Ported Cab's or non Ported....

[SS73]

Just playing round with kit n comparing speaker cabs and thinking out loud, so I'm playing through my Trace 810 ( which has no porting at all, really from a cab designers view its basic and not very clever with no baffle material, nothing, just bare mdf and good speakers) now drag in the Hartley Thompson 410 (specially designed reflex porting, nice materials etc) from the garage :-
The 410 has def a lower freq range and goes really low, nice tone and quite pure, but its slow.
The 810 is def more middle the kind of middy growl just like the old SVT 810's , but its so fast and really responsive.

Now I'm not sure how all these things change when your 30ft back from the stage but I'm loving this fast sound from the 810 n could live with the drop in definition too, just to get that middy growl, could be wrong but all 6 string lead guitar cabs are non ported too, must be a reason. Just thought I'd throw this in and see where it goes.

[Mr. Foxen]

What do you mean by fast? Does the ported cab lag behind notes? Fairly sure that thing was made up because that 'slow response to transient peaks' idea would just produce distortion. Mostly, middle agrees with your ears more, which is why people of unsubtle taste are drawn to the sound of guitars, and guitar cabs are sealed, guitars have rather more range than guitar cabs, and sound rubbish if that whole range is being produced, you just want everyhting piled into the middle bit, which is why guitar cabs are sealed with no tweeters; less low, less high. Other forum members have a bit more tech to them, but if you want to argue the 'slow' point, go right ahead, I'll watch.

I use a sealed 8x10 for guitar type distortion, loads of mids and not much horrible squeal, but I run another ported cab for lows.

[rodl2005]

I posted a 'highly debated' thread over on TB a yr or so ago rethe 'fast vs slow' response of cabs...... as I said- HIGHLY debated! General consensus is that ported cabs have to be designed nicely so that the sound outa the ports is 'tuned' & not outta phase(???????) I'm a total dweeb when it comes to tech stuff here, BUT I do know what I like etc... & I know that my sealed cabs do sound tighter in the bass response than the ported SVT410HLF I A/B'd it with. This was an A/B test using a 300w all tube SVT, into A-SVT410HLF & B-Bergantino NV610. Apart from the NV610 blowing the Ampeg outta the water-TOTALLY, we noticed that the sealed cab seemed-as I said- tighter in bass response & had far more clarity at high(ish) volumes. Sure these 2 cabs are chalk n cheese, but it was interesting & fun.

[alexclaber]

A badly designed ported cab may indeed have boomy lows. But a well designed ported cab will be just as quick as a sealed cab - any impression of slowness will simply be due to it having more bottom - lows by their very nature cannot be fast. The overriding factor for whether a cab sounds quick or not is its midrange and treble response - the more it makes of the attack transients, the quicker it will sound. The quickest tightest most impulse perfect subwoofer will always sound slow until a midrange/treble speaker is added.

Alex

[davidmpires]

But that's not the case with the Compact.
It's quick without having a mid or a tweeter and it's also sealed.

now i'm confused

[Stewart]

The Barefaced Compact isn't sealed

[alexclaber]

[quote name='davidmpires' post='565661' date='Aug 11 2009, 09:14 AM']But that's not the case with the Compact.
It's quick without having a mid or a tweeter and it's also sealed.[/quote]

Definitely not sealed - big slot port at the front! The sound has plenty of midrange and a fair bit of treble - although it's a single driver it isn't a subwoofer, hence it has the transient attack to sound quick.

Alex

[SS73]

thanks for the quick responses, informed stuff I can see this has been debated before. The original post came from one of those evenings where boredom overrides logic and you hunt for something. But that something was the 410 did sound different and the 410 did seem slower than the 810, the 410 has been complimented many times on its room filling sound with cutting treble and smooth lows. The 810 makes me think I'm becoming more guitar like!! heaven forbid!! no its a different sound altogether and I do feel its faster, inside its 4 x 210's sat on top of each other, so if you strike a note with a sealed 10 the speaker moves back until it can't compress the air in the cab further then that compression drives the speaker cone back ready for the next signal, with a ported cab it will travel back further creating more sound and pushing more air but on its way back there's not much help from compression so its just the spring in the material to get it back so it must be slower surely.

[davidmpires]

Dumb ass, I meant to say not sealed.

[alexclaber]

[quote name='SS73' post='565668' date='Aug 11 2009, 09:30 AM']...if you strike a note with a sealed 10 the speaker moves back until it can't compress the air in the cab further then that compression drives the speaker cone back ready for the next signal, with a ported cab it will travel back further creating more sound and pushing more air but on its way back there's not much help from compression so its just the spring in the material to get it back so it must be slower surely.[/quote]

If the speaker didn't move back to the centrepoint quickly enough then the note would go out of tune. It has to move at the input frequency - that determines the speed.

One of the key factors which differentiates ported and sealed cabs is that properly designed sealed cabs use speakers which have weaker motors and looser suspension so they rely on the back pressure to damp their movement, whilst a well designed ported cab uses speakers with stronger motors and tighter suspension so the damping comes from the driver itself.

Alex

[SS73]

[quote name='alexclaber' post='565677' date='Aug 11 2009, 09:42 AM']If the speaker didn't move back to the centrepoint quickly enough then the note would go out of tune. It has to move at the input frequency - that determines the speed.

One of the key factors which differentiates ported and sealed cabs is that properly designed sealed cabs use speakers which have weaker motors and looser suspension so they rely on the back pressure to damp their movement, whilst a well designed ported cab uses speakers with stronger motors and tighter suspension so the damping comes from the driver itself.

Alex[/quote]

Ok that makes sense, but because the ported cab is producing more sound and moving more air, would this not affect speed.

[Mr. Foxen]

[quote name='SS73' post='565668' date='Aug 11 2009, 09:30 AM']so if you strike a note with a sealed 10 the speaker moves back until it can't compress the air in the cab further then that compression drives the speaker cone back ready for the next signal, with a ported cab it will travel back further creating more sound and pushing more air but on its way back there's not much help from compression so its just the spring in the material to get it back so it must be slower surely.[/quote]

Its powered both ways so pressure inside and outside the cab affects it both ways. One way you are compressing inside, the other way you are trying to create a vacuum.

[alexclaber]

[quote name='SS73' post='565688' date='Aug 11 2009, 09:49 AM']Ok that makes sense, but because the ported cab is producing more sound and moving more air, would this not affect speed.[/quote]

No.

Alex

[Bill Fitzmaurice]

[quote name='SS73' post='565688' date='Aug 11 2009, 04:49 AM']Ok that makes sense, but because the ported cab is producing more sound and moving more air, would this not affect speed.[/quote]
No. In both cases the cone will move at the same frequency. If the cone is traveling a longer peak to peak distance the actual speed at which it's moving is faster. This doesn't affect what one might refer to as fast versus slow response. If it did then the volume at which one plays, which also changes the distance the cone moves, would change the response.
The primary reason why most commercial vented cabs sound significantly different from sealed is poor cabinet design. They simply put drivers into too small a box, resulting in a boomy midbass. It's possible to produce a vented cab with response indistinguishable from sealed, with none of the shortcomings of a sealed cab.

[Badass]

Think this is on topic...

Is this why my small 1x10 practice combo sometimes sounds like the bottom 'E' blooms, for want of a better word? Almost like it is a little flat and them resolves in a split second. (Ashdown perfect 10 - front ports) Or is that the room, or just poor design of the combo. Just curious.

As it doesn't happen with my larger rigs.

Edited August 11, 2009 by Badass

[alexclaber]

Hard to say unless it does it outdoors - indoors the room effects on bass response are pretty overwhelming.

Alex

[Bill Fitzmaurice]

[quote name='Badass' post='565930' date='Aug 11 2009, 09:32 AM']Think this is on topic...

Is this why my small 1x10 practice combo sometimes sounds like the bottom 'E' blooms, for want of a better word? Almost like it is a little flat and them resolves in a split second. (Ashdown perfect 10 - front ports) Or is that the room, or just poor design of the combo. Just curious.

As it doesn't happen with my larger rigs.[/quote] A small 1x10 combo will have very little output at the 40 Hz fundamental, and not a lot at the 80 Hz second harmonic. So in the lower notes you're hearing virtually no fundamental, a bit of second harmonic, and a lot of third harmonic, around 120 Hz. The third harmonic is a bit 'off' from what your ear wants to hear as the dominant, and that probably explains it.

[Badass]

Thinking about it, it does seem to happen more in the small practice room we have (12' x 10' ) than anywhere else I have tried it, so could be the room.

This whole frequency vs room size vs cab volume vs speaker sizes, vs the always present unknown variable, is a complete mystery to me. I will see if it changes in different spaces.

EDIT:
Ah that may explain it too [b]Bill[/b]. Great little practice amp, just this small annoyance.

Cheers guys

Edited August 11, 2009 by Badass

[Bill Fitzmaurice]

[quote name='Badass' post='565953' date='Aug 11 2009, 10:00 AM']I will see if it changes in different spaces.[/quote]
It will. This explains why:
[url="http://www.padrick.net/LiveSound/CancellationMode.htm"]http://www.padrick.net/LiveSound/CancellationMode.htm[/url]

[Badass]

cheers [b]Bill[/b].

[escholl]

[quote name='alexclaber' post='565637' date='Aug 11 2009, 08:22 AM']But a well designed ported cab will be just as quick as a sealed cab[/quote]

aren't you forgetting group delay? always several times higher in ported cabs than sealed, by their design.

[alexclaber]

[quote name='escholl' post='566984' date='Aug 12 2009, 04:58 PM']aren't you forgetting group delay? always several times higher in ported cabs than sealed, by their design.[/quote]

All the evidence suggests that the group delay of a well designed ported cab is inaudible. Bear in mind that the group delay of a typical highpass filter will be much greater than that of a good ported cab, yet I would still always recommend using such a filter when available because the advantages are clearly audible whilst the disadvantages aren't.

Alex

[escholl]

[quote name='alexclaber' post='567010' date='Aug 12 2009, 05:29 PM']All the evidence suggests that the group delay of a well designed ported cab is inaudible. Bear in mind that the group delay of a typical highpass filter will be much greater than that of a good ported cab, yet I would still always recommend using such a filter when available because the advantages are clearly audible whilst the disadvantages aren't.

Alex[/quote]

i'm not sure where you've gotten your evidence, but all the research and analysis suggests contrarily. group delay is just as important to the time-domain accuracy as any other factor -- i think you are under-estimating it. i'm not saying ported designs don't have their merits, i'm simply saying the group delay of a ported cab is always going to be longer than that of a sealed one. there will be an audible difference.

an electronic filter will have it's own group delay, yes, however it depends entirely on the filter design. it is likely to be less than that of any speaker, however.

[Bill Fitzmaurice]

[quote name='alexclaber' post='567010' date='Aug 12 2009, 12:29 PM']All the evidence suggests that the group delay of a well designed ported cab is inaudible.[/quote]
+1. Group delay is inaudible in the non-directional frequencies, for the same reason that they are non-directional.

[stevie]

[quote name='Bill Fitzmaurice' post='567224' date='Aug 12 2009, 07:48 PM']+1. Group delay is inaudible in the non-directional frequencies, for the same reason that they are non-directional.[/quote]
Lots of strongly held opinions here but not much evidence (make that no evidence). This is not the scientific way, guys. It isn't so just cos you say so.