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Purifi PTT6.5W04-01A 6.5" midwoofer

Ilkless

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I was thinking of the possibility of making a Kef R11 clone with Purifi and the Coaxials from the Reference line (can sometimes be found on the market) which would make the SPL capability rather nice compared to the regular R11.

But I don't know if the coaxials are particularly good at high spls?

Certainly would be above average if not SOTA compared to the best non-coaxial MF/HF direct radiators
 

Ilkless

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I was thinking of the possibility of making a Kef R11 clone with Purifi and the Coaxials from the Reference line (can sometimes be found on the market) which would make the SPL capability rather nice compared to the regular R11.

But I don't know if the coaxials are particularly good at high spls?

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KEF Reference 1 max SPL at 3 and 10% HD. That's pretty much state-of-the-art.
 

Absolute

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KEF Reference 1 max SPL at 3 and 10% HD. That's pretty much state-of-the-art.
So 106-108 dB with 400 watts? Those drivers are not going to survive those SPLs for long. Must be downpadded quite a bit to suit the woofer in the Ref 1, I assume?
 

Ilkless

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So 106-108 dB with 400 watts? Those drivers are not going to survive those SPLs for long. Must be downpadded quite a bit to suit the woofer in the Ref 1, I assume?

The coax is being high-passed to the woofer at 350Hz so excursion may still not be that big a problem. KEF themselves spec 111dB with pink noise. And yeah, factoring in baffle step, and the likely high sensitivity of the tweeter within the MF cone (acting as a waveguide), padding of the midrange and tweeter relative to the woofer is probably substantial to get a smooth response. All the more reason that these speakers should be active, but the market is clearly behind the curve...
 

Absolute

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The coax is being high-passed to the woofer at 350Hz so excursion may still not be that big a problem. KEF themselves spec 111dB with pink noise. And yeah, factoring in baffle step, and the likely high sensitivity of the tweeter within the MF cone (acting as a waveguide), padding of the midrange and tweeter relative to the woofer is probably substantial to get a smooth response. All the more reason that these speakers should be active, but the market is clearly behind the curve...
Thanks for detailed info! I thought about this beefed up Kef R11 a while ago when I came across a set of brand new Reference-coax on the market for about 350£.
Probably should have bought them just to have them, but I had just purchased some DIY JBL M2 and didn't see the need at the time.

Everything should be active, it's time to get out of the 60's! How hard can it be to supply the speakers with an outboard crossover/EQ box with fixed settings for the speakers?

Ya hear me, KEF?? :mad::D
 

Selah Audio

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You'll probably be seeing something like that in the not-too-distant future if all goes well. However, it will require two of the 8 Ohm versions in parallel to get sensitivity up.
As if 2020 couldn't get any weirder - Dennis Murphy using a compression driver. :D
 

jhaider

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So 106-108 dB with 400 watts? Those drivers are not going to survive those SPLs for long. Must be downpadded quite a bit to suit the woofer in the Ref 1, I assume?

Your ears would break before the speakers do in a home setting.

That’s astounding performance given the size. No wonder they went from mediocre 10” woofers to multiples of this monster 7” woofer on the flagship.
 

Rick Sykora

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You obviously have never heard of masking tape or rope calk. The Purifi and Scan 8545 should be drop-in replacements if you can believe factory specs. The SB Ceramic is smaller, but I managed to get screws in it and fill in the gaps with stuff.

For smaller holes, I use polyurethane glue. If you dampen the hole and get a nice thin layer, you can reduce a hole by .25" or so. While you can work it in an hour or so, have to wait overnight if you need to modify. Once dry though, you can trim it more precisely. :)
 

Absolute

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Your ears would break before the speakers do in a home setting.

That’s astounding performance given the size. No wonder they went from mediocre 10” woofers to multiples of this monster 7” woofer on the flagship.
I was thinking specifically about the coaxial and not the woofer, but brainfarted a bit when thinking about power levels.

In absolute distortion-terms I'm not sure whether or not the coax is particularly impressive?


11-KEF-Reference-1-Intermodulationsverzerrungen-4m.jpg

15-Neumann-KH-420-Intermodulationsverzerrungen.jpg
 

Dennis Murphy

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As if 2020 couldn't get any weirder - Dennis Murphy using a compression driver. :D

What I have in mind won't use a compression driver. Something just as sensitive but a whole lot more accurate. I actually did do a design with a compression driver in 2016. That was a weird year for a number of reasons.
 

Ilkless

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What I have in mind won't use a compression driver. Something just as sensitive but a whole lot more accurate. I actually did do a design with a compression driver in 2016. That was a weird year for a number of reasons.

Large format AMT?
 

Absolute

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What I have in mind won't use a compression driver. Something just as sensitive but a whole lot more accurate. I actually did do a design with a compression driver in 2016. That was a weird year for a number of reasons.
What's wrong with compression drivers in general? Referring to the "more accurate". Genuine question because I have zero knowledge on drivers and have only extremely limited experience with compression drivers, namely the JBL D2340k in the M2 horn which I now have.
 

Julf

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What's wrong with compression drivers in general? Referring to the "more accurate". Genuine question because I have zero knowledge on drivers and have only extremely limited experience with compression drivers, namely the JBL D2340k in the M2 horn which I now have.

The main advantage of compression drivers is high efficiency, and when used in that way, there tends to be non-linearity due to the compression, as well as unevenness in the frequency response. You can of course use a compression driver with a very low compression ratio, but what's the point?
 

Absolute

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The main advantage of compression drivers is high efficiency, and when used in that way, there tends to be non-linearity due to the compression, as well as unevenness in the frequency response. You can of course use a compression driver with a very low compression ratio, but what's the point?
I don't know, but judging from the tone, probably no point! :D
I couldn't tell a good driver from a shit driver if my life depended on it on specs/raw measurements alone, but I did take near-field measurements of the D2340K at rather high spls. There's quite a bit of second harmonics, but not much trace of higher ones.

Oh, and it needs a ton of EQ to be flat! About +10 dB shelf. Sounds delicious, though. Must be that distortion!
 

Absolute

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Question; How do I effectively measure driver distortion in near-field? I pointed the microphone in the mouth of the JBL M2 horn and swept away with gradual loudish beeps.
 
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McFly

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Question; How do I effectively measure driver distortion in near-field? I pointed the microphone in the mouth of the JBL M2 horn and swept away with gradual loudish beeps. Examples;

View attachment 73650

View attachment 73651


Couldn't go louder because it's midnight. How loud must I go to get an impression while measuring?
Answer: Start your own thread on the subject
 

McFly

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Sorry, I thought this was the horns thread I was reading at the same time.
Apologies I didn't mean to be harsh, just seeing a lot of thread derailing happening these days
 
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