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Sub crawl for downfiring rear port subwoofer


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Hi all

 

I need to work out where best to place my subwoofer.

Its a wharfedale powercube 12+ as its downfiring and has twin rear ports I am wondering what the best way to do it is.

If I move the couch out of the way and place it there won't the room acoustics differ? Especially if the couch is still in the room

 

Also what is the best song/ sound file to play to test the sound? I have it connected to HTPC so file can be online

 

Thanks

Jono

 

P.S. If anyone knows where to buy a cheap replacement phase switch please let me know

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35 minutes ago, jonooo said:

Hi all

 

I need to work out where best to place my subwoofer.

Its a wharfedale powercube 12+ as its downfiring and has twin rear ports I am wondering what the best way to do it is.

If I move the couch out of the way and place it there won't the room acoustics differ? Especially if the couch is still in the room

 

Also what is the best song/ sound file to play to test the sound? I have it connected to HTPC so file can be online

 

Thanks

Jono

 

P.S. If anyone knows where to buy a cheap replacement phase switch please let me know

For parts try Altronics or RS Components.

 

Theres not enough info from your description to go on so a picture or layout of the room and gear placement would help. However, subs are usually placed next to the system close to the wall, try several spots and see what sounds right, flick phase switch or reverse the cable input and listen to see what sounds right - basically bass notes should sound fullest with impact and not hollow or out of phase. Set controls for around 40-50hz and adjust volume to match the speakers, should not dominate the overall spectrum.

 

For test music or movie sound tracks anything with low doof-doof like Making Sandwiches by Detroit Grand Pubahs or Blue by Eiffel 65 or movies Star Wars and Pacific Rim etc.

Edited by Al.M
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First thanks muon* ill definitely go buy those from Bunnings.

 

Second for A.I.M. here you go a couple images to help you understand what I am working with the T.V. is at the bottom of the room layout. It has to be lounge and dining so the couch is halfway into the room with the dining table on the other side. The speakers are about a metre in front of T.V (Sony 85" T.V.  Wharfedale 220 speakers). Any other room corrections you see would be helpful.

 

When you say set controls do you mean temporarily set crossover lower? Should I unplug all other speakers?(They are bananas so not too hard to do.)

I found out about an app called Sound Analyzer App to measure volume have you had any experience with this? I know it won't be 100% but better than my ears?

 

TL:DR Thanks here's photos please help 🤪

 

P.S. While I do like those songs it is quite an odd selection. No deadmau5? Or tupac?

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Edited by jonooo
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Room layout looks about right perhaps move speakers and gear to centre with equal distance to left and right walls.

 

You don’t really need a sound app, just use your ears for what sounds good in several arrangements like adjust volume balance between sub and speakers, sub crossover level and phase switch or swap the input cable (white/black to red if it’s not mono) to achieve the same. Try carpet rug in front of speakers and read this for room acoustics https://www.audiophysic.com/en/rules-about-positioning/

 

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so this is a 2.1 system?

 

sub choice is interesting if for music as that sub gets very ave ratings from users, but can mean little if it works for you. the thing is down firing are usually for movies and usually placed on a hard "slab".. ie: thick piece of hardwood or a large paving stone etc.

 

try as suggested and centre the set up, to far to the left.

 

try the sub behind your seating.

 

is there an avr in your set up? what auto EQ does it have?

Edited by hopefullguy
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the "sub crawl" implies placing the sub where your head would be at the listening position, then placing a measurement mic and running a measurement at each spot you might want to place your sub...or not as good, placing your head (instead of the mic) in those same spots and listening for best bass.

 

It's a faster way of finding the best spot for your sub, as it's much quicker to move the mic/your head, than moving the sub.

 

Using a mic and doing measurements will provide a much better indication of the smoothness or lumpiness of the room's bass response at each of the spots...but you do need to get the sub in a position that closely replicates where your head is at the listening position...otherwise when you place the sub where the mic was, the response won't be the same...

 

...or just do as above posts say - try your sub in different positions...but this is not what is generally referred to as the "sub crawl"

 

cheers

Mike

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Hi all

 

Thanks for the response everyone.

 

My system is 4.1 i built it on a very limited budget.(although the rear speakers are just add ons which i got for nothing with the sub). I am running a Yamaha RX-V767. It is purely digital. PC audio out to amp via DVI with HDMI out from PC to TV.

 

To hopefullguy yes the sub is not amazing but I got it under 200 which i felt like was a good deal at the time as this is my first system and I wanted to add more to low end without spending too much.

I am interested in your reason for suggesting placing on something solid as it seems to be the opposite of what muon said about decoupling it with antivibration pads?

 

I have a feeling all being said I may have caught the bug... that is the audio bug 😃 and now just seeing the limitations of my system.

 

Thanks again

Jono

 

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On 16/01/2021 at 1:06 PM, jonooo said:

To hopefullguy yes the sub is not amazing but I got it under 200 which i felt like was a good deal at the time as this is my first system and I wanted to add more to low end without spending too much.

I am interested in your reason for suggesting placing on something solid as it seems to be the opposite of what muon said about decoupling it with antivibration pads?

 

Hi Jono,

try quoting the post or using @ if you want to highlight a specific member eg @hopefullguy...

 

On 16/01/2021 at 1:06 PM, jonooo said:

I am interested in your reason for suggesting placing on something solid as it seems to be the opposite of what muon said about decoupling it with antivibration pads?

I'm happy for @hopefullguy or @muon* to chime in, but IMHO I would would offer the below summary:

  • cabinet vibrations are bad and should be minimised - in the DIY world this is achieved via multiple approaches - with commercial designs you're stuck with what you have
  • transmitting cabinet vibrations to the room via coupling is also bad...IMHO you're better off de-coupling speakers from the room structure
  • placing something solid underneath a "down firing" sub is a reasonably common approach - it's not necessarily the opposite of what @muon* said...you could easily de-couple the "solid surface" from the room structure...the object of the solid surface being to reflect acoustic bass energy back into the room, not to physically couple vibrations to the room structure...

It takes a lot of acoustic energy to make windows/rooms rattle...but much less energy if your speaker cabinets are vibrating and transmitting that energy directly to the room via physical coupling.

 

IMHO try to decouple speakers from structures.

 

cheers,

Mike

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thanks @almikel i was wondering how people were quoting others and i couldn't find it in the FAQ

 

So from what I understand is that rather than reflecting off the wooden floor reflecting off something hard would give the sound more punch whereas putting the anti vibration pads stops windows and other things rattling and resonating.

So two different ways to make the audio sound better. 

Thank you for clearing this up for me.

 

I have now moved the sub as suggested by @hopefullguy  It is now behind my listening position in the centre of the room next to the wall and the curtains with the ports firing into the wall its definitely different not sure whether better or worse I will leave it for a week and see how it goes. 

 

I really do appreciate the help from the people here as for someone new to this it can be quite intimidating when so many audio forums and videos focus on single products worth multiple times what my whole system cost.

 

Edited by jonooo
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Hi Jonoo,

 

To quote just a part of another post, highlight the text and you'll see a button to quote the text

910635571_quotesmalltext.png.c327b46baf281c917417af67c0866ed7.png

 

Which gives the below

6 hours ago, jonooo said:

i was wondering how people were quoting others

 

To quote a whole post, there's a Quote button at the bottom of each post...

 

Make sure the cursor is in the spot in your new post where you want the quote to land...but you can drag them around afterwards, by hovering on the quote and dragging the arrow

1153996610_clickanddrag.png.e1a6e1dcd5ca19260a2dfe9e189f0631.png

6 hours ago, jonooo said:

I really do appreciate the help from the people here

👍 - very friendly/helpful/knowledgeable people here - I've learned heaps from members across my 10 years on SNA !

 

cheers

Mike

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