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Box Tuning for W8-1808
Box Tuning for W8-1808
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Old 4th July 2018, 08:36 PM   #1
maLx is offline maLx  United States
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Default Box Tuning for W8-1808

Hi, Everyone.

Trying to get the most out of my Tang Band W8-1808 Full Range 8" Driver. I have been building some test boxes to see what sounds best, I'm getting close, but still having two issues I'd like to solve.

First I build a 1cf box cube and placed it inside sealed. It didn't sound good, there was no bass and it distored.

So, I added a 1" slot port. The box size is 12x12x12 and the 1" slot port is 1" x 11" wide by 11" deep.. That helped with some of the low end bass response.

Next, I was getting a ton of honkyness out of the box. I fixed most of that by using Focal Blackhole, which is the dampening you'd use in a car. It's not a permanent solution, but I had scraps left over from a car project. This seemed to help, however, I'd like to find a similar solution that's more appropriate for a home application.

Finally, the woofer on hard bass beats is distortion. I'm trying to fix that too.

So here are my problems and I am open to suggestions for corrections.

1: A little more low end out of the box. Will extending the port length help?
2: What can I use that is not Focal Blackhole that will do the same thing and be more effective for home use?
3: What is a good way to restrict woofer movement while not sacrificing bass to prevent distortion. Should I add more fill?

Open to suggestions, thanks!
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Old 5th July 2018, 04:53 AM   #2
GM is offline GM  United States
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A longer vent tunes it lower, but the cab's much too small to take advantage of it plus the slot vent should be < 9:1 ratio, hence the 'honk'. A 'classic' alignment [~Vas/1.44] with a 4" dia. vent will allow minimum damping with solid response down to 40 Hz. Anything larger, tuned lower may be too power limited unless average SPLs are in the TV movie viewing range or lower, i.e. trading [mid-bass] efficiency for more [bass] bandwidth [BW].

GM
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Old 5th July 2018, 05:52 AM   #3
maLx is offline maLx  United States
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Quote:
Originally Posted by GM View Post
A longer vent tunes it lower, but the cab's much too small to take advantage of it plus the slot vent should be < 9:1 ratio, hence the 'honk'. A 'classic' alignment [~Vas/1.44] with a 4" dia. vent will allow minimum damping with solid response down to 40 Hz. Anything larger, tuned lower may be too power limited unless average SPLs are in the TV movie viewing range or lower, i.e. trading [mid-bass] efficiency for more [bass] bandwidth [BW].



GM


Thanks. Iíll mess with that tomorrow. I went back to the sealed box for the time being to see what I could change there. I ended up getting a better result thus far vs. ported. The issue at hand is Iím getting a huge dip at 1k (pic attached).

Any ideas on how to approach that? Could there be some cancellation in effect here?

IMG_0669.JPG
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Old 5th July 2018, 08:34 AM   #4
Ugg10 is offline Ugg10  United Kingdom
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1khz has a wavelength of 1ft (30cm) approx. therefore this is function of the size of the box you have chosen. If it is a true cube then you will be getting cancelation from internal reflections at the box natural resonant frequency. This is why most speakers have different dimensions for the three sized typically. I think the only thing you can do to get around this is to add foam or filling to the box to try and reduce reflection waves.......or build a box with the same volume but with different side dimensions.


Typically subwoofers are built around the 1ft cube but as they tend to be used under 200hz this is not a problem, but for full range then it start to be an issue.

SOUND FREQUENCY & WAVELENGTH CALCULATOR

Looking at the W8-1808 data there is a slight dip at this frequency as well that may have a very minor effect.

Interestingly. on the Parts express page they have the following suggested box sizes -
Sealed 1cuft - f3=87hz which is why you were not seeing much bass.
Vented 3.27 cuft - f3=47hz which suggest you need a much bigger box to get down low.

Tang Band W8-1808 8" Neodymium Full Range Driver

Last edited by Ugg10; 5th July 2018 at 08:36 AM.
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Old 5th July 2018, 03:36 PM   #5
GM is offline GM  United States
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Even this borders on too big as the few extra Hz lower 'costs' ~ 5 dB of critical mid-bass Vs the 'classic' alignment, so best suited for corner loaded.

GM
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Old 6th July 2018, 12:18 AM   #6
maLx is offline maLx  United States
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I'm not going to do anything crazy to produce bass out of it if it's not going to be effective, so good points here. The driver does sound really nice in the sealed box, so going to mess with that one first to see if I can get rid of the tip, if I can't, I can mess with the ported one too and see what provides the best results. I did get some more bass out of the ported box, but it wasn't enough to sacrifice sound quality in other ranges to care.

Thanks everyone for the advice!
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Old 6th July 2018, 01:22 AM   #7
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Box Tuning for W8-1808
1 ft3 is small. My miniOnken alignment tends to yeild “small” boxes and the Tan-Ken for the 1808 is about 85 litres.

http://www.planet10-hifi.com/planset...omo-230312.pdf

dave
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Old 10th July 2018, 08:02 PM   #8
Godzilla is offline Godzilla  United States
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Thanks for posting the plans, Dave.

I see this design (and similarly sized ported boxes) with the 1808.

http://www.tokugawa-audio.com/produc...9968;對/

I listened to this driver in .8cf sealed boxes for a while - no bass. Use with subwoofer and enjoy. Also had on open baffle atop H-frame - sounded super detailed.
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Old 11th July 2018, 07:09 PM   #9
maLx is offline maLx  United States
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Thanks everyone.

I was able to get a good response out of its enclosure. Here’s what I did, and maybe you can help me tweak it a bit because I obviously built a test box.

I added a 1” tall slot port that’s about 10” wide on the bottom of the driver. That port goes all of the way to the back of the enclosure and then extends upwards to the top of the enclosure leaving about 1” space on the top like an L. Let me know if that makes sense.

So the total length of the port has to be about 20” if you account for the wood thickness which is a variance of 3/4" and 1/2”

I lined all of the inner walls with Focal Blackhotel to prevent any sort of resonation as well as filled the box about 1/2 with polyfill.

The response I get is attached.

I’m building the final enclosure out of 7/8th inch thick cherry outside dimensions will be 14” x 14"

Here are my questions.
1: Is Focal Blackhole something that makes sense to use here? Otherwise, what else would be acceptable? I’m trying to keep reflections from coming out of the box. The matting seemed to work but I can't imagine this good for a home application and there has to be something more suitable.
2: Should I adjust the slot port at all? The port is a bit on the big side I know and I designed this all on trial and error. Maybe there’s a volume of port I can stick to and it does not matter if it’s slot or round? I want to avoid using a round port because I don't like
3: Any other recommendations to keep that low end bass strong in comparison to the high end? Possibly a capacitor to reduce brightness of the high end frequencies above 1k? The highs on this driver are VERY strong.

Let me know what you think. I’ve attached an SPL chart of what I got so far and some pics of the enclosure so you can get an idea.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Click the image to open in full size.

Thanks everyone!
Joey
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