The speaker with the tightest bass I've ever heard is the JPW AP2 (sealed box 8" 2-way) it has a Q of about 1.4 in around about 16ltr, so in theory should sound very slow, but has very tight, punchy bass. I put the exact same woofer in a 48ltr sealed box (Q 0.85) and it doesn't sound anywhere near as tight, but has a much flatter and more extended low end. The high Q peak in the frequency response becomes annoying after a while, so I prefer the slower - but more accurate response of Q 0.85.
The 8" Vifa driver used in the JPW AP2 has a very weak magnet and floppy suspension, so is an extreme case. What I learnt from this, is, frequency response is far more important than Qtc. Anything below about Q 0.8 usually sounds anaemic, but the only way to really know is to model, and look at the frequency response.
Thanks for all the thoughts. Once May comes I'll have time to start digging in to modeling so I can see some of these things for myself and then compare with my own builds. So far I am just an intuitive tinkerer who's been going through every speaker I can get my hands on, rehabbing and reselling (mostly at a loss, but it is now my hobby) and is unreal how everyone of them sounds as different as they do.
The A26, even hacked into a cabinet I picked up from a driveway and refinished, is way up at the top of the list in terms of smoothness, irritant free treble, and just overall pleasantness. And needs nothing in eq at least above 100hz in its current location. For the most part I can listen to them all day without getting annoyed about something--except for the last bit of the low end. Not bad, just not as good as the rest of the speaker.
So, I find all of this pretty compelling as I realize there is way more to be explored and played around with to see if I can maximize the low end and not give up too much punch/slam/tighness etc.
The A26, even hacked into a cabinet I picked up from a driveway and refinished, is way up at the top of the list in terms of smoothness, irritant free treble, and just overall pleasantness. And needs nothing in eq at least above 100hz in its current location. For the most part I can listen to them all day without getting annoyed about something--except for the last bit of the low end. Not bad, just not as good as the rest of the speaker.
So, I find all of this pretty compelling as I realize there is way more to be explored and played around with to see if I can maximize the low end and not give up too much punch/slam/tighness etc.
Why the hesitancy on building the cabinets for your friend? If he is willing to pay for them and wants them, why not give the customer what they want? You aren't designing them, or saying that they will perform a certain way. You are simply following your customer's direction after advising him that this hasn't been done before and you don't know how they will work. With that disclosure you are in the clear of any responsibility. And who knows, they may be the best speakers ever and you built the first pair.
Personally, I'll build anything the customer wants. That is part of the appeal to me, always a new challenge. I make very little on cutting a new cabinet but I can add it to my inventory and earn a profit on subsequent orders since it gets added to my catalog. Just some thoughts from one builder to another.
He wants me to make changes to the designs based purely on aesthetics. Facebook told him he could put the A26 drivers into a Devore 96 style box and everything would work out great so that's what he wants me to do.
He'll most likely listen to them for a few days, possibly a week, and then either have me build some different cabinets, or he'll sell them for pennies on the dollar. Then he'll go buy some Devores which is what he's got his mind on anyway.
We built him 3 different cabinets for Audio Nirvana 12" based on recommendations he got from his Facebook buddies. He didn't like any of them, sold the drivers to another friend, who we built the correct cabinets for and now he wants to buy them back.
Unless either speaker ends up sounding better than his Wilson's or Harbeth 40.3's (they won't) he won't keep them around very long. Especially if they're a larger speaker that takes up more space.
I also don't want my name attached to a set of speakers where the original customer insisted on deviating from the design.
He's a great guy, and I love him like a brother, but sometimes he's got way more dollars than sense.
i am not surprised he didn’t like those.
You can take the sealed box and juggle the dimensions to be the same ratios as the Devore, i suspect that if the Devore has an edge it will be tweeter/XO refinement. If he wants drawings that is possible.
I expect, that with a well done box they won’t have the box colouration of the Harbeth (haven’t heard Wilsons), but if he likes that you will never win. What kind of amp does he use?
dave
Seeing the response curves of the an12, let alone narrowing dispersion, they could be difficult to enjoy.
As long as you warn him.
I am curious what the exact crossover is in the devores.
I'd to play with the a26 some day
As long as you warn him.
I am curious what the exact crossover is in the devores.
I'd to play with the a26 some day
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I might knockup some cabinets close to the dimensions he wants, he can take some in room measurements, listen to them for a while and if he wants I'll slap some veneer on them and make it nice.
It changes, but last time I was over at his place he was listening to some Krell monos, not sure of the preamp. He's got a whole basement full of gear.
This guy has more money in one set of speaker cables than I have in my entire system.
The AN 12's sound pretty decent with my buddies ST-70, as long as you don't tilt, turn or otherwise deviate your noggin a fraction of an inch outside of the sweet spot. I could see how a person could come away with a sore neck after a few hours of listening.
With my very limited, almost non-existent knowledge of actual speaker design, it seems to me the magic in the A26 kit is actually the 1.5" tweeter. I assume it allows them to handle more of the midrange frequencies than the traditional 3/4 or 1" domes. Having the woofer naturally roll off and be run full range is just an added bonus.
I've often assumed it would be easier to pair the tweeters with other larger woofers opening up the possibilities of using larger woofers in a 2 way design. I wonder how they would match up with the Satori 9.5" woofer, or the 8" ceramic from SB, or maybe get into some pro drivers?
Although at $250 or so each it's not a cheap tweeter to play with.
Could you suggest the software to download, oh and it would help if it is no cost, freeware.
Sincere thanks.
I meant combine a ported speaker with an aperiodic vent. This way you gain low frequency extension due to the port, and the aperiodic vent smooths out bump you get with the high Q woofer.
That is pretty much how my miniOnken alignment works, The highR vents supply sufficient damping in most cases, if not the vents are convieniently stuffed with increasing amounts of open cel foam until th eright R is dialed in.
dave
Dave,
I'm going to build a set of the A26L cabinets from your set of plans as soon as the drivers are back in stock. My external dimensions will be slightly larger as I've got 25mm BB in stock.
Can the dimensions be scaled up slightly as long as the same ratios are kept? Like, adding and inch or two in each direction?
Using the 25mm BB do you think one or two horizontal braces, with one being behind the woofer, is enough to stiffen the cabinet, or should I try and stick with the off-center vertical brace with accompanying side braces?
I was wondering, should the size of the aperiodic vent scales based on total cabinet volume?
Also could you expand on testing impedance to get the right amount of "stuffing" in the vent?
What computer programs can or should be used to measure this?
Or would you recommend using a battery and switch to create a click test?
I assume these measurements and fine tuning of the vent would be best done in room and at listening position to get the most accurate amount of resistance?
Once again thanks a ton to Mr/Ms Anonymous and yourself for providing these plans.
Nathan
I think the Dyna A25 vent stuffing was adjusted with a mic/scope for best wave shape
with a very LF square wave. Much easier than using a battery and switch.
with a very LF square wave. Much easier than using a battery and switch.
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With the enlarged box maintaining the exact box ratio is not critical, and the actual volume not that much either. The differences by taking the simple way out, ie walls make the box 2 x 7mm = 14 mm wider, deeper and taller. Accounting for the fatter brace is 2/3rds that, so say another 4-5mm wider beyond the thicker material pushing the box walls out. And a bit less for the side to side brace.
The 3 boxes A26, A26L, A26S can be thot of as a continuum from as small as possible up to just right. At some point as the volume approachs ideal one can dispense with the need for the aperidoic vent. Also it makes sense to have less & less vent (combination of area and added resistance) as one approaches sealed.
So as long as you make the internal volume a certain size, there are other tuning variables that compensate.
Think about this rule: ANt brace should be placed such that the ratio of sides of the sub-panels created by the brace should be higher than the ratio of the sides of the panel being braced. Also, they should not fall on integer fractions of the dimension being braced.
Horizontal braces are not as effective. Avoid them.
One could, as outlined above. But with the great variability of the damping used to provide the resistance (material plus density plus amount) there is a larg eamount of room to play/
Also could you expand on testing impedance to get the right amount of "stuffing" in the vent?
There are a ton of software programs that will measure impedance. The clik-test is th elow budget quick method. From before we had computers. The former is more objective. You can just listen too, but the clik make sfor a nicely defined repeatable test signal.
With impedance you are pushing for loewest impedance, with the clik-test you are listening for sound quality.
In the same sense you tweak the damping of any loudspeaker to best suit the room it lives in.
dave
Horizontal mid woofer position in the baffle
I'm intrigued by the A26 baffles with the offset woofer. From some quick reading, I've gathered that it can help reduce distortion to offset the woofer on the horizontal axis, but this is so rarely seen in commercial designs. Is that because the speakers then have to be book-matched, or are there other issues that have to be designed into the cabinet? How did you decide on the horizontal position?
Just curious.
I'm intrigued by the A26 baffles with the offset woofer. From some quick reading, I've gathered that it can help reduce distortion to offset the woofer on the horizontal axis, but this is so rarely seen in commercial designs. Is that because the speakers then have to be book-matched, or are there other issues that have to be designed into the cabinet? How did you decide on the horizontal position?
Just curious.
It is harder and more expensive to make matched pairs than lots of singles.
What the offset does is move where the baffle diffraction happens, both LF 2pi to 4pi transition ripple and edge diffraction at higher frequencies. By having a greater range of distances from the driver to the edge of the baffle the response is smoothed out.
dave
What the offset does is move where the baffle diffraction happens, both LF 2pi to 4pi transition ripple and edge diffraction at higher frequencies. By having a greater range of distances from the driver to the edge of the baffle the response is smoothed out.
dave