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CnoEvil's picture
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Transmission Line vs Reflex Ported vs Isobaric

Just wanted to know if anyone knows the advantages or disadvantages of each...in layman's lingo.

This would be in terms of quantity, quality and tunefulness of the bass produced.

I have heard that TL is more difficult to get right and so possibly more expensive to produce...as well as being drier sounding and possibly less weighty. I have also read this, which I don't know if it's true, and I paraphrase:

"Real world TL speakers like PMC are really quarter-wave TLs, ie. the line length is 1/4 the wavelength of the resonance frequency the bass driver is tuned to.

This means it's nothing but a Bass Reflex variant, that offers no real advantage over a classic Reflex alignment."

So any comments, preferences or insights would be much appreciated.

Cno

"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass

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RE: Transmission Line vs Reflex Ported vs Isobaric

My favorite subject ... na, not really

Personally I think, ports belong on the back, better still radiate downwards but if they have to be to the front, a well damped transmission line is probably the way to go.

regards

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RE: Transmission Line vs Reflex Ported vs Isobaric

Why have you left out loudspeakers with sealed cabinets?

The whole industry - barring a few exceptions - have left them out as well. Thirty years ago, sealed cabinet designs occupied every price point including low budget. (AR7s, Videoton Minimax and upwards.)

The world of hi-fi sounded much nicer as a result (better midrange for a start). Have these companies lost the skills they once had? Or is it just too expensive to make them nowadays? 

 

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RE: Transmission Line vs Reflex Ported vs Isobaric

Makes me reminisce of the Sabre's I used to have.

Perhaps it is that cabinets as well as drivers were often larger. Perhaps its speaker sensitivty and show room appeal. It 'looks better' if a volume control is only at 9 ...

With the trend towards ever slimmer/smaller cabinets etc it was probably inevitable that IB's are not that common anymore.

regards

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RE: Transmission Line vs Reflex Ported vs Isobaric

Don't forget the sealed-box (EB2's for example).

I guess each design has its own merits dependant on size of the room. Whilst the reflex ported tend to be more common due to being easier to produce.

I have a thing about rear-ported designs as I have never been fortunate enough to live in a house with rooms large enough to adequately utilise this design. (Downward firing ports are acceptable however).

I have not heard an isobarik design for a long while, I still wonder why it never became more popular, driver costs I suppose.

Loads of second hand expensive kit!

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RE: Transmission Line vs Reflex Ported vs Isobaric

To my mind it is all in the execution - there are good and bad examples of each design. Much like LCD vs Plasma or diesel vs petrol there are pros and cons for each individual user. The great thing is there is plenty of choice.

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RE: Transmission Line vs Reflex Ported vs Isobaric

chebby wrote:

Why have you left out loudspeakers with sealed cabinets?

The whole industry - barring a few exceptions - have left them out as well. Thirty years ago, sealed cabinet designs occupied every price point including low budget. (AR7s, Videoton Minimax and upwards.)

The world of hi-fi sounded much nicer as a result (better midrange for a start). Have these companies lost the skills they once had? Or is it just too expensive to make them nowadays? 

 

 

+1! Also, it seems to me that every other speaker review these days mentions 'giving them some air' and 'moving out from walls' etc. So we're supposed to put our speakers in the middle of the room? In the real world almost every one places them near a wall, and even, God forbid, in a corner!!

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RE: Transmission Line vs Reflex Ported vs Isobaric

chebby wrote:

Why have you left out loudspeakers with sealed cabinets?

The whole industry - barring a few exceptions - have left them out as well. Thirty years ago, sealed cabinet designs occupied every price point including low budget. (AR7s, Videoton Minimax and upwards.)

The world of hi-fi sounded much nicer as a result (better midrange for a start). Have these companies lost the skills they once had? Or is it just too expensive to make them nowadays? 

I purposefully left them out because I grew up with them and have a much clearer idea of the advantages/disadvantages.

When looking at how to get that extra bass depth/efficiency from a cabinet, the above three ways are the most common, so I was just wondering about what made a manufacturer go for one, as opposed to the other.:

Proac/PMC - TL

Kef + most others - Reflex

Linn/Neat - Some Isobaric designs

One doesn't often see this discussed, as it's always Ported vs Sealed that comes up.

Maybe some of the speaker designers on here would like to chip in.

"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass

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RE: Transmission Line vs Reflex Ported vs Isobaric

TheHomeCinemaCentre wrote:

To my mind it is all in the execution - there are good and bad examples of each design. Much like LCD vs Plasma or diesel vs petrol there are pros and cons for each individual user. The great thing is there is plenty of choice.

Yes, but if correctly executed, are there any characteristics of the sound that differ, due to the different implementations?

"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass

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RE: Transmission Line vs Reflex Ported vs Isobaric

CnoEvil wrote:

Transmission Line vs Reflex Ported vs Isobaric

none of the above.

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RE: Transmission Line vs Reflex Ported vs Isobaric

CnoEvil wrote:

When looking at how to get that extra bass depth/efficiency from a cabinet,

doesn't really matter. ports as well as TLs introduce low midrange noise. and this can actually be quite severe. but I gueass everybody prefers phat bass lines rather than ultimate midrange clarity. otherwise sealed designs would have never go out of fashion.

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RE: Transmission Line vs Reflex Ported vs Isobaric

CnoEvil wrote:

Linn/Neat - Some Isobaric designs

punishing for your amp.

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RE: Transmission Line vs Reflex Ported vs Isobaric

oldric_naubhoff wrote:

CnoEvil wrote:

Transmission Line vs Reflex Ported vs Isobaric

none of the above.

I appreciate everybody's input, but almost all the answers are for a question I haven't asked.

I'm well aware of the advantages of a sealed cabinet and even Electrostatic/Maggie type panels, but am less sure about the 3 types I've mentioned in the title.....eg. Does the TL type design have a clear advantage, or is a lot of it to do with "marketing  mystique".

Don't mean to sound ungrateful for input so far

Cno

"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass

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RE: Transmission Line vs Reflex Ported vs Isobaric

oldric_naubhoff wrote:

CnoEvil wrote:

Linn/Neat - Some Isobaric designs

punishing for your amp.

The Linn Isobarik speakers are punishing for amps because the idiot designer wired two nominally 8 ohm drivers in parallel for the bass, midrange and treble, resulting in 4 ohm speakers with dips well below 4 ohms. They'd be an easier amplifier load if he'd used 16 ohm drivers wired in parallel, or 4 ohm drivers wired in series. He also used relatively heavy medium sized bass KEF bass drivers - which keeps the efficiency down. It's no wonder that these speakers make good candidates for active amplification - just to give the amps an easier time.

 

Linn Saras are also punishing loads for similar reasons.

 

Ferrograph S1 speakers are basically half an Isobarik in terms of drive units, and possibly better speakers because of it.

 

I have a feeling that if you took all the drivers from an Isobarik and mounted them all on the front baffle of a larger box you'd have a better sounding speaker. Better imaging for a start, and more dynamic bass too.

 

The big advantage of the Isobarik design compared to the more conventional approach of putting all the drivers on the front baffle is smaller box size.

 

The Linn Majik Isobarik design doesn't work at all for me. You've got two bass drivers put inside the box with the sound from them coming out of the bottom and out of a port near the top front. It sounds like it too. Stupid idea. Echoey, boxy bass that can't start and stop like it should.

 

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RE: Transmission Line vs Reflex Ported vs Isobaric

lindsayt wrote:

 

The Linn Isobarik speakers are punishing for amps because the idiot designer wired two nominally 8 ohm drivers in parallel for the bass, midrange and treble, resulting in 4 ohm speakers with dips well below 4 ohms. They'd be an easier amplifier load if he'd used 16 ohm drivers wired in parallel, or 4 ohm drivers wired in series. He also used relatively heavy medium sized bass KEF bass drivers - which keeps the efficiency down. It's no wonder that these speakers make good candidates for active amplification - just to give the amps an easier time.

Linn Saras are also punishing loads for similar reasons.

Ferrograph S1 speakers are basically half an Isobarik in terms of drive units, and possibly better speakers because of it.

I have a feeling that if you took all the drivers from an Isobarik and mounted them all on the front baffle of a larger box you'd have a better sounding speaker. Better imaging for a start, and more dynamic bass too.

The big advantage of the Isobarik design compared to the more conventional approach of putting all the drivers on the front baffle is smaller box size.

The Linn Majik Isobarik design doesn't work at all for me. You've got two bass drivers put inside the box with the sound from them coming out of the bottom and out of a port near the top front. It sounds like it too. Stupid idea. Echoey, boxy bass that can't start and stop like it should.

Thank you for spelling it out further.

Are you saying that all Isobaric speakers are flawed with regard to the load on the amp (eg. Neat models), or is it that Linn's design is worse than most?

 

"We should no more let numbers define audio quality than we should let chemical analysis be the arbiter of fine wines."  Nelson Pass

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RE: Transmission Line vs Reflex Ported vs Isobaric

I think most Isobarik designs tend to be fairly difficult loads, due to the doubling up of the drivers (I think there are more complex reasons too, i just dont understand them  :oops: )

The Totem Mani-2's are supposed to be pretty well sorted sound speakers that sound great, using the Isobarik loading design. Maybe it works better for standmounted speakers than floor standers?

As an aside, in my experience the bass from transmission line speakers can sound quite different to rear ported speakers, although I dont fully understand why. IMO a well sorted transmission line speaker (IE PMC for eg) can have fantastic bass quality and quantity, from a relatively small enclosure. They are often easier to postition that rear ported speakers too  Smile

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