Hi,
It depends a lot on the drivers but "around .15 ft sealed and
.35 ft vented" is way too small, ballpark is 0.5 cuft to 0.75 cuft.
Car drivers and cheap hifi drivers need to be sealed.
Some drivers can be either in different volumes.
High efficiency types generally are best vented.
Any details on the drivers would help.
rgds, sreten.
It depends a lot on the drivers but "around .15 ft sealed and
.35 ft vented" is way too small, ballpark is 0.5 cuft to 0.75 cuft.
Car drivers and cheap hifi drivers need to be sealed.
Some drivers can be either in different volumes.
High efficiency types generally are best vented.
Any details on the drivers would help.
rgds, sreten.
They're model name is Technics sb-ca10. Can't find much about them. On the back it only says 6 ohm, 100W peak and 50W DIN. But i'm using a very cheap ebay amp powering them atm, until my new one arrives, and they go really loud, and very low, no matter where i place them in my room. With some songs, that contains very low freq bass, I can feel it filling the whole room and in my chest as if they were a pair of subwoofers.
Their original enclosure is very large for a pair of bookshelf speakers, and they have a massive port hole. I haven't actually taken apart the speakers to see if there is a sticker with more information on the back of the actual drivers, but let me know and i'll do it asap. I can also measure their original enclosure if that information would be somehow useful.
That's everything I can tell about the speakers. My plan is to put them both in one enclosure for a boombox im building. I don't need exact calculated dimensions for a new enclosure, rather an estimate is what im looking for. Something to start from and work with.
Any suggestions is much appreciated.
Sorry, those volumes were based on a single driver not two, those volumes came from a dayton 6.5 inch woofer.
I've built an enclosure, it's 47L. Quite bigger than what I imagined, after I assembled it. I'm thinking of putting two 8" bass/mid drivers in there instead. I found a cheap one but rather good quality for the price, 20 USD. This is the datasheet for them http://bit.ly/1MLCcum
Is 47L too small for two 8" drivers? I'm also going to use a 2 channel 30W+30W Class D amp. Considering the amp, is it really worth getting 8" drivers, maybe because of possible lack of output power to them? I'm thinking of going for high sensitivity piezo tweeters and let them give the "loudness" and let the drivers work "calmly" on bass and mid.
But if i go for two 6.5" drivers, isn't 47L volume a bit too much? I'm looking for as deep bass as possible, without having to turn up full blast until it's noticeable. The actual sound quality is less important in this case. Any suggestions is very much appreciated.
Is 47L too small for two 8" drivers? I'm also going to use a 2 channel 30W+30W Class D amp. Considering the amp, is it really worth getting 8" drivers, maybe because of possible lack of output power to them? I'm thinking of going for high sensitivity piezo tweeters and let them give the "loudness" and let the drivers work "calmly" on bass and mid.
But if i go for two 6.5" drivers, isn't 47L volume a bit too much? I'm looking for as deep bass as possible, without having to turn up full blast until it's noticeable. The actual sound quality is less important in this case. Any suggestions is very much appreciated.
No such thing. Every bass driver has parameters and they are used to design the box. Your question is like: "I want to buy a car. It has 4 wheels. What will it cost?"
This is good advice.
Hi,
FWIW 47L sealed and stuffed is a good match to two of those 8" drivers.
rgds, sreten.
But I just noticed that they are 87.5 dB SPL. How much actual real-life difference is it between 87.5 and 90/91?
Also, doesn't sealed enclosure decrease the output levels, compared to ported? As in lower volume, maybe even less bass?
I see, didn't think it would vary that much given that the different speakers would be the same size.
What exactly does double one boxes internal volume mean? As in split the enclosure in half internally and create one section for each speaker?
Yea, I got that part. But I'm still a little uncertain of what exactly I'm supposed to double. Double the volume on the boombox enclosure? Measure the volume of one speakers original enclosure and double that volume into a single box?
I'm sorry if your answers is actually somewhat straightforward, but this is my first attempt at designing a custom box, so this is all still very new to me. So I appreciate every bit of help I can get.
What would be the downside soundwise speaking, of having a too small box volume, respectively too large of a box volume?
Getting a ported box right is tricky even when you have all the driver info. Sealed boxes rolloff sooner but can be forced to have good bass with active EQ, due to the better cone damping from the trapped air inside the box. Ported boxes provide poor cone damping on either side of the tuned frequency.
Generally speaking, if a closed box is too small for the given driver, there will be a rise in amplitude in the lower midrange (200HZ-ish) before the response rolls off below that. If the box is a little too big, it should work fairly well, but the air spring inside the cabinet will be more flexible, so the cone more likely to bottom out if pushed hard.
Generally speaking, if a closed box is too small for the given driver, there will be a rise in amplitude in the lower midrange (200HZ-ish) before the response rolls off below that. If the box is a little too big, it should work fairly well, but the air spring inside the cabinet will be more flexible, so the cone more likely to bottom out if pushed hard.
To add to what Bob is saying, from a listening perspective, when you raise the Q (smaller box) you get a more 'bloated' sound reminiscent of a portable boombox of the old days and when you decrease the Q (larger enclosure) the bass gets 'dry' and seems to reduce in amount. The accepted 'right' number is Q=0.707. This is gained by plugging the woofer's T/S parameters into a simulator to calculate the box size and type.
fitting a driver into a sealed box ALWAYS results in Qbox > Qts of the basic driver.
If you want to target a particular Qbox, then you must start with a driver Qts that is much less than your Qbox.
If you use a Linkwitz Transform you can alter the Qfinal over a range of values. See the Linkwitz website for details.
In my biased view Qbox>0.9 sound terrible in most rooms. My most recent speaker build aimed for Qbox ~0.6, instead of my previous ~0.7
If you want to target a particular Qbox, then you must start with a driver Qts that is much less than your Qbox.
If you use a Linkwitz Transform you can alter the Qfinal over a range of values. See the Linkwitz website for details.
In my biased view Qbox>0.9 sound terrible in most rooms. My most recent speaker build aimed for Qbox ~0.6, instead of my previous ~0.7
2 for stereo right? , If the speakers sound good, then use another box about the same size , make em a little smaller for punchier bass , a little bigger for drier hi-fi sound. keep the boom box against a wall for added sound level.
the question remains whether to the keep the boxes as one or two? that comes down to use ... youll need a center support inside anyway so putting holes in the inside baffle isn't difficult and keeps sizes down. IMO it's really nice to have the ability to disconnect one side for more stereo separation.
FWIW, this isn't completely true in that if the sealed cab is large enough [true IB], then the air mass load will actually lower the driver's Fs, Qts a small amount.
GM
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