Another speaker thread

[Vangelo]

Nick, Vic sent me a link to a thread which may be of interest if you haven’t seen it already-

https://www.diyaudio.com/forums/full-ra ... sures.html

Great, another long thread to digest

Indeed, I started reading it but lost the will to live. Maybe we should form a company that outsources reading of long articles and provides a summary. Bit like Gartner claim to do but never do.

I only pointed this thread out to Ali because there was discussion here on foam baffles. What there were doing with foam on this DIY thread was intrigueing....especially Mattes's foam flower design suspended from the ceiling!

[simon]

Indeed, I started reading it but lost the will to live. Maybe we should form a company that outsources reading of long articles and provides a summary. Bit like Gartner claim to do but never do.

Like so many things, pages and pages could be condensed in to a relatively pithy summary. If only.

[simon]

It's only been in the past few years with the rise of inexpensive digital EQ and class D amplifiers that things like this have become more practical -you could do it before, but the power was more expensive & relatively fewer people had access to (or the skill to design) active EQ systems / circuits of sufficient capability.

Yes, I was thinking in terms of Ed''s 95 years as a whole really.

[simon]

Thanks for contributing Vic. Everything you and Ali say is very compelling! If I do end up down the DSP road this is at the top of my list.

I'm interested that you've tried the AE Dipole 18 (I think?) They look to be ideal for OB but they're not cheap. What did you make of them?

Hi Simon

Look great on paper....but I found them delicate and weak. Fall into the light cone fabric surround category...93db 150W. I bottomed them out easy.
I gather they are great at crossing high, but mine are tucked into a corner gathering dust. Also, AE dont publish a Frequency Response graph. Be nice to know roll off.....but then again, the high QTS was too cuddly for me. I prefer a lower QTS driver that will take eq to give some control.

Thanks Vic, that's great experience. They're not cheap either so a bit of a relief .

Both the UM15 and UM18 model as well as anything I've tried in Basta...

[simon]

How high up do you roll off the UM18s Vic?

[Vangelo]

How high up do you roll off the UM18s Vic?

The crossover depends on the full range I am using. Most of the naked drivers need to cross around 275hz.
Currently I am using sealed box Strada 2's which are crossing @ 120Hz.

[simon]

Thanks.

How are you finding the sealed boxes after naked fullrangers?

[Vangelo]

The Stradas are quite unique and display alot of the open baffle/naked characteristics.
They use mechanical crossover and capacitor to protect tweeter, so not a lot of electronics in the way. They are over 90db efficient too.

Being sealed units means they produce more bass than OB units, but the main thing is there is no hardness to the sound in the 1-4khz region. All the other FR drive units suffered from this and needed eq to tame. Congested rock was very unpleasant to listen to. Now I can listen to everything!

My only issue is I cheated as I did not make this myself

[chris661]

This is my experience and happy to answer any q’s! Cheers, Vic

Question: Do you apply EQ by ear, or with measurements?

If the latter, do you have any curves you could share?

TIA,
Chris

[simon]

The Stradas are quite unique and display alot of the open baffle/naked characteristics.

Are you preferring them to other fullrangers with a baffle? Lots of questions, sorry.

[Vangelo]

This is my experience and happy to answer any q’s! Cheers, Vic

Question: Do you apply EQ by ear, or with measurements?

If the latter, do you have any curves you could share?

TIA,
Chris

Chris, I usually eq by ear. I was curious with the Gallo Stradas to see how they voiced them. Here is a graph comparing Gallos vs EMS Field coils.



Eq has been applied to EMS to compensate for roll-off and throttle back the 1-4k region. Gallos are stock. There is a natural occurring dip on the Gallos from 2-6k which I find favourable and normally would eq the FR's similarly. The treble rise is not a problem.
I would say the raggedness of the EMS above 2k is typical of all the FR's I tested and maybe why the Gallos just sound so good.
With the DEXQ, I have played with getting a perfectly flat frequency response. Sounds pretty horrible in real life and tuning by ear always gives me a dip.

[Vangelo]

The Stradas are quite unique and display alot of the open baffle/naked characteristics.

Are you preferring them to other fullrangers with a baffle? Lots of questions, sorry.

Yes....maybe partly explained by graph I posted.

[simon]

Thanks Vic

[simon]

So I'm thinking the way forward, initially at least, is to try a large pro driver to see how it works in my room and how low it goes. On the basis that bigger is better for OB I looked for drivers with Fs below 40Hz and Qts above 0.5. The intention is to use them in a H frame, and according to Martin King's paper on OB, U and H frames the H frame usefully lowers the Fs.

There aren't many drivers that fulfil these criteria. None at 21", fortunately as they're expensive, and only a handful of 18". There doesn't look to be much to choose between them when modelled in Basta, these are the main contenders, plus the smaller SB Acoustics

Not exactly cheap. I'd never heard of Precision Devices until I started this, but it turns out they're located about half a mile from my office. Fane are located about 100m from PD.

But I keep coming back to the SB Acoustics driver built for OB. This is a plot it and the Beyma.

But this is a plot of the two but with room gain enabled and with a second order LP filter (400Hz for the Beyma and 250Hz for the SB).

[simon]

(Post split because of issues uploading photos)

So I haven't used any science in the room gain, just enabled what it calls an average room. The "OBness" of the SB Acoustics driver is evident and looks much more suitable for a passive OB. These are approximate roll offs of the two drivers.

The negatives - I'm taking some liberties with Basta, actual performance is not likely to be the same, could be better or worse. And the SB Acoustics drivers are 16ohms which isn't ideal. I think the intension is to use two per side for an 8ohm load which would be much better for the class D amps I'm using, for now anyway. But that brings the cost up to over £600. Falcon Acoustics don't list this version so unless they can import it I'd be looking at Europe which I don't particularly want to do right now.

And none of this indicates how they actually sound.

Decisions, decisions. I'm out of my experience zone so would be really grateful for thoughts on this.