Sealed box speakers are better with a TT !

CnoEvil

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Back when I was young and life was simple, reflex speakers were not common....and during my TT owning days, most of my speakers were indeed "closed boxes." I never really gave it much thought, and certainly didn't associate it with being any type of logical solution....until I read this snippet in HiFi News by Keith Howard, when he was talking about Reflex Loaded speakers:

"This (reflex) is a feature that need be of no concern to potential buyers of Digital sources, but may be of relevance to LP aficionados. This is because closed box loading, better controls cone excursion at very low frequencies, obviating the cone flap that occurs when playing warped or rippled vinyl, particularly if the arm/cartridge combination has a poorly placed and damped fundamental resonance.
By using up available cone excursion, and perhaps even pushing it beyond the drivers linear range, this infrasonic diaphragm dance squanders output capability and increases distortion. If you're an LP user, this is something to bear in mind if going for a reflex speaker."

Certainly my speaker cones have not suffered from "Tourette's" since my TT went on permanent sabbatical.

So, what do you think?

Cno
 

CnoEvil

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chebby said:
I would agree with the first five words of the title regardless of what the source is.

I assume you are talking in general, as a construction method to give the best performance, rather than saying that every infinite baffle speaker is better than every ported one?

Do you put any credence in what HFN are saying regarding the suitabilty of ported speakers with TTs?
 

hoopsontoast

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Yes, Closed box speakers (as long as the box has the 'Q' of 0.707 or less) should have less distortion over a ported enclosure for a given level.

But I find sealed box speakers have better quality bass IME, more even bass response and less overhang, hence my love of small sealed mini-monitors (SCM7, Kolt etc).

Although with a TT source, most phonostages have a rumble filter that pretty much removes that problem with warped records. But you can get problems with vibrations through the floor when walking etc that can cause similar 'undulations' with the cone, and a sealed box will help a little with that.
 

CnoEvil

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hoopsontoast said:
Yes, Closed box speakers (as long as the box has the 'Q' of 0.707 or less) should have less distortion over a ported enclosure for a given level.

But I find sealed box speakers have better quality bass IME, more even bass response and less overhang, hence my love of small sealed mini-monitors (SCM7, Kolt etc).

Although with a TT source, most phonostages have a rumble filter that pretty much removes that problem with warped records. But you can get problems with vibrations through the floor when walking etc that can cause similar 'undulations' with the cone, and a sealed box will help a little with that.

Cheers Hoops.

I suppose the trade off is bass depth, unless you have a 12" woofer, like Lindsayt extols the virtue of.
 

hoopsontoast

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It really depends, if the driver has a medium-high Qts (0.4+) then you should be able to get decent bass response from a sealed box.

This graph sort of shows a comparison, where the sealed box (Yellow trace) has a 6dB/Octave roll off and the ported (white trace) a 12dB/Octave roll off.

db393850_htf_imgcache_43104.jpeg
 
A

Anonymous

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A ported design will boost the bass around the frequency the port is tuned to but the trade off is that below the port tuning frequency the cabinet offers no suspension to the cone and so the output drops off massively below the tuning frequency.

The result of this is that A) you actually get LESS bass extention in typical ported designs (not all of course) but more 40-50hz bass (which is a typical tuning point).

In a sealed box you get MORE bass extension as the speaker can work properly as it has cabinted suspension at all frequencies, you do tend to get less output though so really it's swings and roundabouts. Personally I prefer the sound of sealed speakers compared to ported but you then need subs to get decent bass levels and to be honest nowadays I can't be bothered with trying to design such a system which is why I have gone for PMC GB1s which are transmission line and tuned fairly low.

I digress, as ported speakers offer no suspension below the truning frequency the speaker has no protection agains the low subsonic rumble from vinyl which I suppose is A) bad for the drive unit and B) my affect the sound slightly.
 

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