[Guy 13]

Hi JohnR and all Audio Circle members.
Nice looking for a prototype.
So, when will we have listening impressions ?

Guy 13

What's that black round thing at the bottom,
look like dumbel.
(Not sure of the spelling, you know the exercise weights.) 

[JohnR]

What's that black round thing at the bottom,
look like dumbel.

Hi Guy, yep They stop the baffle from falling on its face. I didn't want to put anything on the front of the panel, so this is what I ended up with.

Probably be a few more days before I'm able to get them playing.

There'll be separate dipole subs.

[SteveFord]

This has been more than a few days.
Are you going to keep us in suspense?

[studiotech]

This has been more than a few days.
Are you going to keep us in suspense?

+1

[JohnR]

I've been learning a few things. I put up some technical notes here:

  http://johnr.hifizine.com/2012/12/electro-static-mini-panel/

The main thing is learning how to deal with a tweeter this size...! But it's sounding pretty good.

[medium jim]

JohnR:

Welcome back...Nice article...I wish I had the space and tools to go for it! BTW, it looks pretty impressive as well, bet it sounds even better.  I've always wanted to check out a full on Infinite Baffle & Open Baffle systems.  I got a chance to hear some Lowthers that were rather interesting.

Jim

[studiotech]

Thanks for the info John.  Could you tell us a little more about the build quality of the panel?  Maybe some close-up photos?

Greg

[JohnR]

I'll get some photos in a few days. The panels are plastic, somewhere I read that this gives them better tolerance at reduced cost. There's some insulating tape folded around the edge (wood is not a good insulator) that wants to straighten itself out but once the panel is in a frame it won't. You need to not overdo it if de/resoldering to the terminals. Not really sure what else to remark on wrt build quality... ? I don't feel there is anything to worry/complain about. Oh, the high voltage units are potted.

[josh358]

I've been learning a few things. I put up some technical notes here:

  http://johnr.hifizine.com/2012/12/electro-static-mini-panel/

The main thing is learning how to deal with a tweeter this size...! But it's sounding pretty good.

Thanks, interesting measurements. Looks like they'd be quite usable as midranges for a Tympani IVa (crossovers about 300 Hz and 3k), though they may be too wide for the stock slot (the Neo-8's fit right in).

[JohnR]

Hm, they're quite a bit wider than Neo8s - 167mm, almost double.

[josh358]

Alas, I saw that. So it would require some butchery or a new frame. Ideally, I'd like to get the tweeter and mid closer together than they are -- apparently the reason they aren't has to do with the rigor of shipping rather than acoustics -- but realistically, I don't see how I'd find time for the project.

Still, it does look pretty ideal in the midrange and would probably beat the Neo's, good as they are. And I've seen the 2" ribbon projects on DIY audio, way too ambitious. Have you made a waterfall? I'm also curious too about maximum output levels, though I imagine you wouldn't want to risk arcing by pushing them.

[JohnR]

Have you made a waterfall?

No, but I just tried one in Fuzzmeasure and am not getting a sensible result. I'll look into it but I might need to remeasure with REW. However the parameters will affect the graph, do you have an example that you're looking to compare to?

I'm also curious too about maximum output levels, though I imagine you wouldn't want to risk arcing by pushing them.

Don't quote me on it but I recall that Rob said they won't arc because the stators are insulated. So my guess is they would just buzz. If we knew how far the diaphragm can travel we could make a guess at output level vs frequency.

[tnargs]

... But it's sounding pretty good.

John do you have a parametric EQ to hand? try this: 2700Hz, -7dB, Q 0.8; and 15000Hz, -6dB, Q 0.5. It's a rough mirror of the published FR.

Transformed mine from a bit etched to ooooh....

The above gain values could be cut up to 50% to retain a bit of treble lift for some situations.

[Ohverture]

Hey all, I posted this in another thread on Stereonet, in case it looks familiar to anyone.

I'm the grease monkey (aka engineer) doing the tests on the panels. I find John's results a little bit startling, as not only do our results not match his, but the curves he's getting in no way matches what the panel actually sounds like. We certainly aren't getting that boost in the lower frequencies, nor the fall off at the top end.
I can say for certain that room modes definitely make a difference to the tests, and simple changes in the direction of the speakers / mic in an anechoic situation can make a world of difference in the plot.

Our test setup is as follows:
We're doing all our measuring at 192 kHz 24 bit, using the professional hardware/software combination of Liberty Instruments Praxis audio, and a calibrated microphone, The sound card is the ESI Juli@.
The Praxis Audpod is calibrated extensively before use.

All tests are done in a semi-anechoic room to better simulate a listening environment. This is also going to make the effect of a dipole speaker more sensitive to the room's composition.
We measure with chirp responses, slow sweeps, and sometimes we do RTA plots using pink noise as it's the closest to music in terms of energy content. While I have a number of different plot results, and the one on the website was chosen to best reflect what we heard when we actually listened to it, I'm still at a bit of a loss to explain John's results. Perhaps the test setup / equipment could be different in nature somehow?

Edit: Oh, we use these panels in a prototype bookshelf system that we listen to every day, and it's not EQ'd at all, and sounds clear and without any emphasis or loss at any particular frequency. And believe me, if there was a problem I'd speak up, that's one of the reasons my nickname at work is "The Bitch" - because I bitch about the smallest problems.

Cheers
~David

[JohnR]

I find John's results a little bit startling, as not only do our results not match his

Hi David, perhaps you could post some curves then? I was going to ask tnargs where he found some published, but since you're here perhaps you could post them (with the measurement conditions)?

We certainly aren't getting that boost in the lower frequencies,

You must be referring to the dipole peak around 500 Hz. Those curves are simulations, the actual measurements I posted didn't go down that low. The location and shape of the dipole peak varies with the width and shape of the baffle and is just a consequence of the baffle geometry.

simple changes in the direction of the speakers / mic in an anechoic situation can make a world of difference in the plot.

Yes, and I posted curves measured at several (small) angles.

Actually, I'm actually not clear what you're saying at all, to be honest I feel that you haven't really read or understood my blog post. If you could post some actual data instead of just trying to discredit mine, I'm sure everyone would appreciate that.

[tnargs]

Hi guys,

The curves are published on the website (who would have thought?  )

http://www.eraudio.com.au/Mini_Panels/mini_panels.html

That is the curve my EQ is drawn from.

[chucky3042]

Hi

I am Davids partner and a co designer of the panels.

For a clearer look at the curves go to the attached pdf at the bottom of this web page.

http://www.involveaudio.com/products/electrostatic-panel-evaluation-kit

Regards

Charlie

[chucky3042]

Hi

Looks like that link is down - I will complain to our web person and have it back mid week.

Regards

charlie

[JohnR]

The curves are published on the website (who would have thought?  )

http://www.eraudio.com.au/Mini_Panels/mini_panels.html

Oh, that one. I was hoping for something with a bit more detail. I puzzled over that graph, and had assumed that it was of the panel in a completed speaker like the Liquid Base, but it's not. Here's a comparison of the published:



.. and one of mine:



As you can see, the overall features are pretty similar, although there's some variation above 10 k which could easily be due to mic position. The plot I'm showing there is a smoothed (1/6 octave) nearfield measurement - that is, with the mic 5 cm (IIRC) from the panel. So it seems likely that the published one is taken under similar conditions.

Transformed mine from a bit etched to ooooh....

How are yours set up? (distance from walls and floor, on a desk or shelf, mounted on a baffle, etc)

[JohnR]

So, a minor update. I have gone from a 3-way down to a 2-way i.e. the bass/mid shown in my prototype pic is not being used. On the main baffle is the mini-panel and a separate baffle holds a dipole woofer (12" for now).

I've also learned a few things, and in a discussion with Rob from ER Audio he's given me a couple of hints that have had me thinking about my approach. So I've got a new design in my head now.

The bad part of this is that I have to build another baffle! That's why you make prototypes eh. They served their purpose though, to enable me to try some things and take measurements to better understand the panel.