things two high up in frequency.  If the sub has a XO, set it between 50 and 80Hz.  A lot of integrated amps don't have a sub out and will not help with getting the sub an mains to work together.  It will then have to be done manually.  If the sub is vented, it's a 4th order or LR 24 db. slop.  If it is sealed, then a 2nd order slope of 12 db. is the correct one.

 

You did not give enough info about your system for further help.

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On 11/15/2016 at 11:04 PM, derrickdj1 said:

You did not give enough info about your system for further help.

The bookshelf speakers are running full range and have a 55Hz low end cutoff. I can use the high pass output of the subwoofer if I connect the bookshelvers to the subwoofer but I'm not currently running them that way.

 

The subwoofer is a ported 12"er.

 

Let me know if I need to supply more info.

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The Bookshelf speaker should be set to small anc XO at 70 Hz.  This way the sub will be active all the time.  Turn the XO on the sub all the way up.  This should give a better blend of the sound.

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3 hours ago, Peter P. said:

The bookshelf speakers are running full range and have a 55Hz low end cutoff. I can use the high pass output of the subwoofer if I connect the bookshelvers to the subwoofer but I'm not currently running them that way.

 

The subwoofer is a ported 12"er.

 

Let me know if I need to supply more info.

You're always better off with an active crossover on your speakers, either from an AVR, or by using the high pass filter on the sub as you said.

 

i think doing one of these, and crossing at 60-80 will drastically help. If you use an AVR to crossover, go full range on the sub and just use the AVR cross.

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As others have said ^^^ you don't need to turn the gain down on the sub, instead the crossover point needs to be 80 Hz or less.

 

The reason is most people don't like voices coming out of their subwoofer.  The 80 Hz number is nearly universal for stopping that from happening.

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Thanks for the replies.

 

I don't have an AVR but a simple 2 channel receiver with no facilities to limit the frequencies; both channels run full range.

 

Sounds like my best option is to run one pair of speaker wires to the subwoofer speaker inputs, and from the subwoofer's speaker outputs to the bookshelf speakers. I presume the subwoofer will internally high pass to it's speaker outputs whatever I set the subwoofer's crossover to pass. Time to get more speaker wire! I'll report back.

 

Thanks again!

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34 minutes ago, Peter P. said:

Sounds like my best option is to run one pair of speaker wires to the subwoofer speaker inputs, and from the subwoofer's speaker outputs to the bookshelf speakers. I presume the subwoofer will internally high pass to it's speaker outputs whatever I set the subwoofer's crossover to pass. Time to get more speaker wire! I'll report back.

Sounds like a plan to use the high level inputs.  :emotion-21:

 

I have a 2-channel receiver that I run to a sub exactly the way you laid out.  There is almost always a knob on the sub which will allow you to set the XO and the gain.  You can ignore the phase when running one sub.

 

Here is a video which will help you dial-in the sub.

 

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Some high level outputs from the plate amp are filtered at a set frequency.   Some are adjustable.   Some pass,a full signal.  Consult your owners manual to see how yours works.

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Update: I bought some speaker wire and wired the subwoofer to receive a full range signal from my receiver's speaker outputs (the receiver has no LFE or sub output).

 

I wired my 2 speakers to receive their input from speaker level outputs on the subwoofer.

 

I presumed my subwoofer's crossover control provided a high pass signal to the speakers. But listening to them, it sounded like they were still receiving a full-range signal.

 

I swung the crossover control to both extremes (50-170Hz) but it sure didn't look like they were moving less when observing the woofer cones.

 

To confirm what I was seeing, I put a voltmeter on one speaker level output from the subwoofer, and using a Max Hold feature, measured the voltage with the crossover at both extremes, playing the same bass frequency sweeps. I assumed if the sub was set to pass 50Hz to the satellites vs. 170Hz, I'd see a higher voltage across the output. Instead, there was no change.

 

So if the subwoofer isn't filtering the signal, sending only a high pass to the satellites, then it's not taking a load off them. It's an inexpensive subwoofer purchased second hand, so I can't expect much but it's a learning experience. It's one of the  main reasons I want a kg SW.

 

Judicious experimentation with the Level and Crossover controls would not remove the pop on the sharp consonants I mentioned in my original post, unless I practically turned the subwoofer level output to zero. This subwoofer is probably not suited for speech, nor is it necessary. I think the pop might be partially due to the 12" diameter of the subwoofer and a smaller driver might be more compatible.

 

Nevertheless, I'll live with it and probably turn the subwoofer off when listening to NPR.

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Plan on getting an avr with room correction.  This is Black Friday month and it does not have to be expensive.  Best Buy sells Sony avr's at a good price.

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The subwoofer you own is not worth repairing.

 

The KG series sub is a poor choice for a replacement.

 

The Dayton SUB series subwoofers are actually pretty good buy, the ones shown in the video previously posted/

 

 

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Update: Since my subwoofer does not appear to have a high-pass filtered output on it's speaker output terminals, I started looking around to see if there was an aftermarket solution.

 

I found Bass-Blockers; simple, first order high-pass filters used in car stereo applications. Well, if they work there, they could work for me, no?

 

But Bass-Blockers assume your speakers have a particular resistance, and they come in limited choices of crossover frequency.

 

I got the bright idea to make my own.

 

I found a handy site that does the calculations for you. I went to my local electronics supply shop and bought the nearest value capacitor that was available, and some other supplies.

For those that want to try this themselves, Parts Express has the best selection.

 

When doing your calculations, you have to consider how much power your amp produces and select the correct voltage capacitor to handle the output. In my case, my 75W (amp) into 6 ohms (speaker) works out to 21V. I brain farted in my initial calculations and thought I needed 100V capacitors, which limited my available choices. Since I already had measured the voltage output of the amp at my listening levels saw only 6V output, I figured I'd be safe with the 63V capacitors the local shop had, and I was right.

 

Again, since the local shop had a limited selection, my chosen crossover frequency would be limited, too. My subwoofer's crossover runs from 50-170Hz and since it appears from the dial I run it typically mid-range, I figured anywhere from 100-120Hz would be acceptable to start. I settled on 120Hz/220mF.

 

IMG_1584.jpg

 

I put spade terminals on one end so I could remove them from the speaker lead and insert a bare jumper if I ever wanted to run the speakers full range again, or swap in other filters. I failed to buy shrink tubing to fit over the capacitors which is why they're covered in two separate sections.

 

Since the filter is only 6dB/octave, the results aren't that dramatic but they definitely work. Maybe next up will be a 12dB/octave filter...

 

As to my original problem with the pops on certain consonants spoken by radio hosts, I've determined it's partially due to the equalization specific radio stations use, combined with my subwoofer adjustments. Some rock stations for instance, boost bass for a fatter sound. You would think my local NPR station, or any NPR station, would leave their equalization flat, but no. It's plain to me there's a difference from station to station. It's only the local programming the has the issue; when they forward syndicated feeds it's not a problem.

 

Thanks for reading and thanks for all the replies!

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I need some advice and I am not that familiar with components.  My REL StormIII bit the dust and cannot be repaired...no parts.  So I bought an SW 12" 400 W sub.  Hooked it up with the single cable.  Can't say I notice any difference in base at all.  I have Klipsch Forte II speakers, center channel and Solid back speakers as well as a year old Onkyo receiver.  What do I do to know if I'm getting the base I want and I want base.  Thanks.....

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10 minutes ago, Diane1349 said:

I need some advice and I am not that familiar with components.  My REL StormIII bit the dust and cannot be repaired...no parts.  So I bought an SW 12" 400 W sub.  Hooked it up with the single cable.  Can't say I notice any difference in base at all.  I have Klipsch Forte II speakers, center channel and Solid back speakers as well as a year old Onkyo receiver.  What do I do to know if I'm getting the base I want and I want base.  Thanks.....

 

It would be best if you started a new thread.

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1 hour ago, jason str said:

 

It would be best if you started a new thread.

And refer to it as bass.

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