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Discussion Starter #1 (Edited)
Dear all,
I wanted to share my latest subwoofer build.

Edit: This sub build was so successful (to me!) that I built a second Alpine SWR-15 using a terminal SWR-1540 and that one is nuts and even more budget too!

I have built a few subs over the years, including my HiSAF's, and a re-purposed Klipsch Synergy Sub 12 but have been itching to do a larger sub after reading all of the insanely large (for me at least) 18" plus sub builds on here.

I'm on a really tight budget so when I chanced upon a fairly well used 1522 for cheap on Gumtree I grabbed it after reading of another build here:

White Alpine Build

For my SAF I went as big as I felt acceptable and settled on a gross internal volume of 108 liters. After subtracting for port and driver displacement I estimate a net internal volume of 97 liters, tuned to 21hz.




Using Sketch Up for the first time was a real boon as it allowed me to:
- very easily and quickly calculate the net volume once I'd constructed my virtual box; and
- derive a cut list for all my panels.



Once I had my cut list I headed down to my local Bunnings which sells a cheap 30mm ply and they do cuts on some very nice panel saw tools for $1 per cut!

I was lucky in that I arrived early and there was no rush for the saw operator. He took his time and made really accurate cuts for me. Certainly not CNC level accuracy but good enough for my purposes.

My build uses no screws or nails. Just lots of traditional PVA wood glue. Some photo's for your enjoyment.

Bringing her home, takes up my entire front passenger seat:



Boxing up:









There's a reason for why I got this cheap. Years of rubbing on the contents of the previous owners boot. Doesn't seem to affect performance however...



Going together for a test fit:





In situ (HiSAF on left):




Will the wife notice?...



Some final touches; a brace, round overs, wiring, paint - its rough I know, but matt black can hide a thousand sins...
















I'm still getting my head around REW but will post some sweeps when I do.

Initial listening impressions are great. Gets noticeably deeper than my other subs subjectively. Plays louder (is more efficient) at normal listening levels than any of my other subs, seems smooth (where its placed in room, about 1 meter from my listening position). I'm really pleased with how this has turned out, had a lot of fun and have a really solid addition to my system, for under 200 bills! :)

Edit: Some progress shots...

Little brother meet big brother...

Alpine SWR-1223D Budget Build



Surround repaired from the inside. The donor...



Looking from the rear of the driver. I used an EVA glue provided with the surround foam ...



Needed to improve spousal acceptance factor so built some grills entirely out of scrap in keeping with the budget approach....







Her new home is furthest from my MLP. I figure the most efficient sub should be at the greatest distance...



Measured via Audessy mic - seems to work great...



Close mic'ed with LR24 HP at 20hz and 90hz low pass measured response...



And here is the measured response at main listening position (MLP) (no HP, low pass set to 200hz)

 

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awesome...did a great job on a small budget...well done!!
 

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Discussion Starter #4 (Edited)
Port chuff

Cheers for that Chad.

G'day Audyo,
Thanks for the encouragement mate!

Short answer - yes.

Longer answer - no, not in practice.

A couple of comments:

Using the DCX2497 I have a high pass filter LR 4th order at 20hz. This makes a big difference for chuff as you can see here:

No filter:


With filter:



Now granted I'm only modelling with 250 watts input and at 4 ohms the XLS2500 running this off one of its channels is capable of about 700. So I did take a chance with the 20mm port opening. I just didn't want the extra cut and build complexity on this first, from scratch build for me, of a narrower/taller port. I did use the biggest round over bit I have on the front and rear ends of my port to help.

Happily the punt paid off. If I run a 25hz sine wave into the 1522 I really only get audible chuff at reference levels, ie. 0 volume level on my Onkyo pre/processor and I never listen at this volume because my 97db KG 5.5's are ear bleedingly loud at this level, which all the rest of my system is referenced to.

So at my kind of normal listening levels, which are up to about 20db below reference, the Alpine is completely silent playing 25hz sine waves. I believe this is a far more punishing test than real world music or a movie sound track. Tron Legacy will soon settle the matter once I have a chance to run through some fav tracks/scenes.

By way of comparison, the Klipsch Synergy 12" Sub, which has a 4" port with substantial plastic flares at each end starts chuffing at about 10db lower than the 1522 and by the time it gets to reference is making some awfully distressful mechanical noises too. The HiSAF's on the other hand make no noise but are literally walking across my tiled floor at reference, and I reckon they weigh around 30 kgs a peice!
 

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Admittedly I grew concerned with the picture of the driver in the car seat.

"How is this guy driving his car if there a massive subwoofer buckled in to it?" Then of course I realized you are from a country where they drive on the wrong side of the road. :cool:

I'll be interested in seeing how well it plays with the HiSAF, assuming you will be enjoying them both at the same time. Also, I wonder if there is a simple rubber coating that might remedy that small tear in the surround?
 

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You could use black RTV for that hole in the surround. I just had to do something similar with one of my drivers. I would smear some on the inside and outside to ensure it is airtight. Good looking build!!
 

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Discussion Starter #7
Thanks for your inputs gents.

JC, yes we still drive on the left in the colonies. When I started reading your "How is this guy driving his car if there a massive subwoofer buckled in to it?" quote I was thinking "what is this bloke smoking" but when I realised the full context I did a small LOL! :)

Will definitely be using all 4 subs simultaneously in accordance with Dr Earl Geddes recommendations and readings from the Bass Integration Guide

Notfastenough, thanks for your surround repair suggestion - what is black RTV? Its not a product I'm familiar with. I did wonder if it might be like this Sikaflex polyurethane product?

I recently refurbished some nice old RS Minimus 77 woofers with foam surrounds.


I have purchased an extra surround for $1 from eBay with the intention of gluing a small section in behind the tear as a patch. The foams for these small speakers are very thin and light weight. I figure it'll have no impact on the woofers performance as I'll just use a thin slither to close over the tear.
 

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I had 4 of those 15's vented tuned to 19hz. The motor strength is high at 140 bl^2/re. I was never able to bottom them out using 2 bridged Peavey CS4080hz's which put out 4400 watts as tested by Luke. They sustain for 3.5 seconds. I post this simply to say they handle far more than advertised. Each one took 2200watts and I pounded them for about 6 years until I upgraded to TC Sounds 18's. I gave them to a friend and they still work and look as good as new.

Your box looks top shelf.
 

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Every screen shot I had from REW was lost with photobucket. Besides, every time I start a thread for a build, 3 people comment and it falls into obscurity. I'm just not very important:frown:
 

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Every screen shot I had from REW was lost with photobucket. Besides, every time I start a thread for a build, 3 people comment and it falls into obscurity. I'm just not very important:frown:
LOL, damned photo-crapbucket. So many ruined threads because of them. Anyway, you made a good point about why you upgraded but I was more directing my post to the OP. Don't give up Spin, you know your stuff just keep on truckin'.

No big deal if you don't have a measurement rig Mazz, but I was just curious to see how the build came out to perform like in the real world (outside of the sims).
 

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Discussion Starter #14 (Edited)
All good Shreds. I need and appreciate the bump!

I live next door to a sound engineer and he's going to come over one night and help me do some measurements. He uses professional grade gear and wasn't familiar with REW when I mentioned this was what I'm planning to use. I have it all installed and have given it a test run using an Audessey mic which was the subject of a shoot out in this thread on AVS and found is entirely adequate for sub measurement purposes...

"it does indeed look like these Audyssey mics are good enough for the hobbyist to use between 10hz-10khz without worrying about applying any correction"

The process will be a learning opportunity for us both, but I'm sure he'll look at the software and immediately understand how to use and properly interpret what it measures.

I'll post as soon as I have something.
 

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All good Shreds. I need and appreciate the bump!

I live next door to a sound engineer and he's going to come over one night and help me do some measurements. He uses professional grade gear and wasn't familiar with REW when I mentioned this was what I'm planning to use. I have it all installed and have given it a test run using an Audessey mic which was the subject of a shoot out in this thread on AVS and found is entirely adequate for sub measurement purposes...

"it does indeed look like these Audyssey mics are good enough for the hobbyist to use between 10hz-10khz without worrying about applying any correction"

The process will be a learning opportunity for us both, but I'm sure he'll look at the software and immediately understand how to use and properly interpret what it measures.

I'll post as soon as I have something.
My take on that thread regarding the Audyssey mic was this: You can use it to work on response, but for db level, it will have to be calibrated against a higher quality mic. The big variable is the sound card on the PC will let you adjust levels on the mic input and that can easily skew your db numbers. Heck, my laptop won't show a db response when I tried this very thing. I'm sure this is only one factor why @Shreds is posting his responses. I'm going to move on to a umik-1, which is a known quantity with a reasonable calibration ready to go. Good luck bud!!
 

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LOL, damned photo-crapbucket. So many ruined threads because of them. Anyway, you made a good point about why you upgraded but I was more directing my post to the OP. Don't give up Spin, you know your stuff just keep on truckin'.

No big deal if you don't have a measurement rig Mazz, but I was just curious to see how the build came out to perform like in the real world (outside of the sims).

Download this add-on and it will restore all photo bucket pics back;)

https://addons.mozilla.org/en-US/firefox/addon/photobucket-fixer/
 
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