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quik ? on av+1 design...


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#1 of 9 OFFLINE   Geno

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Posted April 21 2003 - 01:08 PM

I posted a while back that i was in the market for some speakers, well i moved, car insurance doubled and taxes suck, so now that that is all past, ive decided to save the $ and get the better set of speakers. I am still in the long process of designing them [and saving for them so plz bear with me] I have just a few ?s.


a) cant they be in a sealed enclosure? if yes, how big does it have to be? if yes, should I stuff with polyfill?

b)if not [must be ported] could the port be up front instead of in the rear? and what phasing issues would arise from that?

c) required tweeter height?

d) i am looking at an enclosure that is ROUGHLY 12"wx15"dx30"tall would the av-3's be the better choice? and if so repeat above ?'s [im still in the designing phase so ill post exact interior volume when i can and when y'all answer these]

thanks in advance for your help
geno

PS i will post plans when I get them done to aquire the HTF stamp o' approval first.

#2 of 9 OFFLINE   Brian Bunge

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Posted April 21 2003 - 01:31 PM

Geno,

a) IIRC, Danny recommends a sealed enclosure that is the same height and width but with a 7.5" internal (9" external) depth.

b) I think you will only have an F3 around 80Hz with the sealed enclosure. I also know that Danny much prefers the rear ported cabinet.

c) Danny recommends 25" tall stands for the A/V-1+'s.

d) If you change the baffle width of the A/V-3's, or any other speaker, then the crossover needs to be reworked as well.
Brian Bunge
RAD Home Theater

#3 of 9 OFFLINE   Geno

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Posted April 21 2003 - 04:37 PM

d) If you change the baffle width of the A/V-3's, or any other speaker, then the crossover needs to be reworked as well.

Brian, i kinda nderstand this but is there nayway you can clarify?
I assumed it would be if the depth changed because of the reverberating soundwaves bouncing back at the cone are different at different depths not widths. can anyone go into this or is this a standard diy ? that im just not getting?

#4 of 9 OFFLINE   Brian Bunge

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Posted April 21 2003 - 04:42 PM

The baffle width is taken into account when you design the crossover. You have a 6dB drop off in the low end response of a speaker and at what frequency this starts at is based on the width of the baffle. So baffle step compensation is used in the crossover design to flatten out the response. So drastically changing the width of the baffle will also require a drastic reworking of the crossover.
Brian Bunge
RAD Home Theater

#5 of 9 OFFLINE   Geno

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Posted April 21 2003 - 04:53 PM

ok i gotcha, im not drastically changing, well like i said ill post pics or i guess the design to get the HTF stamp. I wouldnt do anything that doesnt wow ppl in here, have you seen those DIY's Hartwig made? sheesh! anyway, thanx for the answers.

geno

#6 of 9 OFFLINE   Chris Tsutsui

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Posted April 21 2003 - 05:41 PM

I'll join your thread too Geno as I'm working on some designs for the AV-1+ and an in-ceiling AV-1.

I forgot how the AV-1+ are rear vented which could complicate matters due to them being installed in an entertainment center cabinet. An F3 of 80hz? that is barely acceptable yet it seems to be the only solution if the AV-1+ are to be mounted inside a cabinet.

I think I am just going to build the speakers to spec and toss them in the center and ceiling and see how they sound. I just don't have the testing equiptment to begin tweaking the crossovers to provide flat responses for custom applications. Posted Image

I may end up playing with acoustic foam inside the entertainment center to see if that helps with the resonance due to the rear vents. I don't think it'll be a big issue though.

As for sealing the AV-1+. If you can live with the loss of 2ch bass, I think they may be able to integrate better with a subwoofer due to the lack of phase issues with ports.

Stuffing with polyfill may help reduce the internal resonances that add distortion. This could benefit vented speakers as well as sealed as long as they don't physically block the flow of the vents.

Tweeter height should be ear level if you want improved frequency response. Depending on the height of your head and the seat you'll be using, this may vary from about 35-40 inches or so.


#7 of 9 OFFLINE   Brian Bunge

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Posted April 22 2003 - 02:23 AM

Chris,

I imagine Danny would be able to modify the crossover to allow for in/on wall placement of the speakers. You could always make the cabinets taller and place the port on the front and make the cabinet shallower.
Brian Bunge
RAD Home Theater

#8 of 9 OFFLINE   Yousaf

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Posted April 22 2003 - 04:29 AM

Chris and Brian,

Actually, you could just build A/V-1+ center channels; they are front ported and would not require any reworking of the crossover or anything.

#9 of 9 OFFLINE   Brian Bunge

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Posted April 22 2003 - 07:59 AM

Yousaf,

They would still require reworking the crossover for optimal performance for on-wall/in-wall use. Danny simply changed the driver/port layout for those who must use the A/V-1+ within a cabinet as a center channel. The A/V-C has the exact same crossover as the regular A/V-1+. He still much prefers the A/V-1+ with the port in the back.
Brian Bunge
RAD Home Theater