I just finished construction of two 12" sealed subs with a bit of a funky shape, due to the shape I cannot get an exact internal dimension of the finished project. My design should have yielded a 1.4cu ft box without accounting for the driver, internal bracing, and on the fly construction changes.
WinISD says I should have a 1.375cuft box.
Driver is Dayton Audio RSS315HF-4.
Amp is a Behringer NU1000dsp
I have them crossed over at 40hz and used subtractive EQ to net a flat response from 20-40hz. Thus was done via REW using a Dayton Audio calibrated mic. I have not performed rigorous testing, yet.
I have been listening to them for the past week and very pleased; even my wife noticed the change as a positive. Usually she thinks I'm nuts.
I am really wondering if I need to use polyfill in these boxes.
- When I first loaded them I put in 1lb (loose) in each cabinet (Which really filled them up).
- Last night I opened them up again to caulk all the interior seams, this time I only put in 10oz of polyfill per cabinet, which visually seems a bit more reasonable.
All my listening has been with 1lb in each, tonight will be with 10oz each.
The real questions are:
- how do I know if I even need it?
- would some result in REW (I'm a novice) indicate I do or do not it?
- since WinISD suggest a 1.375cuft cabinet and my cabinets are within a few percent of that size, should I need it?
I am not going to share photos of the speakers until they are completed, right now they are still in rough shape and not veneered. I have attached a couple photos to give you an idea what I am working with.
WinISD says I should have a 1.375cuft box.
Driver is Dayton Audio RSS315HF-4.
Amp is a Behringer NU1000dsp
I have them crossed over at 40hz and used subtractive EQ to net a flat response from 20-40hz. Thus was done via REW using a Dayton Audio calibrated mic. I have not performed rigorous testing, yet.
I have been listening to them for the past week and very pleased; even my wife noticed the change as a positive. Usually she thinks I'm nuts.
I am really wondering if I need to use polyfill in these boxes.
- When I first loaded them I put in 1lb (loose) in each cabinet (Which really filled them up).
- Last night I opened them up again to caulk all the interior seams, this time I only put in 10oz of polyfill per cabinet, which visually seems a bit more reasonable.
All my listening has been with 1lb in each, tonight will be with 10oz each.
The real questions are:
- how do I know if I even need it?
- would some result in REW (I'm a novice) indicate I do or do not it?
- since WinISD suggest a 1.375cuft cabinet and my cabinets are within a few percent of that size, should I need it?
I am not going to share photos of the speakers until they are completed, right now they are still in rough shape and not veneered. I have attached a couple photos to give you an idea what I am working with.
Attachments
Great driver. I run mine in a sealed cab about twice that size and once equalized to correct the levels of the over damped alignment, they give the best bass I've ever heard. I would stuff that box completely to increase effective cab size. You will give up a spec of max spl, but the tight bass is worth it. Although really that small change in alignment may be barely audible so we're kind of splitting hairs probably.
Last night I spent a little time adjusting my system using REW. I did not do any close measurements, purely from my listening position.
Ran sweeps with my full range speakers (Goldenear Triton Fives) then integrated my subs as a pair, not individually adjusted.
Full range are respectable down to 30hz but really hit their stride at 40hz in my room.
I have the subs rolling off at 35hz with 12db slope and a bit of additive/subtractive EQ to extend the response.
From my listening position I am relatively flat from 17hz up to 200 - the limit of my sweeps.
I am not going to get crazy about optimizing my system until after I complete the speaker cabinets (veneer, bezels, speaker grills) and NAD releases DIRAC for my c658 preamp/DAC.
Question in regard to your response:
- Is the sole purpose of polyfill to increase the "perceived" cabinet size to the driver?
- If so, if the cabinet is within a few percent of the optimal size, is polyfill required?
I apologize if my questions are redundant or elementary.
Ran sweeps with my full range speakers (Goldenear Triton Fives) then integrated my subs as a pair, not individually adjusted.
Full range are respectable down to 30hz but really hit their stride at 40hz in my room.
I have the subs rolling off at 35hz with 12db slope and a bit of additive/subtractive EQ to extend the response.
From my listening position I am relatively flat from 17hz up to 200 - the limit of my sweeps.
I am not going to get crazy about optimizing my system until after I complete the speaker cabinets (veneer, bezels, speaker grills) and NAD releases DIRAC for my c658 preamp/DAC.
Question in regard to your response:
- Is the sole purpose of polyfill to increase the "perceived" cabinet size to the driver?
- If so, if the cabinet is within a few percent of the optimal size, is polyfill required?
I apologize if my questions are redundant or elementary.
1, in a subwoofers, I believe that is the sole purpose. In a cabinet operating at higher frequencies, the fill absorbs standing waves. But at sub frequencies, there are no standing waves because the wavelengths are so long compared to the cabinet dimensions.
2. No, I don't think it's required if volume is already right. I'm sure someone else will chime in if I'm mistaken on that.
My point was that I believe that the bass quality is better in a larger enclosure for this driver, so optimal according to what the model says, doesn't give you the full story as far as bass quality.
On another note, positioning is everything with subs. You probably know this already but I'll share my technique. Put one sub in the listening position and play white noise, then move around the room with your head near the floor. In some positions you will hear almost nothing, in some it will sound loud and even. Those are your potential positions. Put the sub in each of the potential positions and take a REW measurement at the listening position. Find the best spot, then add the second one to the other positions and remeasure being sure that things get more even and/or louder. 1 sub in the right spot can outperform 3 that are together in the wrong place. Usually with 2 subs, 1 will be in a corner and the second will be about in the middle of one wall, that tends to fill in the holes better than 2 corners.
Having done the hvy stuffing vs empty on subs, here is my perceptions: For H/T & auto if the cab is on the small side stuffing does typically help it dig a little lower in Fq.
For PA gear I'd take the worse low roll-off vs the reduced output and noticeable compressed transient response from hvy stuffing. In PA land mid-bass punch is a golden commodity.
For PA gear I'd take the worse low roll-off vs the reduced output and noticeable compressed transient response from hvy stuffing. In PA land mid-bass punch is a golden commodity.
Drill a very small hole to ensure pressure is equalised inside and out so cone isn't offset
Interesting. I've never seen that recommended. Then seal the hole after I assume?
My test for a well sealed box is to hold the driver in for a few minutes, then let it go and see it very slowly crawl its way back to center. If it pops back immediately, you have a leak. Not sure how the air gets in/out with my test, but it seems to.
Thanks for the link, that's very interesting. I wish he explained his rationale more. Funny it's not more commonly done.
I came up with dozens of cabinet designs but nothing that I, as a woodworker, could be proud of. I wanted to build something I could be proud to show off, not just a box.
The cabinet shape was inspired by the boat tail Austin cars. Cabinet shape is the rear of the car while the 10* angle of the face is akin to the raked grill.
This has speakon connectors and will have binding post too (future proof it), I can remove/reinstall the speakon to equalize the pressure if needed.
I don't have patience to go tweak crazy and not trying to reach unrealistic goals; I just want a flat response at my seated position from 20hz up, which I have accomplished.
If the weather is nice I may take them outside to do some measurements with and without polyfill, see what I get.
In my case:
1lb stuffing = very slow return
10oz stuffing = slightly faster return
No stuffing = have not tried that
I imagined it was the friction of the fibers inhibiting the air movement thus slower return; but I have no idea what I am talking about.
I Hate User Names,
From the thumbnail pic I'd say they'er going to turn out museum grade! If woodworking is your craft (hobby?), perhaps seek out some smaller and perhaps highend/esoteric speaker mfg's. You might drum up some cabinet production contracts (if that would interest you).
BTW, although the Austin Healey cars were always cool, it was the Jensen Healey's with the 400SBC engines that always intrigued me.
And yes, the art-deco aeronautical look on audio gear never looks bad! Steampunk is like its inbred distant cousin - and its still cool.
From the thumbnail pic I'd say they'er going to turn out museum grade! If woodworking is your craft (hobby?), perhaps seek out some smaller and perhaps highend/esoteric speaker mfg's. You might drum up some cabinet production contracts (if that would interest you).
BTW, although the Austin Healey cars were always cool, it was the Jensen Healey's with the 400SBC engines that always intrigued me.
And yes, the art-deco aeronautical look on audio gear never looks bad! Steampunk is like its inbred distant cousin - and its still cool.
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Sublimacon said:
I appreciate the kind words. I am a hobbyist working in a two car garage, not a production shop. What I may entertain is building custom pieces for end users in the audio world - one off's and quite expensive; I already have a full time job.
Sublimacon said:
CRAP! I meant Auburn.
I hate user names,
Wow that thing is super swoopy, reminds me of a Cord.
I'm I seeing that correctly, looks like the headers are dumping into the front fender(s)? On a convertible I could see the occupants getting a little loopy from exhaust fumes. Is that an English, American, or other mfg?
In the realm of high-end/esoteric home audio - part of that segment enjoys having the braging rights of spending astronomical amounts on their gear. So cost no object exotic materials (cabinets) is actually kind of the norm.
Wow that thing is super swoopy, reminds me of a Cord.
I'm I seeing that correctly, looks like the headers are dumping into the front fender(s)? On a convertible I could see the occupants getting a little loopy from exhaust fumes. Is that an English, American, or other mfg?
In the realm of high-end/esoteric home audio - part of that segment enjoys having the braging rights of spending astronomical amounts on their gear. So cost no object exotic materials (cabinets) is actually kind of the norm.
Auburn was founded in Elkhart Indiana. Auburn, Cord, and Duesenberg are all related.
The exhaust routes through the fenders into a collector under the car and out the back. They had to do it in order to keep the narrow front end. I always thought those cars were some of the most attractive ever made.
When these are done I intend to show them to a high end shop; guy there has made comments about my work in the past. I don't think I'll be going into the custom speaker building business but there may be some out there wanting custom speaker stands or other associated furniture. Who know. Not holding my breath.
Back to the speakers, I listened to them yesterday with no polyfill and feel like there are not quite as controlled as with filling. I'm going back to 1lb fill and will not get back to the project until the 1st weekend of April.
The exhaust routes through the fenders into a collector under the car and out the back. They had to do it in order to keep the narrow front end. I always thought those cars were some of the most attractive ever made.
When these are done I intend to show them to a high end shop; guy there has made comments about my work in the past. I don't think I'll be going into the custom speaker building business but there may be some out there wanting custom speaker stands or other associated furniture. Who know. Not holding my breath.
Back to the speakers, I listened to them yesterday with no polyfill and feel like there are not quite as controlled as with filling. I'm going back to 1lb fill and will not get back to the project until the 1st weekend of April.
I am at the research and design stage of building my first woofer, and am interested in this aspect of construction. My instinct suggests that although filling a cabinet with stuffing will work and do the job, it may in fact work better when combined with the intricacies of internal construction. Otherwise it seems a bit haphazard to me. When I look at organic forms in nature, it is difficult to see where a structure starts and ends. Nothing in nature looks bolted on, and within context, speaker stuffing looks to me like a bit of a bolt on.
I could be wrong, I often am, and that's OK. ToS
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