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Marshall_SLX

DIY vs Commercial Sub

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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

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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:

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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.

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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

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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.

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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.

 

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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).

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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.

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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.

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On 25/10/2019 at 9:55 AM, acg said:

 

 

330001291_AintShePretty.thumb.jpg.a694b273a51dbde3a50b9e47b05762c6.jpg

 

ACG, haven't been following threads about this build, but it appears that you built this horn hybrid by your own hand, and I must say, irrespective of the sonic angle, it is an exceptional effort and workmanship, especially considering how unforgiving a material steel is.   Several black holes away from the logistics of having MDF panels cut at Bunnings and buying screws and glue.

 

To me, it looks stunning, and will be even more so when adding the massive horn at the bottom with gaping mouth.  Nice curved backbone; assume you can play around with vertical positions of the MR and HF horns.  In all a confident beauty that exudes form-follows-function.

 

Probably a project in itself just to play with crossover settings.    I expect that to do the sound justice, you would want a "really big"  room and I'd guess a minimum listening distance of say, 6m.

 

 

 

 

 

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If you say that the alpine's are good I'll have a crack, if they can out do dayton audio for price/performance then that is a very impressive feat

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Good enough to be replacement drivers for the Danley DTS-10.

 

These must be more that $10k a pop in Aus, the single woofer version the DTS-20 (that inspired my Alpine- Lab12 TH build)  is $9,999.....

 

DSC08945.JPG.eed25318493a18c288d33ae5a54639fd.JPG

 

I like this Lilmike build called the Alpine Geist tuned to 16hz that uses a pair as well.

 

Quote from Lilmike "We used 3 filters for EQ - all cut - and extended that to where we low passed at 80. NO BOOST for flat SPL to low corner before room gain. It's the flattest raw TH horn sub we have collectively measured." 

 

untitled.thumb.png.e016582520dcaf0fd806860c7f067d13.png

 

MMmmmmmm….  Makes me want to build more tapped horns!

Edited by Maz4bz

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25 minutes ago, Maz4bz said:

Makes me want to build more tapped horns

You are wicked man 

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13 hours ago, Wozza_Lee said:

If you say that the alpine's are good I'll have a crack

They are nicely priced, and there are model which have specs which work well in a tapped horn.

 

When used like a "normal" woofer (ie. in a sealed/vented box) where there is higher excursion and higher power (than a horn box), then they are not the last word  (although respectable vs $).

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Dave,

What have you used that you consider the last word for those kinds of enclosures?

Cheers.

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20 minutes ago, Maz4bz said:

What have you used that you consider the last word for those kinds of enclosures?

In a sealed (or high power vented) box?

 

Driver behaviour at the excursion and power extremes becomes important.   The Alpine car subs are some of the best $/displacement (linear displacement) drivers you can get.   There might be others even cheaper, but they're junk.

 

....  but there are a whole category of drivers better.   Aurasound, AE, Seas, Scanspeak, Peerless, ... even the much maligned Dayton.... but they are all significantly more expensive.

 

 

The great think about a big box like a tapped horn, is that you can make lots of noise while keeping the drivers away from their excursion and power limits.

Edited by davewantsmoore

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