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Keg R3 Meta -> R11 transplant

Daka

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Does anyone with more technical knowledge if it’s possible to move Kef R3 Meta UniQ driver and crossover section to R11 (non-meta)?
R3 Meta has higher crossover at 420Hz/2.3kHz compared to R11 Metas at 330Hz/2.3kHz but at the same time old R11 has 400Hz/2.9kHz.
Reason being to save 1.5k in doing so whilst getting close to new Meta sound (yes there is a noticeable difference between R3 and R3 Meta).
 
Hi there,

i think this question is more something for the surgery experts of https://www.diyaudio.com/community/

I'm coming from the DIY corner and have made some positive experience with the full activation of the KEF midrange / tweeter chassis in self made cabinet with hypex plate amps

but this is a no go without measurement equipment like the Clio Pocket measurement system i am using

here some pics of my work, please do not stay with the criticism of the poor carpenter skills of mine, it was all made only for brief testing


HO-KEF-Cubes+Eggs-Capture.JPG12inch-WF-KEF-midrange-coax-Capture.JPG12inch-WF-KEF-midrange-coax-WCD-Capture.JPG

so far - so good, Stefano

P.S.:
there is a post here with the link to the new R series meta R & D whitepaper where you can see the list of improvements of the Uni-Q meta to the old Uni-Q chassis that i was able to buy years ago from a french internet shop as spare parts
but if you look at the wavelet cycle decay diagram with the active crossover it is already nearly free of mid range and high range frequency resonances without the meta stuff
please note the non rectangular cabinet approach of the standalone enclosure of the KEF chassis
KEF-DIY-Rear-Capture.JPGKEF-DIY-Front-Capture.JPG
 
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Impressive - but in this case I’m just want to swap out crossover plate and Uniq which are not that different - speaker size is remaining same so it seems on paper that no advanced speaker DYI knowledge is required. But I wonder if there is something I don’t know that would potentially be fatal here
 
Impressive - but in this case I’m just want to swap out crossover plate and Uniq which are not that different - speaker size is remaining same so it seems on paper that no advanced speaker DYI knowledge is required. But I wonder if there is something I don’t know that would potentially be fatal here
@Daka,

i am quite sure that crossover for the old Uni-Q will not fit perfectly for the new Uni-Q meta chassis

the wrong crossover for the Uni-Q chassis can ruin the whole swap approach

that said the approach to activate the whole stuff with hypex plate amps and find a DIY fellow with measurement equipment is even less risky

question: where do you get the meta chassis, you buy a new R3 meta and have the old R11 non meta already or the old R11 as used speakers?

oops, checked the specs of the R3 Meta against the R11, it cannot work with the swap of the crossover for sure!

the R11 has four bass chassis, R3 Meta only one

the sensitivity of the Uni-Q mid-high range chassis is attenuated much more to work with only one bass chassis in the small R3 meta cabinet


sensitivity difference over all 4 dB, 86db R3 Meta, 90 dB R11 - again this will not work with the crossover swap!

the showstopper:

r3meta nominal impedance 4 ohms
r11 nominal impedance 8 ohms
=> no way the crossover swap can match
for sure you have to completely rebuild the bass crossover section and to remove the attenuation of the mid section and high section of the crossover for the coax

there is a good chance to assume that the Uni-Q chassis for the R11 has a greater sensitivity as the Uni-Q chassis for the R3

to sort this out you have to find somebody that owns an R11 Meta and is willing to open it anyway

KEF use for sure a modified high tech Uni-Q chassis with neodymium magnet motor in the reference series and the blade, hard to find pics of those

last recommendation, buy the r3 meta and use two subwoofers to get the better bass performance

here the DIY fantasy kicks in again, build the subs on your own as floor stands for the r3 meta, e.g with 2 side mounted sw chassis for each floor stand sub for impulse compensation
 
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Old R11 to receive parts from new R3 meta. So you reckon there is difference in crossover section due to extra drivers?
This is more to do with new Dirac Art and I know subwoofers would be better but not keen to have 4 subs, I have two and that’s enough. So was thinking to add/change R3 to R11 that would support better ART as they should go as low as 30Hz
 
Crossovers are designed to match the drivers to their cabinet. So it's extremely unlikely that what you propose will be a success.
 
sensitivity difference over all 4 dB, 86db R3 Meta, 90 dB R11 - again this will not work with the crossover swap!

the showstopper:

r3meta nominal impedance 4 ohms
r11 nominal impedance 8 ohms
=> no way the crossover swap can match
for sure you have to completely rebuild the bass crossover section and to remove the attenuation of the mid section and high section of the crossover for the coax
This will work, r3 and r11 has the exact same uniq units. The sensitivity adjustment is done by adding more resistance in the r3’s crossover.

So theoretically you can swap r3 metas drivers to r11s and make them r11 metas. But since the crossover points are different between r11 and r11 metas, he needs both crossovers- one for the mid-highs and one for woofers to be replaced with r11 metas.


R11 and R11 metas have the same cabinet and woofers. So all he need to buy r11 meta divers and all crossovers and it’s done
 
This will work, r3 and r11 has the exact same uniq units. The sensitivity adjustment is done by adding more resistance in the r3’s crossover.

So theoretically you can swap r3 metas drivers to r11s and make them r11 metas. But since the crossover points are different between r11 and r11 metas, he needs both crossovers- one for the mid-highs and one for woofers to be replaced with r11 metas.


R11 and R11 metas have the same cabinet and woofers. So all he need to buy r11 meta divers and all crossovers and it’s done
On the top this is a viable solution for someone who already has old r series a s reference series. I won’t recommend swapping r3 to r3 meta and ref 1 to ref 1 meta but financially it makes more sense to upgrade the larger speakers. The most value would be ref 5 upgrade. Used ones are well under 10k and upgrade would cost under 3k. The total cost would be still under 10k which is 50 percent less than the new metas
 
On the top this is a viable solution for someone who already has old r series a s reference series.
Putting a resistor in series with the woofers will have a negative impact on the damping factor, which will negatively impact the bass characteristics. I would not do it.

I would remove the passive crossovers and, instead, actively tri-amp the speakers. A miniDSP Flex HTx will work well for the active crossovers and DSP. CamillaDSP is a less expensive option for those that don't mind going a little deeper into DIY. The only modifications to the speakers, other than removing the crossovers, would be modifying the binding post plates to have 3 sets of binding posts. Or, as I did for one of my projects, 3D print new plates.

Another option is to use a Hypex 3-channel plate amplifier for each speaker. That would involve more extensive modifications to the cabinet unless they are mounted externally in their own case(s).
 
Putting a resistor in series with the woofers will have a negative impact on the damping factor, which will negatively impact the bass characteristics. I would not do it.

I would remove the passive crossovers and, instead, actively tri-amp the speakers. A miniDSP Flex HTx will work well for the active crossovers and DSP. CamillaDSP is a less expensive option for those that don't mind going a little deeper into DIY. The only modifications to the speakers, other than removing the crossovers, would be modifying the binding post plates to have 3 sets of binding posts. Or, as I did for one of my projects, 3D print new plates.

Another option is to use a Hypex 3-channel plate amplifier for each speaker. That would involve more extensive modifications to the cabinet unless they are mounted externally in their own case(s).
The case is not about doing anything DIY. I am saying that by just swapping the uniqs+ crossovers, R can be made R Meta and Reference can be made Reference Meta. I don’t think the OP has no plan to do any DIY beyond swapping certain things. With R series, there doesn’t even involve any soldering as the drivers are plugged if m not wrong. But with References, drivers need to the desoldered!
 
The case is not about doing anything DIY. I am saying that by just swapping the uniqs+ crossovers, R can be made R Meta and Reference can be made Reference Meta. I don’t think the OP has no plan to do any DIY beyond swapping certain things. With R series, there doesn’t even involve any soldering as the drivers are plugged if m not wrong. But with References, drivers need to the desoldered!
But the efficiency of the woofers between the R3 Meta and the R11 is not insignificant - 3 dB. If you just swap the crossovers, the midrange/tweeter will not be level matched with the woofers. Depending on whether the R3 Meta has resistors on the midrange/tweeter, and where they are in the circuit, the OP may not be able to just remove resistors to bring up their efficiency without adversely affecting the frequency response. That leaves bringing the R11 woofer output level down. Resistors seem the most obvious choice to do that, but will negatively affect the damping factor, not to mention the overall loss in speaker efficiency.

EDIT: There are additional possible issues:

1. Oftentimes crossovers implement correction for baffle step loss. If the R3 Meta and R11 have different baffle step loss, merely swapping out the crossovers will throw off the step loss correction.

2. All of this assumes that the R11 woofers, in combination, have the same impedance as the R3 Meta woofer in the crossover region. Given the different cabinets, and the possibility that the woofer designs may have changed in the R series, it is likely that the impedances are not the same. That will throw off the crossover tuning, further adversely affecting the frequency response.
 
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But the efficiency of the woofers between the R3 Meta and the R11 is not insignificant - 3 dB. If you just swap the crossovers, the midrange/tweeter will not be level matched with the woofers. Depending on whether the R3 Meta has resistors on the midrange/tweeter, and where they are in the circuit, the OP may not be able to just remove resistors to bring up their efficiency without adversely affecting the frequency response. That leaves bringing the R11 woofer output level down. Resistors seem the most obvious choice to do that, but will negatively affect the damping factor, not to mention the overall loss in speaker efficiency.

EDIT: There are additional possible issues:

1. Oftentimes crossovers implement correction for baffle step loss. If the R3 Meta and R11 have different baffle step loss, merely swapping out the crossovers will throw off the step loss correction.

2. All of this assumes that the R11 woofers, in combination, have the same impedance as the R3 Meta woofer in the crossover region. Given the different cabinets, and the possibility that the woofer designs may have changed in the R series, it is likely that the impedances are not the same. That will throw off the crossover tuning, further adversely affecting the frequency response.
The woofers on r3 and r11 are the same. There is no version made for r3 and r11 separately. Just the numbers are different.

if you take out a woofer from r3 and r11 and measure them they are identical. How do u know it? I swapped one woofer of my r11 under the warranty and back then on the box it was labelled R3/R7/R11 and some other Center speaker.

. I never mentioned to swap crossovers bwteeen r3meta and r11. I meant if you need to convert r11 to r11 meta, what you need is

1. R3meta/R7meta/R11meta uniqs
2. R11 metas crosssover boards.

it would be stupid to buy a r3 meta only to get the uniqs out. Instead the OP can contact KEF for spares as it’s available for repair purposes. So just buy the new uniq pair and r11 meta crossovers and call it a day. Again I agree to you that you cannot use R3 metas croosver in R11 meta as their crossover points are even different and due to the other reasons you mentioned.
 
The woofers on r3 and r11 are the same.
The OP's original post discussed taking the concentric driver from the R3 Meta and putting that in an older R11 (non-Meta). The R3 Meta is the latest generation of the R series, whereas the R11 (non-Meta) is the previous generation. Have you confirmed with KEF that the woofer in the latest generation R Meta speakers has not been updated since the previous non-Meta generation?

I never mentioned to swap crossovers bwteeen r3meta and r11.
I misunderstood your statement "This will work, r3 and r11 has the exact same uniq units. The sensitivity adjustment is done by adding more resistance in the r3’s crossover."

it would be stupid to buy a r3 meta only to get the uniqs out.
I agree.

So just buy the new uniq pair and r11 meta crossovers and call it a day.
Assuming the woofers in the R11 Meta have not been updated since the previous non-Meta generation.
 
The woofers in the R3 and R11 are not the same impedance. The R3 (Meta) woofer is (obviously) designed to run on its own, and the R11 (Meta) woofers are all paralleled together, so, on their own, have a higher impedance.
 
The woofers in the R3 and R11 are not the same impedance. The R3 (Meta) woofer is (obviously) designed to run on its own, and the R11 (Meta) woofers are all paralleled together, so, on their own, have a higher impedance.
actually yes. The crossovers are designed differently on the r3 and r11 to match the impedances and sensitivities. so the crossovers are different on them
 

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Assuming the woofers in the R11 Meta have not been updated since the previous non-Meta generation.
Kef didn’t update the woofers on Rs when they moved the meta series. Same is the case with References.

But they changed the crossover points when they moved to metas.
 
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