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Marshall_SLX

DIY vs Commercial Sub

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Ive been messing around with WINISD modeling software for possibly building a DIY subwoofer pair and its left me wondering about the validity of claimed frequency responses.

For example using the specs of a Dayton reference series 12 inch sub driver i am only getting a -3 projection of 37hz in a 65 liter sealed box and upping it to 100 liters doesnt seem to make much difference. The -6 is 28hz.

This seems like a pretty capable driver with a 14mm excursion so how is it that the lowly SVS SB1000 claims a -3 of 24hz with what seems like a less capable driver and in a 42ish liter box.

I must be using the software wrong otherwise every claimed spec ive ever seen is inaccurate.

What should i be expecting out of this driver in say an 80 liter sealed enclosure?

This is the driver:

RSS315HFA-8 12

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Built a lot of enclosures over time and must say they measure closely to the maths on almost every occasion.

80 litre sealed baffle ? Build it and measure against the maths ! 

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Someone more experienced might know.

But wondering if one claims free air response while the other in room?

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Quite simply that many active subwoofers employ EQ, meaning that the response in a sealed enclosure can be whatever you want it to be, with the downside typically being a requirement for more power from the amplifier and larger power handling requirements upon the driver voice coil.  Of course, the limits of Xmax still apply in determining what the maximum SPL will be at any particular frequency.

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Right so say im using the 4ohm version of that dayton 12 inch driver with the dayton spa250 plate amp... how do i get it into the 25hz and below region?

 

Theres no way my dali e12f sub can get 28hz with a 170 watt amp at -3 in a 45 liter box (yes it is ported so makes it closer) and the Dayton combo cant get below 37hz in a box twice the size... i notice the Dayton amp has a 6 db boost switch at 35hz and below... is this the eq im reading about?

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SVS use digital EQ built into their plate amps - they can (more or less) dictate (program) the frequency response of the subwoofer, but SPL is still limited to the physics of what the amp power/driver excursion/driver design can handle. Digital EQ often also allows limiting where required to protect the driver.

 

Cheers,

 

SS

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Messing around with the numbers again... if i add a 6db boost at 35 hz which the dayton amp can do... i get a +2.7 db bump at 37 hz and a -3 of 26hz... -6 of 22.5hz... -8.25 db at 20hz... its much better but i think i need to use an amp with a variable EQ not just a 6db boost switch.

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MiniDSP works wonders for equalising subwoofers 🙂

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Yes looking further at it if i used the dayton 500 watt amp with an eq... i could boost +6 at 20hz... and get a near flat response to 34hz and a -3 of 21.3hz in a 100 litre sealed box... basically perfect... 150 litres and its flat to 32hz and -3 at 20hz... cheers guys i now understand

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Bullet points;

- a driver in a sealed enclosure will generally have it's Fs move up somewhere around 2x.

- don't use a plate amp; they're generally crap and unreliable (I've had lots across my workbench for repair). Something like an iNuke DSP is a better proposition, or a miniDSP and a pro amp.

- Looking at 100L sealed box, I think a UM18 would work in it (going from memory).

- posting graphs from a simulator is much more helpful to others reading than a list of numbers.

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@A9X

Thanks for the info and yes you are right graphs would be easier than me explaining my numbers.  I think the UM18 might be a bit overkill for me.  I really want dual subs (just sold my 2x Rel T5) so if i go the DIY route i will most likely do 2x12 Dayton Ref series (matches woofers in my speakers).  I get what you are saying with the plate amps and ive definitely ruled out the Dayton SPA250.  Im still leaning toward the SPA500 though as it has enough EQ features to achieve 20hz in WinISD and despite DSP leading the way especially with subs i would prefer to be stubborn do it the old fashioned way.  I also dont really have space for extra boxes in the rack as much as i would prefer to do it that way.

 

Its all very interesting the DIY options and flexibility however after seeing the recent classified add for the Rel Britannia B1 this week i think i may just hold for a while and see if any more pop up over the next few months.  Its basically what i was looking to build, similar dimensions, driver size, better extension, 500 watt amp, i like the speakon connection (for simultaneous HT and stereo connection) and despite not being sealed i trust that coming from Rel its not bloated and boomy plus i want a nice wood grain veneer.

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On 17/05/2019 at 5:46 PM, A9X said:

- don't use a plate amp; they're generally crap

Unless it's Hypex Fusion  ;)

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For my money the Alpine subs are unbeatable.

 

S, R or X they all sound great, and dig deep in compact enclosures. I've built home subs with them all.

 

If you can find the 15" version of the S or R Type second hand jump on it fast.

 

Compared to the Dayton Ultimax that a friend had the R was clearly superior at more than $100 less retail.

 

Some of my builds you may find of interest....

 

SWR-1223D. 75 litres 24hz tune.....

 

Insitu2.jpg.71d6e80f11cbc67cd8893b89bb4d5d2a.jpg

 

SWX-1243D. 75 litres 24hz tune....

 

Alpine_X_12_03.thumb.jpg.ec72477ad2f96bceffaf59dc8969e9fe.jpg

 

 

SWR-1522D. 97 litres 24hz tune.....

Finished.jpg.b4111a4171f3bcae6f45c3e1e0896dda.jpg

 

SWR-1540. 97 litres 24hz tune....

 

Installed.jpg.fd5527ab2e7089d54c2cccb37fdb1b3c.jpg

 

 

And the big daddy 18hz  Lab12 tapped horn that any S Type or R Type 12" seem to love...

 

IMG_20190504_173716815.thumb.jpg.4483cec82f10e833389609da391189cd.jpg.ae5b0ee207ea8ff2147d3ff7fb71a744.jpg

 

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You say superior??

Care to quantify that.

I have only heard car audio subs well in cars. Which of course are a terrible acoustic environment and tend to sound bad.

I heard a dayton ho390 in a home theatre and played music and sounded beautiful once set in. Low distortion, plenty of punch etc.

Certainly alpine subs are very cheap (the local cash converters has about 12 sitting on the shelf for 20-30$ a pop) so I may have to take a chance on one.

It is handy that they are really designed for a small enclosure. Easy to hide for extra WAF

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I don't do small...under construction

 

330001291_AintShePretty.thumb.jpg.a694b273a51dbde3a50b9e47b05762c6.jpg

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I don't do small...under construction
 
330001291_AintShePretty.thumb.jpg.a694b273a51dbde3a50b9e47b05762c6.jpg
I don't see the problem here?

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