tune the box higher
why would you tune it to 20 hz

 

depending on the sub and enclosure size.. It can create a peak in the response, and limit low end response.

If you have ever heard a SVS-sub or adire shiva/tempest recommended design for HT, you wouldnt ask a question like "why tune it to 20hz".

 

i would think that raising the tuning to 25-30 should not be to depermental
building and tuning a box is a balancing act
everybody puts in the output without taking into account what the room will do

 

Yes, thats why you want to start with as flat of a response as possible with a gradual/slow roll of, or a EBS type design which when designed properly will have a flat in room response.

Another reason for lower tuning is driver excursion protection below tuning.. With current Movies having sub bass down to 20hz it helps keep the sub from bottoming out, Which i have heard commerical offerings do.

[ December 28, 2005, 08:25 PM: Message edited by: chev2 ]

 

try running your box results with a good program like leap and then you can balance your excurion output and rolloff
tuning higher will give your driver more power handling where you want it
driver exursion does not go out the window at tuning frequency as most people beleive
tuning lower will actually reduce your power handling where you need it

 

At tuning of course not. At tuning driver excursion is at its lowest. I said below tuning, not at tuning.

If your using it for music i agree with you, 40-60hz is what you want. If you want a rocking HT system that can play all of the LOTR's at reference levels with out bottoming out, i will tune lower. Assuming of course the driver/enclosure needs it and can handle it.

SVS didnt get there reputation for just having nicely carpeted tubes [img]smile.gif[/img] .

[ December 28, 2005, 08:38 PM: Message edited by: chev2 ]

 

The driver in question is this:
Peerless 830845

found here: http://www.solen.ca/pee.htm
Specs
Size: 31cm
VC: 51mm
Type: Paper Cone
Eff: 91 dB SPL
W: 300watts
Z: 4ohms
Re: 3.5
Fs: 18Hz
Vas: 137ltr
Qms: 3.7
Qes: .21
Qts: .20
Xmax: +/- 13mm

I have choosen this driver because it is offered in a kit by Solen, and from what I have read, Peerless makes good drivers.

I am open to other recomendations as long as it is availible from a Cdn supplier.

Design goals:
Flat to 20Hz
High output
Cost effective

Pinhead: This subwoofer wil be used as my reference sub, and as such many comercial subs will be compared to it (cost will not be compared mind you). Therefore it must be able to compete with high-end home theater subs that are very capable of outputing 20Hz at decent SPL's.

The room is always a factor, however I wil be moving in the next year, and in the next two years will have a dedicated theater room. Therefore I am not designing this sub with the room in mind as that factor will change.

I am planing on using either a plate amplifer with built in EQ, or a standdard amp and seperate EQ. X-over is not necessary as my HT processor will take care of that.

This will be used as my reference sub, as a DIY project for Secrets of Home Theater and as a learning tool for myself.

I will be learning about this as I go along, so feel free to add any info that may be of help.

So far I have been gathering info from;
www.diysubwoofers.org
www.diyaudio.com
www.audiocircle.com
etc...

Thanks everyone...

[ December 28, 2005, 08:49 PM: Message edited by: JRace ]

 

Jrace you sure there tuning it to 20hz? it doesnt really look to good on paper.. 25-30hz tune seems more resonable.

Ever condiser a Parts express dayton DVC 12? I know its not CDN, but...

 

I have seen a few plans that are tuned to 20Hz using one passive rad and less power. Solen recomended two rads with the upgraded amp to increase ouptut and low-end response.

I had considered the Dayton kit...just wanted to explore my options up here first.

 

hrrmm... $227 + tax & shipping for that Peerless driver is reasonable...

Having said that Ive got a nice svc 4ohm MTX 8500 in the 4sale section that will definatly outpreform that peerless for about the same $$$$... [img]graemlins/deal4u.gif[/img]


I agree with the notion you should tune low.. 20hz is perfect for HT SQ..