Interesting summary article about Loudspeaker Bass Reflex Alignments on AudioXpress

[JonMarsh]

https://audioxpress.com/article/loud...lex-alignments

Their summary description:

The use of standard filter alignments represents a foundational concept in the loudspeaker industry, with an impact nearly as significant as the invention of the electro-dynamic loudspeaker principle itself. As one of the creators of Speakerbench, a web-based speaker design tool, in collaboration with Jeff Candy, Claus Futtrup is in a unique position to discuss the evolution of enclosure designs based on this electrical filter theory, including the concept of an alignment chart.

The author has some great pictures from the past.. (well, great for those of us of a certain age...). Could YOU tell who's who?




Find out how these compare... it's more than just the amplitude response. Considerably more.




Worth a read, IMO.

[technodanvan]

There is a lot of interesting facial hair in that photo.

Seriously though, thanks for sharing. Interesting stuff.

[Evil Twin]

This is an interesting article for both the historical perspective, the pictures of past leaders, and some critical information points.

The most interesting information point is how many alignments can be realized with drivers over a reasonable range of Qts... but the most interesting one and which by one subjective listening test performed significantly better, requires a very specific Qts range of 0.32 to 0.34.

I have on hand two possible candidates...

MW19P-8 - Papyrus cone driver









MW19TX-8 - Textreme cone driver







A quick attempt at approximating a Bessel alignment but using Passive Radiators looks promising...

This holds potential for a design inspired by a new Italian made speaker developed by what appears to be engineering talent from Sonus Farber and custom drivers built by Scanspeak to the designer's specifications.

[technodanvan]

What is the box volume and which passive radiators are we looking at Jon?

[technodanvan]

Seems the forum does not like my VPN any longer.

[theSven]

What VPN are you using? I don't block VPN's from the server where the forum is hosted. The VPN should work without issue...

[Evil Twin]

Steve has had a very busy travel schedule lately. I suggest you PM him with details of your VPN setup. The forum has had some issues with bots and other manifestations of the more useless part of the Dark Side...

[Steve Manning]

Steve has had a very busy travel schedule lately. I suggest you PM him with details of your VPN setup. The forum has had some issues with bots and other manifestations of the more useless part of the Dark Side...

That would be Sven ..... Steve doesn't know squat in that department!

[Reet]

Sven had to make me a moderator of sorts in order to fix the "VPN problem" or whatever you want to call it, the auto-unapproved posts. Not the right solution, perhaps this aging forum is in need of a revamp. At the least, make it searchable via a web search engine. No thread here will ever come up in a google search for example, big contributor to low human traffic.

[theSven]

Oh, it could be the spam service that the forum uses. That could be the issue why Danny is having issues with his VPN. I don't do anything on the server level to block VPN. If needed I can add Danny to the group that Reet is in.

[technodanvan]

No thread here will ever come up in a google search for example, big contributor to low human traffic.

I was wondering about that. Are crawlers banned here or something?

I've seen this issue with my VPN before (I use Mullvad), but it's usually very dependent on the location I select to be from. One server in LA may be blocked, for example, while others in LA are fine. Probably depends on the age of the server and how long its IP has been static I suppose, as those more 'useless' parts of the dark side are certainly prevalent.

[theSven]

Are you using OpenVPN or wireguard? I would suggest using wiregaurd, as performance is much better and it has a lot let issues getting flagged/detected. I use ovpn for my services, they are a Swedish company and have servers in all the places I need to egress through.

[JonMarsh]

Sven would have the answers to that, but my first guess would be yes.

There's been a lot of stuff in the last six months that Sven has had to address because so much bandwidth was being sucked up that I couldn't get on the site- "too busy- try again later"

[technodanvan]

I have seen that on occasion as well. Can we plus up our available bandwidth theSven? I'd be happy to contribute if necessary.

[theSven]

We have been getting pounded by bots that do not respect the robot.txt. I don't think we have maxed out the bandwidth at all. The forum is run in AWS, and if it goes over I just get a bill for it. When I get back to the states next week we can chat when you have time to get this working for you. I'm happy to spend the time to make sure you have a good experience at the forum. That goes for all the other active members too. The forum truly values all of your contributions and collaborations!

[eb15]

Does this look right?

If I want a Bessel-ish aligned passive radiator box, First I need to find a woofer with a Qts of between 0.31 and 0.34.

Then I consult the handy alignment table to get in the ballpark for alpha and h factors to set box volume and tuning frequency

then the target box volume equals driver Vas/alpha
and desired tuning frequency fb should be (woofer fs * h)

Ql	Qt	h	alpha
3	0.3535	0.9696	1.4036
5	0.3376	0.9725	1.7488
7	0.3312	0.9735	1.9076
10	0.3266	0.9743	2.0311
15	0.3230	0.9749	2.1296
20	0.3213	0.9751	2.1797
50	0.3182	0.9756	2.2713

So for example the Dayton DSA215-8 8" designer series aluminum woofer with a Dayton DSA270-PR 10" aluminum passive radiator + additional 126g mass added in a 20 litre box
models in Unibox like so...

[Evil Twin]

I believe you have the sense and details of this idea firmly in hand... thank you for this useful contribution.

It's useful to ponder the system possibilities, limitation, and configuration considering this driver's characteristics at this very reasonable price.




The SPL plot is basically reasonable, but must be considered in light of the impedance behavior. The question might be, how high a frequency range is suitable for use, at what quality expectation?



The impedance does begin to rise above 250Hz, and this characteristic is usually associated with inductivity modulation with increasing frequency, and may include higher levels of HD2, as some of the other LF transducers do, in the low midband, like the E180HE-44, which is deemed by some not to be suitable for a two way application.

It would also be interesting to see how linear the DSA270PR suspension is- this is a problem many brands have issues with, sometimes resulting in product recalls, and for that reason I tend to be overly conservative with regards to PR excursion ratings.

[chrisn]

[FONT=Verdana]https://audioxpress.com/article/loud...lex-alignments



The author has some great pictures from the past.. (well, great for those of us of a certain age...). Could YOU tell who's who?

I'd have guessed some combination of Colonel Sanders and Orville Redenbacher for the first 4, and Weird Al for the guy on the right