DIY Array-O-Wave. Yesterday's progress - pix

[RayW]

1. Buy new plywood and mount the drivers from the back with the front holes rounded over with a roundover bit.

You know that that's going to be putting a little bit of a waveguide onto the drivers, right? It will likely change the power response and may change things audibly on axis. I would grab a scrap piece if you can find it and try that mounting scheme before committing it to the final design.

 

[Grainger49]

djnagle,

I have a question. How open is the back of the board, I mean do you get a good back wave from the speakers?

I'm figuring each group of four for my application should be 8 ohms, two in parallel in series with the other two in parallel. I can put them in series and run the tweeter directly across the inputs with a high pass. That would yield 16 ohms till the crossover point where it would drop below 16 ohms. Remember I'm using a 2A3 amp that is currently tapped for 8 ohms.

How's that sound?

 

[djnagle]

Thanks much! This is the type of information I was hoping to find. The speakers--they are pulls out of a Yamaha HTIB setup that a friend gave me (just the speakers). The manufacturer is "205", but I couldn't find that in any of the online databases listed by Google. And, I don't have a woofer tester either. Kind of a shot in the dark, but a shot I'm probably willing to take.

I'll play with EDGE and see what comes out the other side.

Thanks again!

I ran mine through WT3 but only got the Qts, it did not give me the Xmax. But I know they would not be doing much below 100hz, I figured it would be ok. Since then, I found the T/S on them. Either way it is a cheap experiment.

You know that that's going to be putting a little bit of a waveguide onto the drivers, right? It will likely change the power response and may change things audibly on axis. I would grab a scrap piece if you can find it and try that mounting scheme before committing it to the final design.

Yep, I figure it will Ray, but that is not a big deal because I will try them back mounted and if they don't sound good, I will flip them over and front mount them with the back already rounded over. By that time I hope to have test equipment in the house.

djangle,

I have a question. How open is the back of the board, I mean do you get a good back wave from the speakers?

I'm figuring each group of four for my application should be 8 ohms, two in parallel in series with the other two in parallel. I can put them in series and run the tweeter directly across the inputs with a high pass. That would yield 16 ohms till the crossover point where it would drop below 16 ohms. Remember I'm using a 2A3 amp that is currently tapped for 8 ohms.

How's that sound?

The holes in back are still not rounded over. That is for the next phase. As for how to wire them, I still can't understand how to turn a light on or off. I'm sure someone else will chime in . I just followed the THAL plans I had. That is where the wiring scheem came from a couple pages back.

 

[RayW]

I ran mine through WT3 but only got the Qts, it did not give me the Xmax. But I know they would not be doing much below 100hz, I figured it would be ok. Since then, I found the T/S on them. Either way it is a cheap experiment.

The WT3 can't measure Xmax. It's a physical property. To really find it you need to dissect the driver, subject it to Klippel testing, or push it to its limit and use a homebrew sliding gauge to figure the movement.

Yep, I figure it will Ray, but that is not a big deal because I will try them back mounted and if they don't sound good, I will flip them over and front mount them with the back already rounded over. By that time I hope to have test equipment in the house.

Cool, a man with a plan. :thmbsp:

As for how to wire them, I still can't understand how to turn a light on or off. I'm sure someone else will chime in .

You did the same thing Grainger said but put the 2 banks in parallel instead of series giving a 4Ω final impedance.

 

[djnagle]

Yaeh, well, Im not very smart but I can lift heavy objects

 

[Grainger49]

. . . You did the same thing Grainger said but put the 2 banks in parallel instead of series giving a 4Ω final impedance.

Um... not according to his schematic. In his schematic the top four are parallel, 2 ohms, then in series with the bottom four in parallel, 2 ohms, total 4 ohms. That is an almost worst case use of my feeble 3.5 WPC. It just doesn't use enough of my output transformer.

 

[RayW]

D'oh! You're absolutely right. I hadn't looked at his schematic in a few days and my memory reverted to the ones that I had built. Tough to keep stuff filed correctly for more than a few seconds.

If you could grab another couple you could do 9 per side and go with 3 parallel groups of 3 series drivers and end up with 8 ohm final impedance.

 

[Zilch]

If you wire them in series pairs, you end up with four 8-Ohm pair. If those pairs are symmetrical, top and bottom, you are set up to experiment with shading/steering.... :yes:

 

[RayW]

Keele would be proud.

 

[Andyman]

I have a question. How open is the back of the board, I mean do you get a good back wave from the speakers?

That was my first concern when I looked behind; I'd be shocked if he's getting much of any wave.

The drives sit in a 3/4" deep hole that is about 1/4" bigger than the rear diameter of the basket and the opening in the web is an oblong cutout maybe 3/8" in width and 1-1 1/2" long.the magnet bell housing is very big and covers quite a bit too, which is why I suggest that he rout the champher back there; these babies are really buried.

Here's a blowup of one of the pics. Do you see any cone or even cutouts in there???

All that being said, they do sound very, very nice, so it's tricky business and opening it up could result in a whole new animal and perhaps one not as well loved as the original

I'm all for the scrap prototype myself :yes:

 

[Grainger49]

If you wire them in series pairs, you end up with four 8-Ohm pair. If those pairs are symmetrical, top and bottom, you are set up to experiment with shading/steering.... :yes:

I'm not following. The top four, wired in series pairs of 16 ohms each, but do I then put them in parallel? That yields 8 ohms. The bottom done the same way gives another 8 ohms so either in series (back to 16 ohms) or parallel gives 4 ohms.

I'm probably just being dense!

Sorry for the huge skid sideways!

 

[Zilch]

Any two of them in series is 8 Ohms. That makes four 8-Ohm pairs.

Two of those 8-Ohm pairs in parallel makes a 4-Ohm quad.

Two of those quads in series makes an 8-Ohm octet....

 

[Grainger49]

Ok, you are saying that they are 4 ohm drivers? I didn't get that. It makes it all simpler, thanks!

 

[Zilch]

Looking back, they're not, rather, 8 Ohms.

SO, double my impedances.

[You have a 16-Ohm tap, no? ]

 

[Grainger49]

Yes, I just have to solder it onto the 5 way binding post.

 

[djnagle]

If you wire them in series pairs, you end up with four 8-Ohm pair. If those pairs are symmetrical, top and bottom, you are set up to experiment with shading/steering.... :yes:

Will doing it like you said change the spl or crossover point or anything else? I'm alway game to mess around with these, but I'd like to get some measuring equipment here to see what is changing.

 

[djnagle]

That was my first concern when I looked behind; I'd be shocked if he's getting much of any wave.

The drives sit in a 3/4" deep hole that is about 1/4" bigger than the rear diameter of the basket and the opening in the web is an oblong cutout maybe 3/8" in width and 1-1 1/2" long.the magnet bell housing is very big and covers quite a bit too, which is why I suggest that he rout the champher back there; these babies are really buried.

Here's a blowup of one of the pics. Do you see any cone or even cutouts in there???

All that being said, they do sound very, very nice, so it's tricky business and opening it up could result in a whole new animal and perhaps one not as well loved as the original

I'm all for the scrap prototype myself :yes:

I'll be messing with these for a bit before I settle of the final design. I will mount them in back first and see what happens.

 

[mayhem13]

Nice Job Guys!.....i'm following this one closely. Any reason given the baffle width NOT to use the standard E-wave guide PH612?

As stated earlier and as you're progressing, the rear mounted midwoofers should open up quite nicely BUT baffle width may be of more concern with dipole radiation/cancellations.

 

[djnagle]

I have the standard wave guide, but I wanted the smaller guide that fit visually with the smaller drivers. I like the sound of the 6x6, as it turns out, better than the 6x12.

I don't know what rear mounting will do to the sound of these but if you think about it, the distance from front to back is not changing so maybe no issues....don't know till I try it. They sure are a big open sound as is and I hope that does not change.

 

[audiozaz]

I have the standard wave guide, but I wanted the smaller guide that fit visually with the smaller drivers. I like the sound of the 6x6, as it turns out, better than the 6x12.

I don't know what rear mounting will do to the sound of these but if you think about it, the distance from front to back is not changing so maybe no issues....don't know till I try it. They sure are a big open sound as is and I hope that does not change.

If you give the holes a good pass with a roundover bit as you mentioned previously, it should be just fine. You might notice an improvement as the back of the speakers will now be radiating freely instead of being stuck close to the hole walls.

az