I was referring to woofer actually. Say 8" woofer. Will the dagger length be sufficient for big woofer? Obviously there will be speaker depth issue
Oh no, for woofer, it's not as critical to use a spiral to absorb back wave as wavelengths are very long. It would be useful if full range 8in driver etc where high frequencies are also required. But below 200Hz, no need - just use a box stuffed with fiberglass.
It is helping, but not needed from standpoint of eliminating back reflections to the extent of what is needed if used as a woofer and not mid range.
In that case rs225 in sealed box I read in your another build would just make sense. I will couple it with a suitable 3"full range available locally
Xrk,
I've gone through each post in this thread with great interest and despite others having done so before I also want to congratulate you. Excellent work!
Throughout my reading I was envisioning a sealed spiral chamber to absorb the backwave in my midbass section (80 to 350Hz), within my active 4-way system. And a straight closed dagger for mids, and maybe one for tweeter too. Subs are sealed square boxe, servo driven.
But this post confused me:
Would you say sealed spiral chamber is a good idea for 80 to 350Hz with dual 10" per side? Thinking a heavy front panel, wooden sides and top, and foam core for the spiral (maybe the larger radius areas with wood instead).
Thank you!
I've gone through each post in this thread with great interest and despite others having done so before I also want to congratulate you. Excellent work!
Throughout my reading I was envisioning a sealed spiral chamber to absorb the backwave in my midbass section (80 to 350Hz), within my active 4-way system. And a straight closed dagger for mids, and maybe one for tweeter too. Subs are sealed square boxe, servo driven.
But this post confused me:
Would you say sealed spiral chamber is a good idea for 80 to 350Hz with dual 10" per side? Thinking a heavy front panel, wooden sides and top, and foam core for the spiral (maybe the larger radius areas with wood instead).
Thank you!
350Hz half wave is 1m long so if cabinet is under 1m you are not going to have any standing waves. The spiral always helps to prevent back reflections of any wavelength so should help to make the sound more clear and less muddy due to back reflections. It acts as an acoustic black hole so the speaker has the clarity and openness of an open baffle but sigh compactness of a sealed box.
Great. I misunderstood your prior post then. Indeed, my intent is to prevent the back reflection, and keeping it a sealed enclosure.
I'm planning to use two Beyma 10G40 per side: Qts=0.3, Vas= 49 liters, fs=45Hz. How long should the line be?
Front panel to be 50cm wide, while the internal chamber width will be 27 or 28cm. I envision a larger version of your Nautaloss II with two 10". Depth has some leeway, but hopefully under 75cm. Same for height.
Would anybody have a view about the line length? An 80Hz wavelength is 420cm long, so half is 210cm. But xrk mentioned earlier that it didn't need be half wavelength long. How short? Have the urge to go build 😀
Make the length based on the volume of the box you need for a sealed alignment. This ensures that the driver reaches the bass response you need. The exact length is unimportant as you just need it to act as an absorber. About 3 ft long is fine for a woofer.
Thank you!
What's your opinion considering my drivers: go shorter and get Qtc=0.5, or go 3 feet and Qtc=0.47?
For my 10G40, a sealed box of 28 liters would have Qtc=0.5. So since I'll have two drivers per side I would need a 56 liter.
Thinking of the sealed transmission line as a triangle of rectangular cross section (to later be rolled into a spiral), a 90cm long (3 feet) by 58cm base triangle by 26cm chamber width equals 68 liters, that would yield Qtc=0.47.
Alternatively, keeping the chamber width and 58cm base and shortening the length to reach 56 liter (Qtc=0.5) leads to a length of 71cm (28"). Too short to yield back wave black hole properties, or inconsequential for this application?
Q of 0.47 or 0.5 is same thing. Don’t worry about it. You can also taper the triangle down faster in mild curve to reduce volume. Or make shorter - 28in is fine.
hi XRK,
for the loop inside the box, can we use 6mm flexi ply?
here i am intending to cross it over 200hz so i am guessing if 6mm flexi ply will do the job.
other option i have is to go with stacked frame approach
for the loop inside the box, can we use 6mm flexi ply?
here i am intending to cross it over 200hz so i am guessing if 6mm flexi ply will do the job.
other option i have is to go with stacked frame approach
tried with flexy ply. and faced problems bending the ply as we go more into spiral center. finally realized its not worth of struggle. switching to CNC approach, which i think will be much cleaner. i am wondering if anyone tried using CNC for this speaker?
one person has tried this using stacked panel method,
What causes this peak-dip in frequency response?
but there is no much details on building
one person has tried this using stacked panel method,
What causes this peak-dip in frequency response?
but there is no much details on building
Make the exterior with wood and curve the spiral with foam core as recommended I. This thread. It’s easy and is actually superior for sound absorption, which is the whole point.
That dip in measurement is probably artifact of mic being too close. Measure at 1/2m or more and it will be fine.
That dip in measurement is probably artifact of mic being too close. Measure at 1/2m or more and it will be fine.
Nautaloss MTM mod
I made an MTM out of this speaker with a simple XO and inexpensive Dayton ND25FA-4 dome tweeter. More about it here:
MTM with TC9fd
impedance is 3.5ohms to 7.5ohms:
I made an MTM out of this speaker with a simple XO and inexpensive Dayton ND25FA-4 dome tweeter. More about it here:
MTM with TC9fd
impedance is 3.5ohms to 7.5ohms:
Xrk, you mentioned in the mini-karlsonator thread that it would be nice for someone to veneer a foamcore speaker. Well, here's my Nautaloss I. I used the 6.5" buyout speaker from PE and a small tweeter, and the veneer is Mozambique I stained walnut. The bass is outstanding, and these are my main speakers now. I use mini-karlsonators as side speakers. I'm a 75-year-old ex-F-15 mechanic who has loud tinnitus at about 8kHz, as a result of being unable to put on my ear protectors in time when an F-15 would be run up to high idle next to me, so the 8kHz is my upper limit of hearing now. Oh, well. I hope you like them.
Attachments
Jaxboy,
Wow! Those look great. The 6.5in PE polycone woofer is an excellent sound driver. With sufficient volume in the rear chamber it gets 50Hz and is sealed for a tight defined bass. Sorry to hear about your tonight from job related injury. F15 mechanics are way cool. There is so much technology there and you got to fix or rebuild $30M jets. Very cool.
Wow! Those look great. The 6.5in PE polycone woofer is an excellent sound driver. With sufficient volume in the rear chamber it gets 50Hz and is sealed for a tight defined bass. Sorry to hear about your tonight from job related injury. F15 mechanics are way cool. There is so much technology there and you got to fix or rebuild $30M jets. Very cool.
Yeah, it was cool. I was stationed 15 miles from the Luxembourg border in Germany, and we were tasked with keeping the Russian camera jets out of German air space. Daily, they would enter at the top of the Eastern side of West Germany at top speed and run toward Italy, spy cameras rolling. 2 of our F-15s would crank up and fly to meet them. We many times actually caught them before they got out of German air space. Now that was flying! In a contest, we once did 123 sorties in 23 hours, then ran out of pilots, with only 2 F-15s out of commission of the 24 in the squadron, a world record that can't be beat, because the Defense Dept changed the rules after that contest. Speaking of being way cool, that's you, xrk. You changed my music-listening life, and I will forever be in your debt. The 3 foamcore designs from you are my only sources of sound now, and I love them, plus the total cost of all 3 pair was less than I expected to pay for 1 set of wooden speakers, and they each sound better than the 1 wooden pair I anticipated building. Thank you.