The 30 ppi foam is not adequat to significantly reduce energy coming from unwanted diffraction but that's what foam on or near a loudspeaker enclosure should do. I'm still not decided what combination of enclosure shape and foam would be best.
The foam is excedingly expensive and very difficult to cut. Using it strictly for cosmetic reasons is not a good idea. It would boost the costs quite a bit. A stretched cloth grill costs pennies.
I'd like to have the best performing loudspeaker not the best looking 🙂
I believe that it would make a lot of sense to minimize very early reflections and control directivity directly at or around the enclosure.
Is $2/sq ft exceedlingly expensive.
The trouble with cloth is that the frame creates diffraction.
I remember you said to stretch it over the driver frame and that leaks don't matter.
Maybe OK for sealed, but not ported where leaks can seriously lower port output.
I guess a thin round frame that goes directly over the woofer would work.
The other thing with cloth is that it doesn't match the plug like the foam would.
If several inches of foam is OK at tweeter freq, I don't see how 1/2" of it could be a problem at woofer freq.
There shouldn't be a problem with the woofer. Cloth grill is probably the best solution. The foam in the waveguide can be cut down to baffle level.
The foam that Earl uses is indeed quite expensive (and I can vouch for the "hard to cut" comment since I experienced that when I trimmed mine down to accommodate conventional grill cloth). There may be some 1/2" open cell stuff available in sheet form that would work though.
Yes, I don't know where Noah is getting the stuff for $2 a ft^2, basically its sold in volume not area. A ft^3 of what I use is more like $25. So maybe if it .75 inches thick its 2$ ft^2, but that thickness is going to be optically transparent - won't look right. And I did do foam once to try it out. I didn't like the look myself.
The next batch of cabinets will have the woofers mounted from the back. There won't be a rim to diffract from even if a cloth grill is used. Its a much better solution all round.
The next batch of cabinets will have the woofers mounted from the back. There won't be a rim to diffract from even if a cloth grill is used. Its a much better solution all round.
McMaster 2072K5, 2' wide 25' roll for $126, and lots of other places; very common as filter media.
So typically it would only be about 1/2" thick. Yea thats about right $75 ft^3.
McMaster has 1/2" and 1"; other places have it down to 1/4".
Anyhow, doesn't seem prohibitive for grills.
Earl,
Don't know if this was covered here before but I just noticed that there's a new version of the Abbey out. You mention on your website that the latest 12a has a cast urethane cabinet and a new crossover. Could you please give us a few more details, like what this newer version of the x-over has addressed vs. the previous one.
Also, I know that the cast cabinet will exhibit better dimensional stability over time and probably offer better sound as well, but where would this improvement fall relative to the kit builders' wooden boxes all other things being equal?
And Lastly, when can we see some pictures? (no pressure though😀)
Don't know if this was covered here before but I just noticed that there's a new version of the Abbey out. You mention on your website that the latest 12a has a cast urethane cabinet and a new crossover. Could you please give us a few more details, like what this newer version of the x-over has addressed vs. the previous one.
Also, I know that the cast cabinet will exhibit better dimensional stability over time and probably offer better sound as well, but where would this improvement fall relative to the kit builders' wooden boxes all other things being equal?
And Lastly, when can we see some pictures? (no pressure though😀)
And would this crossover be available to those of us who have the older abbey design? Does the new crossover design require the alternate woofer mounting? Did you switch to the 3rd order woofer crossover as you had previous mentioned.
If I wanted to, would it be possible to upgrade my speakers to the 12A version by buying just the enclosure, transferring my driver to those enclosures, and then building the new crossovers for them? Any chance any sort of discount would be available for those of us who have been good past customers.
If I wanted to, would it be possible to upgrade my speakers to the 12A version by buying just the enclosure, transferring my driver to those enclosures, and then building the new crossovers for them? Any chance any sort of discount would be available for those of us who have been good past customers.
The new crossover smooths the response right at the crossover point a bit. It adds only a single component, but changes the values a little on most of them. If you own a set of Abbey's I'll send you the new schematic and you can change it if you like. This would be costly however as a set of all new componets for a pair of Abbeys could easily reach a couple hundred dollars. IS it worth it? Clearly yes if starting from scatch, but a complete replacement? Probably not.
I am also going to make the foam plug a little larger on the Abbey to help smooth out the mouth resonance at about 6 kHz. I do not have data from this change yet, so I do not know how effective it will be. Again, its trivial to do when making the systems from scratch, but an expensive upgrade to buy new plugs.
The new cabinet is not all cast polyurethane, they will be made from polyurethane boards as opposed to MDF, but the waveguide will still be cast in. This material takes a finish far far better than MDF and polyurethane on polyurethane is a bond that cannot be easily broken - an ideal finish. The glues also work better for stronger joints.
Well all things aren't equal so I don't know how to answer this question. Wood cannot compare to the polyurethane boards for dimensional stability, damping and rigidity, but they are very expensive. I will sell the kits with or without the sides done in Polyurethane, but the baffle will only be poly. The back panel will not likely be poly as this makes no sense from a cost standpoint.
I have to make a pair of these new cabinets, but in reality they won't look much different once they are assembled. The woofer screws will not be visible, but that all that will change apperance wise.
I am also going to make the foam plug a little larger on the Abbey to help smooth out the mouth resonance at about 6 kHz. I do not have data from this change yet, so I do not know how effective it will be. Again, its trivial to do when making the systems from scratch, but an expensive upgrade to buy new plugs.
The new cabinet is not all cast polyurethane, they will be made from polyurethane boards as opposed to MDF, but the waveguide will still be cast in. This material takes a finish far far better than MDF and polyurethane on polyurethane is a bond that cannot be easily broken - an ideal finish. The glues also work better for stronger joints.
Well all things aren't equal so I don't know how to answer this question. Wood cannot compare to the polyurethane boards for dimensional stability, damping and rigidity, but they are very expensive. I will sell the kits with or without the sides done in Polyurethane, but the baffle will only be poly. The back panel will not likely be poly as this makes no sense from a cost standpoint.
I have to make a pair of these new cabinets, but in reality they won't look much different once they are assembled. The woofer screws will not be visible, but that all that will change apperance wise.
Earl and all,
My Abbeys I have here were the prototype to see if the new 12A crossover was worth the change. From a measurement standpoint, there are differences at the crossover point as Earl has stated earlier. Its on the order of 1-2dB and given that the crossover point is about 1Khz where the ear is sensitive, I am sure the differences are audible but how audible is extremely difficult to say. I haven't ever listened to the Abbey with the original crossover. And in fact the only person who can comment on that is Earl and you probably won't get a comment out of him from a subjective standpoint! I have feeling that it is a 5% difference at best, but it is an improvement and it doesn't increase costs so Earl and I both thought it would be a good idea for all new Abbey kits/completed speakers to have this new crossover implemented. Simply put the low pass becomes a 3rd order and there are other small, very subtle changes to values in some of the LCR tank circuits in the tweeter network. That's about it.
Earl, did you change the crossover to better optimize the response at the crossover point or were there any changes to the drivers that B&C is now supplying that required these modifications?
Whether it is the original Abbey 12 or the newer 12A, it is a state of the art loudspeaker. Earl is just pushing the state the art without appreciably increasing costs. Increasing the cost by $200 per speaker imho is a very small change honestly given the overall cost of the loudspeaker and more importantly, given the overall cost of competitors products.
Just my $.02 🙄,
Anand.
My Abbeys I have here were the prototype to see if the new 12A crossover was worth the change. From a measurement standpoint, there are differences at the crossover point as Earl has stated earlier. Its on the order of 1-2dB and given that the crossover point is about 1Khz where the ear is sensitive, I am sure the differences are audible but how audible is extremely difficult to say. I haven't ever listened to the Abbey with the original crossover. And in fact the only person who can comment on that is Earl and you probably won't get a comment out of him from a subjective standpoint! I have feeling that it is a 5% difference at best, but it is an improvement and it doesn't increase costs so Earl and I both thought it would be a good idea for all new Abbey kits/completed speakers to have this new crossover implemented. Simply put the low pass becomes a 3rd order and there are other small, very subtle changes to values in some of the LCR tank circuits in the tweeter network. That's about it.
Earl, did you change the crossover to better optimize the response at the crossover point or were there any changes to the drivers that B&C is now supplying that required these modifications?
Whether it is the original Abbey 12 or the newer 12A, it is a state of the art loudspeaker. Earl is just pushing the state the art without appreciably increasing costs. Increasing the cost by $200 per speaker imho is a very small change honestly given the overall cost of the loudspeaker and more importantly, given the overall cost of competitors products.
Just my $.02 🙄,
Anand.
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Hi Anand
No the B&C drivers did not change that I am aware of. That said, every set is slightly different - few manufacturers can hold to 1 dB over several production runs. This is why I check every pair of speakers that I make. This idea goes against my principles that the design should be fixed and if everything is on track need never change, but I find that the control over various lots of everything is simply too wide to not test every completed system. About 1 to 2 in ten builds needs to be fixed. About half the time its my eror but the other half is just tollerance stackup. Too wide to allow for anything but 100% testing.
Actually the crossover point did not change, what changed was the ripple at the crossover. As you said it was about 1-2 dB smoother. Theoretically just on the edge of audible.
The material cost increase with poly is about $100 each speaker and another $50 in cost increases on the parts and the additional components.
No the B&C drivers did not change that I am aware of. That said, every set is slightly different - few manufacturers can hold to 1 dB over several production runs. This is why I check every pair of speakers that I make. This idea goes against my principles that the design should be fixed and if everything is on track need never change, but I find that the control over various lots of everything is simply too wide to not test every completed system. About 1 to 2 in ten builds needs to be fixed. About half the time its my eror but the other half is just tollerance stackup. Too wide to allow for anything but 100% testing.
Actually the crossover point did not change, what changed was the ripple at the crossover. As you said it was about 1-2 dB smoother. Theoretically just on the edge of audible.
The material cost increase with poly is about $100 each speaker and another $50 in cost increases on the parts and the additional components.
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