BillFitzmaurice.info

I'm curious if any one has phase traces of the DR line or Otop 12 ? If so feel free to pm me. I'm not starting this thread to get into an argument on the legitimacy of phase response! These speakers sound great, thats all that needs said. I'm only asking from place of personal academic curiosity. Any transfer function screen shots are appreciated!

I've never bothered with them myself, as you can't hear phase. It can be a problem if you mix different speakers within the same pass band, but the cure is just don't do that.

I took two comparative traces of my DR200s when I had them, one with ribbons and the other with piezo arrays. Spl is uncalibrated and measurement conditions were not precisely identical but you’ll get the idea.

And you don’t want to know what the unsmoothed Response of the melded arrays is.

Sorry guys. Truth is truth.

Thanks for the replies. That is not exactly what I expected, but it is exciting to see. What software are you using?

Also was there any EQ/x-over being used?

amcsc4 wrote: ↑Wed May 02, 2018 7:29 pm Thanks for the replies. That is not exactly what I expected, but it is exciting to see. What software are you using?

I believe that was done with REW. It was probably seven or eight years ago at this point (those attachmnets were uploaded in November 2011, so sometime before that) so I don’t remember too many of the details, except that it would have been done outside with the speaker and mic on poles at a distance.

CoronaOperator wrote:Also was there any EQ/x-over being used?

The piezo array may have been EQ corrected, I don’t remember. EQ does affect the phase response, but I do remember running at least one measurement with no EQ and the phase plot looked similar. With the piezo configuration, they would have had the 2008-09 era filters. The configuration with planars would have been without EQ and active crossovers, probably 48db LR at something like 2.5 kHz.

BrentEvans wrote: ↑Wed May 02, 2018 5:40 pm Sorry guys. Truth is truth.

There's nothing to be sorry about. You can't hear phase. You also can't hear response deviations at more than 1/6 octave resolution. That's why I don't even look at phase charts. If there's an issue with respect to phase in the crossover region it will show up on the response chart, if there's a response zit that can't be seen at 1/6 octave it's not a big deal.

Bill Fitzmaurice wrote: ↑Thu May 03, 2018 9:32 am There's nothing to be sorry about. You can't hear phase. You also can't hear response deviations at more than 1/6 octave resolution. That's why I don't even look at phase charts. If there's an issue with respect to phase in the crossover region it will show up on the response chart, if there's a response zit that can't be seen at 1/6 octave it's not a big deal.

You may not be able to hear such Response deviations tonally but they can cause other problems. I had far less feedback with planars than with the piezo arrays. I attribute that to the piezo arrays having a very jagged response that couldn’t be eq’d Away. I never had much of a problem getting them to sound good with either parametric or graphic EQ but in situations which require high gain microphones, like theater, choirs, performances with young kids, etc, the performance of the piezo arrays in regards to feedback control is far inferior to the planars, and to the compression drivers in my current rig.

I'd say that difference is due to the radiation pattern of the planars. Piezo arrays are more feedback resistant than single HF drivers, due to the radiation pattern. Even rudimentary line arrays like the Bose are more feedback resistant than point source cabs.

Respectfully,

Huh?

Planars have a much wider and smoother radiation pattern than the piezo arrays. There is almost no difference between on and off axis. If anything, MORE HF energy would have returned to the mics with the planars in the configuration they were deployed.

That aside, I ran some side by side tests while I was retrofitting the DRs and I can say with some assurance that the piezo arrays' jagged raw response is more to blame than radiation pattern. I basically took each cab let a driverack EQ it flat. Both cabs sounded pretty similar and measured pretty similar with smoothing. Without smoothing, the piezo arrays were much more jagged even after letting a driverack do its thing (this was with one of the ones that used graphic EQs to do the auto EQ, can't remember which one off the top of my head). I then pointed the cab at a microphone and let the driverack auto-feedback control work. I let it go until multiple frequencies were ringing out. That actually never really happened on the planar cab. It knocked out a few frequencies and stabilized. The piezo array cab rang out early and the driverack never stabilized it completely in that configuration.

Also, at one gig over two years of the same gig, with all other equipment the same, I was able to gain up the choir mics by about 6-10db with planars over the piezos. In fact, the poor feedback resistance at that show was what put me over the edge with the decision to replace the piezos with planars. I get even better results now with my commercial compression driver loaded rig (yes, the need to have branded hardware did eventually win out when I started losing higher profile shows).

Bill, you've said in the past that the piezo array was a cost consideration. I have no problem with that... but why is it that every time it comes up that other HF sections sound better and perform better that we always have to go back to defending them like they are a premium product?

BrentEvans wrote: ↑Thu May 03, 2018 9:51 pm why is it that every time it comes up that other HF sections sound better and perform better that we always have to go back to defending them like they are a premium product?

Because they're still better than point source horns.

Bill Fitzmaurice wrote: ↑Fri May 04, 2018 6:46 am Because they're still better than point source horns.

Better than anything in their cost class,for diy, I’ll give you. Better than ALl point source horns? I’ll take the point source horns in my rcf boxes for sound quality and feedback control on stage any day, and the pattern is plenty wide.

That said, all this is opinion.