Jump to content

DIY vs Commercial Sub


Recommended Posts

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
Link to comment
Share on other sites



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.

  • Like 2
Link to comment
Share on other sites

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?

Link to comment
Share on other sites



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

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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

Link to comment
Share on other sites

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.

  • Like 1
Link to comment
Share on other sites



@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.

Link to comment
Share on other sites

  • 5 months later...

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

 

  • Like 1
Link to comment
Share on other sites

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

Link to comment
Share on other sites



10 hours ago, Wozza_Lee said:

You say superior??

Care to quantify that.

Fair question - I have to say that my experience with the Dayton subs is limited to a 12" Ultimax and the 18" Classic Subwoofer that I did a build with last year.

 

The Ultimax a friend imported from Parts Express but it was DOA with coil rub. This problem has been reported on PE's reviews section for these drivers.  Return shipping cost meant that it wasn't viable to claim warranty on and so he binned it despite us trying to re-seat the suspension to align the coil.

 

That aside when we had the Ultimax side by side with the 12" Type R he replaced it with, the R was in another league in terms of build quality and finish.

 

I'm sure that when the Ultimax work, they are great, and  I don't doubt the RSS is "musical". The Classic 18" Sub is epic value when it cost $250 AUD shipped.

 

The great thing about the Alpines is that they are cheap, for what they are, seem unbreakable and have very good specs that combine relatively low Fs and Vas simultaneously - inferring strong motor force. As an example in 100 litre boxes the Alpine R 15's get down to around 13hz in my room for peanuts. Josh Ricci did a review of the SWR-1522D over at DataBass.

 

My point is that comparatively, the current model R 12" (with 20mm Xmax no less) cost $250 locally. The local supplier Wagners/Loud Speaker Kit is very good value for Dayton products (I buy all my caps/inductors/horns/Dayton Omnimic/DATS from them and BTW don't work for them!) but the Ultimax is $460 and the RSS $395 exc shipping. That's not LSK's fault, I just don't think the Dayton subs in 12" sizes stack up when compared to the Alpines. Particularly when you can readily get them secondhand for next to nothing.

 

I have a pair of the original R Types on my shelf at home awaiting my next build.  I rescued one from the bin and the other cost all of $30. I beat on these in the tapped horn build linked above and they laughed at me. The bass energy from that enclosure is simply monumental and the value with a driver like this unbeatable IMHO.

 

My next build using these old drivers is going to be a pair of series tuned 6th order bandpass subs using Brian Steele's box modeller available over at diysubwoofers.com. Check it out, it's a wonderful resource.

 

If you have a google search you will see some epic builds that use the Alpines.  Lilmike over at AVS recommends Alpines in most of his tapped horns for example.

 

Cheers.   :thumbsup:

 

Edited by Maz4bz
  • Like 2
Link to comment
Share on other sites

6 hours ago, acg said:

I don't do small...under construction

 

330001291_AintShePretty.thumb.jpg.a694b273a51dbde3a50b9e47b05762c6.jpg

Epic!

 

All I can think of is that this wouldn't look out of place mounted on the front of a destroyer and that my kids would want to climb all over those master pieces.  :hyper:

Link to comment
Share on other sites

15 hours ago, Wozza_Lee said:
15 hours ago, acg said:
I don't do small...under construction
 
330001291_AintShePretty.thumb.jpg.a694b273a51dbde3a50b9e47b05762c6.jpg

I don't see the problem here?

I do; horrible polars, unnecessarily complex LF design (not need for the staged individual enclosures) and the MB flare way too high.

  • Like 1
Link to comment
Share on other sites

7 hours ago, A9X said:

I do; horrible polars, unnecessarily complex LF design (not need for the staged individual enclosures) and the MB flare way too high.

 

The bass stack does look unneccesarily complex doesn't it?  But it is only as complex as it needs to be.

 

I guess my aim at posting that photo was to show that if you need to, and if you have the compulsion to, you can do so much more with a DIY sub than you can do with the purchase of any commercial sub,  DIY widens the scope that you have for shape and size, sensitivity, aesthetics and amplifiers that you use to drive your subs. 

 

Damping factor/output impedance of your amps?  Who cares!  Design the sub/speaker so that it is agnostic or even designed to operate best with a specific output impedance, not just a near zero output impedance that is the default standard for modern small size speakers.

 

Got sensitivty issues with the other channels?  Then the sub has to be big if it is to match high sensitivity horns, no way around it.

 

Got to fit in with the decor or the room?  Well when you design it you are in control of how it looks.

 

Got specific requirements for amplification and filtering?  Nothing more flexible than doing it yourself.

 

Actually want good sound from your sub?  Then low excursion is paramount and low excursion only comes with driver surface area or with horns.

 

So, for the bass stack that you see in that photo I can tell you some of why it is designed the way that it is.  Firstly, the other five channels are 110dB/w/m sensitive and I only have 9w of power in the amplifier channel that feeds that stack (active system - 6 amp channels directly driving 6 speaker channels)...so the sub-bass solution has got to be large in size and I do not have room for a 20Hz horn so direct radiators are the answer.  Then there is the question of how to build them, and I am much more comfortable using steel than wood, so steel subs are the way to go:  12" steel pipe, 5mm wall cut into meter lengths to get the desired volume for the drivers, a bit of laser cutting/welding/powdercoating and they are built.  This also works out well because mass is needed to curb sound transmission through the cabinet walls, and steel is heavier per unit volume than any wood.  The steel is damped internally and I use the external braces to apply pressure to the pipe wall to reduce the energy storage to a minimum, less than the little ML1 standmounts also in the picture and with an equivalent ringing time of the double-brick wall at the northern end of the room...perfect.  Put some industrial pneumatic isolators underneath the stack to greatly attenuate the transmission of noise to the floor of the room and hence to downstairs and out of my soundproofed area.  The stagger of the cannons is not necessary, but it does look better in the flesh than a straight alignment, plus I can have just enough cannons up there (8 pictured) to get a perfect sensitivity/volume match to the remaining channels of the system without need of an attenuator on some sort in the crossover filter/s.

 

End result is -1dB 18Hz in-room at 110dB at the listening chair driven by a 9w single ended triode, a tad over 1mm excursion.  Best lower bass I've ever heard by quite some margin.

 

So plenty of reasons there for an "unnecessarily complex" design, but there is nothing commercially built anywhere that could have done that job preciselt as required.  DIY is much more flexible that way.

 

   EDIT:  That top horn is 250Hz and runs only 600Hz - 1kHz.  Not pictured is a 100Hz upperbass horn (80Hz-500Hz) and the midbass channel.

Edited by acg
  • Like 4
Link to comment
Share on other sites



On 14/05/2019 at 11:52 PM, Marshall_SLX said:
I must be using the software wrong otherwise every claimed spec ive ever seen is inaccurate.

Neither.

 

Typically subwoofer manufacturers are using an electronic filter to transform the response of the driver.... rather than simply "what you get" from putting the driver into a box.

 

 

 

Here's the Dayton Reference 10" in a 40L box....    Yellow is the driver on its own.   It's -3dB is 40Hz, and it rolls of at 12dB/octave.   Not very useful.

 

Orange is the driver with a filter calculated to transform the response to a 24dB/octave rolloff, with the -6dB points:

 

Green = 25Hz

Orange = 20Hz

Red = 10Hz

 

image.png.47e7b7ed9121fdcf4ceb6b4586ccee80.png

 

 

If you increase both to the point where the drivers reach maximum excursion.....   You see:

 

(You can see we've been kind to the driver without EQ, as the excursion continues to increase below 20Hz)

 

image.png.e03f75d0e8a25907e1c62542065fedd5.png

 

 

Which results in the following SPL: 

 

image.png.90d9b9ebd1cde053a838abc0839d877d.png

 

These are the filters being applied to the drivers:

 

image.png.dd2dfeb383b030456879c122a42ad6c6.png

 

 

You can get whatever "-3dB point" you want, from any driver, using the right filter.   It just results in more/less maximum SPL.

 

Without a filter, you are relying solely on the driver parameters and the air in the box to dictate the SPL of the driver.... this might sometimes work.

  • Like 2
Link to comment
Share on other sites

On 14/05/2019 at 11:52 PM, Marshall_SLX said:
This seems like a pretty capable driver with a 14mm excursion

Here's the 10 inch version again.... which has similar max excursion and power handling.

 

Here's it's maximum SPL vs frequency.   ie. where it is either power or excursion limited  (the reference series are usually excursion limited).

 

image.png.27829ad14165f12522fbf1a0ecc2f7a6.png

 

As mentioned before.... with the correct subwoofer amplifier to transform the input signal, you can have whatever response you want, as long it is below this red line.    If you want to make 110dB of noise, then you'll have to start rolling the driver off below 50Hz .... if you want to play flat to 10Hz (ignoring room gain), then you're only going to make 80dB of sound.

 

 

If you don't want to use electronic EQ .... then another form of EQ, is adding a vent/port.   This will lift the low end of the response.... which can get you down into the mid 20s (Hz) in theory ..... but vents in subwoofers are extremely problematic due to the non-linearities.

 

It is much (!!!!) more flexible, reliable, and higher performance to use (electronic) EQ to shape the driver response.....so that is what most manufacturers do.

 

Link to comment
Share on other sites

13 hours ago, A9X said:

I do; horrible polars, unnecessarily complex LF design (not need for the staged individual enclosures) and the MB flare way too high.

100%

 

('cept that's not the MB horn .... that will go down the bottom where the little 2-way speaker is sitting).

Link to comment
Share on other sites

9 hours ago, acg said:

The bass stack does look unneccesarily complex doesn't it?  But it is only as complex as it needs to be.

I specifically mentioned construction complexity, not to get high SPL at LF.

 

Rather than a point by point response as I have cooking to do now, I'll just point out that you are lecturing me an a subject I understand well. My last horn system was a 5 way: 4 LABsubs, a large hypex midbass horn (pathlength over 6 feet), a hypex lower mid and an Arai A290 with a BMS coax. Originally passive with a class A (to full output) 50W PP amp: I loath SETs. Then DSP active. Only dissembled as I had to move from a house to an apartment and it won't fit..

 

Have fun designing a great a passive xover for yours.

 

Current system is about 100dB for mains and circa 96 for the surrounds. More than enough as it's all active and I don't need to design for silly little amps. Subs are 95dB each native, but there are 4 and are close enoug and crossed low enough that they will combine to give well over 100dB.

 

As to building to DIY unit how you like, I thought that would have been bleedingly obvious.

 

Your post was good as it actually explained some things rather than simply showing a 'wow' picture.

Link to comment
Share on other sites

4 hours ago, davewantsmoore said:

('cept that's not the MB horn .... that will go down the bottom where the little 2-way speaker is sitting).

Thanks for the clarification.

Link to comment
Share on other sites



  • Recently Browsing   0 members

    • No registered users viewing this page.




×
×
  • Create New...
To Top