DR280's....from 2" comp drivers to cheap piezo's......

[DAVID_L_PERRY]

edit:- since adding the throat filler and filter component retrofit, the eq curve is considerably smoother than shown below. When I get chance I will update the photo.

I have been a happy fence sitter since joining this forum regarding the use of piezo's in a high quality PA tops....I much prefer the comfort of proper traditional high cost/quality compression drivers...simple

During the build of my DR290's I tried out a small piezo array as a simple trial using the DR290 as a bass cab so it became a DR280 effectively...For bass it sounded stunning. I have owned and used a large number of top of the range bass manufacturers and this cab sounded great.

I am very happy with my DR290 PA tops, so decided to build a pair of DR280's with 12bank piezo array for my bass backline. This weekend I fired the DR280's up as part of my PA just to see how the DR280's would fair up against the DR290's.

Bearing in mind that my DR290's are bi amped and have a pair of meaty JBL2416 1" sompression drivers in each cab for the HF, I allready knew that the output of the 12 super cheap £1.50 piezos in my DR280's would be ok but could not possibly compare to the HF output of my DR290's....

Having allready gone through some major eq trials/testing on my DR290's I was well ahead of the game when it came to sorting out the polarity/phase settup of the subs/tops and also knew the sort of main EQ curve I would expect to require. Using the Auto EQ on the Behringer ultradrive works very well to obtain a fairly flat response. As I have said many times before, EQ is absolutley imperitive to get the most out of these cabs.

So, I set them up side by side(DR280/DR290), eq'd them to give a fairly flat response, and sat back to listen....

EQ setup using pink noise as a reference with measurement mic at approx 4m on axis crossed over at 80hz. Once eq'd the RTA response is fairly flat.



My mind keeps telling me It cant be true.....Clearly I knew the low mid range element would be the same as its the same woofer section....but how can these 12 crappy little plastic bits of cheap rubbish piezo's sound that good....no something must be wrong with my DR290's....check the crossover....No they still sound great....back to the DR280's.....Yes, they actually sound just as loud...just as clear...

Ok lets put one of my Audix OM 7 vocal microphones (outstanding vocal mic) through the cabs and do the same A/B test of the DR290/280...

Ok the DR290's sound great....The DR280's sound....no, this cant be right, they sound better, smoother....This is silly

OK...I have just leapt off the fence with a resounding slam of my feet on the ground.

I am going to be using my DR280's as Pa tops at my next gig, rip out the expensive JBL 1" horns from my DR290's, sell them, buy some more piezo's....(I still cant believe It even as I am writing this)......and change my DR290 into DR280's.......

This has been a massive learning curve for me....I know many people have kept telling me the piezo's are great, but I am the sort of person that needs to try something for myself before I can comment...now I can.

Before building the DR290's I was using a pair of dedicated mid/high tops loaded with JBL2020HPL 12" drivers and 2" compresion drivers bi-amped and digitally crossed over....I am now going to be using some ludicrously cheap drivers in cabs with no internal or external crossover, and get a better sound, carry less weight......oh wait a minute, thats exactly what Bill said would happen when I first stumbled on this site....



Follow on review at war volume:-

I went down to my usual test hall to try out the DR280's at war volume alongside the DR290's. I have a couple of PA pals coming down who have been at all of my previous DR290 trials.

As well as CD playback we will be setting up a vocal mic and acoustic for one of the guys to wail along while we listen. I am looking forward to their faces after hearing the cheap piezo's....

Just as a frame of reference, all three of us present at the trials of the DR290's and these DR280's have owned and operated PA systems well above the range of the standard Peavey hysis/sp2 box on sticks....but we are all still weekend warriors

I had all 4 of my DR's up and running A/B ing the DR290 against the DR280's. Re checked the EQ - very similar to the one I listed on the EQ page but with some minor adjustment for the different room.

First we listened to the DR290 single cab ,then the DR280 single cab..
Both sounded great...but Quite simply the output from the DR280 was fantastic. The clarity of the top end from the piezo array was superb...Two of the guys who came down with me both own very good Pa systems (HK and Concert Systems gear). My previous two Pa systems have been large active 3 way Concert systems PA's with 2" compresion drivers. All of us where simply blown away with the clarity and smoothness of the top end once eq'd...

I then plugged in the second DR280 stacked vertically and re-eq'd. The resultant eq curve was very similar but a little less adjustment required.
http://www.frappr.com/?a=viewphoto&id=1 ... myphotos=1
I did adjust a couple of freqs to smoothe out the curve....sounded superb Not a single glitch.

One less amp to carry, and profit to be made in selling the JBL 1" horns from my DR290's and replace with the CPC piezo's.

In a word...awesome

One of the PA guys used to work in high end HIFI sales. After the tests and while talking about the piezo's being so cheap, I kept grinning and saying I dont get how it can sound so good, it makes no sense, he simply said audio doesnt have to make sense, just sound good....

Dave Perry

[Bill Fitzmaurice]

One of the PA guys used to work in high end HIFI sales. After the tests and while talking about the piezo's being so cheap, I kept grinning and saying I dont get how it can sound so good, it makes no sense, he simply said audio doesnt have to make sense, just sound good....

Dave Perry

The technology we're utilizing with our piezo arrays is over 30 years old, and the theory behind it is over 60 years old. The only question unanswered is 'why didn't someone think of doing this before now?'

[Alan Star]

Ok the DR290's sound great....The DR280's sound....no, this cant be right, they sound better, smoother....This is silly

This begs the question ... is it possible to get the dr's that use comp drivers to sound as good as the dr's using piezos ?

[Dave Non-Zero]

Ok the DR290's sound great....The DR280's sound....no, this cant be right, they sound better, smoother....This is silly

This begs the question ... is it possible to get the dr's that use comp drivers to sound as good as the dr's using piezos ?

And this begs the question...why bother!

[Alan Star]

Why bother using comp drivers ?

a) because I already have a pair of dr300 cabs

b) because I need a long throw top box that goes down to 80hz

[Dave Non-Zero]

Ahh.. dr300s. i was assuming the dr280/290 debate. apologies.

[Alan Star]

no worries at all

edit: for simplicity's sake as well ... if I could use piezos in the 300's I probably would

[gdougherty]

To answer the question about can the CD's sound as good, I'd answer, "I doubt it." My understanding is that the piezo to CD comparison is like a dynamic to condenser comparison. Both can sound good and a top-notch dynamic can sound very good, but no matter how you EQ it, the dynamic mic will never have the faithfulness of a condenser mic. The capsules work in two different ways with two similar though different results on the mics and the two HF drivers do the same.

[Bill Fitzmaurice]

To answer the question about can the CD's sound as good, I'd answer, "I doubt it."

Agreed, as a CD horn is a conglomeration of compromises. A horn being wider than it is high runs counter to basic audio engineering concepts, and while one can force this square peg into a round hole you're much better off to just build the horn the way it wants to be, which is vertically aligned. But don't confuse a CD horn with a compression driver. On the smaller DRs small compression driver loaded horns cut and glued into vertical arrays could work just as well as piezos, but since doing so would cost at least five times as much there's no advantage. DR300 can't use piezo drivers because there are no piezo drivers that will work to 1.2kHz with +105dB sensitivity, and since the HF section must go to 1.2kHz a grouping of small short horns won't work either. OTOH, the HF horn section of the DR300 is not significantly different from the HF horns of the vast majority of commercial large format line array cabinets, nor does it perform any differently.

[gdougherty]

So I got the answer correct, but for the wrong reason

[Bill Fitzmaurice]

JBL line array cab w/two vertically aligned HF horns:


The HF section isn't much different from that in the DR300.

[Mark Coward]

JBL line array cab w/two vertically aligned HF horns:


The HF section isn't much different from that in the DR300.

I've noticed several similar line array designs which use two horizontally oriented LF drivers and HF in the middle. Does this not introduce comb filtering?

[Bill Fitzmaurice]

I've noticed several similar line array designs which use two horizontally oriented LF drivers and HF in the middle. Does this not introduce comb filtering?

Not if the outboard LF drivers are within 1/4 wavelength of each other, which is why these JBLs, for instance, cross the woofers to the midranges at 300 Hz.

[bgavin]

If so, then an electric bass 4x10 could cross over to a vertical stack at 300 Hz, and also not suffer comb filtering issues.

[Bill Fitzmaurice]

If so, then an electric bass 4x10 could cross over to a vertical stack at 300 Hz, and also not suffer comb filtering issues.

With the spacing in a 4x10 it could cross as high as 1kHz or so no problem. But since the electric bass cab companies apparantly don't employ audio engineers they cross at 3 to 5 kHz, if at all.