Questions on Horizontal Center With Passive Radiator (i.e. DCM TP160C etc)

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slipperybidness

slipperybidness

Audioholic Spartan
I have never seen a center speaker design such as this. It "looks" like a conventional horizontal CC, but there is only a single woofer, while the other one that looks like a woofer is a passive radiator.

So, in practice, it seems to me like a "normal ported speaker layed on its side".


@TLS Guy
@shadyJ
@KEW
@zieglj01
 
John Parks

John Parks

Audioholic Chief
KEF Q series - (1) active driver (1) passive radiator (not including the Uni-Q mid/tweet) :)
1578495920702.png
 
John Parks

John Parks

Audioholic Chief
Yeah, I think I gotcha. I'm counting the Uni Q as a driver also. Still an odd design tho.
I had the Q750, which uses two ABRs in addition to the LF driver (not including the Uni-Q driver assembly) in a 2 1/2 way design (which this is) and it was nice. No comparison to the R series...
 
TLS Guy

TLS Guy

Audioholic Slumlord
I have never seen a center speaker design such as this. It "looks" like a conventional horizontal CC, but there is only a single woofer, while the other one that looks like a woofer is a passive radiator.

So, in practice, it seems to me like a "normal ported speaker layed on its side".


@TLS Guy
@shadyJ
@KEW
@zieglj01
Yes, that is exactly what it is. So it will have an off center lobing axis and have a somewhat different response whether you are on its right or left.

Center speakers are a terrible problem, with no easy solutions. As far as I can tell they are very inclined to make matters worse than a pair of left and right speakers.

The trouble is that layout generally requires a horizontal rather than a vertically aligned speaker. That really means a coaxial or full range drivers. There is no doubt in my mind that resources really do need to be thrown at good full range driver research. I used a full ranger in our Eagan Townhouse and it was excellent.

For the new home I have designed this.


The 10" woofer is the sub crossed at 40Hz so ignore that. So the woofers crossed at 400 Hz are horizontal, and the mid and tweeter vertical crossed at 4 KHz.

The speech clarity and overall fidelity is excellent. However the lobing problem is not completely avoided. There is a slight change in the balance around the crossover dependent on listening axis to the speaker, with a slight rise in the balance below 400 Hz moving center left or right. This is slight, but it is audible. This confirms my experience that the optimal for a center is a coaxial or full range driver, anything else is suboptimal.
 
KEW

KEW

Audioholic Overlord
I have never seen a center speaker design such as this. It "looks" like a conventional horizontal CC, but there is only a single woofer, while the other one that looks like a woofer is a passive radiator.

So, in practice, it seems to me like a "normal ported speaker layed on its side".


@TLS Guy
@shadyJ
@KEW
@zieglj01
On a more superficial level, I see it as simply avoiding problems.
The driver presumably (based on the TP60s and the TP160) works best in a vented enclosure.
A rear ported center is a concern for placement in the locations centers often end up (in a cabinet or close to the back wall).
A front ported cabinet has a bit more chance of having issues with chuffing or other port noises that are less audible when on the rear of the speaker.
A passive radiator on front is a straight-forward way to avoid those issues, while giving the driver the general characteristics of a vented enclosure.
 
slipperybidness

slipperybidness

Audioholic Spartan
Is this design better than a conventional horizontal center? Worse? Or pretty much a wash?

I haven't listened to mine much yet, so I don't have a real opinion either way.
 
Kingnoob

Kingnoob

Audioholic Chief
I have never seen a center speaker design such as this. It "looks" like a conventional horizontal CC, but there is only a single woofer, while the other one that looks like a woofer is a passive radiator.

So, in practice, it seems to me like a "normal ported speaker layed on its side".


@TLS Guy
@shadyJ
@KEW
@zieglj01
Were is the passive on the back I don’t see it ??? Looks like a high end center speaker


Reptilians invading in year 2025
Tesla spoken to them
 
Kingnoob

Kingnoob

Audioholic Chief
KEF Q series - (1) active driver (1) passive radiator (not including the Uni-Q mid/tweet) :)
View attachment 33221
What is a unique Q driver is it made of a special material or does it do more then a normal mid /woofer ?
Must cost a fortune for such nice speakers do they sound very clear. ??@99& nice


Reptilians invading in year 2025
Tesla spoken to them
 
TLS Guy

TLS Guy

Audioholic Slumlord
Yeah, I think I gotcha. I'm counting the Uni Q as a driver also. Still an odd design tho.
No, this one makes sense. The crossover to the mid cone of the UniQ will be low enough there will not be a significant lobing issue. There will be a slight one. The axis in the speech discrimination band will be central. The use of an ABR avoids the rear port and port chiff issues. That looks to be among a very select group of sensibly designed and thought out center speakers.
 
TLS Guy

TLS Guy

Audioholic Slumlord
What is a unique Q driver is it made of a special material or does it do more then a normal mid /woofer ?
Must cost a fortune for such nice speakers do they sound very clear. ??@99& nice


Reptilians invading in year 2025
Tesla spoken to them
I'll answer your two questions together. The UniQ drivers are coaxial. In this case there is a midcone. The tweeter is placed in the pole piece of the midcone's magnet. This avoids lobing issues.

Of the two outer cones one is active and has a voice coil and magnet. The other cone is an ABR and has no magnet, voice coil or electrical connection. It takes the place of the port. The alignment is very similar to a port loaded speaker, but roll off is faster being 36 db per octave, rather than 24 db per octave.

Here is a diagram of a coaxial speaker.



Tannoy have made coaxial speakers since the mid fifties at least.



But KEF have really developed the concept. SEAS produce a range of these drivers under license from KEF. I use these in my center speaker in the AV room. Thiel also produced a coaxial for their center speaker. Altec Lansing and Electrovoice had cruder versions of the Tannoy Monitor Gold series of speakers back in fifties thought the seventies. There probably were others.
 
slipperybidness

slipperybidness

Audioholic Spartan
Hi Slip, If you don't need it and want to sell it PM me.
I just don't have the real estate to install it right now, work in progress.

You did see my DCM haul over in the DCM thread?
 

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