New build suggestions

[ocdSCHACK]

I'm starting a new build and would like some suggestions. I don't have pics yet, but the enclosure will be about 11-12 inches wide, 4" deep and 24" tall. The internal area is .54 cubic feet.

Any ideas?

The enclosure is modern looking, so I am thinking a (semi) line array...about four or more 3.5" full range drivers and 1 or more tweeters.

If more detail is wanted: Just pretend they will they will be for music only. They will be used for Home-Theater/TV at moderate levels and Music at decently loud levels. I prefer SPL's and clarity over a Sub-20Hz extension. I have a sub to use with them, but would prefer to build musical speakers that don't require a sub.

[Brewski]

I'd probably look at changing the dimensions a bit I'd be partial to a design along the lines of Axiom Audio's M22 speakers 19.8" x 7.3" x 8.0"

http://www.axiomaudio.com/m22.html

Appearance wise the tall narrow bookshelf design of the M22 is appealing to the eye.

Take it easy
Jay

[kmibb]

I'm starting a new build and would like some suggestions. I don't have pics yet, but the enclosure will be about 11-12 inches wide 4" deep and 24" tall. The internal area is .54 cubic feet.

Any ideas?

The enclosure is modern looking, so I am thinking a (semi) line array...about four or more 3.5" full range drivers and 1 or more tweeters.

If more detail is wanted: Just pretend they will they will be for music only. They will be used for Home-Theater/TV at moderate levels and Music at decently loud levels. I prefer SPL's and clarity over a Sub-20Hz extension. I have a sub to use with them, but would prefer to build musical speakers that don't require a sub.

Can it be 4" wide and 11-12" deep? If so, I'd buy a bunch of the ND105's.

[hyperlite]

Yeah, you definitely sound like a candidate for an ND105 build! get 'em while they're hot!

[ocdSCHACK]

Alright, nothing against ND105's, but I decided on something different. I chose an all Peerless/Vifa/Tymphony setup.

Here is the enclosure.


It's .5"MDF and 4" PVC cut in half for the sides.


The MDF edges were chamfered with the tablesaw and glued with PL Premium to increase the bonding strength. Its hard to see, but the PVC edge fits right into a slot on the wood.


Here is shot of the drivers. You can also see the weird PVC "cups" I made to use as the midrange enclosures.

[ocdSCHACK]

I'm having trouble deciding the layout of speakers... they are
1 x 6.5" Peerless HDS woofer http://www.parts-express.com/pe/show...number=299-281
1, 2, or 3 x 3.5" Peerless fullrange drivers http://www.parts-express.com/pe/show...umber=264-1064
1 x Vifa Tweeter http://www.parts-express.com/pe/show...umber=264-1028

How much does spacing and having speakers placed off the center axis affect the Sound? I know it's better to have the drivers as close as possible and its more important at higher crossover frequencies than low, but what can I get away with? Will having 2 or 3 midrange drivers solve the problem by lengthening the point source?

Here are some layouts I was considering:




I welcome all suggestions or tips, as this will be my first passive build(done right) starting completely from scratch.

Thanks for your help!

[ocdSCHACK]

EDITED: me being a jerk... I get the feeling too many people turn their heads to people with legitimate questions and choose to comment on posts written by people who already have the knowledge most are looking for.
Come on fellaz, help a brotha out!

[r-carpenter]

are you capable of measuring or interested in measuring your loudspeaker? If you are, these layouts will make a very interesting sets of graphs.
Diffraction will be different. How different could be calculated but I would just measure.
As a rule of thumb, space your drivers equal or closer center to center,wavelength of the crossover frequency. 2 or 3 mid ranges, you are looking at comb filtering but lowering distortions associated with driver movement.
It's hard to say. Many issues at the same time. Get ARTA or HOLMI or pay for Sound Easy. Mic and mixers are cheap.
I'd place mids in MTM configuration.
What crossover order and topology are you planing to use?

[turn2]

WTF!!!!!!!!!!!!!!!!!!
I thought this forum was about helping DIY's! Am I missing something? Prior to this post, did I come off as an as$ hole? How can the concentration of all this knowledge and intelligence not have a single (tip, warning, hint)? Sorry to so sound harsh, I get the feeling too many people turn their heads to people with legitimate questions and choose to comment on posts written by people who already have the knowledge most are looking for.
Come on fellaz, help a brotha out!

Are these going to be placed on a stand, mounted on the wall or...?

Keeping in mind that you'll want to end up with the tweeter close to ear level height, I'd wager that a MTMW arrangement centered on the baffle will work best for you. Definitely keep your mids and tweeter in a vertical line. With the PVC edges I don't THINK you'd see much advantage for not lining them up right down the center of the baffle. Measure each way and let us know the result.

[johnastockman]

WTF!!!!!!!!!!!!!!!!!!
I thought this forum was about helping DIY's! Am I missing something? Prior to this post, did I come off as an as$ hole? How can the concentration of all this knowledge and intelligence not have a single (tip, warning, hint)? Sorry to so sound harsh, I get the feeling too many people turn their heads to people with legitimate questions and choose to comment on posts written by people who already have the knowledge most are looking for.
Come on fellaz, help a brotha out!

Sorry...I like the cabinet idea and the rabbet for the pipe halves. Looks like you have some bracing in there, very good. I'm not a XO guy, but driver spacing is usually determined by what cross freq. you can use with that specific combo of drivers. Rule 'o thumb, closer is better. For that layout, having the tweeter between the two mids, MTM-style above the woofer, will sound better...but only if the XO is done properly. If you use textbook formulas, pre-made XO's or on-line calculators, the results will be less-than-listenable no matter what layout you use. There's just too many variable parameters at work to use fixed-number calculations; or pre-mades that say "for 4 (or 8) ohm drivers". Even more so when you add midrange drivers like yours or a 3-way design. The XO frequencies that work for those drivers will determine the layout and/or spacing with the best SQ. Putting the mids together like that is a recipe for comb-filtering, like the other guy mentioned. Your ears are more sensitive to the midrange frequencies, so it's an effect you don't want.

John A.

[Wolf]

I didn't even see this yesterday, must've shifted to the second page quick.

Yes- go MTMW, and close, with maybe a 1-2" horizontal offset for the MTM if you can swing that aesthetically. If you still wish to go TMMW you will need to do a 2.5-way + woofer.

I agree with John that you'll require a custom xover as well for these to sound right.

It would be more than instinctive to heavily mass-load and line the rear-walls and the chamber backs to eliminate standing waves.

One last thing- Your room-placement will be of concern to know how much BSC will need applied.

Later,
Wolf

PS- great minds think alike!!


PSS- Just because you don't get a reply does not mean you won't be helped. Just bump it in a day if you don't get a response. The crude way you responded leads me to believe you should be less upset if you are not helped within 24 hrs. It isn't life or death.

[ocdSCHACK]

Thank you all for the suggestions. Using most of everyone's advice, I settled on a MTM configuration. I didn't really like the look of the circle shaped tweeter so I flattened the top and bottom edges.
First, I found a scrap piece of wood about 53MM wide. 52-53MM is as narrow as I could make the tweeter without affecting the round part of the waveguide.


I mounted the tweeter to it and sanded away.




I then cut the driver holes and test fitted everything.



I glued the midrange enclosures to the inside and when the glue dries, I'll be able to start measuring. Thanks again for everyone's input.

[johnastockman]

Thank you all for the suggestions. Using most of everyone's advice, I settled on a MTM configuration. I didn't really like the look of the circle shaped tweeter so I flattened the top and bottom edges.
First, I found a scrap piece of wood about 53MM wide. 52-53MM is as narrow as I could make the tweeter without affecting the round part of the waveguide.


I mounted the tweeter to it and sanded away.




I then cut the driver holes and test fitted everything.



I glued the midrange enclosures to the inside and when the glue dries, I'll be able to start measuring. Thanks again for everyone's input.

That's nice work. Your ears will be happier, too. Let us know how the measurements are going and if you have any concerns about the XO alignment. Should be a fine sounding design.

John A.

[ocdSCHACK]

I'm starting to test the drivers, but have a problem. How should I wire the midranges? In series(they are nominal 4ohm)? The reason I ask is, they are terribly inefficient.... SPL is 85db. Can I wire them in parallel somehow without frying any amps? Thanks again for the help.

P.S. I'm asking before measuring because I plan to measure and use PCD treating the pair as a single speaker.

[Wolf]

Don't wire in parallel, unless you have to 'repad' to make the mids the same level as the rest of the system with a minimum 2 ohms resistor and/or DCR.

If you have a woofer that is 86dB, and the mids are 82-83dB, then series shouldn't be an issue once baffle-step is factored, UNLESS these are to be placed on a wall.
Later,
Wolf

[ocdSCHACK]

When I tested them with WT3, the impedance sweeps looked almost identical wired both ways. Does that seem normal? Does this affect any of your suggestions?

[Wolf]

It should look the same in curve, except on the height of the peak and the amount increasing in the top-end, EXCEPT overall level should be different.

If the impedance is the same above Fs in magnitude, then you have not wired them different. They are 4 ohms, so the impedance should be either 2 ohms or 8 ohms nominal for the different ways you wire them.
Later,
Wolf

[ocdSCHACK]

Once again, I can't thank you enough for your help.
You were right. Not sure what or how I measured, but I
remeasured and got normal results.

If I didn't know better, I'd think a higher power is against this build. Here's the newest issue: I used RoomEQWizard to measure for FRD files, but there is no phase. Is there a way to copy the phase from the .zma and put it in .frd? PCD won't load it correctly, and I'm guessing it's because another column should be there.

[Wolf]

.zma and .frd are corresponding with different phase plots, so they don't transfer well.

You have to open the files in a text-editor, and enter a 3rd column with zeros from top to bottom. The just extract the phase with Jeff's RM program.

Later,
Wolf

[ocdSCHACK]

.zma and .frd are corresponding with different phase plots, so they don't transfer well.

You have to open the files in a text-editor, and enter a 3rd column with zeros from top to bottom. The just extract the phase with Jeff's RM program.

Later,
Wolf

Will this impair my results? I have so much invested in "equipment" I thought was adequate, I'm not against buying the right program if it's needed.