Need help with sealed subwoffer and Scanspeak DISCOVERY 30W/4558T00

[darkpink]

Hi Tommie here,

I want to build two subwoofers that will be used for music first and second
for movies. I was thinking abouot this subwoofer Scansspeak DISCOVERY 30W/4558T00 in sealed boxes, because I've red that sealed is best for music or more hifi. I intend to use minidsp as crossover and a powerfull PA amp (2x 1200W/4 Ohms).

I've calculated the box size in WinISD with the parameters from this datasheet:
http://www.hifikit.se/images/4331/30w-4558t00.pdf

1.
And i get a box size of 50,8L - I just wanted to know if it is correct or if I've done something wrong.

2.
And i get F3 at 37,5hz (the purple line 🙂) can someone please tell me what that means?

 

[Shadydave]

-3 Db @ 39 Hz, looks good.
- 10 Db @ 21 Hz, so there is some room to boost the very low end if you are not running it full out.
Looks to be a quality speaker but beware the power rating is 350 W max long term.
It is good to have extra power, but don't abuse it.
Most likely if you did abuse it the speaker would tell you with some nasty distortion.

Dave

 

[Inductor]

Hi Tommie here,

I want to build two subwoofers that will be used for music first and second
for movies. I was thinking abouot this subwoofer Scansspeak DISCOVERY 30W/4558T00 in sealed boxes, because I've red that sealed is best for music or more hifi. I intend to use minidsp as crossover and a powerfull PA amp (2x 1200W/4 Ohms).

I've calculated the box size in WinISD with the parameters from this datasheet:
http://www.hifikit.se/images/4331/30w-4558t00.pdf

1.
And i get a box size of 50,8L - I just wanted to know if it is correct or if I've done something wrong.

2.
And i get F3 at 37,5hz (the purple line 🙂) can someone please tell me what that means?

Some POWERFULL amps don't go low, better you mention the model. There are amps suited for subs and generally good amps adequate for the driver you mention for each situation. You must be in EU?! What amps are available 4U?
About the speaker, you are fine between the 50 and 60L (lower Q) sealed. Movement of the cone is minimal and you will need an amp (good sub quality to work to 2 ohm impedance) of about 100/120 W@4 Ohms, each driver or channel. Driver accepts to 150W máx (RMS). Have in mind that if you later change your enclosure to BR you will need 200/260W for máx. excursion.

 

[darkpink]

Some POWERFULL amps don't go low, better you mention the model. There are amps suited for subs and generally good amps adequate for the driver you mention for each situation. You must be in EU?! What amps are available 4U?
About the speaker, you are fine between the 50 and 60L (lower Q) sealed. Movement of the cone is minimal and you will need an amp (good sub quality to work to 2 ohm impedance) of about 100/120 W@4 Ohms, each driver or channel. Driver accepts to 150W máx (RMS). Have in mind that if you later change your enclosure to BR you will need 200/260W for máx. excursion.

Thanks guys for the help, yes I live in Sweden. I've been recommended to look at amps on thomann.de, here are some amps that I'm looking at.

Prestanda förstärkare till 800 watt - Thomann Sverige

Prestanda förstärkare 850 – 2000 watt - Thomann Sverige

-----------
I was thinking about the t.amp TA2400 MK-X and maybe Behringer EPQ 900.
Maybe they are unnecessarily powerfull? Whitch one would be the best suited to you think on thomann.de? Or is there any other better amp solution?

I've heard that a separate amp and a minidsp is a more sound solution than a
plate amp like https://www.hypexshop.com/DetailServlet?detailID=1210

What do you think?

 

[tinitus]

you need to look at response curves to have any idea of the actual roll off

don't know, optimal box could be twice as big
but 60liter is probably better than 50
also remember these numbers are netto volume
and you may need to ad another 10 liter
personally I might go even higher and consider 80-90liter

I may have some doubts about the very low 17hz Fs
regarding Qts
the bigger box will save you if Qts is higher than specced
but a smaller box could result in loss of control and sloppy bass

 

[darkpink]

you need to look at response curves to have any idea of the actual roll off

don't know, optimal box could be twice as big
but 60liter is probably better than 50
also remember these numbers are netto volume
and you may need to ad another 10 liter
personally I might go even higher and consider 80-90liter

I may have some doubts about the very low 17hz Fs
regarding Qts
the bigger box will save you if Qts is higher than specced
but a smaller box could result in loss of control and sloppy bass

The size of the boxes aren't an issue at all 80-90 L is fine with me.
When I calculate 80L in WinISD I get a 0,6 qtc - is that better than a 0,71 qtc in 51L?

The amps frequency response is from 20hz-20khz that should be adequate right? The drivers has Long term max power of 350W does that mean that I shouldn't get a 1200w@4ohm amp?

 

[Inductor]

The drivers has Long term max power of 350W does that mean that I shouldn't get a 1200w@4ohm amp?

No, look at my previous post. 😀
You can if you want, but be careful not to blow the driver, limiting the extra power. EQ always needs the extra power from the amp behind the one I mentioned for the max. excursion in limited (no EQ) conditions.