What sealed cabinet VOLUME for 8" full range speaker?

Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.
For my new Dayton Audio PS220-8 8" Full-Range Speaker with Neodynamium magnet I've calculated something but want somebody with more knowledge confirming if i've done it correctly or not.
product page
frequency Chart

For a sealed fully closed enclosure I want to achieve and maintain as low as possible base notes as linear as possible. Its for a large living room 6x6x3 meters and there is plenty of wood available to make a large floorstanding loudspreaker box for this driver.

Question: what volume box size, would give me the deepest base notes all the way to 40 Hz?


Using the following method from Audio Judgement I calculated 30-50 liters...
Qtc = Qts * (Vas / Vc + 1)1/2

... however the Dayton Audio's product page advises an optimal volume of only 14 liters for a sealed box! What am I missing?

Does "the larger the speaker cabinet, the deeper the base notes" hold true or not? Thanks!

An externally hosted image should be here but it was not working when we last tested it.
 
Last edited:
I suspect you are correct in this Litrage as the VAS is big 90L.
However I would run it in a BR box, I dont like Sealed boxes,
the BR duct made the bass big and a bigger box always will delivery more bass.
Althoug manufacturers dont like big boxes as it made the cone excursion larger,
if the VC beat in the botton it may damage the VC or a short circuit may occour.

If you dont like BR boxes try the Metronome, it will delivery a clear, defined with good extension, but with less volume.

If you must use Sealed box use the Visaton B200 in a 100L sealed.
Usally a Sealed box is smaller than a BR for the same driver.

Usually manufecturers dont like BR boxes as it made the cone excursion larger.
 
Last edited:
frugal-phile™
Joined 2001
Paid Member
Max flat (Q-0.707) butterworth alignment) needs ~37 litres F10 50 Hz (anechoic). I like bessel (Q=0.58) which requires 68 litre, F10 43 Hz. It starts rolling off sooner, So anywhere from 25-55 litre well damped should do. Room gain will usually get you a bit lower than this, but rooms dominante and its dimensions will typically cause a “roller-coaster” response very much dependent on room placement and listening position.

Note that less volume is needed when damping is considered.

14 litres has a Q of about 1 (underdamped) and a near 2 dB peak at ~150 Hz and F10 not much better than 60 Hz.

I have a 60 litre miniOnken for these that reaches near 40 Hz F10 and rools off later.

dave
 
Thanks very much guys!! Very informative and helpful. Appreciated!

So for my sealed box I can go for a nice big 55L enclosure? I have a very powerful amplifier but will listen to low volumes not upset my neighbours ears :) Now what if I would go for higher? say 70 liters or 100 liters box? What would then happen to the deep base response?

I think I am not understanding this graph. It shows that at Q=1 the base reaches very high dB, while at Q=0.5 the base drops significantly. This is counter intuitive as the larger the speaker volume the deeper the base should extend indeed... Can you explain mate how I should be reading this graph correctly?

Frequency-response-QTC-sealed-enclosure-530x789.jpg
 
Aah thanks! Right let us go for the sweetspot: 40Hz F10 sounds great! (means "only" 10 db drop at 40hz right?)
With the deepest base sweet spot you get 68 liters for Q= 0.58 but I get 44 liters:
0.38*(90/44+1)^1/2 = 0.58

I've done probably something wrong there...

And still I dont get it why a Larger box has a lower base response (lower Q number) and a smaller box has a higher db base response at a larger Q number?
 
Last edited:
I think I am not understanding this graph. It shows that at Q=1 the base reaches very high dB, while at Q=0.5 the base drops significantly. This is counter intuitive as the larger the speaker volume the deeper the base should extend indeed... Can you explain mate how I should be reading this graph correctly?

Frequency-response-QTC-sealed-enclosure-530x789.jpg

It's not a graph you can 'read' per se in terms of practical design, because the graph conditions assume the same tuning frequency for the purpose of illustration. However, for a given driver, Q changes with the box size & tuning frequency. The lower the Q, the larger the box and the lower the nominal box tuning frequency, but the higher the acoustical damping of the alignment, i.e. the less output you will have. And visa versa.

So from that, you can infer that a 'nice big box' may actually end up being overdamped & lacking in LF energy, unless positioned near walls to pick up some boundary gain from the room. This is particularly significant for drivers like the Dayton, which has an elevated HF response some 10dB higher than that of the bass end and can sound rather bass light without some correction applied.

Technically a system Q is the ideal in terms of tight bass output & minimal group delay / overhang. It's the 'fastest', most accurate sound -providing the driver allows a low tuning to ensure sufficient output. In this case -I doubt it, frankly, especially as you say you have a 'very powerful' amplifier, which implies a more or less pure voltage source, so it won't be getting any help from that quarter.

FWIW, while Fullrangeman's post above has a truly remarkable number of technical and historical inaccuracies, I suspect you'd be better off with a vented box, be it Helmholtz or quarter-wave derived. The miniOnken Dave refers to should be very decent. In terms of a more conventional vented box, 70 litres tuned to 42Hz would be quite effective. And here is a decent MLTL as an alternative (they look like a normal vented box but the physics are slightly different) Speaker Design Works
 
Last edited:
Waauw what a great find thanks Scottmoose! I will investigate in that Speaker Design Works website project, awesome they're using the exact driver as I. But you know I've heard from so many audiophiles that, in the end, a sealed closed box will give a more linear, more subtle and more diverse base response through out various low notes, while a base reflex box will give elevated base for SOME music but is not the audiophile way, they say... And so I'm no impressed by your suggestions to go for the vented solution but what about if I would choose for the 60~70 liter sealed box? how would the frequency graph of the two variants differ in the area between 30 Hz and 500 Hz? Thanks guys!
 
Note that the braces in that box run the wrong way, you will have better performance if you orient the braces along th evertical axis, bit because they will no longer impede the quarter-wave action and they will better brace the box.

You won't hear me disagreeing; TBH I didn't look too closely at the details although the tuning looks reasonable. I suppose I should do something for the PS220 at some point soon; it's one of those units that I haven't got round to yet.
 
Waauw what a great find thanks Scottmoose! I will investigate in that Speaker Design Works website project, awesome they're using the exact driver as I. But you know I've heard from so many audiophiles that, in the end, a sealed closed box will give a more linear, more subtle and more diverse base response through out various low notes, while a base reflex box will give elevated base for SOME music but is not the audiophile way, they say... And so I'm no impressed by your suggestions to go for the vented solution but what about if I would choose for the 60~70 liter sealed box? how would the frequency graph of the two variants differ in the area between 30 Hz and 500 Hz? Thanks guys!

Who are 'they', I wonder? On second thoughts, I don't want to know.

The issue with this is that you've either been given incomplete information, haven't understood all of it, or both.

All loudspeakers are a compromise. We live in that sort of universe. However, this notion that vented boxes are somehow poor is complete nonsense. Many are. That doesn't mean they all are. A badly designed vented box can suffer from all the usual buzz words: 'boom', 'one-note bass' etc. etc. etc. The key phrase there is 'badly designed'. A competently designed vented box (which can include Helmholtz, quarter-wave of various types etc.) does not.

Technically, a sealed box with a system Q of < 0.707 can (as in 'can' not 'instantly will' -it depends on implementation) have an advantage over many vented boxes in terms of group delay, transient response etc. But this is a matter of degree, is implementation specific as noted, and comes at a price. Therein is the compromise. Added to which a very low tuned EBS enclosure for example can actually equal the transient behaviour of a well-damped sealed box in its main passband -a point often overlooked. That's an extreme example applicable primarily to very low tuned subwoofers, but it gives you an idea about the dangers of oversimplification. The world is not so simple as some may have you believe.

As for you wanting frequency graphs -why not use one of the many free programmes out there and look for yourself? You'll learn more.
 
Last edited:
Dr Scott, would you mind looking at your e-mails? Of the several projects I’m on a tight timeframe to complete, those new Castles are at the top of my personal bucket list.
The XO design needs to await rough assembly of enclosures for acoustic measurements of drivers in situ to proceed. Or, I could just use an on-line calculator :eek:
 
Yeah, when I hear or read the word "audiophile", I'm thinking, " here we go again".

In the field of hifi audio, there are so many "experts" out there that seem to think their words are dogma.

As a DIYer, you are not restrained to a single design only, spending the big bucks to impress the neighbor hood.

You can actually design a system that will shine in your particular room, expectations and constraints.

As Scott said, there are pros and cons to just about every designs out there. As far as fast and tight bass, my big Open Baffle setup trumps any 8" sealed boxes I've heard so far. Both in clarity and feel.

My MLTLs are just so much fun to listen to, I get involved in the music.

I also have a set including a sealed bass driver and open baffle mid-tweet. I enjoy these in a smaller room very much.

One last thing, you came here seeking suggestions from knowlageable folks in here, and when they do, you throw in that you heard some wannabe audiophiles tell you otherwise so you don't want to consider their suggestions. That's a bit.... Well... I'll restrain...

Either consider their suggestions, or just build what you want to build. If it turns out like you expected, then great! If not, then you tweak the design and try again. This is why it's called DIYAudio, and a great way to learn more about the subject and actually form your own opinion on the matter.
 

ICG

Disabled Account
Joined 2007
I think I am not understanding this graph. It shows that at Q=1 the base reaches very high dB, while at Q=0.5 the base drops significantly. This is counter intuitive as the larger the speaker volume the deeper the base should extend indeed... Can you explain mate how I should be reading this graph correctly?

Frequency-response-QTC-sealed-enclosure-530x789.jpg

The graph only shows the amplitude of the Qt but does not take into account what else changes, namely the fb and the lower cut off slope shift upwards and the time till the speaker returns to standstill after an impulse and the waterfall decay becomes much longer with rising Qt.

Here a simulation of a real-world driver (12") with different enclosure volumes.

attachment.php


How does this apply to your Dayton? It looks like this:

attachment.php


As you can see, even if you'd add the roomgain, none of it are really satisfying because of the low spl and not very deep cutoff. That means, if you absolutely want a sealed enclosure, you'd have to use a subwoofer.

On the other hand, a ported enclosure looks so much better:

attachment.php


If you want to stay fullrange and bassreflex is an option for you, that's the way to go.
 

Attachments

  • Q-factor.jpg
    Q-factor.jpg
    117.8 KB · Views: 1,644
  • Dayton_BB_BR-SE.jpg
    Dayton_BB_BR-SE.jpg
    95.9 KB · Views: 1,311
  • Q-Dayton_BB_SE.jpg
    Q-Dayton_BB_SE.jpg
    102.7 KB · Views: 1,297

ICG

Disabled Account
Joined 2007
Drivers got different parameters and in some enclosures they work great, in others not so good. Sealed isn't good for every driver. Well, I thought I'll cut the crap, that's why I just posted the simulations. There you can picture yourself what's more versatile, linear and detailed. I mean, if you don't have bass, there can't be details in it, can it? :rolleyes:
 
Everybody thanks for these new insights! Your suggestions and insights has formed a new understanding on the subject matter and a new valuation of both vented and sealed enclosures, depending on the "many factors" indeed of proper desings.

ICG, your graph is exactly what I was looking for! Great comparison! What programm is that? Is it only in German? How much does this program cost? I would love to play with it and learn more myself playing around with such graphs will allow me to choose for the "best" compromise according to my personal needs and future drivers. If you could personal message me with the saved file I would be very happy.

Your graph is convinving as it compares both "optimal" volumes of the sealed and vented in one gragh, for the frequency responses of this promising driver.

The 80L vented green line looks very nice indeed, I agree with you.
I'm curious how the graph lines would look for a 100 Liters, and 120 Liters vented box.

Sothat I can comapre the vented 80L, 100L, 120L to see how those volumes would theoretically influence the frequency response for this particular modern full range driver.
Thanks everybody, and thanks ICG for your awesome visualisations! Much much appreciated! Sometimes a single graph says more than a thousand words...

Finally just to be sure:
Does "Röhrflache (qcm)" mean the opening size in squared centimeters?
Does "Röhrlange (cm)" mean the length of the opening in centimeters?
 
Status
This old topic is closed. If you want to reopen this topic, contact a moderator using the "Report Post" button.