Earl, I appreciate your answering my questions on the previous page.
If I understand correctly, use of bandpass subs adds a fixed-frequency 2nd order lowpass function to whatever variable -frequency lowpass filter the plate amp has. So if the plate amp has a 2nd order lowpass filter, the final net acoustic rolloff will be 4th order... but if the acoustic lowpass and the electrical lowpass are at different frequencies, there would be a "transition zone" in which the rolloff is only 2nd order, before accelerating to 4th order. Is this correct, and if so does it play a role in how you blend your subs with the main speakers?
The "blender" sub(s) that you have going up to 150 Hz or so, at a low level - are these also bandpass subs?
Thanks,
Duke
If I understand correctly, use of bandpass subs adds a fixed-frequency 2nd order lowpass function to whatever variable -frequency lowpass filter the plate amp has. So if the plate amp has a 2nd order lowpass filter, the final net acoustic rolloff will be 4th order... but if the acoustic lowpass and the electrical lowpass are at different frequencies, there would be a "transition zone" in which the rolloff is only 2nd order, before accelerating to 4th order. Is this correct, and if so does it play a role in how you blend your subs with the main speakers?
The "blender" sub(s) that you have going up to 150 Hz or so, at a low level - are these also bandpass subs?
Thanks,
Duke
Elliptical shape
At some point later, maybe Earl should work with a company who makes horns, like DDS or 18Sound. He could give them the exact parameters for a 15 inch elliptical wave guide and have them manufacture it.
DDS has a 10 inch round close to what Earl is doing.
http://www.ddshorns.com/catalog.php?page=ENG190Pro
And 18Sound has the XT1464 elliptical horn.
Future Project:
Here is what might be better than the Summa.
A 15 inch, or larger, elliptical wave guide, designed by Earl, with a 2 inch entry for the BMS 4592ND coaxial driver. This driver can be used as low as 300 hz. Then use a 15 inch woofer from 300 hz down. The BMS coax would be crossed over at about 6500 hz.
At some point later, maybe Earl should work with a company who makes horns, like DDS or 18Sound. He could give them the exact parameters for a 15 inch elliptical wave guide and have them manufacture it.
DDS has a 10 inch round close to what Earl is doing.
http://www.ddshorns.com/catalog.php?page=ENG190Pro
And 18Sound has the XT1464 elliptical horn.
Future Project:
Here is what might be better than the Summa.
A 15 inch, or larger, elliptical wave guide, designed by Earl, with a 2 inch entry for the BMS 4592ND coaxial driver. This driver can be used as low as 300 hz. Then use a 15 inch woofer from 300 hz down. The BMS coax would be crossed over at about 6500 hz.
poptart said:
It is a lot cheaper to turn something on a lathe than have to set up a numerical control for a CNC machine. Something like 1/2 the cost.
And the driver change is not simply price. I have to have a company that will drop ship the drivers to the customer and only B&C and Eminence are willing to do that. Now for convenience reasons I am not going to mix and match drivers - they both have to come from the same company. Its NOT the woofers that is the problem it is the compression drivers. The B&C woofers and the Emninece woofers are pretty similar, but the compression drivers are not. Hence, I cannot go to Eminece woofers for the (slight) price advantage without degrading the performance because of the tweeter. It just makes sense to stick with B&C.
Variac said:
Price out a solid chunk of alluminum that size and youll see that cutting alone is not the only problem.
Re: Elliptical shape
The existing companies have no interest in making my designs - none. Whats in it for them - unless I pay them big bucks to do it. But where does that come from? The big companies are all sitting behind the scenes (if they care at all) hoping I fail so that they don't have another competitor on their hands.
Sometimes the comments on these threads reflect a real nievete about business. Do you believe that I am doing all of this because I like cutting wood, or pouring plastic, or certainly for all the money I make!!? I'm doing it because no one else will.
From what I have seen of the BMS coaxials they are not a good choice. I once used one in one of my waveguides and it was a disaster at the crossover between the two diaphragms - which was quite audible.
tomcat9 said:
The existing companies have no interest in making my designs - none. Whats in it for them - unless I pay them big bucks to do it. But where does that come from? The big companies are all sitting behind the scenes (if they care at all) hoping I fail so that they don't have another competitor on their hands.
Sometimes the comments on these threads reflect a real nievete about business. Do you believe that I am doing all of this because I like cutting wood, or pouring plastic, or certainly for all the money I make!!? I'm doing it because no one else will.
From what I have seen of the BMS coaxials they are not a good choice. I once used one in one of my waveguides and it was a disaster at the crossover between the two diaphragms - which was quite audible.
Variac said:
I am not convinced that elliptical would sound better
But what do I know...I have never even heard a good CD/waveguide
I may do an elliptical, but mostly because I think a big elliptical looks fantastic...and the because of the challenge
audiokinesis said:
Hey Duke
Don't get too fixated on "crossovers" at LF. Down at the frequencies that we are talking about, with multiple subs and non-high-passed mains, room modes, etc. there is far too much going on for details of any one crossover to be much of a factor. You need to look at these frequencies as large lumped averages of the details.
But yes, what you are saying is quite true, but of minimal significance. That is unless all the subs were identical, with identical LP filter slopes and frequencies, then the "average" would be effected. But making all the LP filters at different points will cause a smoother slower transition because of this averaging effect.
Yes, all the subs are bandpass. You can see examples at www.ai-audio.com.
poptart said:
I don't pay retail and my price difference might be $50 - $75 each on these drivers. Thats not going to be a very big savings. Hardly worth the effort.
Sent a 10cm deep elliptical part for CNC equivalent of USD150 including material. I can't bear to think how much it would cost for a whole guide.
tinitus said:So, using different sub drivers would be ok too
I don't follow.
I don't make subs at this point, but what I am looking at does not use B&C drivers. I would probably not use the B&C drivers for subs as they are too expensive in that application.
Kit Status?
I don't mean to hijack this thread but I am new here and just read most of the 31 pages of posts and I am a bit confused.
I landed here becuase I was (maybe still am) very close to pulling the trigger on a pair of Emerald Physics CS2s. However, it sounds like Dr. Geddes is really onto something here.
I have done lots of DIY in the past but I am now at the point that I want to buy a finished product. Are the assembled Nathan 10 and Abbey 12 units actually available and if so, do they favorably compete with the Emerald Physics CS2s?
I don't think the assembled prices are out of line if the quality is there but are these smaller units vastly inferior to the Summa15?
Lastly, I assume that www.ai-audio.com is not a viable option either?
I don't mean to hijack this thread but I am new here and just read most of the 31 pages of posts and I am a bit confused.
I landed here becuase I was (maybe still am) very close to pulling the trigger on a pair of Emerald Physics CS2s. However, it sounds like Dr. Geddes is really onto something here.
I have done lots of DIY in the past but I am now at the point that I want to buy a finished product. Are the assembled Nathan 10 and Abbey 12 units actually available and if so, do they favorably compete with the Emerald Physics CS2s?
I don't think the assembled prices are out of line if the quality is there but are these smaller units vastly inferior to the Summa15?
Lastly, I assume that www.ai-audio.com is not a viable option either?
gedlee said:
I was referring to your statement about the advantage of having different rolloffs on the subs...so I supposed it would also be ok to even use 3-4 different sub drivers, fore whatever reason...would be a mess though to find the best sub fore each position
Re: Kit Status?
The reviews on my web site specifically compare the Summa to the Emerald Physics. One guy sold his EP's to buy a pair of Abbeys.
Ai is not a viable option at this point until such time as Ai gets back in business.
In a finished product you can get the Nathan, Abbey or the Summa. In terms of cost the sweat spot is the Abbey as it is very competitive with the full Summa at a much lower cost. But be assured that there is a reason for the price differences - bigger is better and the full Summa is the best. Are they "vastly superior" no not at all, they are simply marginally better. In fact some people don't even find much of a difference at all. To me there is a difference - a small but audible difference. Is this difference worth nearly double the price? Actually, if I were buying them, I'd probably buy Abbeys.
The Summas were a revolution as far as I am concerned. They were a no-holds-barred design intened to be the best that could be done. They succeded in impressing me and apparantly everyone else who has heard them or bought them. But I have learnded a lot since they were first developed. I applied what I have learned to the latest models the Nathan and the Abbey. I took out those things that I did not feel were worth the money (mostly the expensive composite cabinets), but left those that I knew were making a "substantial" difference (like waveguides with flared mouths, foam plugs and radiused edges). Thus I ended up with 95% of the performance at 1/2 of the cost. But if you want 100% of a Summa, you have to buy a Summa.
Horizons said:
The reviews on my web site specifically compare the Summa to the Emerald Physics. One guy sold his EP's to buy a pair of Abbeys.
Ai is not a viable option at this point until such time as Ai gets back in business.
In a finished product you can get the Nathan, Abbey or the Summa. In terms of cost the sweat spot is the Abbey as it is very competitive with the full Summa at a much lower cost. But be assured that there is a reason for the price differences - bigger is better and the full Summa is the best. Are they "vastly superior" no not at all, they are simply marginally better. In fact some people don't even find much of a difference at all. To me there is a difference - a small but audible difference. Is this difference worth nearly double the price? Actually, if I were buying them, I'd probably buy Abbeys.
The Summas were a revolution as far as I am concerned. They were a no-holds-barred design intened to be the best that could be done. They succeded in impressing me and apparantly everyone else who has heard them or bought them. But I have learnded a lot since they were first developed. I applied what I have learned to the latest models the Nathan and the Abbey. I took out those things that I did not feel were worth the money (mostly the expensive composite cabinets), but left those that I knew were making a "substantial" difference (like waveguides with flared mouths, foam plugs and radiused edges). Thus I ended up with 95% of the performance at 1/2 of the cost. But if you want 100% of a Summa, you have to buy a Summa.
tinitus said:
I was referring to your statement about the advantage of having different rolloffs on the subs...so I supposed it would also be ok to even use 3-4 different sub drivers, fore whatever reason...would be a mess though to find the best sub fore each position
The easiest thing is just to use subs with different LP filter points. A bandpass sub can be slightly chenged in tuning by how and where its put. For instances facing the port into a wall will lower the tuning, things like that.
Thanks for the detailed response Earl.
You know, the more I read on your site, the more I want to buy the kit or revamp my DIY stuff!
Do you sell your waveguides separately? The reason I ask is that I have a DIY job now that uses the B&C DE250 but I am using this B&C horn and I have never been happy with the results.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=294-618
I am wondering (hoping) that if I could use your waveguide on my DE250s, many problems would be solved. I am currently biamping them at 1K, 48 db/octave with no eq. Without giving away any of your secret sauce, does the DE250 with your waveguide need any EQ or other compensation?
You know, the more I read on your site, the more I want to buy the kit or revamp my DIY stuff!
Do you sell your waveguides separately? The reason I ask is that I have a DIY job now that uses the B&C DE250 but I am using this B&C horn and I have never been happy with the results.
http://www.partsexpress.com/pe/showdetl.cfm?&DID=7&Partnumber=294-618
I am wondering (hoping) that if I could use your waveguide on my DE250s, many problems would be solved. I am currently biamping them at 1K, 48 db/octave with no eq. Without giving away any of your secret sauce, does the DE250 with your waveguide need any EQ or other compensation?
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