surround with Visaton FRS8, measurements and design.

[ßart West-VL.]

Hello,

I played around with some measuring on the 14 FRS8 drivers I have laying in storage for way to long.
10 of them will be used for 5 enclosures.
These aren't high end drivers and the only thing I want to do is try and pull the SPL up a bit, starting at 80hz. I'm thinking bass reflex?

Around 3.2khz there is a rise in response that needs to be suppressed at least 6dB (I think...) starting at 2khz until about 6khz
I really could use some help with the filter!
The impedance at 3.2khz is 9.5Ω

Pics taking while 'braking in' the small drivers at 5V with brown noise and the setup for measurement, 10cm (4") distance to mic.

Are there other things to consider?
There is one driver that surprised me; a huge sharp narrow dip at 15830hz, what can cause this? (orange curve)

Thanks.
Bart.

[chris661]

For surround, I'd consider spreading the 4 extra drivers around, maybe have 4 drivers on the front L/R, and 2 in the rest.

You won't need to worry much about the rising response to ~3kHz - remember that you measured them with no baffle or cabinet, so dipole cancellation will occur below 3kHz, resulting in much reduced output (as is seen in the graph).

[ßart West-VL.]

Nice idea on the extra drivers for the front L/R!
But then I'm down to 8Ω again. Still beneficial? Is it as simple as putting the front L/R at +3dB?

In the graph I see a drop in respons from 3khz on up too, that does let me worry a bit.
When measuring at 1cm, the peak is there too

Thanks.

[ßart West-VL.]

Quick measurement, two drivers, 1/6 oct. smoothing.

Thanks for watching.

[ßart West-VL.]

Suggestions on the notch filter? anyone?

A simple bass reflex box would be nice to pull up the 80hz region but I see the box becomes quite large for two and even larger for four drivers
Closed box is the best option but then it doesn't reach as low as I want.
What's the best compromise?

[xrk971]

I don't know what application you plan on using the drivers for but the FRS8 would work well in a smaller cornu spiral. That will definitely boost the bass to even out the high freq response end.

[ßart West-VL.]

It's for home theatre, so the size shouldn't be to large or preferably slim, height is not a big concern.
Could The Needle, Bushhorn, FH3, etc. be adapted to house two or even four FRS8's?

[xrk971]

I think someone is building a set of 5 cornus for HT, citing the slimness of the cabinets (circa 3 to 4 inches) and how they are wall mounted so they don't take up any space in the HT room floor space.

[ßart West-VL.]

In my room that will not work well and I can't point them to a certain direction just because of the wall mounting, flat on the wall.
The placement of the TV is not optimal so I'll have to be able to point the boxes in certain directions.
And I will use two drivers in the enclosures, probably four in the front L/R.
I don't think it can be done in existing small tapped horn's like a Needle...?

[Barleywater]

Target enclosure should be built/mocked up and driver measured mounted for crossover/EQ determination. IMO, 1/6th octave smoothing hides too much detail.