SB Acoustics SB20FRPC30-8 (8" Fullrange Cheap Monster II)

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#321
gnat_leader said:
One of the best bookshelf speakers I ever heard had a cabinet made of concrete, so... clearly many different materials can work.
I don't think there's anything special about plywood. And then there's thickness, and internal bracing, etc.
It's false that you can't make a good sounding cabinet out of MDF.
The first serious speaker I ever built was the Ariel which was veneer wrapped MDF. Not a simple build but sounded good.
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Yes, also can use pine and oak wood, al least pine wood is cheaper than plywood or MDF.
Some interesting info:
https://hammeraddict.com/the-5-best-woods-to-build-a-speaker-box/
https://www.sawinery.net/woodworking/best-wood-for-speaker-box/
 
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#322
gnat_leader said:
One of the best bookshelf speakers I ever heard had a cabinet made of concrete, so... clearly many different materials can work.
I don't think there's anything special about plywood. And then there's thickness, and internal bracing, etc.
It's false that you can't make a good sounding cabinet out of MDF.
The first serious speaker I ever built was the Ariel which was veneer wrapped MDF. Not a simple build but sounded good.
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is well know at diyaudio that mdf have a problem in energy storage ,and is NO go for full range ,you still do not understand that isn't a woofer
 
#323
Nicoch58
Do you know of any source that show measurement of the problem with energy storage (in the midrange) compared to good plywood?
Energy storage should be measurable, unless there is musical and unmusical energy storage, if that is the case we are all lost.

The correlation or lack there of between measurement and perception is an interesting subject.
 
#324
DrBoar said:
Nicoch58
Do you know of any source that show measurement of the problem with energy storage (in the midrange) compared to good plywood?
Energy storage should be measurable, unless there is musical and unmusical energy storage, if that is the case we are all lost.

The correlation or lack there of between measurement and perception is an interesting subject.
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first study on wood start at BBC long time ago , famous LS 3/5a is based on.... you still can find the paper,
For mdf I know from 15 year at last..you need search that's diy in the and 🙂 AES paper too.
You will find here good info for sure https://www.diyaudio.com/community/threads/frugel-horn-mk3-builds-build-questions.172937/ I suggest this Thread for made a good fullrange speakers
 
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#325
ask if this can work for SB ,is really good
1669972843229.png
 
#333
e_fortier said:
Hi,

Did anyone compare the actual frequency response of the SB20FRPC30-8 vs the spec sheet? Is it similar or way of ?

Thanks
Eric
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I don't think it will ever be exactly the same. They must measure on an infinite baffle, which I doubt you can replicate at home.
I haven't got my hands on a pair yet, my distributor is dragging his feet, but as soon as I get a pair, I will measure them.
 
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#334
e_fortier said:
Hi,

Did anyone compare the actual frequency response of the SB20FRPC30-8 vs the spec sheet? Is it similar or way of ?
Click to expand...
Hello

yes - i tried that this weekend.
Measurement in my living room, 1m apart, window 1.5 to 3.5msec, enclosure 35cm wide
on axis (black) and different angles, 30° and 60° in green or red as in data-file.

in all, very close to the spec-shet show by manyfactorer.

For a 8" Fullrange driver very nice between 15-20° - an thats how i listen to them.
 

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#336
joern said:
Hello

yes - i tried that this weekend.
Measurement in my living room, 1m apart, window 1.5 to 3.5msec, enclosure 35cm wide
on axis (black) and different angles, 30° and 60° in green or red as in data-file.

in all, very close to the spec-shet show by manyfactorer.

For a 8" Fullrange driver very nice between 15-20° - an thats how i listen to them.
Click to expand...
Hi @joern thanks for sharing. Do you have an idea where the dive at about 2.8k comes from? Maybe a room-related cancellation?
 
#337
Hi
this small gap is also found in the original data / graphs .... 😉
Room-effects are minimized by using the signal filter 3,5msec ...

My suggestion is interaction whizzercone to phaseplug. Wavelenght 3kHz is about 12cm, 1/2 or 1/4 is 6 to 3cm....
As this is a very small gap, i don't care about when listening ....

Very nice and smoth sounding fullrange - allthough rich in details.
 
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#340
I’m thinking of building an OB line array with these SB20FRPC30-8 drivers. It would be my first attempt at a line array. Should I do it?

I know comb filtering can be a problem. Should I use a single tweeter in the middle of the array?

I was also thinking about blending from a single fullrange unit at high frequencies to a full array below the c-c wavelength. Has anyone ever done something like that? Instead of power tapering, high-frequency tapering?

Or with the driver’s rising on-axis response above 3k maybe comb filtering won’t be a big deal?
 
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