Fertin project - calling all open baffle experts

[bcherry]

Originally posted by Steve Eddy


The effective baffle size is larger than your dimensions would suggest seeing as it's a folded baffle. It's effective size is more akin to a flat baffle measuring 37" x 38". Hell, slap one more side on it and it's infinitely large.

se

OK, so extrapolating here: If I extend the top/bottom/sides 30cm 90deg towards the back wall, then I could expect a little more bass heft with no downside? Given the 60 x 200cm baffle, how much would I have to extend from the edges to get down to a clean 70hz?

How about placement for open baffles? They image like crazy no matter where I stand off axis. So far placement seems to have more affect on R-L channel balance. The golden ratio system doesn't seem to work.

Brian

[planet10]

Originally posted by bcherry
OK, so extrapolating here: If I extend the top/bottom/sides 30cm 90deg towards the back wall, then I could expect a little more bass heft with no downside?

The downside is that the cavity caused by the sides causes a tincan resonance. Unequal length sides helps.

dave

[Peter Daniel]

It all depends on aesthetics. I wanted my open baffle speakers to look nice and not too big (or rathe wide ), that's why folded enclosure for woofer. The baffles are sloped so less resonances I hope. I also think that sloped pedestal has something to do with the bass response (took it from Wilson WAMMs), because although I'm not using any low frequency correction circuits, the response is down to 25Hz without a problem. Open baffle produces the best bass you can get.

A friend of mine wa so impressed with the look of mine design, that he took out the drivers of his cheap 3 way system and built enclosure similar to mine, placing his drivers there. He said that they sounded way better.

[roddyama]

Peter,

“My point is that the size of a baffle doesn't really have to be big. No frequency correction was required.”

I sure you’re getting the bass you say you’re getting, I just don’t see how you’re avoiding the cancellation below 100Hz.

One of the problems in trying to analyze a speaker’s bass output is that the wavelengths are so long that you can’t ignore the room interaction. In the final analysis, the placement of the woofer in relation to room boundaries will always have to be considered. This is even more true with an open back system.

Rodd Yamas***a

[Peter Daniel]

And this is what matters. The speakers would probably not produce much below 100Hz in different invironment, but I design them for my room and I'm quite happy with their response there. Should I ask for more, or complicate things when it's not needed?

I also have to point out than since their creation in 1996 I used them in 3 different rooms and results (or measurements) were always similar.

[dice45]

All,

before i started my open baffle thing (i also have a pair of Fertin FLB20EX) i tried out several speakers in open baffle mode and alway got results much more pleasant and open and detailed to my ears compared to enclosure operation. I also got way more bass than i expected. Subjectively. This is self-delusion. The brain reconstructs the base wave from the harmonics.

I talked to several acquaintants who had tried out open baffle, all seconded this opinion. Measured: there is not much below 100Hz for an open baffle of, say, 160cm wide, 200 cm high.
Subjective perception is quite another matter. One of my buddies finally built an open baffle woofer, EQed and going down to 25Hz. Now this is bass, he reported, before this was a fake.

And this is what i do with my Fertins: i have them in a folded open baffle of 100cm width (effective width is more) and 175cm height. Part of this baffle is an open-baffle subwoofer having two Beyma 18"ers mounted; this subwoofer is the pedestal on which the Fertin's open baffle is mounted. The subwoofer pedestal has a baffle inside which is 25° tilted against level and carrying the 2 woofers. The two woofers are fed by a 100W AKSA amp having the necessary EQ at the input.
The Fertin is fed by a tiny PP tube amp.

One warning: the Fertin has to be mounted by it's magnet, oops, fieldcoil motor. The basket it too weak to carry the huge motor.

Fertin sonics:
Break-in time is considerable. But already from the start the Fertin was by far the best FR driver i ever heard. They are simply seductive.
Highly Recommmended. Who trusts me on the MKVs should trust me on the Fertins. I rate the Fertins as i rate my Koetsu Urushi phono cartridge:
.. i must be starving before i sell it.

[bcherry]

Originally posted by planet10


The downside is that the cavity caused by the sides causes a tincan resonance. Unequal length sides helps.

dave

So what if I tilt the baffles back 5 degrees but mount the drivers so they are canted 5 degrees so they're still firing straight into the room?

Brian

[bcherry]

Originally posted by dice45
All,


One warning: the Fertin has to be mounted by it's magnet, oops, fieldcoil motor. The basket it too weak to carry the huge motor.

.. i must be starving before i sell it.

Really? Thanks for the tip, but the basket segments are thick steel and the whole unit is 8 kg. The basket doesn't seem overstressed. Is that based on the German dealer's experiences? Do you have a picture of the mounting you used?

Brian

[Peter Daniel]

Originally posted by bcherry


Do you have a picture of the mounting you used?

You'll find a good example of it here: http://www.linkwitzlab.com/m_panel.htm

Linkwitz is one of the recent pioneers of open baffle speakers.

[Peter Daniel]

Originally posted by bcherry


So what if I tilt the baffles back 5 degrees but mount the drivers so they are canted 5 degrees so they're still firing straight into the room?

Are you talking about woofers here? (and not Fertins)