Seas FA22RCZ full range project

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borispm

borispm

Member
Joined 2010
Pano said:
OK, I'll "Spill the Beans"

The reason the measurements that Marcus took in his lounge look so much better than the factory graphs is - Application.

The factory FR shows a big high end rise that is typical of many FR drivers. But the measurements we showed were done at the listening position, and Open Baffle. Seas probably did their measurements on a big standard baffle, too - but they show only the front radiation at 1 meter from the driver.

Once you get back into the room a bit and start getting sound off the front and the back of the driver, things start to balance out. There isn't as much HF getting to you off the back, so the balance starts to tip away from the rising HF. Or in other words, the sound off the back of the driver fills in the mids to come up to the level of the highs. In this case, almost perfectly filling in.

As you might guess, this would not work in a box speaker because the rear radiation is (almost) completely contained in the box. You don't get the blend off the back of the driver.

My friend John Busch has also been working with this driver and has found the same thing. It does not need a series inductor to tame the top end when used open baffle. John found this out by listening to it, then the measurements in London confirmed it. It's a great driver.
Click to expand...

But wouldn't the rear radiating wave cancel out part of the mids too? I wonder. I suspect it has more to do with the close miking measurement done by Seas.
 
B

Barbieboy

Member
Joined 2010
Pano said:
OK, I'll "Spill the Beans"

The reason the measurements that Marcus took in his lounge look so much better than the factory graphs is - Application.

The factory FR shows a big high end rise that is typical of many FR drivers. But the measurements we showed were done at the listening position, and Open Baffle. Seas probably did their measurements on a big standard baffle, too - but they show only the front radiation at 1 meter from the driver.

Once you get back into the room a bit and start getting sound off the front and the back of the driver, things start to balance out. There isn't as much HF getting to you off the back, so the balance starts to tip away from the rising HF. Or in other words, the sound off the back of the driver fills in the mids to come up to the level of the highs. In this case, almost perfectly filling in.

As you might guess, this would not work in a box speaker because the rear radiation is (almost) completely contained in the box. You don't get the blend off the back of the driver.

My friend John Busch has also been working with this driver and has found the same thing. It does not need a series inductor to tame the top end when used open baffle. John found this out by listening to it, then the measurements in London confirmed it. It's a great driver.
Click to expand...

Thanks for this, makes sense. Sooo if SEAS were to make say a 15" FR (Or is 8" as big as FR's go ? and not sure kitchen draws come that size ;) then we would all be happy - OB / Full range / xoverless.
Does look like single driver heaven is in the form of a horned enclosure, but misses the whole point of OB for the very reasons you just pointed out.
 
Pano

Pano

Administrator
Joined 2004
Paid Member
borispm said:
But wouldn't the rear radiating wave cancel out part of the mids too?
Click to expand...

Yes, it does. Some. But in a real room setting not enough to matter. It seems that with this driver the balance works out pretty well. Getting back a few meters does help.

Marcus. You're not likely to get a 12" FR that will work well. 8" is a practical limit. Altec did make "Biflex" 12" and 15" fullrange drivers. The 412C and 415C. They sound much better with a tweeter, believe me. ;)
 
borispm

borispm

Member
Joined 2010
Pano said:
Yes, it does. Some. But in a real room setting not enough to matter. It seems that with this driver the balance works out pretty well. Getting back a few meters does help.

Marcus. You're not likely to get a 12" FR that will work well. 8" is a practical limit. Altec did make "Biflex" 12" and 15" fullrange drivers. The 412C and 415C. They sound much better with a tweeter, believe me. ;)
Click to expand...

Thanks, that encourages me to make a pair of desktop dipole speakers!

I suspect the Biflex don't have much output above 12kHz!
 
Godzilla

Godzilla

Member
Joined 2005
speakerprojects.wordpress.com
>>> Take it you prefer two 12"s to the one 15"

The 'drawer' speaker is great! Thanks for sharing! I have been thinking about using two 12" drivers for bass in an OB setup with full ranger on top. Currently using a single 15" but thinking about reducing the footprint.

Personally, at the moment, i believe full range on an open baffle with bass support is the best way to go for sound quality at home. All of the projects in my mind are based around this concept lately. EVERY type of box speaker seems like a compromise to me now after living with OB... i still enjoy box type speakers (love my BIB back horns!) but OBs offer more ghostlike realism and produce wider and deeper soundstages. And with full range drivers you get very good efficiency too. I've got a pair of Fostex 168s and TB 1808s boxed and unused... at least one set will end up on an ob of sorts (with bass support). Very enjoyable sound!
 
Pano

Pano

Administrator
Joined 2004
Paid Member
The SB Acoustics 10" drivers are very nice. For a box. But not great for open baffle, not great at all.

You could do 2X12 or even 15". It needed be expensive. Even taking a loss on the SBs, you should be able to get new woofers for what you out of selling the SBs. Or keep them if you want to to a box speaker.

What are the places in the UK where you can buy raw drivers? Something equivalent to Parts Express or MCM here.
 
B

Barbieboy

Member
Joined 2010
Hi Pano,

I think best I ditch those 10"s and opt for some 12s. Over here we have some places to source them from:

Europe Audio - Home page

Speaker Repair, Speaker Kits, Loudspeaker Repair, Kits and Drive Units, Subwoofer Amplifier Kit

Loudspeaker Design| Loudspeaker Drive Units| Loudspeaker Measurement, Restoration, Repair Services

for xover components and coils etc:

amplifier valve kits, HIFI pre-amplifiers, speaker kits,AMP Parts, upgrade components

Or what about using miniDSP:

Home | miniDSP
 
B

Barbieboy

Member
Joined 2010
Nisbeth

Nisbeth

Member
Joined 2001
theslowdiyer.wordpress.com/
I have a pair of FA22's lying around and I am considering putting them in the enclosure that Seas recommends in the app. note for the F8 as I like the proportions of that better than the one in the app. note for the FA22. Are there any problems with this? Volume is roughly the same and since I'd expect to be playing with the notch filter values anyway I expect that would compensate for the changed baffle width as well?

/U.
 
B

Barbieboy

Member
Joined 2010
Pano said:
You could do 2X12 or even 15". It needed be expensive. Even taking a loss on the SBs, you should be able to get new woofers for what you out of selling the SBs. Or keep them if you want to to a box speaker.

What are the places in the UK where you can buy raw drivers? Something equivalent to Parts Express or MCM here.
Click to expand...

I have found the 12" that JoniR here uses, not cheap when need x4:

Peerless 830669 Sub-woofer
 
J

JoniR

Member
Joined 2006
piiras.net
Barbieboy said:
I have found the 12" that JoniR here uses, not cheap when need x4:

Peerless 830669 Sub-woofer
Click to expand...

I think that price is very similar than price in Finland. If I understand correctly that price is also include shipping, so they are no so expensive after all.
I don't know the situation on UK, but in Finland these drivers are very popular and used elements are very easy to find from other DIY'ers for half of price.

Br, Joni
 
Z

zig zak

Member
Joined 2011
Nisbeth said:
I have a pair of FA22's lying around and I am considering putting them in the enclosure that Seas recommends in the app. note for the F8 as I like the proportions of that better than the one in the app. note for the FA22. Are there any problems with this? Volume is roughly the same and since I'd expect to be playing with the notch filter values anyway I expect that would compensate for the changed baffle width as well?

/U.
Click to expand...
Hallo Nisbeth I got FA22 in 230mm x 1000mm , 150mm center from top :cool:
And the response is on the picture :
Blue on axis
Red 15* off axis
 

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