Wow, it's good to be young. This is just too much work for me (unless I was retired, of course and had the time). wish I was closer so I could hear the results of these projects Rich.
Looking good.
Road trip! :thumb:
Rich ... Rich ... wake up!!!
Someone call the paramedics.
Are you still planning to build 4pi Mike?
Spike those speakers Rich.... :thumb:
The old ones get sold if they are any good, or more often go to the dump.
Spike those speakers Rich.... :thumb:
These horns are a bit too much detail for me. I focus on reverb trails and cracked notes, stereo pan instead of the melody.
Come hear it if you want Shane, but there is a lot more work to do before it is worthy of golden ears. Set your expectations accordingly. ;)
woohoo!! that sounds very encouraging, Rich! Now I definitely can't wait to hear them :)
If not I have to find a way to shorten them in place, or make a mess of the box.What kind of access to them do you have? I have one of those dremel Multi-Masters you might be able to use in tight quarters, or even a palm sander if you can get to the end of the port axially and have a lot of time on your hands. :?
...may not be here if painful contractions happening now are good sign of things to progress......
i suspect next time we here from you, there will be a new member in the sangster family... congrats!!! :thumb:
doug s.
...
Advice from father of 3: get as much sleep as you can now.
But there is hope! Look at at all the fun Rich is having with these speakers *AND* being a father of 3!
Well... I secretly think Rich is either a robotshhhh, my secret.... ;)
Rich
Just to take the box vibration out of play, have you thought about temporary external bracing? You could even go so far as to make an outside form and fill with grout.
Sorry this has turned into one of MY home improvement projects ](*,)
If they're still bottom heavy, they may need a longer port, not shorter.
Would a passive radiator have an affect reducing vibration into bass ? Did you use any viscoelastic dampening [ black hole pad ] material between driver and box ?
You need to measure to see where the boom is. If it's ported too high, you'll have a large peak in bass response too.If they're still bottom heavy, they may need a longer port, not shorter.
Thanks Mike! Won't that lower the tuning freq? I am under the impression that it is already too low.
Based on Simon's advice I am ignoring the simulations for TD12X that say 48litres, but I think the sims are more correct than wrong. 120 and 85 liters sound too boomy. To me that means box too big or port tuned too low. The Fs of these two drivers are 25 and 30Hz.
According to eminence simulation this volume and port should resonate at 50Hz with the Eminence driver.
Thanks Mike
I played with WinISD again. I simmed the Eminence design that I am trying to copy now. See attached. This is what Eminence recommends for this driver. 78 liter box with two 4x5.5" ports, Fb 50Hz. WinISD predicts 54Hz Fb. Notice the 2+dB bump. This is also shown in Eminence published design. See attached green curve.Ports are cheap. ;)
My ports are a little shorter, and I don't know what the exact volume is of mine with the foam fill as there are some small voids for air to go, but mostly solid and probably larger than 78l. If I sim 90l with my ports I get 50Hz and the bump is a little less than 2dB. But measuring the port gives SPL peak at 42Hz which puzzles me. Am I confusing port resonance with Fb? Are they the same or different?
Now if I lengthen the ports to 12" to bring the simulated Fb down to 40Hz, the red curve flattens out which is what I want. But since the actual tuning is much lower than predicted, will lengthening bring the actual measured port resonance down too low?
I could also remove the foam to increase the volume, and lengthen the ports but Eminence says 120liter is too big, even though sim predicts it as max flat alignment.
I don't want to do the 12" ports unless there is a chance for improvement. What do you guys think?
OK, then I'll try longer ports. Thanks MikeThis is what I do...and using this program: http://audio.claub.net/software/jbabgy/WBCD.html (http://audio.claub.net/software/jbabgy/WBCD.html)
So the design process is:
Measure the driver.
Simulate box as a starting point.
Build the box.
Tune port length and stuffing as simmed, leaving ports a little longer than recommended.
Measure nearfield.
Fine tune stuffing and port length by measurements and ears
This is gonna piss off 2two, er I mean Evan who hates the same thread hogging up the whole forum... hehe
Blue is 2mH on the woofer, two 1mH in series. Red is 1mH. 2mH the 1.5-2k peak at xo. 1/6 octave smoothing.
Now for the peak at 650 and dip at 1200. Hopefully just acoustic. although I'm not so sure about the 1200.
Face, how do you recommend to measure drivers for importing into PCD? Should I do it in room where the speakers will play, or should I do it outside up high to eliminate as many reflections as possible? Tom Danley says measure without reflections, then apply filters. What do you do?For PCD, I measure at 1m with bass traps all around, eliminating all reflections.
Face, how do you recommend to measure drivers for importing into PCD? Should I do it in room where the speakers will play, or should I do it outside up high to eliminate as many reflections as possible? Tom Danley says measure without reflections, then apply filters. What do you do?
I got the smaller air cores on both sides now. Do coils need to break in? Sounded a little tight at first. Opening now after a couple hours. I got a couple sizes that will allow fine tuning. I'll need to measure to see the changes.How well braced is the box?
With the iron cores gone, the bass is much cleaner, the whole speaker sounds much better, and plays louder. The iron cores seemed to really suck out the life and the volume.
So now, of course, with cleaner bass I can hear new LF flaws. :x :) The bass seems slightly resonant, chesty on alto girls and guitar low notes, etc. The box is sized for Q .57 with the Eminence Deltalite 2512, and it's way too big for this AE TD12X driver.
EPB of this driver is 110. Probably shouldn't be sealed anyway. But that wouldn't make it too warm in the mid bass.
The simulated AE TD12X needs 30 liters for Q .7, 50 liters for Q .57, 75 liters for Q.5. The box is currently at 120 liters, which spells Q .43 :shock: What is the sonic penalty of too large sealed box? I've searched hi and lo for the answer. Grant me this wisdom, mighty Oracle.
Also, there is minimal fill inside the sealed box now. Usually sealed boxes will have more fill, sometimes even stuffed full. I don't need more volume, so I didn't bother filling it with fluff. But maybe more is necessary to damp the driver better?
More stuffing and smaller box?
Thanks :D
Thanks Mike. They are well braced. I do have some extra pavers that I could jam in there. But I could not kill off 50 liters with bricks. I can fashion a removable divider board that cuts it down.Yes, it's possible. A new cab or divider would be your best bet.
Do you think the low Q could be the cause?
Radian says the 475 biding posts are marked correctly, red is positive. So ignore previous rant.I believe JBL marks them incorrectly for those who have no idea what they're doing. :D
I believe JBL marks them incorrectly for those who have no idea what they're doing. :D
There are a lot of bad recordings out there! Maybe a good reason why tubes go well with horns.
I can't do infinite baffle test, but I can test the driver free air outside.
I can also measure with the cabinet stuffed solid with acoustic damping.
I don't notice the 750Hz null much, except on trumpet recordings that I've listened to for 35 years, then only if I concentrate and look for it. I do notice the warm midrange glow of the bump just below at 400-600. I'm hoping that's room related.I would recommend concentrating on the null first. Eliminating this might also eliminate or show irregularities that otherwise could fool us.
If interfering waves cancel with floor bounce, can they not also combine to make a peak at adjacent frequencies to the null?Reflections within 0-20ms would add to our perceived frequency response. Bouncing waves will induce phase shifts and can sum up to a nasty result.
One thing I am noticing is that the speakers sound really good out of the sweet spot, especially far away, owing to the good power response, and the pro-audio origins of the design (horn + woofer.)Glad to hear you are getting some good stuff from the boxes already :D
The speakers seem to reveal flaws in recordings very well. I think some of the flaws are still in the speakers, but some stuff is obviously recording related. There are a lot of bad recordings out there! Maybe a good reason why tubes go well with horns.
If interfering waves cancel with floor bounce, can they not also combine to make a peak at adjacent frequencies to the null?Nyes... Yes if the first reflection was the only thing causing the dip. No since I believe that we also see ringing, similar to resonance/standing waves.
The dip at 700 on the AE woofer was seen in free air FR sweep, and corresponds with a small blip in the impedance curve, and is common with high Xmax drivers like this. The cloth accordion surround M version of this speaker is said by the mfg to have less surround resonance.The M has higher efficiency, but a smaller x-max.
I have 4 TD-10M's here that I'm waiting to do something with. Maybe I'll pair them with some SEOS 12's.
Slow work takes time...The dip at 700 on the AE woofer was seen in free air FR sweep, and corresponds with a small blip in the impedance curve, and is common with high Xmax drivers like this. The cloth accordion surround M version of this speaker is said by the mfg to have less surround resonance.The M has higher efficiency, but a smaller x-max.
It's all about trade offs. ;)
I have 4 TD-10M's here that I'm waiting to do something with. Maybe I'll pair them with some SEOS 12's.