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SO Imperial cutoff (Read 3452 times)
jason300b
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SO Imperial cutoff
11/08/07 at 17:09:38
 
Hi,

I'm thinking of building a SO Imperial.  I'm new to this forum and I tried to find the answer to my question in the archives but was unsuccessful.  So here goes, does anyone know the upper cutoff frequency of the SO imperial?  I'm thinking of building a set to go with my Avantgarde Duos and I need an upper cutoff of about 160 Hz, possibly less but I'd like to keep a little 'wiggle" room.

Thanks for your help.
Jason
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Young_SC
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Re: SO Imperial cutoff
Reply #1 - 11/09/07 at 23:32:40
 
90 Hz is my recollection.

Read the design notes on the Decware site.

Simon
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jason300b
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Re: SO Imperial cutoff
Reply #2 - 11/10/07 at 00:44:24
 
Hi Simon,

Thanks for the help.  Sounds like the standard Imperial may be more appropriate to build for my setup.

Jason
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industrial_greyd
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Re: SO Imperial cutoff
Reply #3 - 01/29/08 at 00:02:38
 
I was wondering where I could find the "design notes" as mentioned in a post by Young_SC. I have looked all over the site for them and have come up with nothing.

I have the same question about what the upper frequency cutoff is, and also the lower cutoff when corner loaded, and the cabinet gain over a standard vented box.

I think that I have read somewhere that a driver that performs well in a 4 cubic foot box is ideal, I have the Dayton Reference Series 15"  HF  http://www.partsexpress.com/pe/showdetl.cfm?&Partnumber=295-468 any help would be appreciated.

Matt
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Steve Deckert
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Re: SO Imperial cutoff
Reply #4 - 01/29/08 at 01:14:11
 
jason300b wrote on 11/08/07 at 17:09:38:
Hi,

I'm thinking of building a SO Imperial.  I'm new to this forum and I tried to find the answer to my question in the archives but was unsuccessful.  So here goes, does anyone know the upper cutoff frequency of the SO imperial?  I'm thinking of building a set to go with my Avantgarde Duos and I need an upper cutoff of about 160 Hz, possibly less but I'd like to keep a little 'wiggle" room.

Thanks for your help.
Jason


Jason,

The cutoff of about 160 Hz is certainly not going to be a problem provided you plan to place the cabinets behind your Duos.  I use mine with no crossover and a rather inefficient woofer designed for a sealed box with a natural response decay at 500Hz.  In the cabinet I'm still getting 500Hz out of it, but at a very reduced level - perhaps 20dB down from where it would be at say 20Hz.  I find this blend to be superior to a stiff crossover point.  I always run my main speakers full range btw.

Steve
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Steve Deckert
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Re: SO Imperial cutoff
Reply #5 - 01/31/08 at 16:03:08
 
With the slot shaped as it is to allow a clear view of the dust cap, you can figure the upper frequency roll off will be determined by the driver, not the cabinet.   Low frequency roll off remains unknown since I've only tried a couple different drivers in the cabinet since I created it.   Flat response to 20 Hz has been confirmed with drivers having an fs near that figure.  

Regarding the Dayton woofer you listed, the only two considerations with it would be the lack of efficiency.  87dB 1w/1m is the same as 90dB 2.83v which is actually 2 watts.   Also the plastic cone material is less than ideal for any frequency above 90Hz.  Pulp cones are going to sound better.  

While I haven't measured the gain (I will eventually) in my cabinets 500Hz is about 6db down from my main speakers rated at 99dB 1w/1m using a similarly inefficient woofer in the SO.  20Hz is about 6dB up making the estimated gain at around 12dB when both speakers are driven by the same amplifier and no crossovers are used.

Steve
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industrial_greyd
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Re: SO Imperial cutoff
Reply #6 - 01/31/08 at 23:46:14
 
Thanks for the reply Steve, let me see if I got this straight: the gain @ low frequency is roughly 9db greater than if the woofer was in a standard box? Oh and BTW the woofer has an Anodized Aluminum cone and dust cap, I'm not sure if that is better than polypropylene plastic for higher frequencies, i would definitely be interested to find out though. Thanks for the help,

Matt
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