[sfdoddsy]

A while back I did a simple OB for a bedroom system - a folded acrylic baffle, a Seas W22 and Seas 27TDFC.

It sounded very nice and played down to 60Hz at moderate levels.

Then, for various reasons, I sold my main Linkwitz Orion-based system which I had for ten years, and then their replacement (Apogee Duetta Sigs).

They were replaced with aesthetically nice and baby-safer Gershman Avantgardes.

But these fine speakers were missing something.

I think I'm addicted to OB/dipole sound.

So I've whipped up the most aesthetically cool yet good sounding OB I could think of.

Since I had them on hand, I started with a BG Neo3 run dipole, BG Neo10 and Peerless SLS10 in a tapered acrylic baffle. Although with EQ they are flat to below 40Hz, the idea is to run them down to 80Hz and then cross to a pair of monopole Rythmik subs. Crossover and EQ is with a MiniDSP at 300 and 3000.

The CNC guys cut it wrong, but it still sounded very nice. Possibly better than the Gershmans and at around the same level as my Orions.

However I was unsure about the Neo3s. They seemed a little 'tizzy' up top.

So now I've gone to the infamous Raal 70-10, Neo10 and SLS in the correct-sized slimmer folded baffle.

The idea is to not make the baffle heroically thick and rigid, but simply hold the drivers at the correct height. So it does wobble back and forth if nudged, but at a frequency so low it isn't worth bothering with. Much like you'd get if you hung the baffle from the ceiling.

Gaskets decouple each driver from the baffle to a degree. The SLS is at floor level for extra output and to avoid the Allison effect.

Not wired up yet as I'm still trying to work out the best way of temporarily hooking up the Raals. They have no binding posts and hence must be soldered. Which is really annoying if yu're not sure if you'll keep them. They don't even mark + or - on the terminals.

The difference between the dipole Neo3s and monopole Raals will be interesting, but I have highish hopes.

Otherwise it will be LX521s.

[Guy 13]

Hi sfdoddsy and all Audio Circle members.
Not easy to remeber and spell your nick name,
I am afraid to ask the meaning of it.
Who bent the base of the acrylic baffle?
Nice and interesting looking baffle.
The mid and hi drivers to me don't look at the right angle,
shooting to high, maybe.

Guy 13

[sfdoddsy]

The baffles were bent by the acrylic supplier, who also did the CNC cutting.

There is a tilt back. This was for stability, but also comes close to aligning the drivers, although this wasn't a priority.

The acoustic center is only 85cm high because I slump whilst listening. The mid and tweets do fire slightly upwards, but with the Neo3 test baffle the vertical dispersion was just fine.

I'll see how the Raal handles this.

[nickd]

Nice Build!

Not sure why you did not like the Neo3 in OB? It might be a crossover or amplifier issue. They also like a bit of a wave guide in the front baffle at the side of the diaphragm (not really needed top and bottom). The RAAL is a bit easier to just "bolt on" in that regard. Having lived with a couple of designs using the Neo3, "Tizzy" is not typical. Something was going wrong there?

The look is way cool. I might have the fabricator cut out some braces to install along the sides of the woofer to stiffen things up a bit and reinforce low frequency's. I don't know what epoxy they use to bond that stuff, but the joints on fish tanks don't look bad at all.

[sfdoddsy]

'Tizzy' is probably the wrong word. 'Excessively airy' might be more apt.

On the other hand the Raals sound rather subdued in comparison.

I suspect this is the difference between dipole and monopole tweeters.

[Poultrygeist]

Very nice!

Were the back covers removed from the Neo 3?

[walkern]

I've tried the NEO 3 in dipole and monopole configurations, and I noticed that I much preferred the monopole.  I too felt that there was an excess of treble energy when the NEO 3 was used as a dipole.  There are 'back cups' you can get for the NEO 3 that will convert it to monopole (and they are fairly cheap), just in case you want to give that a try.

Neil

[scorpion]

I certainly like the looks of your speakers. And the sound will be very satisfying, no doubt.

Myself, I have used Neo10 together with Neo3W and there is no treble rise with the W-model.
All Neo3s come with a back cup that has to be removed for dipole use. The PDR-models have a
bit more wide sound spread but seem to have an issue at least in dipole use with a peak in the treble band around 7 kHz.

Run with AE IB15 I have found the Neo10, Neo3W combination producing an OB-sound absolutly exellent.

/Erling

[Rudolf]

The PDR-models have a
bit more wide sound spread but seem to have an issue at least in dipole use with a peak in the treble band around 7 kHz.

This is the 0°-90° response of the "nude" dipole Neo3 PDR in 10° steps:



Never ever try to equalise that 7 kHz dip to "flat" in the on-axis response. I'm tempted to make it even deeper  . The response will even out at the listening distance, because the dip disappears off-axis. 

Rudolf

[sfdoddsy]

I've done a bit more experimenting and adjusted the levels properly comparing between the Neo3 in the new narrower baffle and the Raals.

Now I'm undecided. The Raals sound a bit smoother and mellower, but there is a certain 'liveness' to the dipole tweeters which I find enticing.

[sfdoddsy]

Very nice!

Were the back covers removed from the Neo 3?

Yes. I think they sound better that way.

[Juhazi]

When the tweeter radiates bidirectionally, reflections from front wall, ceiling, side walls elevate decay response spl. This is why when the midranges is dipole, a monopole tweeter sounds attenuated despite it may measure flat.

If a open-back Neo3 sounds too bright, you should add something absorbtive to attenuate backwards radiation. Other trick is to make dispersion narrower backwards. With twin tweeters the backside can be attenuated with a series resistor.

Here is My AINO gradient with and without rear tweeter. After this v2 I added a resistor to attenuate back tweeter some 6dB.

[AJinFLA]

Then, for various reasons, I sold my main Linkwitz Orion-based system which I had for ten years, and then their replacement (Apogee Duetta Sigs).
They were replaced with aesthetically nice and baby-safer Gershman Avantgardes.
But these fine speakers were missing something.

I was going to suggest having your hearing checked. Whew.

I've done a bit more experimenting and adjusted the levels properly comparing between the Neo3 in the new narrower baffle and the Raals.
Now I'm undecided. The Raals sound a bit smoother and mellower, but there is a certain 'liveness' to the dipole tweeters which I find enticing.

Steve, have your hearing checked immediately!!!

Btw, nice acrylic baffles 
Project looks good. Do any baffle sims?

cheers,

AJ

[sfdoddsy]

Yes, I know it is heretical to not instantly fall for the lure of a pair of Raals, but whilst I think they are probably a better tweeter, I'm not 100% sure they are a better tweeter in my application.

I'm pondering a dipole AMT as well. The dipole Raal is too wide for what I'm trying out.

I did a few sims, but basically had an idea of what I wanted to try. The narrowing baffle certainly models better, looks better and sounds quite nice.