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Topic # 128999 31-Aug-2013 10:49
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Hi everyone, I have an issue with a very lazy sub woofer. My gear is as follows

Sony STR DH520
Technics SB-TW50 Subwoofer
Kef C5 speakers

I have tried setting the receiver at different crossovers for the front speakers between 80-120hz, Subwoofer volume on the receiver at between +5 and +7 Front speakers are set to small. The subwoofer only hits about half the low notes, and the front speakers carry the most of it. Its almost intermittent as I type this post I'm playing Calvin harris and Bruno Mars and the sub is happily working however the next track it might take a lunch break, that's the way it seems to work. Tried all the sound fields of music and movies dolby, neo etc.

Before anyone asks this sub has no crossover control on the unit itself, everything has to be handled by the receiver.

Any help would be greatly appreciated.

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  Reply # 887545 31-Aug-2013 20:30
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Most pop music has all the bass stripped out of it so that they can compress it to louder, and because most of the time it is played on systems that cannot do bass anyway. There is some horrid processing that some recording "engineers" use to make harmonics of bass which is enough to make the average idiot think there is heaps of bass there.

Play something from the 70s/80s, or something more recent that is mastered properly and you will have the sub doing heaps. Stick to the same stuff they play on ZM and similar and it will be hit and miss if your sub ever sees anything.




Richard rich.ms

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  Reply # 887833 1-Sep-2013 16:53
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Most folks have their subs (and surround speakers) up far too loud.

If you can tell its thumping away, it's too loud.

 
 
 
 


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  Reply # 887876 1-Sep-2013 18:34
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it is possible your sub is overheating and shuts down and then comes back on.

100W for an 8" driver trying to do 15Hz is going to start pushing things from 40Hz down

how loud do you run it?




Swype on iOS is detrimental to accurate typing. Apologies in advance.


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  Reply # 887877 1-Sep-2013 18:35
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my 15" sealed sub doing 1000W can't even handle 100dB at 15Hz

(the bigger the cone the more efficient it drives, the less power you need to generate the bass tones, so your 8" ones are suffering much I reckon ... does it have a low frequency cut off - NOT cross over but cut off so that is doesn't try so hard to do the low tones, hence will survive your pains longer and doesn't overheat as fast)




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  Reply # 887914 1-Sep-2013 19:35
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Whats the connections like to the sub... does it use plugs or bare wire?

If bare wire... perhaps cut and strip properly (making sure you dont cut any of the copper strands) and ensure a good fit.

Have you checked the condition of the cable... could there be any small breaks?
If the cable is connected using plugs of sorts.... are these crimped properly?

Is the earth decent? (not only on the unit, but also the sub where I assume it will be negative ground (unless its powered)).


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  Reply # 887915 1-Sep-2013 19:40
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I just read your original forum topic when you purchased the sub.
http://www.geekzone.co.nz/forums.asp?ForumId=34&TopicId=113572

How many wires are comming off the sub to the unit? Is it just one pair or two pairs as you say in the previous forum that the sub is 100 + 100 RMS independant?? Have you got the polarity of the wires correct (otherwise yad be running 'out of phase' which bascially means you could be cutting your bass (where one cone is pushed out while the other retracts for the same note)).

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  Reply # 887916 1-Sep-2013 19:42
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NEXT; once you have assertained its not the wiring or unit settings... perhaps it may be the components inside i.e. solder joints may have cracked on the board as afterall the board and components are being forever thumped and vibrated.

Just my thoughts... I could be totally wrong !

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  Reply # 887920 1-Sep-2013 19:47
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oh and I found another forum topic you created about wiring the subs...
http://www.geekzone.co.nz/forums.asp?ForumId=34&TopicId=95968

So I guess this answers most questions and your using the Y connector still?

Would be great if you could post a pic of the rear of the Sony unit and the input panel of the sub.

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  Reply # 887937 1-Sep-2013 20:27
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a few points

1) according to the specs of your KEF C5, you probably should set your sub at 60-80Hz crossover. your KEfs are rated to 41Hz (but I can't find at what dB - usually at -3dB if it's a respectable maker), so it probably stops producing bass at around 50-55Hz, but the only way to be sure is to use test tones. of course the crossover will depend on how good your sub makes 60-80Hz (or even higher but we won't get into that) compared to your speaker but chances are your speakers are better ..

2) you sub is rated to 15Hz at MINUS 15dB so it probably only does 40Hz is my guess, you might get 35 if you were lucky - again best way to check is test tones

3) your KEFs are rated 90dB loudness at 1W at 1m and the sub is a lot less http://www.vintagetechnics.stereomanuals.com/loudspeakers/speakers2.htm hence the difference in the autocalib setting

4) your sub is probably overheating

5) to solve it
- do an auto calibration but don't plug in the sub (so the receiver doesn't try to crank the bass up, if it does that - if you know it doesn't equalise the bass then it's fine)
- put the sub where it produces the most bass in your room - usually somewhere in a corner but unequal distances from the wall. also try to turn it 90deg. try the bass crawl described by dunnersfella.
- buy a new sub




Swype on iOS is detrimental to accurate typing. Apologies in advance.




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  Reply # 888265 2-Sep-2013 13:12
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richms: Most pop music has all the bass stripped out of it so that they can compress it to louder, and because most of the time it is played on systems that cannot do bass anyway. There is some horrid processing that some recording "engineers" use to make harmonics of bass which is enough to make the average idiot think there is heaps of bass there.

Play something from the 70s/80s, or something more recent that is mastered properly and you will have the sub doing heaps. Stick to the same stuff they play on ZM and similar and it will be hit and miss if your sub ever sees anything.


Ok, I tried Phil Collins, Fleetwood Mac, David Bowie all with no action from the sub. However then I tried Chemical Bro's and it sprung to life I guess there is a lot of low frequency action there. But it performed well with that type of music. I'm not sure what's going on. Perhaps its something to do with the way its being delivered through iTunes over airplay?



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  Reply # 888266 2-Sep-2013 13:12
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Goosey: oh and I found another forum topic you created about wiring the subs...
http://www.geekzone.co.nz/forums.asp?ForumId=34&TopicId=95968

So I guess this answers most questions and your using the Y connector still?

Would be great if you could post a pic of the rear of the Sony unit and the input panel of the sub.


Thank you, I will try and get some photo's



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  Reply # 888268 2-Sep-2013 13:16
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joker97: a few points

1) according to the specs of your KEF C5, you probably should set your sub at 60-80Hz crossover. your KEfs are rated to 41Hz (but I can't find at what dB - usually at -3dB if it's a respectable maker), so it probably stops producing bass at around 50-55Hz, but the only way to be sure is to use test tones. of course the crossover will depend on how good your sub makes 60-80Hz (or even higher but we won't get into that) compared to your speaker but chances are your speakers are better ..

2) you sub is rated to 15Hz at MINUS 15dB so it probably only does 40Hz is my guess, you might get 35 if you were lucky - again best way to check is test tones

3) your KEFs are rated 90dB loudness at 1W at 1m and the sub is a lot less http://www.vintagetechnics.stereomanuals.com/loudspeakers/speakers2.htm hence the difference in the autocalib setting

4) your sub is probably overheating

5) to solve it
- do an auto calibration but don't plug in the sub (so the receiver doesn't try to crank the bass up, if it does that - if you know it doesn't equalise the bass then it's fine)
- put the sub where it produces the most bass in your room - usually somewhere in a corner but unequal distances from the wall. also try to turn it 90deg. try the bass crawl described by dunnersfella.
- buy a new sub


Thank you for all your help, I will change the crossover setting to what you have suggested.

I don't believe the sub is over heating because its just been turned on, so it would be cold. It worked great with Chemical Brothers playing and that is super rich in bass. 95% of other music its asleep. As I mentioned in another post maybe its something to do with playing the music over airplay through iTunes? All of my music in itunes was mp3 based smallish files, perhaps this is where the problem is?

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  Reply # 888286 2-Sep-2013 13:37
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then perhaps your problem lies within the receiver's LFE crossover or it is true there isn't much bass in your music.

are you able to set it to LFE + main; speakers to large (ie BOTH the speakers and sub gives bass); just to see what happens [purists will say you never do that, but if bass is what you want ...]

now in all honesty, if the sub is set right you shouldn't notice it's there. of course when testosterone filled people use a sub they want it to be noticed, so try setting the crossover to 100Hz




Swype on iOS is detrimental to accurate typing. Apologies in advance.


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