John Sayers' Recording Studio Design Forum Archive

There is a line of (push-pull) planar magnetic loudspeakers called the Z-Line Series that seem to be interesting with their low X-Over point and the line source type. I've heard them in a tradeshow and they seem promising, with their controlled vertical dispersion(narrow) and their wide horizontal dispersion (good for home cinema, maybe even for studio monitoring) and the possibility to mont them flush wall.

They are not intended to be full range speakers but could be used alone depending of use(like in churches for voice amplification)

The bandwidth: 150Hz to 20Khz, sensitivity 90db/2.83 Vrms/1 m
Quite linear impedence curve: 6 ohms or 4 ohms depending on models
Power handling: between 125 and 375 Watts "continuous" (does it means long term RMS or short term RMS?)
Maximum SPL between 114 and 120 db.

Any comments?

get a look at : www.radiapro.com

NO! I'm not a dealer!!

OOps! I've checked the link and it is on maintenance!

Look later.

See there for summary: http://www.dinotech.com.hk/product/AV&C ... PS/rps.htm

Thanks!

My Cousin has these in his home theatre. They sound nice. Little lacking up top to me though. Might be his room.

Not sure how they will live in a studio.

Might be a great install for my new theatre. 1' for the rear surrounds.....

Bryan Giles

So what Mr Barefoot tthinks about theese one

Line arrays have some very attractive properties, but the there is one major problem. The physical size of the driver causes time smearing in the high frequencies. Let's take a typical example. The length L of the array is 1 meter and the listening distance dmin is 3 meters. So, dmin is the minimum distance from the listening position to a point on the line array - that being the center point. The maximum distance dmax occurs at the ends of the array. Using a little geometry we find:

dmax = sqrt(dmin^2 + (L/2)^2) = 3.0414 m

dmax - dmin = 0.0414m

Now we can calculate the delay corresponding to dmax - dmin.

delay = 0.0414 m ÷ 344 m/s = 0.12 msec

This difference in distance also corresponded to one wavelength at 8308Hz. So, the sound radiating from the ends of the array will be shifted by more than a wavelength relative to the sound radiating from the center of the array for all frequncies above 8308Hz.

This would present no problem if we were just listening to continuous sine waves. The resultant waveform simply sums to a flat response. Music, however, isn't just sine waves. Music contains a lot of short duration pulses. And a pulse emitted from any other point on the array will arrive slightly later than that emitted from the center. We can perceive these differences in arrival times. This is why line arrays tend to have a strange ethereal, almost reverberant quality to them.

The difference in arrival times can be reduced my moving far away from the array. To achieve the same SPL at the listening position, however, you need more power in the array. This defeats the whole point of having a large surface area moving very little.

From a purely performance perspective an outstanding solution is to build a concave array where all points on the array are equidistant from the listening position. This give all the benefits without any time smearing. Practically, however, it creates a very small focal sweet spot.

Hope this helps.

Thomas

That explains what I heard when I was in My cousins listening room. (The top end sounding funny or dull to me)

Bryan Giles

I forget what brand of speaker he had. But I do recall when fiddling around trying to improve the performance, the closer I got to the cabinets the crisper they sounded. If memory serves me he had a 5' tall unit pair that was mounted to a speaker cabinet with a LF driver.

Well expliained!

So that theory would be translated to near all large electroacoustic panels like Martin Logan, Stax, Beveridge, Magnepan and others (maybe except Quad ESL because of their time compensation/propagation)