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Get familiar with the reaction system: Introducing the Reaction System
Sealed? Ported? PR?
Let’s just say each one is well implemented. What is your go to to listen to in the low region? I’m really starting to like the PR over the ported.
Comments
PR
Sealed, assuming in this fantasy world Hoffman doesn't exist. Otherwise PR because physics is a bitch and WAF matters.
JB always said ported is more efficient. My go to for design is ported assuming I can control the port noise. My go to for listening is big woofers (15s+) sealed, below 15s ported. I'm to cheap to buy big PRs.
In order of preference:
1) Traditional quarter wave transmission line
2) ML-TL
3) Sealed Isobarik
4) Sealed
5) Ported
6) PR
If I can make ported work, it usually is what I want. PR rolls off steeper below tuning than vented, but you get no port noise. Not every woofer can work sealed. Aperiodic also is not an unknown and can sound great.
InDIYana Event Website
I have built many ported designs, but now my preference is strongly for MLTL, or just tapered TL.
Ported for me if I can keep the diameter and length reasonable enough to limit chuffing and resonance issues. After that, PR and then sealed. I never hear any benefit to MLTL or TL over a standard BR design unless the BR would have otherwise had resonance issues.
For total room response > eq'ed large open-back / open-baffle (I was an early maggie fan for what a panel could do in the upper low-end, the mid range and up, and room response of a dipole, so I'm a bit biased I'm guessing for the luv of open backs). Low on the WAF scale. That being said:
Best for bottom ½ to 1 octave > large sealed sub (or two).
Sealed: aperiodic vented and/or iso has some merit
TL if executed well (i.e. more on damping the mid frequencies over low end 'support')
PR, then Port. Tough to get these right so as to avoid one note bass due to tendency to get a pump followed by a fast rolloff in frequency.
Bass head so I lean toward ported, then PR if lengths are too long. Sealed generally matching to a sub. Mltl has some benefits and Paul K has helped me in designing 3 of them now.
What do you perceive about MLTL benefits? I've been unable to prove a difference with BR empirically, but MLTL sounds better to me.
Don,
You probably have seen this, and while its a bit marketing, it speaks towards potential advantages of TL. I see, my 2 cents worth, the ML as a further way to control/ limit the output, with the TL absorbing/ attenuating the mid and higher output from the rear of the driver.
https://pmc-speakers.com/technology/atl
Thanks, I was aware of PMC and their tech notes. It's interesting to now (that I understand a bit) to read their stuff. Like "TLs require a different transducer design than BR or sealed". Um ok. Not going to buy into that. I WAS interesting to hear that efficiency of a BR speaker will vary with drive level. I usually like solid bass from a BR, but sometimes I'm not sure that it's really accurate.
When used in a tower design, it can help to reduce midrange energy and ripple. Less energy being reflected back into the cone. The caveat is higher group delay which if long enough can become audible
Ported FTW. Most flexible alignment, and the MLTL is still technically a ported alignment just with a churched up name and a bit of stuffing to tame a pipe resonance.
This is one of the main downsides of a BR, in addition to midrange leakage at resonant frequencies, and audible wind noise at high output. A port is usually much smaller area than the driver radiating surface, so at high output, air needs to be compressed through a smaller hole at higher velocity, resulting in back pressure and loss of efficiency. Designing a 3-way or subwoofer use can avoid the midrange leakage and resonant mode issue. From my experience, designing a port for <30Hz tuning often runs into diminishing returns of a port that's too long to reasonably fit in the cabinet, and resonance modes too low in frequency for comfort.
A PR is less efficient than a port due to mechanical losses, but we are talking like 0.5-1dB generally. IMO the benefits outweigh this loss. It does increase surface area dramatically over a port, so wind noise is gone completely, midrange leakage is reduced significantly, no resonant modes at higher frequencies either. Downsides are mechanical excursion limitations, but can be avoided with the right choice of parts. I find PRs are fantastic for big subwoofers with deep bass production, at least that was my experience with a Adire Tumult 15" with a pair of 18" PRs, tuned to 20Hz.
TL is like a port, but with some benefits of having larger area to avoid the compression / wind noise problems, and with some damping to absorb the resonant modes higher up in frequency. Main downside I see is that everyone seems to need to know a guy named Paul K or Martin K to design one.
Horn Response has a TL wizard based on MK's tables.
Someone should really write an idiots guide to Hornresp.
Thinking a highly damped aperiodic design (to control the Q freq response of the sealed box system) with a tapered line to absorb the mid upper frequency (to some extent) and attenuate back wave reflection back to and through the driver. A bit of eq vs a system (ie port / PR) that exhibits frequency dependent constructive and destructive interference.
There's a hornresp for dummies.
https://www.hometheatershack.com/threads/hornresp-for-dum-hmm-everyone.36532/
There are a few others as well.
With driver design and material technology improvements allowing for drivers that can dig lower in smaller boxes, and at higher outputs... The port volume can begin to rival the enclosure volume. Makes PRs less gimmick and more necessity.
One thing I always wondered is if the higher air velocities from a port makes it more likely to couple with nearby airmass when near walls. The effect would be reduced from a much larger PR by comparison. Potentially making PR less "boomy" sounding in the same room position, and thus more pleasing. Then again I would have no data to back that up. Just spitballing.
Hmm, I was just thinking about that for this group at least. HR was slow going for me for a long time, but I've got it rocking now. Lots of fun modeling various designs once you get the hang of it.
That's the resource that I learned from, but I think that I can do better. For one thing, the pertinent tips are mingled through 10 pages of HTML, when really everyone needs a concise PDF. I'll see what I can do. Paul K helped me a lot at the beginning, but now I don't need to go to him anymore.
I'm interested in seeing what you come up with.
Sealed or ported, it really depends on the driver that I am using.
Whatever it takes to hit the desired Low end SPL for the given form factor and application.
There’s a saying that Music lives in the midrange, but IMHO, 300Hz to 3Khz, or 200Hz to 4KHz or whatever doesn’t cut it IMHO.
For anyone who’s used DSP or real-time equalisers/filters, music really lives in the 50Hz to 15Khz range.
Get that covered at the required SPL and everything can sound good enough, from a speaker the size of a bar of soap… to a speaker the size of a truck.
What tktran said about hitting a target.
I went to the Home Theater Shack link but it was pretty old so I did a Google search and found this. Is this a decent summary?
https://audiojudgement.com/hornresp-tutorial-transmission-line-design/
Meh, the help file in horn response is better imo
Yeah, I was about 50% done when I posted that. It seems okay to start, but especially for an MLTL two-way rather than a sub seems to be missing some things.
One thing for @rjj45 to consider would be to survey what is out there and look for errors and poor and/or incomplete instructions.
I'm in the planning stage at the moment.I will add a review of other tutorials.