Whether bass reflex or transmission line, you can get the best in each by tuning to approximately >20hz.... The same approach and benefits can be seen if you simply keep the tuning note, an octave or better below the lowest intended reproduction note. The same philosophy is used with horns... and for no different reason.
There has been very much discussion on this board and Martin King Facebook group about what is a true transmission line… I came to the conclusion that calling it an aperiodic transmission line helps to differentiate what we are talking about here from all the other variants.
There has been very much discussion on this board and Martin King Facebook group about what is a true transmission line… I came to the conclusion that calling it an aperiodic transmission line helps to differentiate what we are talking about here from all the other variants.
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Why bother with TL enclosures at home? Seems that simple closed box (or bass reflex) with power and EQ is all that is needed, go for big enough transducer to reach SPL. What is the benefit for the added complexity here? Backwave suppression? but for that leaky cardioid box would be smaller, less SPL though.
edit. dum me, should have read the previous page
aperiodic was suggested. Anyway, always think what is the benefit and what is the trade-off.
edit. actually, TL might not be any more complex to build than simple closed box, if bracing can be skipped. Design phase and tuning with damping material is some extra work.
edit. dum me, should have read the previous page
aperiodic was suggested. Anyway, always think what is the benefit and what is the trade-off.edit. actually, TL might not be any more complex to build than simple closed box, if bracing can be skipped. Design phase and tuning with damping material is some extra work.
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Filling ports is an excellent idea. I fill my ports with a roll of large Scotch Brite pads. Adjust density as desired. Bass is more integrated with a normal size room. Bass detail is better. The roll-off introduced combines better with the room's rising response.
I'm caught up enough on the board to see your pics of the cab - slotted opening for the TD18's. I like what you are doing.
One thought I have is to split the signal to the 18's and the 15 with an electronic first order subtractive x-over before the amps and any other dsp or eq. It would be in phase and in time. It seems the AETD drivers have the bandwidth to do it. Then, split the high pass to the 15 with what ever filter slopes work between the CD/horn and the 15. A series/parallel combination.
I'm going to try and refrain from more comments till I fully catch up with the posts.
First order crossovers behave the same whether they are of subtractive topology or separate high and lowpass with the same pole frequency.
While the 18" drivers do indeed have good extension on axis this might not be longer the case with slot loading. And the midwoofer LF cutoff frequency would be too close to a potentially optimal crossover frequency for using a first order crossover. Its phase shift would render the first-order crossover non transient perfect.
Regards
Charles
Why bother with TL enclosures at home? Seems that simple closed box (or bass reflex) with power and EQ is all that is needed, go for big enough transducer to reach SPL. What is the benefit for the added complexity here? Backwave suppression? but for that leaky cardioid box would be smaller, less SPL though.
edit. dum me, should have read the previous page
edit. actually, TL might not be any more complex to build than simple closed box, if bracing can be skipped. Design phase and tuning with damping material is some extra work.
We are always going to trade off something. But, since we are talking DIY, trade offs can be fewer.
An excellent TL can be as simple as a loosely and vertically connected sonotube on a wood baffle. Modular. Ready access to tuning the tube. Slot loading at the floor.
I have some Hartley full range drivers. 10". I tried an experiment with a 4' 12" dia. sonotube. Put the driver on a baffle at the end of the tube. tuned the pipe with a pillow in the tube. Just pushed the pillow back a forth in the tube until it sounded right. A-B'ed it with my full range Audire ribbons. Put the Hartley on the left, horizontally mounted, and the ribbon on the right. Sound was close in quality and bandwidth. Hartley in tube weighed about 25 lbs. Full range dipole ribbon was 6' high, about 30" wide, and 110 lbs. The Audire ribbon was about 10 times the cost.
Back to reading and caching up with posts...
The Bastanis Matterhorn is more of a wideband 15" + tweeter instead of a 2 way system. However, the BLH could be adapted with a bigger horn and a more sensible crossover frequency.
The drivers are from Oberton and the woofer looks like a modified 15MB500. It's a nice driver with an extended response, but no 15" should be crossed above 1200 - 1500 Hz imo.
The drivers are from Oberton and the woofer looks like a modified 15MB500. It's a nice driver with an extended response, but no 15" should be crossed above 1200 - 1500 Hz imo.
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I've been eyeing the Altec 604's like.....should I...lol. Seems so simple... Docali doesn't like the Axi2050 because of its sensitivity on the high end. He really loves his 18sounds driver ND4015Be. Its neither here nor there for me. I've been considering a mini CNC for the producing a large horn. Seems less involving for the finish work vs 3d printing...
Another full week...I was able to sell my aquaplas diaphragms...the jmlc350 horns are sold but not shipped since I could not find the address in time =(
I've been pulling long days (12-17hr), another supposed 12+hr day coming this Saturday even, which is great because its all over time and normally they chop us down to 8 or less hours on this day because of that.
I think I am over this deal with thiele specs now that I see that the advertised specs are bloated out of control and unnecessarily........................... in order to set me up for forward momentum maybe a little hand feeding on this damping issue of lower section?
The lower section is going to look something like the above (I think I use a deeper 2nd order XO in
VituixCad to achieve similar results...the above is one peak filter on top of the resonant note around 150-180hz and a low pass...I could of just used a 4th order LR low pass at 130hz for similar results).I have to get the null section down below -25db to keep the output homogenous (lol)....Do I need to put damping material in this box? I believe I've read that damping material doesn't do much for bass boxes?
Another full week...I was able to sell my aquaplas diaphragms...the jmlc350 horns are sold but not shipped since I could not find the address in time =(
I've been pulling long days (12-17hr), another supposed 12+hr day coming this Saturday even, which is great because its all over time and normally they chop us down to 8 or less hours on this day because of that.
I think I am over this deal with thiele specs now that I see that the advertised specs are bloated out of control and unnecessarily........................... in order to set me up for forward momentum maybe a little hand feeding on this damping issue of lower section?
The lower section is going to look something like the above (I think I use a deeper 2nd order XO in
VituixCad to achieve similar results...the above is one peak filter on top of the resonant note around 150-180hz and a low pass...I could of just used a 4th order LR low pass at 130hz for similar results).I have to get the null section down below -25db to keep the output homogenous (lol)....Do I need to put damping material in this box? I believe I've read that damping material doesn't do much for bass boxes?
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Thanks as always GM.
I am on the verge of starting a separate thread on Isobaric. I just can't figure out if they are relevant in design anymore. I'm pretty sure using my 18H+ in isobaric would be a step backwards in SQ. The topic of diaphragm rigidity and bass comes to mind. Combined BL also is a factor.
I am on the verge of starting a separate thread on Isobaric. I just can't figure out if they are relevant in design anymore. I'm pretty sure using my 18H+ in isobaric would be a step backwards in SQ. The topic of diaphragm rigidity and bass comes to mind. Combined BL also is a factor.
A message I received today from John at AE:
"Update 6/07/2021
Hello,
Thank you for contacting Acoustic Elegance. This is an automated response which includes answers to some general questions about lead times. I will try to get a response to your specific inquiry over the
next few days. Over the past few weeks I have had some health issues
and spent a bit of time in the hospital."
Things happen.
Some of the GPA drivers except for the AE's high power, super low [Le].
Products - Great Plains Audio
Products - Great Plains Audio