Ultimate Open Baffle Gallery

Here's my latest creation.
Fountek Neo CD2.0 - 5" ribbon tweeter (front)
Fountek Neo CD3.0 - 3" ribbon tweeter (back)
PHL Audio 3451 - 10" midrange
PHL Audio 5410 - 15" bass

All drivers have high efficiency, and I need to attenuate the bass and mid quite moderately even though the tweeter is 98dB.

Passive crossover between tweeter and midrange. No highpass on the mid (yet). The woofer is digitally crossed and adjusted for the room via an old miniDSP 2x4 but not dipole adjusted as I don't really find it necessary, it plays a lot of clean, low distortion bass down to below 30Hz.
 

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Put it, it will improve the sound, reducing distortion.

Yes, that's the plan (hence the "yet").
Low distortion is really nice to have, and I agree with you, it could be lower even more. Due to the high efficiency, 98dB (after attenuation), and a small room i don't think I feed the MIDs with more than perhaps 10W or something (I should probably measure this).
 
Finally got my OB's done - dual Eminence Alpha 15" and a Tang Band 5" W5 2143, miniDSP HD with Harsch XO (currently at 200 Hz but playing around up to 270 Hz). Amplification is via Emotiva XPA-5 but am now considering some low watt tubes amps.

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The soundstage is much wider with better placement of instruments, the presence of vocals is bigger than my previous "boxes" and the music is so more engaging.

Many thanks to all who replied via this forum and the advice from the Quarter-Wave Yahoo group run by Martin !
 

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Nice to see your setup finalized.

After playing around, you decided to keep using Harsch, eh? Glad you like it.

I just don't know about the low watts amps... those dual Aplhas might get power starved.

Look around. There are plenty of amps that provide the warmth of tubes, but with some grunt behind them to push big woofers happily.
 
After playing around, you decided to keep using Harsch, eh? Glad you like it.

I just don't know about the low watts amps... those dual Aplhas might get power starved.

Look around. There are plenty of amps that provide the warmth of tubes, but with some grunt behind them to push big woofers happily.

I must admit - the Harsch sounds best. My only doubt is the miniDSP only has one option for Bessel but looking at the curve it emulates I think its a 2nd order which is what is required. I tried emulating that with LR + BW and the relevant delay but it doesn't come out as clean.

These work great for driving woofers

Mmmmm - I think I will stay away from tinkering with voltage. I had a little scary moment with my amp going into protection mode and I thought we overcooked the right full ranger as the soldering tabs are tiny and we had a few goes at doing that. Turns out it was a grounding issue in the RCA's that worked fine in another system. If you can share the details of your build I'll take a look at the complexity and reconsider my courage levels !

jklow888, those look great! Would you share a picture of the back of the speaker? I’d like to see how you are supporting the baffle. Looks like you have come up with a simple and clean solution. In addition, have you considered powering the Alpha’s with their own amp and the TBs with their own amp? That’s what I would do.


The back and feet were modeled on the Spatial M-series - I'm sure many will say its not sturdy enough/brace it etc but I didn't want to go that route and my wife wanted a clean look/not ugly/no massive box behind it etc. The baffle is 43 mm thick made of lamellas so strong yet flexible to avoid warping that you get in a solid sheet of timber - I'm happy with the sound and its better than my boxes ! The feet are solid aluminium with two countersunk holes and then I use two M6 60 mm screws to couple each foot to the base which has a 5 mm notch to keep the foot from rotating. Each foot has two tapped thread holes for spikes which then allow me to set the baffle face to perpendicular given the minor tolerances on the feet cut outs. Wiring is run through each driver rebate with the main 6 core sheath going round the bottom woofer and exiting by the bottom woofers 2nd lowest re-inforcing rib:

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Amplification - I do intend to bi-amp low and high separately. Of course cost is a factor with tube amps and this project has take a fair amount of time and money (but worth the exercise). The Emotiva XPA-5 has plenty power as a starting point but the higher efficiency and something in the front area of the room is now revealing a DC hum which is irritating in silent passages. I have a Jolida hybrid that does 75W which I think should be plenty for the woofers given no passive xover components in the way so am thinking of a Glow One for the full rangers or some other locally built tube amp around 6-8 watts. If the Jolida is not enough for the woofers then I will look at a SS amp that is quieter than my Emotiva.
 

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I must admit - the Harsch sounds best. My only doubt is the miniDSP only has one option for Bessel but looking at the curve it emulates I think its a 2nd order which is what is required. I tried emulating that with LR + BW and the relevant delay but it doesn't come out as clean.

Now, next step is to not rely on the miniDSP own curves, but make your own.
Especially since XSim now includes a PEQ and export of biquads into the miniDSP, you can trim the FR and woofers response to follow the real curve used in a Harsch and gain even more clean sound.

The Emotiva XPA-5 has plenty power as a starting point but the higher efficiency and something in the front area of the room is now revealing a DC hum which is irritating in silent passages.

That DC hum is probably some other units on the same supply. Anything from ceiling lights (neons and LED often introduce noise into the electric feed) to fans, etc.... There are products out there that will help isolate these issues.
 
Narrow open baffle (kind of)

Here is the latest result of my pursuit of a narrow OB with plenty of low bass. Four ten inch woofers working in tandem, i.e. not pressurizing the space between them. Eight inch Faital coax on top.
Steel frame with dual layers on front and back baffles, with absorbing material constrained in between.
Mostly fourth order passive filters. Sensitivity around 86 dB, but very amplifier friendly impedance and phase angles.
What stands out most is the very natural transition between bass and midrange, the unforced liveliness, dynamics and articulation of the bass and that it easily goes down into the mid 30 Hz range (-6dB @ 34 Hz rel. 200 Hz)
oido audio
 

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Here is the latest result of my pursuit of a narrow OB with plenty of low bass. Four ten inch woofers working in tandem, i.e. not pressurizing the space between them. Eight inch Faital coax on top.
Steel frame with dual layers on front and back baffles, with absorbing material constrained in between.
Mostly fourth order passive filters. Sensitivity around 86 dB, but very amplifier friendly impedance and phase angles.
What stands out most is the very natural transition between bass and midrange, the unforced liveliness, dynamics and articulation of the bass and that it easily goes down into the mid 30 Hz range (-6dB @ 34 Hz rel. 200 Hz)
oido audio

Very nice work and design. Could you tell us more about the drivers you used? From the pictures we can see that the middle woofesr are different that bottoms.
 
Thank you matejsirk. The top pair of woofers are highish qts (0.55 if I remember correctly)and fairly low fs. They have very nice attack, but limited low frequency (below 40hz) output. Bottom pair are higher qts, lower fs drivers made for ob and go much deeper but not with the same snap. Together they create a wonderful combination of both:)
 
Me, too. I went to Onkens with dual 15" each, to get some wallop out of a 300B set.
Far nicer bass than a sub woofer.

They have 511B horns in again, but I'll be trying either 12P or 12PW open baffles augmented by these soon.

Hi "lowmass" and "MITsound",

The Faital 15PR400 are in the running-in process and I can state they are definitely an improvement over the Alpha-15A. They go deeper and sound very linear till the midrange frequency band. In the moment I have them with a first order low-pass with a single inductor (0.82 mH) and they produce a clean and full body sound.

I attach an image of the rear of my "test bench" baffles. One day in the future I'll give them a definite shape. For the time being, I'll only enjoy it.
 

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The Faital 15PR400 are in the running-in process and I can state they are definitely an improvement over the Alpha-15A. They go deeper and sound very linear till the midrange frequency band. In the moment I have them with a first order low-pass with a single inductor (0.82 mH) and they produce a clean and full body sound.

Yes, they are great! I've chosen them as midbass for my next OB. Don't see the time to start em.
 
How can the 15pr400 work in open baffle with a qts around 0.32? Are you using active lf equalization?

It works really well down to about 50hz, passive. I have simulated with Basta several dozens of drivers for this task and the 15pr400 is my favourite. I'm gonna use a pair, though. And then equalized subs below that.
The 15FH520 has 0,40 Qts and could go a bit lower. But without subs I would choose a 18". Faital pro makes a very nice one (which I have simulated as well)

Edit: I remembered wrong, I'm gonna use a pair of 18Sound 15W500, but the Faitals (both of them) aren't a bad choice either.
 
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