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post #1 of 110 Old 08-13-2009, 08:59 PM - Thread Starter
 
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It looks like Mayhem13 is throwing out the coaxial poll and going a different direction. I am starting this thread to see how many people would be interested in pursuing this. Hopefully Tom Danley is still interested in helping with this. Post here and let me know.
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post #2 of 110 Old 08-13-2009, 09:09 PM
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Has Tom expressed interesting giving access to this technology to the DIY community?
Danley speakers are for sale. But I'm not so sure about the we express interest and Danley provides aspect you seem to be implying. Am I wrong here?

Regards,
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post #3 of 110 Old 08-13-2009, 09:49 PM
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Count me in for three.

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post #4 of 110 Old 08-13-2009, 09:52 PM
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I'll have my eye on it for sure. I'm not sure what direction I'll go in but I'm very interested in something like this as well as what augerpro's working on with the waveguide.
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post #5 of 110 Old 08-13-2009, 10:03 PM
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post #6 of 110 Old 08-13-2009, 11:27 PM
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Quote:
Originally Posted by NEO Dan View Post

Has Tom expressed interesting giving access to this technology to the DIY community?

Danley speakers are for sale. But I'm not so sure about the we express interest and Danley provides aspect you seem to be implying. Am I wrong here?

It's madness.

Tom said he MIGHT be able to help with optimizing a crossover, once a final design is complete. Somebody's got a bunch of work to do first....

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post #7 of 110 Old 08-14-2009, 04:48 AM
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I would be interested in a simple 2 way for surround duty but even more interested in a MTM with 2 8" woofers helping out on the bottom end ala Triple 8. Maybe start out with the 2 way and then convert to a MTM as well.
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post #8 of 110 Old 08-14-2009, 05:08 AM
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I'm in.
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post #9 of 110 Old 08-14-2009, 05:11 AM
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8" pro woofers are pretty weak in the bass, these will almost have to be 3-way, except maybe the surrounds. I don't think they will even reach down to a sub well. Maybe down do a midbass unit? Although the 18 Sound 8NMB420 I tested some time ago actually had alright bass. Don't know if the 8CX400F is the same.
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post #10 of 110 Old 08-14-2009, 05:43 AM - Thread Starter
 
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Quote:
Originally Posted by augerpro View Post

8" pro woofers are pretty weak in the bass, these will almost have to be 3-way, except maybe the surrounds. I don't think they will even reach down to a sub well. Maybe down do a midbass unit? Although the 18 Sound 8NMB420 I tested some time ago actually had alright bass. Don't know if the 8CX400F is the same.

The 8NMB420 has an fs of 60 and the 8CX400F has an fs of 64. Looking at the graph for the 8NMB420 it is a little flatter on the low end, but they both drop off at the same point. Mark is getting the 8CXT down to around 70Hz actively, fs of 76. Do you think we could get the f3 down to 80Hz using the 8CXT or the 8CX400F in a ported enclosure with a passive crossover?
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post #11 of 110 Old 08-14-2009, 05:54 AM - Thread Starter
 
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Quote:
Originally Posted by tsloms View Post

I would be interested in a simple 2 way for surround duty but even more interested in a MTM with 2 8" woofers helping out on the bottom end ala Triple 8. Maybe start out with the 2 way and then convert to a MTM as well.

What sucks, that is the exact direction that the polls led to in Mayhem13's threads. All we were down to, was picking the coaxial and LF drivers. Mayhem13 used the excuse that arguing over which coax to use as a reason to throw it out. In a poll type of situation you are going to have people wanting different drivers used no matter what type of driver you are discussing. Mayhem13 never did want to use a coax and I think he thought that most people felt the same as him. I think he thought that he would be able to put the coaxial talk to bed with that poll, so I think it threw him for a loop when the coaxial won the poll.
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post #12 of 110 Old 08-14-2009, 06:03 AM
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Quote:
Originally Posted by mjg100 View Post

The 8NMB420 has an fs of 60 and the 8CX400F has an fs of 64. Looking at the graph for the 8NMB420 it is a little flatter on the low end, but they both drop off at the same point. Mark is getting the 8CXT down to around 70Hz actively, fs of 76. Do you think we could get the f3 down to 80Hz using the 8CXT or the 8CX400F in a ported enclosure with a passive crossover?

Hey MJG,

You might not want my feedback in your thread, but I think one reason Brandon does not want to push the coax that low is that it tends to sacrifice the midrange performance and clarity, which is very important for HT. If you've ever listened to a 3way design without the woofer connected, letting the mid run full range and then adding the high pass into the mid, so it no longer has to do low end duties as well, you will know what I mean. It can be a night and day difference. IMO, it usually opens the midrange up a lot and it can go from rather muddy to very clear and open when the mid no longer has low end duties as well. You are just trying to get too much out of a single driver and rather than getting excellent bass and midrange, you end up compromising both. If you have dual drivers sharing this duty, as in an MTM it can be different.
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post #13 of 110 Old 08-14-2009, 06:50 AM
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Quote:
Originally Posted by mjg100 View Post

What sucks, that is the exact direction that the polls led to in Mayhem13's threads. All we were down to, was picking the coaxial and LF drivers. Mayhem13 used the excuse that arguing over which coax to use as a reason to throw it out. In a poll type of situation you are going to have people wanting different drivers used no matter what type of driver you are discussing. Mayhem13 never did want to use a coax and I think he thought that most people felt the same as him. I think he thought that he would be able to put the coaxial talk to bed with that poll, so I think it threw him for a loop when the coaxial won the poll.


Mayhem was set unfortunately from the start NOT to build a coax. His mistake was to enter this into the poll about a coax and then having it blow up in his face. It seems to me that this forum wants to build a MTM with a coax. He should have just continued to build what he wanted to instead of trying to entertain a coax. I wish him the best on his build though.
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post #14 of 110 Old 08-14-2009, 07:05 AM
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Interested.

Question is... Everyone can add to the discussion and ideas but who is actually going to build the first test mule and do the grunt work? Tom is a very busy guy. He offered to help with the crossover...Maybe. He's not going to design the thing for us.
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post #15 of 110 Old 08-14-2009, 08:43 AM
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Tom has commented about a particular B&C 8" coax having a fairly optimum horn throat to cone transition and being a good option. Since he has some experience developing a synergy horn crossover for it, it may be the best opiton, as long as he doesn't view it as a conflict of interest.

Here is a decent place to buy them from:
http://www.magnumcaseworks.com/Loudspeakers.html

You might even be able to setup a group buy directly form the US distributor.

Most DIYers are a bit cheap and this may be a little rich for most people's blood though.
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post #16 of 110 Old 08-14-2009, 08:52 AM
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Actually, this is the better place to buy the 8CXT.

http://www.prosoundparts.com/B&CSpea...i513221:page=2
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post #17 of 110 Old 08-14-2009, 10:08 AM - Thread Starter
 
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Augerpro has a B&C 8cxt for testing and he said he should have the results this weekend. That should tell us something. If possible I would like to do this as a 2-way. If we can get to f3 of 80Hz then that would work. I am not positive but I think the f3 of the Sparks is around 70Hz. If we can't get to 80Hz then we need to either add woofers to the design or use them with bass bins.

In the other thread Penn offered to buy the coaxial for testing. If Penn is still open to that we could look at one of the other coaxials such as the 18 Sound 8CX400F.
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post #18 of 110 Old 08-14-2009, 10:13 AM
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Quote:
Originally Posted by mjg100 View Post

Augerpro has a B&C 8cxt for testing and he said he should have the results this weekend. That should tell us something. If possible I would like to do this as a 2-way. If we can get to f3 of 80Hz then that would work. I am not positive but I think the f3 of the Sparks is around 70Hz. If we can't get to 80Hz then we need to either add woofers to the design or use them with bass bins.

In the other thread Penn offered to buy the coaxial for testing. If Penn is still open to that we could look at one of the other coaxials such as the 18 Sound 8CX400F.

I think we should do both 2-way and 3-way options. The crossovers should be pretty similar and it'll give more flexibility for budget/needs.
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post #19 of 110 Old 08-14-2009, 10:18 AM - Thread Starter
 
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Originally Posted by dlneubec View Post

Hey MJG,

You might not want my feedback in your thread, but I think one reason Brandon does not want to push the coax that low is that it tends to sacrifice the midrange performance and clarity, which is very important for HT. If you've ever listened to a 3way design without the woofer connected, letting the mid run full range and then adding the high pass into the mid, so it no longer has to do low end duties as well, you will know what I mean. It can be a night and day difference. IMO, it usually opens the midrange up a lot and it can go from rather muddy to very clear and open when the mid no longer has low end duties as well. You are just trying to get too much out of a single driver and rather than getting excellent bass and midrange, you end up compromising both. If you have dual drivers sharing this duty, as in an MTM it can be different.

I understand what you are saying. I took some small speakers (manufacture gives 47Hz as f3) and using a Behringer CX2310 I have them crossed at 100Hz. I have placed three sealed subs under all three front speakers to cover 40Hz to 150Hz. I like it lapped better than crossed. Moving the small speakers up to 100Hz really opened them up.

From everything that I have read the B&C 8CXT is a very dynamic speaker. Mark Seaton's Sparks uses one in an active design and I believe the f3 is around 70Hz. Every post and review that I have read about that speaker has been raving about it. So it looks to me that it can be done with good success. 70Hz would be great, but I would be happy if we could hit 80Hz. Since I have bass bins/MBMs I could even use it up higher, but that is something that would work for a lot of people and I am trying to get this to work for a group rather than just one person.
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post #20 of 110 Old 08-14-2009, 10:27 AM
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Quote:
Originally Posted by mjg100 View Post

Do you think we could get the f3 down to 80Hz using the 8CXT or the 8CX400F in a ported enclosure with a passive crossover?

DanN answered this spot on, could,yes, should, not in my opinion. Just one person's opinion of course.

Quote:
Originally Posted by mjg100 View Post

What sucks, that is the exact direction that the polls led to in Mayhem13's threads. All we were down to, was picking the coaxial and LF drivers. Mayhem13 used the excuse that arguing over which coax to use as a reason to throw it out. In a poll type of situation you are going to have people wanting different drivers used no matter what type of driver you are discussing. Mayhem13 never did want to use a coax and I think he thought that most people felt the same as him. I think he thought that he would be able to put the coaxial talk to bed with that poll, so I think it threw him for a loop when the coaxial won the poll.

To be fair I have my doubts that we could have pulled of the coax option with the budget listed. It wouldn't be much more, but still it would be more than $750 most likely. $850 would probably work with the dual 8" woofer option as midbass support.
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post #21 of 110 Old 08-14-2009, 10:56 AM
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I'm for the 2-way coax w/B&C 8".

As far as supplying Tom a "design", it's just a box for one driver.

The hard part will be agreeing on its shape/dimensions.

Personally I don't care as I want then for surrounds and will build some cylindrical or elliptical boxes for then and depend on EQ to straighten out the freq resp.

Actually, since people are likely to put their speakers in a variet of room locations, I wonder if we could streamline the process for Tom and just have him concentrate on the woofer/CD transition and not worry about BSC and such.

Noah
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post #22 of 110 Old 08-14-2009, 01:03 PM - Thread Starter
 
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Quote:
Originally Posted by Monger View Post

I think we should do both 2-way and 3-way options. The crossovers should be pretty similar and it'll give more flexibility for budget/needs.

That would be great if we could do that. I would do the 2-way for myself with the option to go to 3-way later if I wanted.
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post #23 of 110 Old 08-14-2009, 04:06 PM
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I think, to get down to 80Hz and preserve midrange clarity, a 12" would be a better option. Unfortunately, the polars of the B&C 12" aren't very good and the others don't provide polars. I've been interested in the BMS 12c362 but I haven't felt like spending $300 to find out how good the polars are.

http://bmspro.com/12C362.bms_12c362_...nsducer.0.html


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post #24 of 110 Old 08-14-2009, 05:10 PM
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Quote:
Originally Posted by catapult View Post

I think, to get down to 80Hz and preserve midrange clarity, a 12" would be a better option. Unfortunately, the polars of the B&C 12" aren't very good and the others don't provide polars. I've been interested in the BMS 12c362 but I haven't felt like spending $300 to find out how good the polars are.

http://bmspro.com/12C362.bms_12c362_...nsducer.0.html


Ditto on all counts.

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post #25 of 110 Old 08-14-2009, 05:56 PM
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After the BSC the 8CXT will be deep into medium efficiency territory

Regards,
Dan
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post #26 of 110 Old 08-14-2009, 06:04 PM
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OTOH it wuld make a cute little speaker with a couple 8" PR's

a micro triple 8

Regards,
Dan
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post #27 of 110 Old 08-14-2009, 08:32 PM
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Actually i was excited when Tom offered with Xo help....who wouldn't be? What forced me away was calls for an increase in budget and baffle size and the benefits of this design as a two way. There was simply no way to satisfy the voters and the select group that chose to post on the subject whose needs and desires are clearly the minority when compared to the polling results. The project isn't dead, but the bickering and coaxial expedition is. Carry on as i'm glad to see that the possibility of a universal 2way xo design for a Coax is on the brink of execution. Brandon's testing should be very revealing. I think in all fairness if possible, to execute an active xo for starters and get some subjective opinions on the overall SQ with various types of material. While some may feel that subjective SQ opinions are worthless, a good listening space combined with a good speaker usually results in a pleasurable listening experience for most listeners.
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post #28 of 110 Old 08-14-2009, 08:58 PM
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So here are some early results of the 8CXT. First the raw response, 7ms gate with NO smoothing, 1 meter away:



I knew right away the woofer would be fairly easy to work with. The dip around 2khz is easily smoothed by a high Q low pass. Here is a LR4 @ 2200hz with super quick two component crossover:



Should be easy to get what we want. The dip around 700hz should also be taken care of fairly well in a similar manner. Once you add the high pass to the woofer this area will be the middle of the midrange passband and you can adjust the peaking of the transfer function here pretty easily, lifting the dip to flat.

The CD does indeed look a bit daunting. While I didn't really try to get it smooth, I just wanted to get the overall contour flat, as it has that hill at the low end and then shelves down above that. That sort shape is fairly difficult to deal with. Another quick pass at the crossover gave me this:



Not the smoothest. The good news is the crossover area on both drivers is decently smooth so the integration there is good. It all depends on how you think that upper treble will sound. Some well placed notch filters may smooth out the upper end significantly, but I haven't looked at that yet, just thought I'd throw this up for now.
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post #29 of 110 Old 08-14-2009, 09:05 PM
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BTW Accuton is the only company out there doing hard cones right. Can you say PISTON? I have a hold of their worst response 7" woofer and it would still be easier to deal with than some paper cones! When I run the MLS signal you can always here the cone breakup of a metal driver, but not on these. Very nice.
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post #30 of 110 Old 08-14-2009, 10:55 PM
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What is red vs. green in the first curve?

Will you be doing polars?

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