Sealed/Ported Speakers

[Freddy58]

Hiya folks

Can someone please explain the different characteristics of ported and sealed speakers? Pros and cons? It seems most these days are ported? Oh yes, please keep it simple, cos I ain't the brightest

Cheers...Freddy

 

[CnoEvil]

When you use Ported (of which Transmission Line is a variation eg. PMC & Proac), the room is being used as part of the speaker to reinforce the bass. Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

Ports are hard to get right, as they can "chuff", as air is "puffed out", and their correct tuning is crucial.

Sealed speakers have a bass that can sound tighter and more accurate, but with the trade-off that it doesn't go as deep (for a given size).They are less efficient and need specially designed woofers to cope with the extra pressure involved inside the cabinet.

There are others who are more technical and so can give greater insight.

 

[JamesMellor]

I thought you where getting your old KEF drive units rehoused Freddy

James

 

[Freddy58]

I thought you where getting your old KEF drive units rehoused Freddy

James

No. The plan as it stands is to build some speakers based on my old Kefs. One can still buy the equivalent drive units. Of course, nothing is set in stone. I just wanted to know the differences between ported and sealed. It just confirms what I thought, that in general terms, sealed work best.

 

[Freddy58]

When you use Ported (of which Transmission Line is a variation eg. PMC & Proac), the room is being used as part of the speaker to reinforce the bass. Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

Ports are hard to get right, as they can "chuff", as air is "puffed out", and their correct tuning is crucial.

Sealed speakers have a bass that can sound tighter and more accurate, but with the trade-off that it doesn't go as deep (for a given size).They are less efficient and need specially designed woofers to cope with the extra pressure involved inside the cabinet.

There are others who are more technical and so can give greater insight.

Thanks Cno, a good description

 

[CnoEvil]

It just confirms what I thought, that in general terms, sealed work best.

IMO. That depends on implementation, the positioning and general preference....but they certainly have advantages......but in the end, everything is a compromise.

 

[JamesMellor]

Oh , I was reading your VAS posts that you had these speakers and wanted them repaired / refurbed , are you really sure your best bang for buck is to have custom made speakers ?

It seems to me from your posts you are playing the long game , ie one set of purchaes after consideration no upgradities . So you have time to check out many speakers

James

 

[Freddy58]

Oh , I was reading your VAS posts that you had these speakers and wanted them repaired / refurbed , are you really sure your best bang for buck is to have custom made speakers ?

It seems to me from your posts you are playing the long game , ie one set of purchaes after consideration no upgradities . So you have time to check out many speakers

James

VAS posts? Sorry, I don't understand.

Am I sure I would get best bang for my buck? No, which is why nothing is set in stone. But, as it stands, I've not heard better.

"It seems to me from your posts you are playing the long game , ie one set of purchaes after consideration no upgradities . So you have time to check out many speakers" Eh? I haven't bought anything yet.

Actually, I don't understand....

 

[plastic penguin]

Hiya Freddy

I haven't heard infinite baffle speakers at home for years, but I do know they pose their own challenges (different from ported); They will require careful amp matching, as they they can low impedance/ohms. However, they major benefits: They are far easier to place, especially for small rooms.

I'm sure some clever Charlie will try to prove me wrong, but by their very definition (closed/sealed box) the drivers lack the air the ported ones have, therefore, in the main, will require a fairly gutsy amp to make the most of them.

 

[Freddy58]

Hiya PP

Sorry, but could you edit your post? It doesn't read right

 

[JamesMellor]

Hiya Freddy ,

"Eh? I haven't bought anything yet." , thats exactly what I meant by the long game , you are taking your time checking all your options.

James

 

[Freddy58]

I see. I still don't understand this though...

Oh , I was reading your VAS posts that you had these speakers and wanted them repaired / refurbed , are you really sure your best bang for buck is to have custom made speakers ?

I'm not on any other forum. Link please?

 

[Rethep]

Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

"Sealed" and "infinite baffle" are not the same! An "infinite baffle" can be compared to a "port", but the hole is much bigger.

 

[davedotco]

This is a pretty complex issue.

Strongly recommend that you take a look at the Speaker Design Cookbook.

https://docs.google.com/file/d/0B_l73GVBBlIUNTc2YTc2YTktNTNmYi00YWNmLTlmY2ItZTU0MTRhMzdkYTAy/edit?pli=1

Chapters 1 and 2 tell you all you need to know, in plain english and with minimal maths.

 

[CnoEvil]

Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

"Sealed" and "infinite baffle" are not the same! An "infinite baffle" can be compared to a "port", but the hole is much bigger.

"Infinite Baffle" is a great description of how I feel about the complexities of speaker design.

If I have got it wrong, then apologies, but this is what Wiki says:

"Infinite baffle" or simply "IB" is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of a driver at low frequencies.

If you meant to say that Bass Reflex and Transmission Line designs are very different, then I agree; with TL showing some of the advantages of a Sealed cabinet..

 

[chebby]

Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

"Sealed" and "infinite baffle" are not the same! An "infinite baffle" can be compared to a "port", but the hole is much bigger.

"Infinite Baffle" is a great description of how I feel about the complexities of speaker design.

If I have got it wrong, then apologies, but this is what Wiki says:

"Infinite baffle" or simply "IB" is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of a driver at low frequencies.

Strictly speaking, the differentiation of the two terms is valid. A true 'infinite baffle' would not present any 'damping' or resistance to large movements of a bass/mid cone because there would be no trapped volume of air like you'd get in a sealed cabinet. The volume of air behind a theoretical 'infinite baffle' would itself be infinite and offer no resistance to the movement of a speaker cone. (Too large a volume of air to be compressed or expanded by the movement of the speaker cones.)

However, for whatever historical reasons, 'infinite baffle' and 'sealed cabinet' (or sealed enclosure) have become (albeit wrongly) interchangeable terms and I have frequently been guilty of using both.

 

[CnoEvil]

Strictly speaking, the differentiation of the two terms is valid. A true 'infinite baffle' would not present any 'damping' or resistance to large movements of a bass/mid cone because there would be no trapped volume of air like you'd get in a sealed cabinet. The volume of air behind a theoretical 'infinite baffle' would itself be infinite and offer no resistance to the movement of a speaker cone. (Too large a volume of air to be compressed or expanded by the movement of the speaker cones.)

However, for whatever historical reasons, 'infinite baffle' and 'sealed cabinet' (or sealed enclosure) have become (albeit wrongly) interchangeable terms and I have frequently been guilty of using both.

Thx Chebby.

So IB means that Driver is just mounted in a much bigger sealed enclosure...if there was no enclosure, it would be Open Baffle (which would be even more Infinite).

 

[davedotco]

Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

"Sealed" and "infinite baffle" are not the same! An "infinite baffle" can be compared to a "port", but the hole is much bigger.

"Infinite Baffle" is a great description of how I feel about the complexities of speaker design.

If I have got it wrong, then apologies, but this is what Wiki says:

"Infinite baffle" or simply "IB" is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of a driver at low frequencies.

Strictly speaking, the differentiation of the two terms is valid. A true 'infinite baffle' would not present any 'damping' or resistance to large movements of a bass/mid cone because there would be no trapped volume of air like you'd get in a sealed cabinet. The volume of air behind a theoretical 'infinite baffle' would itself be infinite and offer no resistance to the movement of a speaker cone. (Too large a volume of air to be compressed or expanded by the movement of the speaker cones.)

However, for whatever historical reasons, 'infinite baffle' and 'sealed cabinet' (or sealed enclosure) have become (albeit wrongly) interchangeable terms and I have frequently been guilty of using both.

Which is why the Americans, in particular, often use the term 'acoustic suspension' to describe sealed box louspeakers.

Though to be strictly correct, this term should only really be used when the limiting factor for cone movement is the resistance to compression of the air inside an enclosure, rather than the suspension (cone surround and 'spider') of the drive unit itself.

In the real world, both factors come into play.

 

[plastic penguin]

Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

"Sealed" and "infinite baffle" are not the same! An "infinite baffle" can be compared to a "port", but the hole is much bigger.

"Infinite Baffle" is a great description of how I feel about the complexities of speaker design.

If I have got it wrong, then apologies, but this is what Wiki says:

"Infinite baffle" or simply "IB" is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of a driver at low frequencies.

Strictly speaking, the differentiation of the two terms is valid. A true 'infinite baffle' would not present any 'damping' or resistance to large movements of a bass/mid cone because there would be no trapped volume of air like you'd get in a sealed cabinet. The volume of air behind a theoretical 'infinite baffle' would itself be infinite and offer no resistance to the movement of a speaker cone. (Too large a volume of air to be compressed or expanded by the movement of the speaker cones.)

However, for whatever historical reasons, 'infinite baffle' and 'sealed cabinet' (or sealed enclosure) have become (albeit wrongly) interchangeable terms and I have frequently been guilty of using both.

Which is why the Americans, in particular, often use the term 'acoustic suspension' to describe sealed box louspeakers.

Remember Wharfedale using that term with their Dentons and Lintons. There were owned by Rank Organisation, which ties in.

 

[davedotco]

Strictly speaking, the differentiation of the two terms is valid. A true 'infinite baffle' would not present any 'damping' or resistance to large movements of a bass/mid cone because there would be no trapped volume of air like you'd get in a sealed cabinet. The volume of air behind a theoretical 'infinite baffle' would itself be infinite and offer no resistance to the movement of a speaker cone. (Too large a volume of air to be compressed or expanded by the movement of the speaker cones.)

However, for whatever historical reasons, 'infinite baffle' and 'sealed cabinet' (or sealed enclosure) have become (albeit wrongly) interchangeable terms and I have frequently been guilty of using both.

Thx Chebby.

So IB means that Driver is just mounted in a much bigger sealed enclosure...if there was no enclosure, it would be Open Baffle (which would be even more Infinite).

There are two factors to consider here.

Firstly there is the issue of the radiation from the rear of the cone mixing with, and cancelling out the radiation from the front of the cone, this is not the case in a true infinite baffle, neither is it a case for sealed enclosures, for obvious reasons.

Secondly there is the issue of 'loading' on the drive unit. On a true infinite baffle there is no loading on the cone as there is no compression of the air caused by cone movement. The drive unit behaves as it would in 'free air' in this respect. If a large sealed enclosure is used then the loading may be minimal and the drive unit will behave in the same way as it would on a true infinite baffle. In the real world, small enclosures are required so the loading on the cone from the trapped air becomes important, often the dominant factor, drive units are built with this in mind so this is not a problem.

Interestingly the parameters that make a drive unit suitable for a sealed enclosure are different to those required for a ported enclosure. Most modern drive units are built for ported enclosures.

 

[davedotco]

Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

"Sealed" and "infinite baffle" are not the same! An "infinite baffle" can be compared to a "port", but the hole is much bigger.

"Infinite Baffle" is a great description of how I feel about the complexities of speaker design.

If I have got it wrong, then apologies, but this is what Wiki says:

"Infinite baffle" or simply "IB" is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of a driver at low frequencies.

Strictly speaking, the differentiation of the two terms is valid. A true 'infinite baffle' would not present any 'damping' or resistance to large movements of a bass/mid cone because there would be no trapped volume of air like you'd get in a sealed cabinet. The volume of air behind a theoretical 'infinite baffle' would itself be infinite and offer no resistance to the movement of a speaker cone. (Too large a volume of air to be compressed or expanded by the movement of the speaker cones.)

However, for whatever historical reasons, 'infinite baffle' and 'sealed cabinet' (or sealed enclosure) have become (albeit wrongly) interchangeable terms and I have frequently been guilty of using both.

Which is why the Americans, in particular, often use the term 'acoustic suspension' to describe sealed box louspeakers.

Remember Wharfedale using that term with their Dentons and Lintons. There were owned by Rank Organisation, which ties in.

The term 'acoustic suspension' was coined in the late 50s by american speaker designer Edgar Villchur, then president of Acoustic Research. The AR speakers of the day were highly regarded and spawned many imitators, most noteably KLH.

British loudspeakers of this period still used the term infinite baffle, possibly in deference to the americans. As I explained above there is a difference between acoustic suspension and infinite baffle (as in sealed box) that was pretty clear at that time but much less defined in later years.

Whether this was to do with the convergeance of the two technologies or loose marketing BS, I could not say.

 

[plastic penguin]

Sealed (Infinite Baffle) keeps its "atmosphere" contained within the speaker, so the room plays much less of a role.

"Sealed" and "infinite baffle" are not the same! An "infinite baffle" can be compared to a "port", but the hole is much bigger.

"Infinite Baffle" is a great description of how I feel about the complexities of speaker design.

If I have got it wrong, then apologies, but this is what Wiki says:

"Infinite baffle" or simply "IB" is also used as a generic term for sealed enclosures of any size, the name being used because of the ability of a sealed enclosure to prevent any interaction between the forward and rear radiation of a driver at low frequencies.

Strictly speaking, the differentiation of the two terms is valid. A true 'infinite baffle' would not present any 'damping' or resistance to large movements of a bass/mid cone because there would be no trapped volume of air like you'd get in a sealed cabinet. The volume of air behind a theoretical 'infinite baffle' would itself be infinite and offer no resistance to the movement of a speaker cone. (Too large a volume of air to be compressed or expanded by the movement of the speaker cones.)

However, for whatever historical reasons, 'infinite baffle' and 'sealed cabinet' (or sealed enclosure) have become (albeit wrongly) interchangeable terms and I have frequently been guilty of using both.

Which is why the Americans, in particular, often use the term 'acoustic suspension' to describe sealed box louspeakers.

Remember Wharfedale using that term with their Dentons and Lintons. There were owned by Rank Organisation, which ties in.

The term 'acoustic suspension' was coined in the late 50s by american speaker designer Edgar Villchur, then president of Acoustic Research. The AR speakers of the day were highly regarded and spawned many imitators, most noteably KLH.

British loudspeakers of this period still used the term infinite baffle, possibly in deference to the americans. As I explained above there is a difference between acoustic suspension and infinite baffle (as in sealed box) that was pretty clear at that time but much less defined in later years.

Whether this was to do with the convergeance of the two technologies or loose marketing BS, I could not say.

Yeah, come to think about it it was the 'E' series which had the term 'acoustic suspension'.

Pity AR still aren't making loudspeakers, they were on e of my favourites back in the late 70s.... way beyond my budget, though.

 

[Freddy58]

Hiya folks, thanks for the replies.

TBH, most of this stuff is over my head. I just wanted to know the basic differences, and their merits/drawbacks.

Thanks for the link Dave, but after a bit, it seemed like rocket science. See? I told you I wasn't the brightest

 

[Freddy58]

Dave, as an aside, are you familiar with the Kef Concord lV's? If so, what were your impressions?

 

[davedotco]

Yeah, come to think about it it was the 'E' series which had the term 'acoustic suspension'.

Pity AR still aren't making loudspeakers, they were on e of my favourites back in the late 70s.... way beyond my budget, though.

I loved the AR18s (the flat fronted ones) of the late 70s, though I do not think they were 'real' ARs by that stage. Villchur left AR in 1967 or thereabouts, the classic line up of the early seventies derived from Villchur's original AR3, we are talking AR3a, the AR6, AR4ax etc, etc.

I do not know who owned the brand by the time of the AR17s and 18s, but they were very different from the classic line up.