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Old 30th October 2014, 08:18 PM   #1
prezden is offline prezden  Canada
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Default Design help needed

I have an Eastech FOW6065-311 sub that I want to build a Bass Reflex cabinet for. Eastech was unable to provide the Thiel Small specs so I need some help with the box size.
The driver is 17.5cm with a cutout requirement of 14cm. It is 4ohm, 15-30W. Could someone kindly help me to figure out the proper size. Can I just resize a standard BR so that the driver cutout is the correct size or is it more complex.

Thanks
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Old 1st November 2014, 03:15 AM   #2
xrk971 is offline xrk971  United States
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If you have REW and a computer with stereo line input sound card, some wire, a resistor, a multimeter, some modeling putty, a gram scale, you can measure your own TS params. The instructions in REW show you how. There are also some on line how to guides.
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Old 2nd November 2014, 12:21 AM   #3
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Congratulations, you have gone back in time to the 1950s!

Yeah, that's how it was like before T-S parameters: VERY hit-or-miss.

Sealed boxes basically add stiffening to the driver's own suspension. Ported boxes add a highly significant resonant element, which should match the driver. So without parameters, it would be very random to make ported box for this.

You really need to figure out how to measure parameters (maybe someone lives near you who has a setup, otherwise you can do it with a good voltmeter and some kind of power amp). It's not that hard, just time consuming; if you want to do it post a different thread.

OR, just build a sealed box. They are much less sensitive to driver parameters. Yes, the numbers may change, but the actual response not so much.

By the way, just to add more excitement, the measured parameters depend on the measurement method AND on the drive level.
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Old 2nd November 2014, 08:49 PM   #4
prezden is offline prezden  Canada
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Thanks guys- I found this drawing for a FE167E that is almost exactly the same as the Eastech drivers. I know that speaker boxes are designed for specific drivers. Would it be possible to use this design and tune with felt and filler. Or would I be better off building a sealed box of the same size. Unfortunately I don't have the ability to figure out the TS specs.

Thanks again
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Old 3rd November 2014, 04:08 AM   #5
xrk971 is offline xrk971  United States
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That is not going to work. Just because they are the same size means they are the same size. You could build a prototype test box out of cheap foam core. Make an adjustable vent and tune it until it sounds ok. Helps to have a mic and software like REW.

Sealed will work but you will limit your bass extension.
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Old 3rd November 2014, 05:18 AM   #6
prezden is offline prezden  Canada
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Thanks X- I was thinking some of making some foam core models. It's been quite a while since I last worked with fc. Should be fun
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Old 4th November 2014, 02:16 AM   #7
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Quote:
Originally Posted by xrk971 View Post
That is not going to work. Just because they are the same size means they are the same size. You could build a prototype test box out of cheap foam core. Make an adjustable vent and tune it until it sounds ok. Helps to have a mic and software like REW.

Sealed will work but you will limit your bass extension.
Yeah, that is not a bad approach. And you can also cap/plug the port tightly, to hear what the sealed design would sound like for comparison.
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