DF of 700 is very high. I didn’t know it was that high but probably because amp uses a dozen MOSFETs in parallel so output impedance is that of single pair divided by number of outputs. That is great though.
Very cool. Can you tell me the part number on that MOSFET puck? IXYS I assume? I would like to know what the RDson value is. Would be 11mOhm if DF is 700. DF=Spkr_Imped/Amp_Imped
Amp_Imped=Spkr_Imped/DF=8ohms/700=11mOhm.
Amp_Imped=Spkr_Imped/DF=8ohms/700=11mOhm.
I must comment, this speaker simply continues to impress. Such a great design. All the imaging qualities of OB, but actually has bass and 92 dB efficiency. Use of unique bass design allows a relatively small baffle, with plenty of bass.
All the best compromises. Someone really had their thinking hat on with this one!
All the best compromises. Someone really had their thinking hat on with this one!
I have a question about a dipole, I had such years ago.
I want to build new, using goldwood 18 inchers, 3 pieces for one box. For
netehrlands I use the devine 18 inches, who looks the same, these speakers
have high qts of 1.1. Your dipoles do let rise qts when chamber
get calculated? Maybe these high qts 18 inchers are not usable.
This system do allow making them small,, the 18 inches have a lot of displacement
who is needed for these systems.
But now the question itself, what is better, 3 big woofers or many small ones?, Maybe
because of bandwidth usable,, you had use it to 470 hz before the trap, the big 18
inches do lower because the dipole is bigger.
Thanks for advice.
I want to build new, using goldwood 18 inchers, 3 pieces for one box. For
netehrlands I use the devine 18 inches, who looks the same, these speakers
have high qts of 1.1. Your dipoles do let rise qts when chamber
get calculated? Maybe these high qts 18 inchers are not usable.
This system do allow making them small,, the 18 inches have a lot of displacement
who is needed for these systems.
But now the question itself, what is better, 3 big woofers or many small ones?, Maybe
because of bandwidth usable,, you had use it to 470 hz before the trap, the big 18
inches do lower because the dipole is bigger.
Thanks for advice.
A manifold with 18" drivers won't work up to 470Hz. If the drivers are up to it you could do a shallow U or H baffle.
THanks, Yes I will use a speaker who get 150 hz easely, This is by the way a dipole, I do not
now if this is qua bass better or even.
But very nice project of author here.
now if this is qua bass better or even.
But very nice project of author here.
He, Yes I did know, the speakers are much better, the kind of system is not a problem, but the bass needs to be as beutifull als
a ripole or depole. Maybe a ripole is a option, these are also quite compact, I do not reach 470 hz but that is not a problem,
125 hz is also oke. But I need to see what and how it will turns out with 18 inchers, Otherwise I need small 6 or 8 inches ones
and a lot more,.
I have by the way the Martin J. King sheets, I did buy these some years ago, I can again play with it to calculate.
http://www.quarter-wave.com/OBs/U_and_H_Frames.pdf
Here I see ripoles, the slot can be made small even with big speakers.
https://www.audiocircle.com/index.php?topic=92003.0
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Hi, need some advice.
Had plans to build just the sub-part with 8x8PR per side but dont want to get too high. Let`s say max 50-60cm.
Will there be problems to build it more like ”cutting” them in half and putting them side by side on the floor?
Thanks!
Want to use it with my tobs:
Had plans to build just the sub-part with 8x8PR per side but dont want to get too high. Let`s say max 50-60cm.
Will there be problems to build it more like ”cutting” them in half and putting them side by side on the floor?
Thanks!
Want to use it with my tobs:
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Side by side is fine, you could even have two chambers sharing a common middle open section and the two usual wings - like a “W” configuration when viewed along the top. But it makes the baffle quite wide and less wife-friendly.
Like this:
Like this:
I wonder what would happen if those 2 middle woofers were the same driver? Or if you were set on 4, could you make it 3 slots?
I understand the middle units wouldn't really be SLOB, but would it matter if the outside 2 are?
Sorry for the bad drawing, I just used my phone haha
I understand the middle units wouldn't really be SLOB, but would it matter if the outside 2 are?
Sorry for the bad drawing, I just used my phone haha
Attachments
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Nice, thanks. Aiming for the same wide as the for the LiiAudio.
And for the WAF: Have my own music chamber 😎
I’ll be starting my own thread next month as the build begins but I thought I’d share the design with you folks who have been following on X’s excellent work!
I’ll be using 4 of these woofers in a push push opposed frame with 2 separate slots…..each slot load with 2 drivers
https://www.parts-express.com/Dayton-Audio-SD315A-88-12-DVC-Subwoofer-295-488?quantity=1
These are crazy efficient for such a low Fs and substantial xmax for OB duty. The slot depth should provide a mechanical 2nd order high pass at 280hz. 4 of these will have the equivalent surface area of 2.5x a single 15. With all that surface area and linear excursion along with some bottom end DSP boost, I suspect an in room F3 somewhere around 35hz……..I can live with this limit given the benefits, power capability and midbass slam these should produce.
This will be a DSP/Hybrid with a 2x4 DSP unit and passive components for the mid and high crossover. I’ve chosen a mid driver with a really nice top end rolloff so creating a 4th order high pass combined with the acoustic and a single coil will get the job done. I’ve chosen this driver for the mid as I have one already for prototyping. IMO, this the finest midrange driver available regardless of price, size and power handling. The timbre must be heard to really appreciate this driver
https://www.parts-express.com/B-C-8PE21-8-Midrange-Speaker-294-652?quantity=1
Troels did an extensive measurement sequence of the driver here
http://www.troelsgravesen.dk/midrange-drivers.htm
I have not chosen a tweeter yet although the plan is for a crossover to the mid in the 3khz range. The actual cone area of the B&C driver is closer to that of a 6.5” and that rib in the cone somehow keeps the directivity constant right up to 2.5khz where it begins to beam but in a very benign manner…doesn’t start narrowing until 4khz.
So criticism and thoughts are welcome. I’m working on the bass bin portion now which wll have an overall height of 28”…I’m building in a slight angle/offset of the stacked 12” woofers for time alignment.
I’ll be using 4 of these woofers in a push push opposed frame with 2 separate slots…..each slot load with 2 drivers
https://www.parts-express.com/Dayton-Audio-SD315A-88-12-DVC-Subwoofer-295-488?quantity=1
These are crazy efficient for such a low Fs and substantial xmax for OB duty. The slot depth should provide a mechanical 2nd order high pass at 280hz. 4 of these will have the equivalent surface area of 2.5x a single 15. With all that surface area and linear excursion along with some bottom end DSP boost, I suspect an in room F3 somewhere around 35hz……..I can live with this limit given the benefits, power capability and midbass slam these should produce.
This will be a DSP/Hybrid with a 2x4 DSP unit and passive components for the mid and high crossover. I’ve chosen a mid driver with a really nice top end rolloff so creating a 4th order high pass combined with the acoustic and a single coil will get the job done. I’ve chosen this driver for the mid as I have one already for prototyping. IMO, this the finest midrange driver available regardless of price, size and power handling. The timbre must be heard to really appreciate this driver
https://www.parts-express.com/B-C-8PE21-8-Midrange-Speaker-294-652?quantity=1
Troels did an extensive measurement sequence of the driver here
http://www.troelsgravesen.dk/midrange-drivers.htm
I have not chosen a tweeter yet although the plan is for a crossover to the mid in the 3khz range. The actual cone area of the B&C driver is closer to that of a 6.5” and that rib in the cone somehow keeps the directivity constant right up to 2.5khz where it begins to beam but in a very benign manner…doesn’t start narrowing until 4khz.
So criticism and thoughts are welcome. I’m working on the bass bin portion now which wll have an overall height of 28”…I’m building in a slight angle/offset of the stacked 12” woofers for time alignment.
Isn't a Qts of .33 a bit low for an OB sub? I thought Qts >= 1 was preferred, or is this ameliorated by the SLOB design and multiple woofers? (Says the man who has yet to design one for himself 🤔 and may very well need a primer on the subject)
The high QTS allows woofers to play below their resonant frequency in free air/dipole. Since these woofers already have a very low Fs, it’s not needed. Also the slot loading with raise QTS and lower Fs a bit too. What’s really Important is Xmax and these woofers have it at 11mm.
If Fs is low, the low Qts will go to the Fs since it has authority. High QTs allows you to go below Fs as Maybem said.
I am so happy that you got it working and you are happy with the sound!
Despite being in Sweden, you managed to buy the flatpack and the shipping was quite reasonable from what I understand.
Bravo!👏
Despite being in Sweden, you managed to buy the flatpack and the shipping was quite reasonable from what I understand.
Bravo!👏