New 15" full range - FANE

Thank you for your insights! Out of interest, would you expect this bump to be there too when the back were open (which is the case ATM)?

In this case it could be, as they are close to the wall so the small gap act like a very bad tuned port. If you put them further away from the wall, the bump will disappear, but so most of the lower bass (due to cancellation where the front and the backwave meet each other out of phase (like with all open baffle speakers)
 
Today I made the frames and finished 'boffling' one of the enclosures. Construction wise I am quite happy about how things turned out.

Unfortunately I'm almost certain I got the wrong fabric. Went for a carpet by the name felton. It didn't cost a lot but doesn't seem to be dense enough for this specific application. There's still quite a bit of sound coming out of the back of the speaker box, which as I understand it should have been more of a faint rumble.

Will do the other one with the felt underlay that I initially had in mind. Hopefully that works a bit better, and more like described in the original articles.

A very premature initial impression from listening to this one speaker is that this type of enclosure might have a tendency to take some of the life out of the speaker if this makes sense. It is still very early days and I am not at all done experimenting, but I can see myself eventually dropping boffle stereo console idea it all started with. Have I secretly been bitten by the OB bug when I played them boxless and got so delighted?
 

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I want to try that JBL diffusion slot that was shared.in another thread. It has a special shape to reduce some of the negatieve effects and should reduce beaming in at least part of the bandwidth. A 60x40 pattern is claimed, but I suspect that will not be at 15kHz. Worth a try though.
 
Do you make acoustic measurements?
Not yet, but certainly planning to!

Do you apply EQ?
At the moment, some. The Sony receiver has a rudimentary 3 band PEQ, allowing you to set gain and frequency, but not Q. Not sure if bands #1 and #3 are actually shelving filters. Can't seem to find any documentation on this.

Obviously at this stage I could also use a software EQ, should the Sony turn out to be really too limited.

The frequency response curve had a huge influence on sound character. I use my AV receiver with autoEQ for a quick equalisation.
That's amazing. To great effect if I recall correctly? I am secretly thinking of picking up a YPAO receiver, for their built in PEQs. An RME ADI-2 is on the end game wish list. One step at a time though. :)
 
I want to try that JBL diffusion slot that was shared.in another thread. It has a special shape to reduce some of the negatieve effects and should reduce beaming in at least part of the bandwidth. A 60x40 pattern is claimed, but I suspect that will not be at 15kHz. Worth a try though.
Saw that one too. I also read good things about a foam ring in front of the driver to improve dispersion. Rear mounted my Fanes to make room for this in advance.
 
I want to try that JBL diffusion slot that was shared.in another thread. It has a special shape to reduce some of the negatieve effects and should reduce beaming in at least part of the bandwidth. A 60x40 pattern is claimed, but I suspect that will not be at 15kHz. Worth a try though.

Very interested in any findings.

IMO the most problematic area is with the various resonances 1-8khz.
Two relaxed shelving filters (One low-ish to dampen and another up over 10khz to regain) and a few dip notches take care of most of it.
 
Nice!

What makes you want to open them up? Have you considered aperiodic vents?

I think with this small sealed volume (150l each for two drivers, 75 each) I feel like I’m holding back low end and introduce uneccessary heat to the coil with bass eq, especially after burning one it seems to be the case. Wondering if I can somehow increase the low end sensitivity so I don’t need to boost with eq but rather use a subsonic filter to protect over excursion. Sonically I need to buy an eq to tame the mids but was hoping to avoid eq boosting in the low end and rather achieve somewhat deeper bass and less booming midbass by opening up. Have no idea what size diameter or lengt would fit here though. 45Hz-50Hz tuning would be great. I’ve connected the drivers in series to see if the amp behaves a little better but not sure if 16 ohm is good for the amp? The sensitivity is definitely not a problem these play load with minimum gain even when serial connected. The amp doesn’t get as hot now so that must be a good sign. No melting coil smell either so far so good but sonically not perfect.
 
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I see.

Have you tried to model your question

inputs: fixed box dimensions, two drivers with given parameters, 45-50Hz tuning target
output: BR tube diameter/length

with software?

Also, your use case as I understand it, i.e. playing outside at driver-frying levels, does not appear to call for skimping on box size. Does it?

I vaguely remember having seen a simmed enclosure design (not Ivo's) that might be an interesting starting point, should you be open to letting go of the first two constraints. Might actually be somewhere in this thread. Will try and find it.
 
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A quick update.

Last night I finished the other box, now with the 6mm felt carpet underlay.

This seems to work a bit better. However I think I could still get a lot closer to Hartley's outcome if I had access to the stuff that he used himself. Which would be about 10mm felt on a burlap core. Maybe there are modern materials that would work even better. Carpet tiles? How does one in general suck up backwaves in 2021?

First listening impression, with essentially two different speakers, is that some of the magic is back again. So that's good. Some obvious flaws still remain, for instance quite a pronounced resonance with male voices. Expecting these (and more) to clearly appear in my first measurements.
 

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I see.

Have you tried to model your question

inputs: fixed box dimensions, two drivers with given parameters, 45-50Hz tuning target
output: BR tube diameter/length

with software?

Also, your use case as I understand it, i.e. playing outside at driver-frying levels, does not appear to call for skimping on box size. Does it?

I vaguely remember having seen a simmed enclosure design (not Ivo's) that might be an interesting starting point, should you be open to letting go of the first two constraints. Might actually be somewhere in this thread. Will try and find it.

I have not done any simulation for this design no, we designed it as a sealed box to limit xmax, achieve tight mid-bass and smooth roll-off to fit the primary user musical taste within classic rock, blues etc from the 70s and 80s where the need for the lowest few octaves are of less importance.

At first we made only one cabinet and wanted to keep the footprint at minimum but realized the next year we wanted to cover a larger outdoor area with sound and build another.

Id wish I made the baffle 10cm taller and the depth 10cm higher increasing volume from 150 to 240l, I'm sure that would allow us to not use any eq boost in the low end and only focus on mid-taming but there is no science which is more exact than hindsight we are not starting over but we have to option put some ports below.

Ill definitely install some software and play around as I'm building some other speakers now that I decided to port for the same reasons as above.

The frying of the driver might be an accident from some of the kids playing Drake, these drivers nor the current amp are built for that kind of music at the level we play 80s stuff.

People think that just because they are large they tolerate anything, they do not. If you see it moving from distance you are pushing its limits and I can hear it distorts easily. I guess the kids didn't know that but now they do. Good thing the drivers are cheap.
 
O no, I'm sorry to hear about the accident. Somewhere in this thread a couple of breaking in methods are mentioned from which I had the impression that the drivers are quite indestructable. Apparently not so. Good to know.

I hope you'll be able to find the required port dimensions. Most interested in your findings.
 
To get an idea of the effectiveness of the boffle concept, at least the way I executed it so far with the Fanes, I took one of the speakers outside and measured the response at its back side, in four configurations.

1) A totally empty boffle, just the naked wood and the driver
2) The first configuration but with the inside lined with carpet tiles
3) The second configuration with the addition of the frames with 'Felton' carpet
4) The second configuration with the addition of the frames with 6mm underfelt

Measurements were done on the backyard lawn, speaker placed on a 45cm high stool, mic centered at 20cm distance from the back side.

Attached the results. I am just posting this for the record, not at all because I believe I have achieved anything yet. In fact I highly doubt the boffle strategy is going to get me anywhere near this integrated media console I had in mind. Even if I would be able to increase its effectiveness considerably.
 

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Parking the boffle for the time being I went back to this configuration, but now with the drivers on their 47x47cm boffle baffles.

Then I took a three point in-room measurement, averaged them, and let REW generate a set of EQ filters for the attached target response. I know this is not the recommended way to do speaker/room EQ, but one has to start somewhere. Anyway I applied the filters in EQ APO, and played some music.

What I ended up with was a gorilla in a bell boy suit. The resulting sound was very polite and well-behaved. I added little bit of bass and treble, which helped somewhat. But as others have noted before, EQ-ing the magic out of these Fanes is quite easy. Even if the result would be more correct on paper and maybe even to the ears. A very interesting experience indeed.
 

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You could try stuffing the entire box with damping material. Absorb as much of that backwave as you can and make it more like a "normal" cardioid loudspeakers.

A sealed box, perhaps with a high pass filter, might do fineas well.

Why did you want to try out a boffle? Out of curiosity for the oldtech, or to achieve a special effect? I have built hornloudspeakers out of softboard, the brown wood fiber underfloor for laminate flooring. This has a strong absorption of frequencies above 200Hz. Maybe you can try this material for the internals of the boffle.