Open baffle: Big fullrange vs small fullrange and baffle

[hedphones]

I see these two types being as common in open baffle speakers.

For an example let's take Eminence 12LTA, vs 4" driver such as a Fostex FE103, then placed in a big baffle, for example 20" x 20".

People say that bigger drivers give natural dynamics, then in the other hand, smaller drivers tend to be more linear and have better high freqs.

If I was making an open baffle speaker, and didn't need output below 200hz, which one should I choose? What should I be looking for?

 

[Godzilla]

Something in between.

Just kidding.

If you don't need output below 200Hz you can go smaller. On a 20" x 20" baffle you should hit 200Hz with a Fostex 103 or at least come very close.

 

[rjbond3rd]

In general, smaller does a better job on upper midrange and treble. (There are some expensive exceptions.) The driver gets more dynamic as it becomes a midrange or midrange/tweeter (rather than "fullrange" playing bass).

But if it's dynamics you want, widebanders aren't really the top choice (nothing can compete with compression drivers for that, but widebanders can often win on "tone" on certain music, and if you're not listening to orchestral, then dynamics may not even be relevant, as most non-orchestral recordings aren't very dynamic compared to Stravinsky, Wagner, Rimsky-Korsakov etc.)

 

[Juhazi]

Different baffle and driver layouts can easily be evaluated in The Edge Simulator Home of the Edge

Wtih dipoles, baffle effects are of huge importance and it is necessary to understand what each factor contribute (width, shape, driver position, driver width etc.) Here is good learning material auf Deutsch Dipolplus - Alles über offene Schallwände

 

[planet10]

then placed in a big baffle, for example 20" x 20"

That is not a big baffle.

If you want an OB with bass, a big bass driver + a small FR IMO is the route to go. You still end up with a baffle larger than 20x20

Martin King's passive baffle is a good example (we did this with Alpha15 + FF85KeN).

We have, at diyFEST gotten good results with a big baffle with a smallish driver. That was with an unobtainium 6.5" Korean AlNiCo driver designed for OB on a shared baffle 1.2m tall, and over 5m wide (totally impractical for domestic use)

dave

 

[wesayso]

If I was making an open baffle speaker, and didn't need output below 200hz, which one should I choose? What should I be looking for?

That is not a big baffle.

If you want an OB with bass, a big bass driver + a small FR IMO is the route to go. You still end up with a baffle larger than 20x20

dave

Looks to me he's not asking/looking for a lot of bass out of the OB speaker?

 

[xrk971]

If you only need 200Hz and want good dynamics, a great driver with excellent sensitivity, clean sound, good polar dispersion, and great sound is the PRV 5MR450NDY. It has an fs of 175Hz and in a suitably wide baffle can probably reach 200Hz before roll-off. it is large enough and has huge reserves (250 watt max power handling if high passed appropriately) that the dynamic range is outstanding for the size.

More info here:

http://www.diyaudio.com/forums/full-range/259293-prv-5mr450-ndy-fast-applications.html

Note that a 20in wide baffle will have falloff due to OB effects starting at 400Hz - you will have a hard time getting a solid 200Hz with any driver - unless you use wings, or have a partial H-frame box, etc.

 

[hedphones]

That PRV looks hella good driver. I would buy it if it was more easily available.

I'm currently using a pair of Philips AD7080 drivers (high qts, 105fs) in open baffle crossed over to sub at ~100-150hz.

Bought them from a thrift store yesterday. They sound pretty damn good. I'm listening in nearfield, and my amp seems to rarely exceed 2 watts during normal listening. But sometimes I like to crank it up. The philips seem to bottom out very fast.

I'm going to buy some serious fullrange drivers to replace these, but I can't decide which size of a driver to go with.

The reason why I want to try OB speakers at all is because I tend to get alot of bass problems with my monitors in this room. OB is more directive in the bass, thus less room problems.

 

[xrk971]

OB doesn't like to be to close to walls. You need a good 3 ft from a wall for it to work well, preferably a little more. Just make sure you are not using them as speakers set right against a wall due to space reasons. If space is an issue I would go with a wall mount speaker. There are some flat wall mount back loaded horns as well as MLTL's available to try.

 

[hedphones]

I could mount my genelecs on the wall too, but that would make the bass response even more ****** up.

I think some kind of cardioid enclosure would be nicest. Hard to make?

Or maybe I just build a pair of small fullrange 3-4" desktop monitors, to be accompanied with a dipole sub from 200 or 400hz down.

 

[xrk971]

What is your physical speaker mounting constraint/arrangement? For desktop, I have found that a small 0.4x scale Karlsonator works very well, as well as a DCR with a Vifa TC9FD. All these approaches can utilize a small slot loaded band pass sub in the corner to fill the room with sub 100Hz bass.

http://www.diyaudio.com/forums/full-range/239338-mini-karlsonator-0-53x-dual-tc9fds-16.html#post3722988

http://www.diyaudio.com/forums/full-range/252627-viva-la-vifa-curvy-cabinet-dcr-tc9fd.html

http://www.diyaudio.com/forums/subwoofers/258433-light-air-slot-loaded-band-pass-sub.html

 

[hedphones]

General idea what i'm trying to make. I want to try open baffle for cheap price and elimination of enclosure resonance. Also the bass will be more natural since it's not bouncing around the room as much as boxed speaker.

I have a pair of studio monitors but they won't just work in my room due to bass problems..

The idea of the thread was to discuss what is the difference between a small fullrange placed in baffle vs a big driver such as 8-12".

Currently using a 12" sub in 80 liter enclosure, with a 100watt plate amp which contains hi pass and lo pass filters at 150hz.

An externally hosted image should be here but it was not working when we last tested it.

 

[xrk971]

This is a desktop application with a nearby back wall. I would recommend the 0.40x Karlsonator for this. I just upgraded my 0.40x Karlsonator from a 85dB Vifa TC9FD to a 91dB Faital Pro 3FE25 last night and it sounds excellent. The 3FE25 is an excellent driver with very nice highs and a great smooth midrange. It has bass down to 90Hz in open space (70Hz near a wall/floor), and should work well with your sub. It works well near a back wall and will have more bass down to 100Hz than any reasonably sized OB you can place on your desk. Plus it is compact for desktop use. The K aperture provides a wider more uniform polar response than you would have with a bare faced driver.

Here is the measured response:

Here is the harmonic distortion:

Here is a sound clip (no sub, no EQ, driven full range by a TPA3116D2 amp from CD player):

http://www.diyaudio.com/forums/attachments/full-range/439063d1411026705-mini-karlsonator-0-53x-dual-tc9fds-3fe25-karlsonator-0.40x.zip

Very easy to build...

 

[hedphones]

What is the meaning of the odd shaped baffle in front of the driver? btw that freq response looks pretty sick for a cheap 3" driver.

 

[xrk971]

What is the meaning of the odd shaped baffle in front of the driver? btw that freq response looks pretty sick for a cheap 3" driver.

Thanks, the response is rather nice for such a tiny driver. It really fills up the room quite nicely at a good sound level.

The Karlson aperture is meant to prevent a hard edged boundary condition so that multiple wavelengths can terminate without sharp resonances. There is a lot of material in the Karlson thread or Speaker that Kicks Butt in Large Spaces thread. Job Ulfman does a good job summarizing it here: The Karlson Homepage

 

[hedphones]

Thanks I'll give it a read later.

 

[hedphones]

https://www.youtube.com/watch?v=MRY7v3ktq_4&feature=youtu.be

I uploaded a video of my 22RH's just for fun. Damn they sound good..