Dera all,
i would like to understand beyond the technical issues, what changes tonally in sound between a closed box and an aperiodic one such as the Dynaudio variovent.
Thanks
i would like to understand beyond the technical issues, what changes tonally in sound between a closed box and an aperiodic one such as the Dynaudio variovent.
Thanks
Here are some observations that have been made regarding the tonality of an aperiodic enclosure compared to a closed box of the same volume.
1. The lower amplitude of the bass resonance hump improves the reproduction of speech (aperiodic means 'without period', i.e., without resonance).
2. The bass cut-off frequency is slightly lower.
3. The transient response is better resulting in a more accurate reproduction of rapidly-changing music signals.
I hope that's sufficiently "beyond the technical issues".
The reduction in the impedance peak as such is of no interest. However, it should be easy to measure if the vent reduce the driver output or not.
Any vent resisitive or not will reduce the protection against large cone movements especially subsonic ones that a closed box gives.
Any vent resisitive or not will reduce the protection against large cone movements especially subsonic ones that a closed box gives.
1. Yes, and bass is generally tighter.
2. Well, my measurements tell otherwise - slightly higher cut-off frequency. Not that can be heard as deficiency.
3. Yes - in the bass range.
Wrong. It tell us the Qtc parameter (the closed box Q) is lower, which means tighter bass reproduction.
As far as I'm remembering an aperiodic enclosure was used to linearize the response of a high-Qts-Driver mounted in an closed enclosure which is actual too small to get a flat response in bass.
Kind regards
Michael
Kind regards
Michael
I bow to your measurements. I based my statement on what speaker designer Steve Hutton wrote back in the 70s - the low frequency cut-off of a well designed aperiodic enclosure is in the order of 1.5 to 2.0 x Fs, not as low as a reflex, but better than a closed box of the same volume.
However, I also read that the bass rolls of at 18dB/octave compared to the 12dB/octave of a sealed enclosure.
I perceive the sound to be more 'open' - less confined to the box if you know what I mean.
You did say "beyond the technical issues", didn't you? 🤓
If you HEAVILY stuffed a closed box enough, would it behave like an aperiodic vented box? On some bass enclosures, I've firmly stuffed the lower half (kept in place by the bracing) and left the upper half where the bass drivers are) empty, and they sound quite taught, dispight the small volume.
When discussing aperiodic vented speakers, shouldn't vented to atmosphere designs be distinguished from two chambers with a vent connecting them?
When discussing aperiodic vented speakers, shouldn't vented to atmosphere designs be distinguished from two chambers with a vent connecting them?
Don't think they will sound the same.
It is not the same fighting enclosure air springiness which creates a very defined single peak combined with moving mass than loading same cone with an untuned resistive load, even if you can damp closed box a lot
In any case, aperiodic cabinets were very popular way back then to solve then prevalent stiff high Q under magnetized speakers.
Only way to get some Bass was to use a larger speaker, but in general it created unbearable boominess.
Losing some crude Bass by resistive means was well worth the flatter response.
We've advanced a lot since.
It is not the same fighting enclosure air springiness which creates a very defined single peak combined with moving mass than loading same cone with an untuned resistive load, even if you can damp closed box a lot
In any case, aperiodic cabinets were very popular way back then to solve then prevalent stiff high Q under magnetized speakers.
Only way to get some Bass was to use a larger speaker, but in general it created unbearable boominess.
Losing some crude Bass by resistive means was well worth the flatter response.
We've advanced a lot since.
In the context of the question being asked by diypass, I would think both variations offer the same tonal advantages over a closed box.
That's me being "non-technical" again!
Pictured below are Dynaco double chamber enclosures. The 'blue' slit connecting the upper chamber with the lower is filled with compressed fibreglass, forming an 'acoustic resistance'.
Something i associate with low-pressure boxes.
Aperiodic is used for a wide ranghe of boxes. I doubt any are truly aperiodic. How it will sound will depend on the driver and the box and how aperiodic it is.
The faltter impedance means the speaker will be happy with a wider variety of amplifier output Z.
The Dynaaudio Variovent is a poorish aperidoc vent.
My miniOnkens are relex pushed towards aperiodic, works well.
I have used aperiodic loading to help lower the total box Q of woofers that really aren’t happy in a box and end up flattening the hump and extendeding the bass response.
I have used (semi-) aperiodic midTL for my midTweeters. Bass response is not as deep.
dave
Hi,
I use the scanspeak variovent. I found the sound is better, the sound is less boxy, less compression on the sound, the displacement of the cone seems easier. The midrange is improve.
Regards.
Well, that's what I rather think too... But I may be wrong, since I never exeprimented that formula.
Personally, I am not so sure that the "Variovent leak" offers enough aperiodicity, compared to a sealed, rather large, fully filled enclosure with a QTC of 0.71...
T