I think I want to build a TH for bass, Cubo Sub or similar - diyAudio
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Old 27th December 2011, 05:05 AM   #1
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Default I think I want to build a TH for bass, Cubo Sub or similar

It seems to play down to 25 Hz louder than a BR of the same size (Free Speaker Plans - Free Speaker Plans ? View topic - Cubo 18). How is the sound quality of these horns or distortion? I was originally looking to build a TH with two CSS SDX10 drivers, but some one wrote their horn was "ringing."

Free Speaker Plans - Free Speaker Plans ? View topic - Cubo Sub
Cubo Sub

I would like to build a cubo sub with a RCF L18P200-N. I don't know if a driver with such a low fs will play lower in a cubo or just quieter. Maybe I can change the shape of the cubo, to a longer horn (25 Hz perhaps). I haven't figured out how to use hornresp yet, though.
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Old 27th December 2011, 06:59 AM   #2
col is offline col  Australia
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maybe try one of these in a cubo sub:

http://www.mcmelectronics.com/produc...-2985-/55-2985

cheap enough and if you buy 2 you get free shipping!
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Old 27th December 2011, 07:37 PM   #3
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That's a 21" driver, but they do have an 18" version.

I was wondering about the sound quality of horns such as the cubo sub. I was told I can make the cubo 770x700x480 mm, but I want to make one of the 770 mm dimensions longer, therefore increase the length of the horn.
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Last edited by Jimmy154; 27th December 2011 at 07:41 PM.
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Old 27th December 2011, 08:09 PM   #4
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Originally Posted by Jimmy154 View Post
That's a 21" driver, but they do have an 18" version.

I was wondering about the sound quality of horns such as the cubo sub. I was told I can make the cubo 770x700x480 mm, but I want to make one of the 770 mm dimensions longer, therefore increase the length of the horn.
The Cubo is a variant of the tapped horn type of sub, the Cubo has a larger throat which works as a band pass.

The band pass probably reduces some of the objectionable upper peaks that are common for TH designs. I have not heard this particular TH, nor seen any measured response curves.

Distortion will be lower for a given SPL with TH compared to BR (bass reflex) of a similar size, but higher for a given excursion.

TH sound different than FLH (front loaded horns) or BR, sort of "in between" the two.

Good punch, but not as wide of a range of frequencies that sound good as BR or FLH.
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Old 27th December 2011, 08:19 PM   #5
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Quote:
RCF L18P200-N
That's a nice sub driver for home use. It has lowish Fs (for an 18" PA driver)but efficiency wise that's partially compensated for by higher Vas (and medium Qts). As a side note: Cubo Sub is also designed to fit 21" drivers but at 480 mm width that's not a good fit

If you send an e-mail to questionsaboutcubo[at]gmail[dot]com, I can see if it's possible to mod Cubo Sub to go lower and fit the dimension you mentioned. The depth/height up to 1215 mm and small width favor such a modification.

Most if not any sub horns (of all kinds) tend to have a particular sound in the mid bass area.

Best regards Johan
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Old 28th December 2011, 07:16 AM   #6
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I haven't decided on a woofer yet. I also like the Eighteen Sound 18LW1400 because of the weather protected cone and double demodulation rings (I'm not sure if other 18" pro drivers have these).

I'm also looking at the P Audio C18-650EL because it's cheap, but I don't know how it compares to the RCF or 18 Sound or the almighty JBL (2242).

I also bought two Peerless XLS 830500 subs, but I don't think they will be as loud as one 18" in a horn and I think these high excursion subs produce quite a bit more distortion, but I am not sure. The only up side they would have is the box would be 1/2 to 1/3 of the size.

The cones in home subwoofers seem to be more ridged, but the voice coils are small. And they need to move a lot to be loud.

I also thought about building a TH with one or two CSS SDX10 subs. Some already did this, but they wrote it was "ringing." Oh, I already wrote this
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Old 24th January 2012, 02:25 AM   #7
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Originally Posted by weltersys View Post
The Cubo is a variant of the tapped horn type of sub, the Cubo has a larger throat which works as a band pass.

The band pass probably reduces some of the objectionable upper peaks that are common for TH designs. I have not heard this particular TH, nor seen any measured response curves.

Distortion will be lower for a given SPL with TH compared to BR (bass reflex) of a similar size, but higher for a given excursion.

TH sound different than FLH (front loaded horns) or BR, sort of "in between" the two.

Good punch, but not as wide of a range of frequencies that sound good as BR or FLH.
That's rough. I can't really imagine anything having more distortion than a BR. For a given SPL it's less though, so that's good.

The cubo seems to play down to 25 Hz. That's should be plenty good for me, I think. I can't find the graph, but the cubo sub is louder than a BR above 25 Hz.

I wanted to build a Thor subwoofer, but it won't be loud enough. I like home subwoofer cones but not the motors. And pro subwoofers, I like the motors, but not the cones.
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Old 24th January 2012, 07:38 AM   #8
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Originally Posted by Jimmy154 View Post

The cones in home subwoofers seem to be more ridged, but the voice coils are small. And they need to move a lot to be loud.
A given driver size driven with a given frequency to a certain amount of excursion will be as loud as any other (be it home or pro audio). I suspect you're getting more extension out of the home subwoofers, so they're using up their excursion going lower.

1) Are you sure you want to go to 25Hz for bass guitar?
2) how loud does this need to be?

... and just because one subwoofer is louder than another at a certain frequency, it doesn't mean either should be used that low: you may find excursion gets silly for relatively little output. Remember these are pro audio subwoofers: going loud is the primary design goal.

Chris
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Old 8th February 2012, 09:28 PM   #9
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I'm going to go with two Peerless XLS 12" (830500) in about 3 cu. ft. (88 liters) volume sealed. I will be running of of my computer so my EQ opinions are for all practical purposes infinite. I can't have 12 cu. ft. or even 8 in my bedroom. I don't know why I have these crazy ideas sometimes.

2 Peerless should max SPL level should be 105 dB at 25 Hz at 1 meter in anechoic chamber. Not sure though. Here's a link:
SubZero, a Peerless 12 inch XLS based subwoofer
and
THOR - subwoofer
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Old 9th February 2012, 12:11 AM   #10
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Originally Posted by Jimmy154 View Post
I'm going to go with two Peerless XLS 12" (830500) in about 3 cu. ft. (88 liters) volume sealed. I will be running of of my computer so my EQ opinions are for all practical purposes infinite. I can't have 12 cu. ft. or even 8 in my bedroom. I don't know why I have these crazy ideas sometimes.

2 Peerless should max SPL level should be 105 dB at 25 Hz at 1 meter in anechoic chamber. Not sure though. Here's a link:
SubZero, a Peerless 12 inch XLS based subwoofer
and
THOR - subwoofer
The THOR s output at Xmax (typically 10 % distortion) is only about 55 dB in the low B range of a bass guitar.

That is barely audible.

A pair of the SubZero can do about 105 dB at 25 Hz, which sounds to the ear about like 70 dB in the 1000 Hz range, around conversational level.

Seems like you have lowered the SPL bar quite a bit .
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