Which drivers for my next open baffles?

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Moondog55

Moondog55

diyAudio Member
Joined 2007
Just looked at the Eminence Beta 8, little hot on the top-end but otherwise OK, I'd cross a little higher 120/150.
Simon the last 3 speakers I've built have been OB using 8inch mids ( because it's a common cheap driver in old 2-way boxes ) and 8inch does seem to be the way to go, crossed anyold how to a tweeter about 2.5/5K.
What cost the Beta 8 in the UK??
 
SimontY

SimontY

Member
Joined 2003
diymediahome.org
LineArray said:
Hi,

i edited my post above ...

I had good experience in using a passive line
level crossover, circumventing those big caps.

You need separated power amps then for LF and HF.

Maybe the equaliser for the CSS could be integrated
into the Passive Line Level XO, omitting all those passive
components between power amp and speaker ...

Would be a new solution, which i have not seen here
so far...

Cheers
Click to expand...

A valid idea no doubt, however I honestly don't have rack space for even one more amp! I'm in a tiny little room. I might look to active x-o later, when I've worked out how to shoe-horn more amps in!!!

Simon
 
SimontY

SimontY

Member
Joined 2003
diymediahome.org
LineArray said:
If you are using a single driver of the FR125 size (4.5")
with a cutoff below 100Hz, the dynamic headroom of your
speaker will be very limited. Even if you choose a 2. Order
highpass.

If you want your speaker to be able to reproduce material
different from "vivaldi as background music for dinner"
you need either a higher cutoff frequency or more displacement
volume.

With XO under 100 Hz displacement volume is essential for
your fullranger especially if you choose a narrow baffle.

IMO you can forget about using a small sized fullranger with
small Xmax, with a XO that low. I know what i am talking about,
since i use 6 of the FR 125 per side ...
Click to expand...

I currently use just 100uF or 150uF in series with my midrange driver to save it from the bass. Am I just not bothered by the distortions that you suggest must be occurring? Perhaps I don't listen loud enough - often enough - to notice.

Nevertheless you seem to know your onions and I'll accept that this is not the way to do things.

Perhaps another learning speaker is in order before anything more "ultimate" :D

Simon
 
Moondog55

Moondog55

diyAudio Member
Joined 2007
Just my $0.02, but second order on the mid is probably going to sound a bit cleaner, I usually work on XO frequency or components until midrange stops pumping - therefore reducing Doppler distortion I guess, mid-range really shouldn't be handling too much of the bass.
Then again I have to admit to using a lot of first order on the woofers but I do that more for economy reasons when not Bi-amping.w
I took a recommendation from David Weems book, when doing the bandpass calculating the mid frequency spread for slightly less than the low/ high cut-offs.

So if the low cuts out at 150 and the highs come in at 3000, then bandpass is ~ 200 / 2700.
No overlap
 
SimontY

SimontY

Member
Joined 2003
diymediahome.org
panomaniac said:
For an 8" mid, I'd still go with the Beta 8A. Great driver, great price.

Depending on your baffle size, you should be able to use just a small inductor on it. In the 0.3-0.5 range just to flatten it and mate it to a tweeter at about 6K. Easy...
Click to expand...

That sounds pleasingly easy to use and the size of this mid seems appropriate.


Moondog55 said:
Just looked at the Eminence Beta 8, little hot on the top-end but otherwise OK, I'd cross a little higher 120/150.
Simon the last 3 speakers I've built have been OB using 8inch mids ( because it's a common cheap driver in old 2-way boxes ) and 8inch does seem to be the way to go, crossed anyold how to a tweeter about 2.5/5K.
What cost the Beta 8 in the UK??
Click to expand...

It looks like it costs about £30 or so apiece, so it's very affordable. I'm looking into it now :D

Simon
 
SimontY

SimontY

Member
Joined 2003
diymediahome.org
Moondog55 said:
Just my $0.02, but second order on the mid is probably going to sound a bit cleaner, I usually work on XO frequency or components until midrange stops pumping - therefore reducing Doppler distortion I guess, mid-range really shouldn't be handling too much of the bass.
Then again I have to admit to using a lot of first order on the woofers but I do that more for economy reasons when not Bi-amping.w
I took a recommendation from David Weems book, when doing the bandpass calculating the mid frequency spread for slightly less than the low/ high cut-offs.

So if the low cuts out at 150 and the highs come in at 3000, then bandpass is ~ 200 / 2700.
No overlap
Click to expand...

That is interesting, I will bear this all in mind. By the way I did try 2nd order in my speakers for bass AND mids. It simply didn't work, it sounded awful. The tone was completely out - piano and vocals sounded shocking!!!

I think I need drivers that need less work to begin with to be honest, then 2nd order may be able to sing.

Thanks
Simon
 
SimontY

SimontY

Member
Joined 2003
diymediahome.org
I've been looking at various PA woofers and not many seem to meet the required criteria:

* Enough XMAX
* 12" diameter
* Medium-high Qts
* Low Fs

For now it seems 2nd hand Celestion 12" woofers from the Ditton range are a good bet.

I looked at Eminence Alpha but the FS of the 12" is nothing special, nor is the xmax! The 15 is the treat there!

I wonder if I can somehow SQUEEZE a 15" woofer in, and taper the baffle above there, so it's not overly intrusive...

Then I could be looking at something like:

* Tweeter
* Eminence Beta 8 (or 8A)
* Eminence Alpha 12
* Eminence Aplha 15

In this arrangement I'd probably only run the Alpha 15s on T-bass. I'd hope the 12" would help to bridge any perceived differences between an 8" and 15".

I suspect this array would please Mr Maynard as it avoids rubber or foam surround drivers, uses a fairly large mid driver and might have reasonable output.

Simon
 
SimontY

SimontY

Member
Joined 2003
diymediahome.org
As further progression to my previous post I am thinking out loud:

* Do I want a 15" AND a 12"?
* 1 x 15" has greater radiating area than 4 x 7"
* 2 x 12" (e.g. Eminence Beta 12LTA) have a nice, big area

I suspect 15 + 12 would be the best as it would minimise excursion and distortion, and I think would smooth out some irregularities and mate to the 8" Beta a bit better.

Amazon.co.uk sells ("resells") all of these drivers, cheaply!

Simon
 
Pano

Pano

Administrator
Joined 2004
Paid Member
Moondog55 said:
Just looked at the Eminence Beta 8, little hot on the top-end/B]
Click to expand...


Not to worry - it's sounds very balanced indeed with just a coil to flatten it. Then pick it up about 6K with the tweeter.


SimontY said:
I'd hope the 12" would help to bridge any perceived differences between an 8" and 15".
Click to expand...

I can't see why you'd need it. There will not be much difference between the 15 and the 8 in the crossover region. The 12 will only complicate the crossover - and your life. :p You don't need it.
 
Pano

Pano

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Joined 2004
Paid Member
Beta 8A

Hey Simon - I looked at the uK links you posted. Does not seem to be the same driver I'm talking about.

see the Beta 8A on the Eminence page.

You'll notice the small dust cap and the odd purple color of the cone. That's the driver I heard and liked so much.

But it's not the only 8" midrange in the world, so you may find as good or better in the UK.
 
SimontY

SimontY

Member
Joined 2003
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I noticed big differences too, but look at the Amazon one:
http://www.amazon.co.uk/Eminence-Be...3?ie=UTF8&s=electronics&qid=1227038269&sr=8-3

Looks correct!!

Now then, thanks for setting my mind at ease WRT 12+15. So can we agree on 2 x 12" Eminence Alpha / Beta?

My only gripe is the mediocre Fs of 48hz.

Beta 12A-2, 12CX or 12LTA have slightly lower Fs.... (so the Beta on Amazon should be fine.)

http://www.eminence.com/standard.asp?speaker_size=12

I think we're narrowing things down nicely now.

Thanks,
Simon
 
Pano

Pano

Administrator
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SimontY said:
I noticed big differences too, but look at the Amazon one:[
Click to expand...

Andy: "I want that one!"
Lou: "Are you sure?"
Andy: "That one!"

Yeah, that's it. Pretty good price, too.

What do you want to do with the 12s? Thought you were going 15...

The APT tweeter is loved by some, liked by others. I haven't heard it.
 
Gary P

Gary P

Member
Joined 2002
pimmlabs.com
Yep, the Amazon Beta 8 looks like the correct one. And a good price too.

A tweeter to look at is the . Hi-Vi RT8-II. It has the sensitivity to match the Beta 8.

Here's a pic of the current damped U-Baffle system using 2 Beta 8 bass/mids and the RT8-II tweeter. Upper Beta 8 runs full range and the lower Beta 8 is used for bass fill. The subs have 2 Dayton IB15 drivers in them.
An externally hosted image should be here but it was not working when we last tested it.


The Subs now have damped 16" extensions out the back that were not installed when this pic was taken.

Edit:
Oops, Panomaniac beat me to commenting on the amazon link...
 
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