Tang Band Tang Band W8Q-1071F 8 X 12 box reccomendation - diyAudio
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Old 7th December 2011, 03:51 PM   #1
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Default Tang Band Tang Band W8Q-1071F 8 X 12 box reccomendation

Hi All, I have been lurking on this site for a while and feel it is time to ask for some input.

I have two tang band 8 X 12 drivers with the following specs.

Specifications: Power handling: 250 watts RMS/500 watts max VCdia: 2" Impedance: 4 ohms Re: 3.2 ohms Frequency range: 27-200 Hz Fs: 27 Hz SPL: 88 dB 1W/1m Vas: 2.49 cu. ft. Qms: 4.6 Qes: 0.36 Qts: 0.34 Xmax 12 mm Dimensions: Overall diameter: 8-1/2" x 12-1/8", Depth: 5-3/4".

I have modeled a 6.5 cubic foot slot ported enclosure tuned to 28hz that is essentially flat down to 25 hz. I am satisfied with the design but I don't get much gain from it. My problem is that I only have around 200 watts RMS available for the system so sensitivity and gain are very important and this design is lacking in those departments. Can anybody reccomend a solution with response below 30hz that could offer me a nice increase in sensitivity to make the most out of my limited power?

6th order band pass
Tapped Horn? (modeled up some, but they are HUGE!)

thanks much folks
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Old 8th December 2011, 07:18 PM   #2
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by permo View Post
Hi All, I have been lurking on this site for a while and feel it is time to ask for some input.

I have two tang band 8 X 12 drivers with the following specs.

Specifications: Power handling: 250 watts RMS/500 watts max VCdia: 2" Impedance: 4 ohms Re: 3.2 ohms Frequency range: 27-200 Hz Fs: 27 Hz SPL: 88 dB 1W/1m Vas: 2.49 cu. ft. Qms: 4.6 Qes: 0.36 Qts: 0.34 Xmax 12 mm Dimensions: Overall diameter: 8-1/2" x 12-1/8", Depth: 5-3/4".

I have modeled a 6.5 cubic foot slot ported enclosure tuned to 28hz that is essentially flat down to 25 hz. I am satisfied with the design but I don't get much gain from it. My problem is that I only have around 200 watts RMS available for the system so sensitivity and gain are very important and this design is lacking in those departments. Can anybody reccomend a solution with response below 30hz that could offer me a nice increase in sensitivity to make the most out of my limited power?

6th order band pass
Tapped Horn? (modeled up some, but they are HUGE!)

thanks much folks
Hi permo,

Here is a simulation using two series connected Tangband W8Q-1071F in a T-TQWT that should not be driven with input powers above 200W Rms:

The design challenge is to provide enough of clearance behind the driver magnets...

b
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Old 8th December 2011, 07:53 PM   #3
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by bjorno View Post
The posted picture deleted by a mistake?
Here it is again:

b
Attached Images
File Type: jpg 2xTB-W8Q-1071F_T-TQWT.JPG (287.4 KB, 1734 views)
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Old 8th December 2011, 07:57 PM   #4
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Wow, now I can see it. What kind of enclosure is this? It looks like the volume is workable for sure and it looks great. I can see the basic design, but all I get is L23......what is L12, L34..etc..etc... What driver configuration do I pick in hornresp? Clearly not a tapped horn..but looks AWESOME. Heck, I can start cutting wood tonight if I can figure it out.

Last edited by permo; 8th December 2011 at 08:05 PM.
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Old 9th December 2011, 08:15 AM   #5
bjorno is offline bjorno  Sweden
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Quote:
Originally Posted by permo View Post
Wow, now I can see it. What kind of enclosure is this? It looks like the volume is workable for sure and it looks great. I can see the basic design, but all I get is L23......what is L12, L34..etc..etc... What driver configuration do I pick in hornresp? Clearly not a tapped horn..but looks AWESOME. Heck, I can start cutting wood tonight if I can figure it out.
Hi permo,

Here is a picture that might help:

PS: You can export the enclosure dimensions in HR by clicking on 'file' at the schematic diagram screen: Example in th picture.
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File Type: jpg TB-W8Q-1071F_wizard.JPG (590.6 KB, 1631 views)
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Old 9th December 2011, 09:17 AM   #6
mdocod is offline mdocod  United States
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In my limited understanding and experience, there is no free lunch on this sort of thing. You can either play deep or have efficiency up higher. Playing deep with decent efficiency requires more driver surface area.

With your current drivers I came up with the following:

A 6th order bandpass with 2ft^3 @ 65hz and 4ft^3 @ 35hz will give you over 94db@1w@1m efficiency from 40-80hz, but will not be playing below 30hz and is basically limited to the 35-90hz range. It would deliver better efficiancy from 35-90hz than your current model by as much as ~4.5db across most of it.

A 6th order can be used to replicate the rolloff of your current model, but the efficiency gain is only about 1-2db, and the box size is 50% larger.

Out of curiosity, what size room is this being used in? If it's a small room then you may be able to get away with tuning them even lower and still get respectable performance with some EQing. If it's a large room, then I would suggest larger drivers to begin with

Eric
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Old 9th December 2011, 12:12 PM   #7
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My room I am looking at a theater room of roughly 225 square feet. I guess it is not that large. I could just buy a larger amp too I guess.

The surface area of these drivers when combined, is more than a normal 15" driver. I assumed that would be enough but I guess not.
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Old 9th December 2011, 12:42 PM   #8
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Quote:
Originally Posted by bjorno View Post
Hi permo,

Here is a picture that might help:

PS: You can export the enclosure dimensions in HR by clicking on 'file' at the schematic diagram screen: Example in th picture.

I appreciate your efforts and your patience with me. I want to build this horn, but I need to get it right.

I noticed L12 was 158 cm. So that means that there are 158 centimeters between S1 (beginning of throat) and S2 (middle of driver(s)) correct? That puts the drivers a ways up the horn I think?

S4 would be the lenght of the opening at the end of the horn I think? What is S3 in this design?

if you don't have time to help or are frustrated with my slow learning curve, i sure understand.
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Old 9th December 2011, 01:03 PM   #9
mdocod is offline mdocod  United States
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225 sq ft isn't too aweful daunting. I think they are going to work fine as long as you aren't expecting listening levels that are nutty

Personally I would suggest building 2 separate boxes for them though, and setting them up as a sort of stereo pair of subs. You'll have more freedom to tweak the way they sound also. You may find that with proper room placement you can eek out some better bottom end from them.

I would personally build them ~1.5-2.5ft^3 per box. Tuning frequency anywhere in the 25-35hz range just depending on how much low end capability you want to strive for at the cost of efficiency. When you start trying to eek out the bottom end with over-sized boxes it seems like the quality of the bass reproduction can take a dump. (though, this varies depending on the box built quality and the driver dampening characteristics). If you can live without that 30hz and lower stuff, the smaller(ish) boxes tuned higher will probably result in lower distortion reproduction with faster transients.

I wouldn't worry about the amplifier power. The pair of speakers are rated to handle a combined ~500W RMS. The difference between 200W and 500W is roughly 4db. I wouldn't bother upgrading the amp UNLESS it's a lousy amplifier in terms of cleanliness and dampening characteristics. You want clean and well controlled power first and foremost. Quality>Quantity IMO.

Eric
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Old 9th December 2011, 01:12 PM   #10
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Quote:
Originally Posted by mdocod View Post
225 sq ft isn't too aweful daunting. I think they are going to work fine as long as you aren't expecting listening levels that are nutty

Personally I would suggest building 2 separate boxes for them though, and setting them up as a sort of stereo pair of subs. You'll have more freedom to tweak the way they sound also. You may find that with proper room placement you can eek out some better bottom end from them.

I would personally build them ~1.5-2.5ft^3 per box. Tuning frequency anywhere in the 25-35hz range just depending on how much low end capability you want to strive for at the cost of efficiency. When you start trying to eek out the bottom end with over-sized boxes it seems like the quality of the bass reproduction can take a dump. (though, this varies depending on the box built quality and the driver dampening characteristics). If you can live without that 30hz and lower stuff, the smaller(ish) boxes tuned higher will probably result in lower distortion reproduction with faster transients.

I wouldn't worry about the amplifier power. The pair of speakers are rated to handle a combined ~500W RMS. The difference between 200W and 500W is roughly 4db. I wouldn't bother upgrading the amp UNLESS it's a lousy amplifier in terms of cleanliness and dampening characteristics. You want clean and well controlled power first and foremost. Quality>Quantity IMO.

Eric

Amplifier is Dayton Audio APA150, I think it is a pretty good amp.

I was also thinking 2.5-3.0 tuned to 28-30 hz ported. Likely a slot port but might break out the heat gun and mold some flared ports. We will see.

I would like to get the horn design to work out, but my brain can't quite wrap itself around the concept well enough yet.

I have modeled a 6th order BP just like you did, and I get a nice flat passband with good gain, but below about 35hz she shuts down. I want it to go to 25hz...or lower. Movies are my main objective.
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