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give me a suggestion for an 8" sub

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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Topic: give me a suggestion for an 8" sub
    Posted: 15 December 2020 at 12:50pm
i cannot take a decision, and now its months that im running around it!
And im listening a lot with real music too!
My goal is design a sub for home use with a 8" speakers, i know is little, but is my choice as compromise in sizing the boxes; It will be a part of a 3 way active home system.

One important thing is that ive 300w of power at @8 ohm (per side) for powering it.
The measure is made with all same settings in gains.



both have pros and cons:
-the purple one is a double reflex box, with 2 speakers in series; 
is very good in bass response and its deep! you can really hear the 30hz!!! but from 100hz and above it miss a lot, even with a little value of qts the bass are nice imo. The size of the box is huge too; in the final project it will be about 4 8" in total, 2 per side. Due the low headroom i must use at least 2 for side! So more cost for speakers, more cost for wood etc. each speaker 4@ohm150 W rms

-blue one is a single speaker reflex box; not so deep in bass but very powerful in comparison with the other one;  qts almost the same but bass are different from the above...they hits but not so deep as the others; very cheap speaker that can be fit in a box that is almost 1/4 int he volume of the other one; is a very efficent driver too with n0 of 0.7%. it have a veri good ebp too, so maybe i can consider an horn enclosure too...or is too small? 8@ohm 300 W rms


tell me your choice! or add more doubt :D
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 1:05pm
Are those measurements from prototypes you've already made - or theoretical?

In any case, what frequency range do you want to cover? Anything above 80/100Hz can't realoly be called "sub"!  Smile




Edited by Earplug - 15 December 2020 at 1:06pm
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_Natty_ View Drop Down
Young Croc
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 1:56pm
thats are real meusurement in nearfield (ports and speakers) of the prototypes, its so clear what u tell me, maybe i can lower the subs of course. it was just a rough approach, the upper cut will be setted in the feature when i found the mid woofer. im not afraid to move it from 80 to 150hz or where it will be best
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 3:07pm
Ok, yes - of course. And when you say "huge", how big? For sub a big(ger) box is normal.

Maybe post some pictures?


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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 4:15pm
we talk about 74l for the double vs 16l for the single.....
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Post Options Post Options   Thanks (0) Thanks(0)   Quote bob4 Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 5:01pm
Hi Natty,
Which speakers are you using in your prototypes? 

For my taste, i definitely want 30 hz...... 

Have you tried to sinulate the cheaper driver in a bigger enclosure? Is it possible to get a lower low corner?  If it is so cheap, maybe you could use multiples.....

I remember there is also a trick of connecting a capacitor in series or parallel with the woofer to manipulate overall q value and get lower bass..... forgot the proper terminology for this. 

Since it is for hifi and indoors, you could consider open baffle as well.
I use two 12" woofers on a single 250w channel with eq boost in a small room (10 sqm, concrete apartment building). Gives good punch AND full deep notes down to 30 hz. 

Even some old studio1 ska 7" have 35hz double bass notes, i can feel them Smile


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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 5:42pm
Originally posted by bob4 bob4 wrote:

Hi Natty,
Which speakers are you using in your prototypes? 

For my taste, i definitely want 30 hz...... 

Have you tried to sinulate the cheaper driver in a bigger enclosure? Is it possible to get a lower low corner?  If it is so cheap, maybe you could use multiples.....

I remember there is also a trick of connecting a capacitor in series or parallel with the woofer to manipulate overall q value and get lower bass..... forgot the proper terminology for this. 

Since it is for hifi and indoors, you could consider open baffle as well.
I use two 12" woofers on a single 250w channel with eq boost in a small room (10 sqm, concrete apartment building). Gives good punch AND full deep notes down to 30 hz. 

Even some old studio1 ska 7" have 35hz double bass notes, i can feel them Smile



I dint mention the speakers brands just to talk in neutral way about ts, enclosure and performance.

the cheap, si not really cheap but cheaper than most hifi cones it comes from PA and def is not a speaker designed for sub, but it have a lot of sensibility and untill reach its fs its works and break it, its almost impossible.

The wrong step about multiply speakers its allready done with the other configuration thats have the significant risk to be too big in the final projects when shapes will matter!
it can takes until 600w as peak so if i run multiple, i take some serius risk of underpowering and square waves can be really dangerous....
and coupling I dont think thats can gives under hz... fs is 51hz, and as you can see i move it of around 40hz by set the Fb of the box around 40hz.
Vas is tiny -15l- so if i make bigger i think to loosing controls over transient could be the only result or I wrong?

I think that u mention some teqniques for lowering Qes, but not clear to me how to mod it for having different response, but if you have some link to read it could be interesting as esperiment!

One of the best home system that ive ever heard was about 4 15" in a open baffle powered by 3w of valves each!!!!so i can understand what u saying but its not the goal of this project, it will comes with a proper shape ;)
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Earplug Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 6:11pm
Originally posted by _Natty_ _Natty_ wrote:

we talk about 74l for the double vs 16l for the single.....



Ok, that is a big difference. The problem is that this is all very subjective. How much 20Hz - 30Hz do you want? And if space is a problem, even worse.

And have you looked at other configurat¡ons for the 2 x 8"? I have heard some very nice push-pull, bandwidth limited cabinets, etc. You could save quite a lot of liters there.




Edited by Earplug - 16 December 2020 at 6:58am
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BJtheDJ Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 7:49pm
Originally posted by Earplug Earplug wrote:

Originally posted by _Natty_ _Natty_ wrote:

we talk about 74l for the double vs 16l for the single.....



Ok, that is a big difference. The problem is that this is all very subjective. How much 20Hz - 30Hz do you want? And if space is a problem, even worse.

And have you looked at other configuratu¡ions for the 2 x 8"? I have heard some very nice push-pull, bandwidth limited cabinets, etc. You could save quite a lot of liters there.

Isobarik cabs as well
If your vaccinations were mandatory and nobody in your class had measles,
then you know that you're not a Millenial kid.
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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 15 December 2020 at 10:32pm
Originally posted by BJtheDJ BJtheDJ wrote:

Originally posted by Earplug Earplug wrote:

Originally posted by _Natty_ _Natty_ wrote:

we talk about 74l for the double vs 16l for the single.....



Ok, that is a big difference. The problem is that this is all very subjective. How much 20Hz - 30Hz do you want? And if space is a problem, even worse.

And have you looked at other configuratu¡ions for the 2 x 8"? I have heard some very nice push-pull, bandwidth limited cabinets, etc. You could save quite a lot of liters there.

Isobarik cabs as well

i dont know a lot about isobarik enclosure... maybe a magnet to cone configuration coul be interesting.

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_Natty_ View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote _Natty_ Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 11:24am
Originally posted by _Natty_ _Natty_ wrote:

Originally posted by BJtheDJ BJtheDJ wrote:

Originally posted by Earplug Earplug wrote:

Originally posted by _Natty_ _Natty_ wrote:

we talk about 74l for the double vs 16l for the single.....



Ok, that is a big difference. The problem is that this is all very subjective. How much 20Hz - 30Hz do you want? And if space is a problem, even worse.

And have you looked at other configuratu¡ions for the 2 x 8"? I have heard some very nice push-pull, bandwidth limited cabinets, etc. You could save quite a lot of liters there.

Isobarik cabs as well

i dont know a lot about isobarik enclosure... maybe a magnet to cone configuration coul be interesting.


I've read something about isobaric, and all articles that ive found describe the parallel way, but as I mention i need to wire them in series due the 8ohm loading for the module. 
So i simulate it with winisd, but it seems that just parallel is simulated. or I wrong?
I switched to bassbox pro 6, and trying different things the result of the sims isobaric/compound its extactly the same for parallel or series, but this is strange to me because the ts are trathed in different way or i wrong again?

the result is good, in comparison with my big double reflex:
-yellow double reflex (the one measured above)
-in red and green(not visible because is identical) the 2 curves of compound 20L parallel and series wired. the reflex is so long so i need to work around this


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Post Options Post Options   Thanks (0) Thanks(0)   Quote 4D Quote  Post ReplyReply Direct Link To This Post Posted: 16 December 2020 at 11:40am


Add ten inches .. Satisfaction guaranteed.. 
DMZ. "The bass was intense. Girls were literally running up to stand next to the subs"
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