Multichamber Aperiodic Progressive Damping
Here's an article that explains the adavantages and also gives some rules of thumb for the dimensioning of the chambers and cabinets.
http://www.northcreekmusic.com/MAPD1.htm
Dave, what I don't realy get is, does this cab design result in a lower f-3db than a sealed cab or does it just improve the control in lower frequencies for high QTS drivers, compared to sealed or vented cabs?
lc
Here's an article that explains the adavantages and also gives some rules of thumb for the dimensioning of the chambers and cabinets.
http://www.northcreekmusic.com/MAPD1.htm
Dave, what I don't realy get is, does this cab design result in a lower f-3db than a sealed cab or does it just improve the control in lower frequencies for high QTS drivers, compared to sealed or vented cabs?
lc
Re: Multichamber Aperiodic Progressive Damping
I believe someone has built one of these for the FR125 with mixed results...
Mostly the latter. The damped/aperiodic port slowly goes from opaque at high frequencies to transparent at low frequencies effectively giving variable box volume.
dave
lovechild said:
I believe someone has built one of these for the FR125 with mixed results...
Mostly the latter. The damped/aperiodic port slowly goes from opaque at high frequencies to transparent at low frequencies effectively giving variable box volume.
dave
Re: Re: Re: Re: Multichamber Aperiodic Progressive Damping
That was me. Here's the thread.
Well, the speaker sounded very nice, I won't knock it on that front. Unfortunately, as stated in the linked thread, this speaker was for my sister for her college graduation present. She'll probably be moving to NYC soon and will be dwelling in a small apartment where space is crucial, in other words...no sub. The bass that I was able to get out of this alignment with the WR125 was just anemic, it wasn't there. On top of that, I really did not notice any real big improvement in the midrange where the difference should shine. Overall, due to the project constraints, I decided to go with a ported alignment in the end as the midrange was not apparently worse, but the bass response was much better.
I still have the MAPD cabinets in the picture I think. I also have a pair of FR125s that I built a slot-ported enclosure for about a week ago. Seeing as how the slot port has been echoing like mad and I've had to plug it up, I may make up a new baffle and stick them back in the MAPD enclosures to see how they sound again. I'll check when I get home tonight and give a new update. I have a sub that I use regularily, so the bass response is not nearly the concern for me that it would be for my yuounger sister.
planet10 said:
That was me. Here's the thread.
soongsc said:
Well, the speaker sounded very nice, I won't knock it on that front. Unfortunately, as stated in the linked thread, this speaker was for my sister for her college graduation present. She'll probably be moving to NYC soon and will be dwelling in a small apartment where space is crucial, in other words...no sub. The bass that I was able to get out of this alignment with the WR125 was just anemic, it wasn't there. On top of that, I really did not notice any real big improvement in the midrange where the difference should shine. Overall, due to the project constraints, I decided to go with a ported alignment in the end as the midrange was not apparently worse, but the bass response was much better.
I still have the MAPD cabinets in the picture I think. I also have a pair of FR125s that I built a slot-ported enclosure for about a week ago. Seeing as how the slot port has been echoing like mad and I've had to plug it up, I may make up a new baffle and stick them back in the MAPD enclosures to see how they sound again. I'll check when I get home tonight and give a new update. I have a sub that I use regularily, so the bass response is not nearly the concern for me that it would be for my yuounger sister.
Re: Re: Re: Re: Re: Multichamber Aperiodic Progressive Damping
Thanks Dave, tha't s kind of what I thought about the MAPD.
bogoes, you might want to try the second Chamber with a port for more bass, here is an example where Visaton has designed a Double Chamber BR with the internal port damped, especially for high QTS drivers, to get rid of the typical bass peak, which is also present with the FR125 in the small BR .
http://www.visaton.de/english/artikel/art_781_6_89.html
there's also a construction plan, so you might be able do guess if that would work with your cab and the FR125s.
Thanks Dave, tha't s kind of what I thought about the MAPD.
bogoes said:
bogoes, you might want to try the second Chamber with a port for more bass, here is an example where Visaton has designed a Double Chamber BR with the internal port damped, especially for high QTS drivers, to get rid of the typical bass peak, which is also present with the FR125 in the small BR .
http://www.visaton.de/english/artikel/art_781_6_89.html
there's also a construction plan, so you might be able do guess if that would work with your cab and the FR125s.
Re: Re: Re: Re: Re: Re: Multichamber Aperiodic Progressive Damping
Interesting idea, I haven't done a lot of study on Double Reflex boxes, I might give it a try some time in the future, but it's not going to be this weekend.
I found the MAPD cabinets. I'll have to cut new baffles to try them sealed, but I'm also thinking that since I have a pair with tweeter holes already in them, I will plug that hole with a cover and port and see if I can port them with any success. Saturday's probably shot as I'll have to come into the office for a few hours, but Sunday is looking plausible.
I'll report back then...
lovechild said:
Interesting idea, I haven't done a lot of study on Double Reflex boxes, I might give it a try some time in the future, but it's not going to be this weekend.
I found the MAPD cabinets. I'll have to cut new baffles to try them sealed, but I'm also thinking that since I have a pair with tweeter holes already in them, I will plug that hole with a cover and port and see if I can port them with any success. Saturday's probably shot as I'll have to come into the office for a few hours, but Sunday is looking plausible.
I'll report back then...
Just got a pair of FR125s a few days ago and I'm quite excited.
It's going to be a while before I have access to a router, so if anyone has a pair of the machined CNC front baffles they're not using and would like to pass along, I'd gratefully take them and make good use of them.
I'd be able to pay for shipping costs, of course.
Thanks!
KT
It's going to be a while before I have access to a router, so if anyone has a pair of the machined CNC front baffles they're not using and would like to pass along, I'd gratefully take them and make good use of them.
I'd be able to pay for shipping costs, of course.
Thanks!
KT
doorman said:
Wow! a CNC rig. Looks like FALL is poised for bigger things!
None of them are mine, but access to the monster one at Chris' work, and i just connected with a guy that has 2 smaller ones for doing the more interesting stuff....
dave
PS, for those that are confused by the acronym FALL = Finlayson Arm Loudspeaker Laboratories
(my street is Finlayson Arm Rd and Finlayson Arm is the fiord just to the west)
dave
Dave,
That fiord looks ideal for prohibition rumrunners to hole up in. The US IRS would like to see all of your cash receipts and bank books for 1926 through 1932.
Your cooperation will likely result in a shorter sentence.
Yours Truely,
Agent Olson
dave
Dave,
That fiord looks ideal for prohibition rumrunners to hole up in. The US IRS would like to see all of your cash receipts and bank books for 1926 through 1932.
Your cooperation will likely result in a shorter sentence.
Yours Truely,
Agent Olson
Re: Re: Re: Re: Re: Re: Re: Multichamber Aperiodic Progressive Damping
Well, I didn't have to come into the office afterall, so I had plenty of time to play with my speakers. I got the new baffles for the MAPD enclosures finished up on late Sunday afternoon and had them playing by early evening. The aperiodic comaprtment is well stuffed with polyester batting and the larger sealed compartment is totally unstuffed.
The sound... honestly, they sound great. I didn't have time to really sit down and evaluate, but they definately sound better than the plugged up 7.5L slot ported (ports plugged) enclosures they were in. I'm not sure if it's because the other enclosures were leaky or what, but these definately sound better. They seem to be a bit more forward in the midrange, which I like, and the power handling actually seems to be a bit higher as well.
On a side note, I'm also playing with using a Dayton Neo surface mount tweeter (the $5 ones with almost no flange) as a super tweeter to fight the beaming in the upper registers from the FR. I'm bringing them in 2nd order around 10kHz, padded down to about 86dB. I hooked up one side in a top mount rig - it seems to help the top end off axis as hoped. Once I get the rolloff and padding right, I'll post those results here as well.
bogoes said:
Well, I didn't have to come into the office afterall, so I had plenty of time to play with my speakers. I got the new baffles for the MAPD enclosures finished up on late Sunday afternoon and had them playing by early evening. The aperiodic comaprtment is well stuffed with polyester batting and the larger sealed compartment is totally unstuffed.
The sound... honestly, they sound great. I didn't have time to really sit down and evaluate, but they definately sound better than the plugged up 7.5L slot ported (ports plugged) enclosures they were in. I'm not sure if it's because the other enclosures were leaky or what, but these definately sound better. They seem to be a bit more forward in the midrange, which I like, and the power handling actually seems to be a bit higher as well.
On a side note, I'm also playing with using a Dayton Neo surface mount tweeter (the $5 ones with almost no flange) as a super tweeter to fight the beaming in the upper registers from the FR. I'm bringing them in 2nd order around 10kHz, padded down to about 86dB. I hooked up one side in a top mount rig - it seems to help the top end off axis as hoped. Once I get the rolloff and padding right, I'll post those results here as well.
Thanks for posting about the aperiodic design. When you built the enclosures did you use Northcreeks design math for the WR125? Have you made any volume changes to your original enclosure? It would be extremely easy to use the Northcreek formulas to derive the enclosure volumes. Did you purchase the Scanvents or are you using something else to limit the air flow between the chambers or are you using nothing at all?
It might be wasteful, but do you think a planar or ribbon would add to this alignment ?
It might be wasteful, but do you think a planar or ribbon would add to this alignment ?
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