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Old 28th August 2006, 04:37 PM   #1
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Default Any sense in swapping the driver out of this cheap sub?

Hi all, first time poster in this great subforum, have lurked plenty though.

Long story short: I recently picked up a sony SA-WM250 8" vented sub, which is rated 100 watts @ 6 ohms 28hz~khz?. Picked up it for a secondary theatre in my home just to add a few lows to the current bookshelves i have there. It was sort of an impulse buy since i picked it up on clearance for reeal cheap, but anyway. It did get mostly 5 star ratings at all the rating sites if that means anything.

I have not even hooked it up yet but i got to thinking, would i perceive a big difference in sound quality if i were to swap out the driver for something better? If the answer is yes, is there anything i should be aware of? (that oddball 6 ohm rating for example) Or are there certain drivers i should stay away from? Would a high Xmax rating really help with this sub? I wouldn't want to sink much more than $30 to $40 into this swap since that money would have been better spent on a different sub altogether .

I had bookmarked these 8" subs but held off buying till i could get definite answers to the above questions. I have tried researching for a few days but feel like i'm still at square one

- Dayton 8" classic $20: http://www.partsexpress.com/pe/showd...number=295-310
- Dayton 8" DVC $23: http://www.partsexpress.com/pe/showd...number=295-480
- Pioneer B20FU20-51D 6 ohm $23: http://www.partsexpress.com/pe/showd...number=290-055
- Audax Aerogel 6 ohm $37: http://www.partsexpress.com/pe/showd...number=296-175
- Dayton 8" reference series 4 ohm or 8 ohm models ($43)
- The Apex Jr Super 8" perhaps? http://www.apexjr.com/SuperSub.htm
- This 8" Vifa sub for $23 shipped: http://cgi.ebay.com/OEM-8-DIY-DUAL-8...QQcmdZViewItem
- I can pick up two Velodyne VLR series 8" subs for $40 AC @ Overstock.com. This would leave me with an extra 8" woofer for a 'possible' future project with this Infinity three-way amp.

Many thanks in advance for any insight or recommendations.
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Old 28th August 2006, 05:46 PM   #2
badman is online now badman  United States
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A more viable approach would be to add a layer of plywood to the outside of the sub- a stiffer enclosure makes a world of difference. Most subs at the bargain price range employ electronic EQ, so swapping out the driver requires testing, either of the driver, or of the amplifier's transfer function.
I write for www.enjoythemusic.com in the DIY section. You may find yourself getting a preview of a project in-progress. Be warned!
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Old 28th August 2006, 06:00 PM   #3
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Interesting, hmm.

Would adding braces inside the enclosure bring any sort of benefit do you think? I ask because it would be a lot less work than adding plywood to the exterior then finishing it off to something visually presentable. I could also add a bit more foam-filler to the interior while i was in there, and perhaps some bonding substance to all the wood joints (?) I just might try the plywood idea though, especially if i can get my hands on some nicer slabs.

I take it that swapping drivers is too hit or miss to recommend? I'm still mulling the idea, and am hoping to stumble upon more information.

Thank you for the info
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Old 28th August 2006, 07:03 PM   #4
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Aside from the important issues mentioned by badman, you also have one huge challenge to overcome. That box was designed for that woofer, hopefully. To see if any of those speakers are compatible you need to download winisd(pro) and model them in the box volume that you have, changing the tuning until the required port length matches the port you have now. If you are willing to by another port then all you need to do is be careful that the length required will fit in the box.
For volume calculation, make sure you factor in port volume and the volume occupied by the speaker basket.

Make sure you can purchase a port that will fit into the box! Sony is notorius for proprietary parts that are only manufactured for sony by sony. Or be prepared to upsize the port hole or glue a loose port in.

On a different note, why do you want to replace the woofer you have?
You need to listen to it so you can put into words what specifically you want to enhance. There are too many conflicting properties with woofers that you need to be careful of:
-high excursion woofers tend to have lower efficiency
-high efficiency woofers usually have lower excursion and therefore reduced low bass output
-cheap and small does not go well with low distortion and high output

Anyways, if the sub sounds ok or better I would advise leaving it alone. If this is for learning then by all means download the software and start modeling the woofers you linked.
Some keywords you might want to read up on:
sealed vs ported, Group delay, plate amps, efficiency, port resonance build up(ramp up?)-this will cause problems mostly with sustained bass notes-,f3,fs, Qts,Vas,rms/peak power, and many more. If you get a good understanding of all of those terms and read several articles on each you wont even need to ask whether or not you should do this project, you'll understand why.
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Old 28th August 2006, 07:18 PM   #5
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It is as i suspected. There is much calculation that needs to be done before someone undertakes what i have proposed.

With my research i had finally begun to understand that building subwoofers could be complicated, you fellas have confirmed it. I 'may' proceed with the minor enclosure modifications but will save the complicated aspects for a possible future diy sub (i like those sonotubes!)

Thanks again to the both of you
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Old 28th August 2006, 09:52 PM   #6
sYkboy is offline sYkboy  United States
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I say just use it as is for awhile. If anything, first spend a good amount of time auditioning for where it needs to go. Placement might help. As for drivers, you may be able to find one to work well in you cabinet but then you are almost at the price of just buying a plate amp and sub and putting it in the proper enclosure.
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Old 29th August 2006, 01:27 AM   #7
dangus is offline dangus  Canada
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The best bang for the buck could be to just buy another one of those subs if the sale is still on. Two subs will play louder than one, and by planting the subs in different locations the room response will be more even than from a single sub.
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Old 29th August 2006, 01:38 AM   #8
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Originally posted by dangus
The best bang for the buck could be to just buy another one of those subs if the sale is still on. Two subs will play louder than one, and by planting the subs in different locations the room response will be more even than from a single sub.

this is dead on great advice... you'll get much more "bang for the buck" by experimenting with room placement than trying to upgrade... try "NOT" placing the 2 woofers in corrners... maybe along the sidewalls, play with the phase (reverse leads to one sub)... check out your listening position, that sort of thing...

adding a second sub makes a world of difference...

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Old 29th August 2006, 05:05 AM   #9
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Originally posted by dangus
The best bang for the buck could be to just buy another one of those subs if the sale is still on. Two subs will play louder than one, and by planting the subs in different locations the room response will be more even than from a single sub.
hmm, oddly i hadn't thought of that, it's something i'm going to have to consider. Now hopefully i can still find more where i had bought it ($50 + tax). If it is sold out then i could just plant that same money into a small 10" or 12" sonosub project. I used to help my buddy build car sub enclosures when we were kids, i remember it being a lot of fun too. I really enjoy the research stage so maybe i should be planning my fall/winter project now
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Old 2nd September 2006, 04:21 PM   #10
Bogie is offline Bogie  United States
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MCM has a dandy little 8" driver that goes VERY nicely into one of Bill Fitzmaurice's tiny horns...
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