[RAW]

Well we have a Array kit coming that will be released at RMAF.
8" wide 65" tall 14" depth.
Using M-130 drivers and the new RA104.5 ribbon.
Kit pricing will be $899.00  
CNC baffles will not be included.
Design objective

-High 95db sensitivity.
-6 to 8 ohm impedance.
-No point source/line source radiation pattern variances.
-No 3db/6db distance doubling issues (consistent output at all distances).
-No lobbing errors.
-Consistent off axis responses horizontal.
-Large vertical off axis window (consistent over a wide range).
-Low distortion design.
-cabinets tuned to 49hz with a -3db in the mid to low 40's.
-Narrow profile design
-High quality crossover parts.
-Easy to build.
-And Inexpensive!!!

This new kit (complete speakers as well) will be available from RAW Acoustics.
AT RMAF the show pair will be on a special price.



This speaker not only has no vertical or horizontal off axis problems but is extremely good on both axis.

Below is the horizontal off axis responses taken at one meter

The Red line is on axis.

The Orange line is 10 degrees off axis. Hardly any change except at 20kHz.

The Yellow line is 20 degrees off axis. Still nearly dead flat!

The Grey line is 30 degrees off axis. It is still within a +/-1.75db range!

The Black line is 40 degrees off axis. From 250Hz and up it's still within +/-2.5db.

Man the off axis response of that ribbon is killer! A 3/4" diameter dome tweeter can't even do that.

Now most people tend to think that the vertical response from ribbons is poor, and for many longer ribbons this is true, but this one isn't very long. What I really like is the smooth output level across a wide range, and this speaker has it in spades.

See off axis vertical response below.

The mic was pulled back to 60", and this is why we see the sensitivity across the board falling off.

The first line, the Red one, was taken on tweeter axis with the mic at 39" from the floor.

The second one, the Orange one, was taken with the mic moved up to 43". There is hardly any change.

The third one, the Yellow one, was taken at 47". It still looks great and shows that the drivers are acoustically in phase very well. From the back of my room and standing (I am 5' 10" tall) this brings the mic to just below ear level, but close. If I were to step back another foot or two then this would be at ear level.

The last one was taken with a mic height of 51", the Grey line. This is above ear level to me and would be even to a really tall person. We are still looking at a +/-2.5db range, and the highs did not fall out of it in the top end. In fact it appears that the peak in the top may be a little hot straight on but off axis it is as much a blessing than a curse.

A speaker with an on axis and an off axis that is this smooth is rare. The total in room response of this speaker will look very good. I like this speaker the more time I spend with it[/url]

[PeteG]

Al,
 Sounds like a good kit, I'll make sure I will check them out at RMAF.

Pete

[sonicboom]

Will this kit use a single tweeter or a line of them?  And by the way, is it a planar magnetic unit or a leaf ribbon?   I don't recall seeing it elsewere, is it a proprietary driver?

[RAW]

Pete
See you then.

Yes the kit will use a single ribbon.
The ribbon used is a custom Aurum Cantus ribbon made for us.
-104.5mm OD custom OD
-6 bolts not the 4 as on all other ribbons this size
-custom opening shape for this face plate.

Yes the ribbons are available from RAW Acoustics only.
$99.00 each

[RAW]

PRE ORDER SALE price of $799.99 is up for those who would like to take advantage of the PRE ORDER SALE.
Shipping will be last week in August .



And for that person who would like the Demo pair taken to Denver we will be posting a special price on the show pair.
Photos will come in the next few days.
[/url]

[RAW]

Cabinets unfinished along with bases but for those looking these will be the demo pair at RMAF.
Finished in figured Cherry.

[RAW]

Here the RA8 are in Cherry
These are off to GR and then to Denver for those who will be around to have a listen.

The complete set can be made for around $1000.00 with materials

[Popms]

i've been looking at arrays for a while now but price has stoped me, how close does this come to the sound of a array with a line of tweeters.

[RAW]

The line array using a single tweeter as we have will have a few benifits over the line of tweeters.
-No point source/line source radiation pattern variances.
-No 3db/6db distance doubling issues (consistent output at all distances).
-No lobbing errors.
-Consistent off axis responses horizontal.
-Large vertical off axis window (consistent over a wide range).

Really a price issue for the money the kit was design to hit a perforamnce level.
We have the Omega and Lambda line arrays for those who are after a larger line array.

[RAW]

Up loaded the Frequency response and Impedance.
95db talk about easy load on a amplifier.

[trekker]

-No point source/line source radiation pattern variances.
-No 3db/6db distance doubling issues (consistent output at all distances).
-No lobbing errors.
-Consistent off axis responses horizontal.
-Large vertical off axis window (consistent over a wide range).
-Low distortion design.
.

If there's only one tweeter, how could there be a Large vertical off axis window?  I thought the ribbon would have a limited vertical off axis.

Why wouldn't there be any 3db/6db distance doubling issues with only one tweeter used?

I'm kinda new to this line source stuff, so may be I just don't understand everything?

Arnold

[Danny Richie]

If there's only one tweeter, how could there be a Large vertical off axis window? I thought the ribbon would have a limited vertical off axis.

Good questions.

Dispersion is directly related to the size of the diaphragm. Any time the diameter of a driver exceeds the length of the wavelength that it produces then the result is that it beams the output into a narrow window.

This is why a large woofer looses off axis response more quickly than a small woofer.

Likewise a smaller diameter tweeter has better off axis response than a large diameter tweeter.

The same holds true for a ribbon but in one plane only. The ribbon is very narrow so off axis response in the horizontal plane is usually very good, especial with this new ribbon of Al's as it has a wider than normal face plate opening that does not restrict horizontal off axis response like the face plate of many other popular ribbon tweeters.

Vertically the off axis response window is also a direct relation to the ribbon length.

The shorter the ribbon the better the vertical dispersion just like a dome tweeter.

The longer the ribbon the more limited its vertical dispersion.

In a continuos line of ribbons or planar magnetics used in a line source, the vertical response window is limited to the length of the line. The trick there is to make a line long enough that you are always in the middle of it or within the length of it at all times.

Al's short ribbon has very good vertical dispersion and similar to that of about a 2" dome tweeter. Not as good as the horizontal but still very good. It will change little at all seated or standing.

Why wouldn't there be any 3db/6db distance doubling issues with only one tweeter used?

I knew this question would come up soon.

With any point source tweeter stuck in the middle of a line of woofers you will get this problem of only being able to match the output levels at one point (distance) only.

Not so with this design. The tweeter crosses over only to the two center woofers. They are a pair of M-130/16's. 16 ohm woofers in parallel to give an 8 ohm load. They are in a sealed box.

At a much lower frequency range the mid-woofers cross to the six outer woofers with a low first order crossover. They are six 8 ohm M-130 woofers in a series parallel configuration. These are in a ported box.

So the speaker behaves like and large MTM throughout a wide range and more like an array at the lower ranges.

You get a big sound stage, with good fullness of sound (no small speaker sound) life like vocals with a sense of air and realism, really low distortion, and lots of other advantages without other drawbacks.

This design REALLY sounds good. I design speakers all the time including a lot of big line sources. I don't impress easy either. This one is impressive. The performance by far exceeds the price point. This speaker is a steal and will be a new bench mark setting design.    

[RAW]

Here is the inside view of the cabinet less a side panel and rear panel.
The 1st driver center is located 14" off the floor to get our tweeter to a height of 38".
As well as Danny noted the MTM in the middle is sealed with the 3 M-130 above and below M-130 drivers ported.

As Danny noted  
These are going to impress a few people in the business for sure

And a center channel to match as well

[trekker]

Thanks Danny for the very informative explanation to my questions.    

Arnold

[BradJudy]

Thanks for the design details.  It's always interesting to hear about the details and the intent behind different design choices.

[trekker]

Will this line source produce a 3-D/holographic sound?  Also, can this line source be used as a center channel if layed sideways and the ribbon tweeter rotated 90 degrees?

Thanks,

Arnold

[Danny Richie]

Will this line source produce a 3-D/holographic sound?

I know of no reason why it won't. Imaging and sound stage will be a strong point.

Also, can this line source be used as a center channel if layed sideways and the ribbon tweeter rotated 90 degrees?

It certainly can. With the close (less than 10") center to center spacing of the two center woofers it it should maintain a smooth off axis response to about 22 degrees before the offset of the woofer distances start to cause any cancelation. The outer woofer don't really play up high enough to cause cancelation problems as the lower wave lengths are fairly long.

Funny thing is that Al and I have already discussed that.

You can also shorten it to six woofers pretty easy too.

Al even talked about a four woofer center version.

The shorter ones will make nice surrounds too.

Our wall mounted A/V-1RS kit will match them well for surrounds too as it uses the same woofers and has a similar voicing.

[RAW]

Here we go a picture of them at the GR facility.
Danny had made mention of getting them together if he had time for a even in Texas this week end.

You never know

And for those attending the RMAF.The pair at the RMAF will be up for sale complete ready to ship from RMAF direct to you.

Ok I will go a little into why.
-**I wanted a line array that the average person could afford.
-Designed to build at a parts cost of  $1000.00 (less shipping)
That is all materials.MDF,Absorbtion material,dampening material,Paint.
Not veneer as veneer costs depend on what a customer picks.
- Simple cabinet contruction.
-Not 80" tall - 65" fits into a average sized room with out being to close to the ceiling.
-Easy mounting drivers.Only need to flush mount the ribbon tweeter, all other drivers are a top mount frame.Less router time.

The braces shown in the picture,yes could have been cut with holes in the braces and not in a double U shaped ends.
This was put this way as a person with jig saw can knock out these braces in less than 10 minutes cutting U shape braces.But if you used a router cutting all the holes in the braces you would be looking at a lot more time.
Not that you can not do the braces with holes and not U shape.
This way router time is less.LESS high flying MDF dust

Now by far the cost of the Kit is a deal by other designs, as well takes less time to construct.

Fully finish cabinet will be available from RAW Acoustics in the standard veneers(Maple,Cherry,Oak), as well as Exotic veneers can be ordered as well.
RAW Acoustics hand picks all veneer to match speaker designs nothing worse than ordering a few sheets of veneer to have 2 sheets look 100% different grains.
For local veneers we can get we hand pick our own sheets.This is thanks to a supplier who allows myself to just walk in and open a few boxs and pick threw veneer untill I see something I like as and if needed matching sheets.This can be a issue when ordering veneer for large speakers those who plan on building cabinets, if that is the RA8 or others that large I recommend contacting a veneer supplier who will sheet match.Some have a sur charge for this as it does take time to match sheet.But worth it on large speakers for sure.

[Gooch]

This might be a silly question but how dose the line array reproduce in the mid to low 40Hz range. When the M-130's has a Fs of 50Hz. Wouldn't you need a driver that has a Fs a round 30Hz to do that

[RAW]

That is in room response.
Not a tuned port response.