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Discussion Starter · #1 · (Edited)
Hey guys, my name is Cliff from Montgomery AL. I was turned on to this site by one of your fellow members Rodny Alvarez. We worked together a few years back in car audio and now work together again.
A few (8 or 9) years ago I got a bug to build some home theater speakers. I went nuts and bought a whole slew of Focal drivers and a JBL 18' driver for a sub. I spent weeks and months doing research on the web and studying the principles involved. I collected all of the parts and got married. That put a damper on all of the building activities for the next 5 years. Now divorced (dont try to stifle an audio nut!!!) and dusting off the boxes of stuff! I had built the FL and FR into some MDF test enclosures, but never built the final products. A couple of months ago I built some junk enclosures for the rears as well. Just to see.

Now I have decided to do the builds. But have forgotten/lost most of my research. Now for my newb question... I have been searching the internet for a couple of months, but cannot find what I am looking for. Maybe I am using the wrong search words.

What I need is a website or article that will help knock the dust off of my memory with discussions on some more advanced principles. I know how to build speakers, now I want to know how to build excellent speakers.:D I find alot of REALLY basic info, but I am looking for the next level. You know... How to overlap crossover points (I know this is basic), where not to put crossover frequencies. I recall that it is not good to put a crossover at the common 2500-4500 area on a center channel. Also looking for info like driver spacing as it relates to crossover freq, baffle width as it relates to driver range, corner round-over to eliminate difraction, etc. I cant seem to find my old copy of Loudspeaker Design Cookbook. :scratch: I think the ex threw it out with alot of my research and tech papers.:paddle:
Thanks for any help. I only hope that I can give more in the future
 

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Hi Cliff, Welcome to the Shack!

I'm not the person to give you the answers to what you ask but just thought I would send a welcome in your direction while you wait for a response from one of our members who can give you the right answer.

Enjoy your stay with us.
 

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It all comes down to mastering the Xover design. Good luck with that. I have built a dozen different designs and I would not even think of trying that...
 

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Discussion Starter · #5 · (Edited)
Trying what? Nothing new going on with my design. :huh: They are as follows:
Front = Direct Copies of Focal/Orca Aria 5 kit (original Focal tweeter design)
Center = Focal Aria 2 (5/tweeter) with two 6.5's added for bass extension
Rear =Direct copies of the Zalytron "Recession relief kit" with Focal tweeter instead of Seas or Phillips

The only change I was going to make to any of this was that I was going to add some dual 10" woofer cabinets to the front stage just like in your avatar buggers. Just to get the front stage down to 30-40hz. I have 4 Focal 4Ω 10's for this. I also have a JBL 18 that I may or may not use for the lowest of extension 40 or 50hz and below. Depending on wat the front 10's end up like.

Really what I am looking for is the following two things:

First, how far to space the M/T/M. I know it relates to the wavelength at the x-over frequency, but I cannot find what the ratio is.

Second, how wide to make the front baffle. I know it has to do with the wavelength of the lowest frequency played by that driver. Again, I cant find the ratio
 

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First, how far to space the M/T/M. I know it relates to the wavelength at the x-over frequency, but I cannot find what the ratio is.
Within a ~1/4 of the crossover frequencies wavelength. The closer the better. This goes for all speaker drivers and port distances.

Second, how wide to make the front baffle. I know it has to do with the wavelength of the lowest frequency played by that driver. Again, I cant find the ratio
There is no certain width. It is all up the the type of dispersion you are after. It is all tied together with the driver diameter, crossover, baffle size, shape, and placement on the baffle. Check out baffle step compensation. The FRD Consortium has a lot for free programs for speaker design and room interactions. They have a baffle simulator program you might find interesting.

Good luck.
 

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Trying what? Nothing new going on with my design. :huh: They are as follows:
Front = Direct Copies of Focal/Orca Aria 5 kit (original Focal tweeter design)
Center = Focal Aria 2 (5/tweeter) with two 6.5's added for bass extension
Rear =Direct copies of the Zalytron "Recession relief kit" with Focal tweeter instead of Seas or Phillips
Are you after specific answers for these kits?
 

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First of all welcome back. I'd be happy to help you design your speakers. I will need T/S parameter in order to model boxes for you. In general you want to not cross in the 350 to 4khz range, but very few drivers are capable of that range. I know of only 2 both are manufacturer drivers you'd need to source and measure. The first and best available is the Infinity MRS driver. It is an engineering marvel and a very powerful driver. The other is the midrange driver in the B&W 802 Series speakers(this is widely considered the best commercial speaker in the world)

Now since you are getting back in the saddle. I will first suggest you do a simple project to start and get your rust off. Try one of the recession buster kits out there. I know of 2 the Madisound Recession Buster kit and the Tri-trix recession destroyer kit. Building a proven design will teach you far more than just reading books. Knowledge, Intuition and Experience are the three things every speaker project needs. Sharpen up that experience.

I suspect your saw blades may be needing replacement for that look at the forrest woodworker blades. They cut wood very smoothly and last for a long time. For a router bit look at the Whiteside or Lee Valley bits both are highly rated by finewoodworking magazine for quality. Don't go cheap on blades and bits. Make sure to refresh safety procedures. I don't want you having a short return.
 

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Discussion Starter · #9 ·
Thanks for the help guys. That is the info that I was looking for on the spacing and baffle. I dont really need the exercise in cabinet building. I do a pretty good deal of woodworking all the time and already have too many pairs of speakers laying around. I appreciate the offers on the box design help and may take you up on that offer for the woofers and subs. I've been playing with them in WinISD for a few years. As for the MTM's and surrounds, these are already proven designs. The drivers and crossover components are already purchased. I already have the cabinet volumes/ports designed and test mules built and playing. I just need to finalize the exterior dimensions on the final cabinets. You know, taller, wider, or deeper? I am thinking of combining the Aria 5 MTM's and the dual 10 cabinets into a single MTMWW cabinet. I havent decided yet. And I have not decided whether to go with a little smaller volume on the 10's and use the 18" sub, or just build a larger cabinet for lower extension on the 10's. I'm always open to ideas, but the driver selection is done. I have no more budget to change it now. The drivers that I am using are:

Front: MTMWW design
1 Focal TC90K
2 Focal 5K4211
2 Focal 10L6411 (Yes L. they are rare aluminum cone 10's)

Center: Mid tweeter vertical with woofer on either side
1 Focal TC90K
1 Focal 5K4211 (thinking or replcing this with Focal 4Kxxxx for height reasons)
2 Focal JM Lab 6VE3251B

Rear: MT design
1 Focal TC90K
1 Focal JM Labs 6VE3251B

Optional Sub:
JBL 2242HPL
 

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Discussion Starter · #11 ·
Hey Isiberian, or anyone else that has an opinion. I am pretty sure that I am going to combine the Aria 5 (MTM tuned to 50-somthing hz) with a dual 10 to make it an MTMWW disign alot like the Canton 1.2DC
http://reference.canton.de/en/products/reference-1.2-dc.htm
The Aria 5 uses something like a .75ft encloseure with a 2" x 6" long port. Since I do not need any bass extension from it, would you change the cabinet to a to a sealed design? The x-over from the mids to the woofers will be at around 200hz and will be first order to stay in phase with the 3rd order on the Mid to Tweeter exchange.

To sumarize, whould you change the mid cabinet to sealed and if so, where should it be tuned? Again dual Focal 5K4211 mids and dual Focal 10L6411 woofers being used.
 

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Trying what?
Oh, I did not know you already had a design...I thought you were going to design the xover, hence my remark
 

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Discussion Starter · #13 ·
Trying what?
Oh, I did not know you already had a design...I thought you were going to design the xover, hence my remark
Nah, using already designed crossovers for everything except the mid to woofer transitions. I think I will use 6db around 200hz so that it will match up phase with the 18db on the mid tweeters. Or I will go active and biamp. I'm about 75% to 25% right now. I may try passive and then active it if turns out badly.:bigsmile:

Any opinions on the mid cabinet? Keep ported or go sealed?
 

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The only reason to go ported is to reach a little lower in the bass region, if you have no sub for instance, otherwise stick with sealed, its smaller and easier to build.
 

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Discussion Starter · #15 ·
That's kinda what I was thinking. The Aria 5 design that is the top half of my speaker is about .75ft with 3 inch port. Question now is what volume to build into mid chanber. Should I build it with an F3 somewhere in the 200-250 range that the crossover will be? If I build F3 to coincide wqith crossover, I'll get a little better cutoff on the frequency... What is the nor.m here?
 

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The box volume is calculated by taking the driver parameters and running it through a program like Winisd (which I have never been able to make work on my computer) or Boxplot or some other, so there is no tuning in a sealed box. Tuning comes in with ported designs. You will need to take into consideration the bracing and driver volumes and calculate accordingly.
 

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Discussion Starter · #17 ·
I know. There's no "tuning" a sealed box. So they say. That is why I put quotation marks around "tuning". My personal rationalization is that there is tuning in all speaker systems. Even IB. Speaker A in a 1ft sealed box is "tuned" differently than the same speaker in a 2ft sealed box.

I have WinISD and several other box programs. The problem with using them in this situaltion is that they figure optimal bass reproduction. But I will not need bass reproduction for my mids, that is why I was asking where they needed to be "tuned". How do you decide what volume of air to put behind your mids. Put F3 at crossover frequency? 1 octave below crossover?
 

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Like I said...the volume is determined by the program. If you want to cut off the bass region you do that in the Xover.
 

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Discussion Starter · #19 ·
Yes I know the crossover cuts off the bass. I just dont see any point in having a ported enclosure for my mids. WinISD is recommending a ported enclosure tuned 60-something hz. I can make WinISD use a sealed and it looks alot more along the lines of what I am looking for. But it recommends a ported enclosure tuned to 60 something hz. I myself have nver seen a 3 (or more) way speaker with a ported mid. hahaha. Going against WinISD recomendations and using in sealed gives something like .2ft with and fsc of 128hz.
 

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Exactly. Ignore the ported enclosure part. A sealed box can be substituted for a ported box most of the time. On the other hand you could go ahead and make it ported and then stuff a plug into it when you want to. Like for experimentation purposes:T Slap a high pass on it to cut off the lows if need be.
 
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