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Speaker designs using Purifi drivers

Rick Sykora

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Moved discussion started on Celuaris review thread.

Thanks @AdamG247 !
 
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RDSChicago

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Are any completely built speakers using Purifi drivers commercially available at this time? If so which is the best one?
 
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Rick Sykora

Rick Sykora

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Are any completely built speakers using Purifi drivers commercially available at this time? If so which is the best one?

Until recently, there were only two AFAIK. The March Sointuva and the Selah Purezza. Recall Selah had more, but matters less as they closed for business. Am working with a supplier for Directiva r1 cabinets, but unless you want to build, I am willing to build for you. If you are interested, PM me.
 

NTK

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Rick Sykora

Rick Sykora

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FeddyLost

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I have a design sold my Jim Salk--the BePure2
Floorstanding design allowed to make proper vertical port?
I'd like to see impedance graph or at least know impedance minimum. Pair of such powerful motors might malke this "easy load" not so easy ...
 
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Rick Sykora

Rick Sykora

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Floorstanding design allowed to make proper vertical port?
I'd like to see impedance graph or at least know impedance minimum. Pair of such powerful motors might make this "easy load" not so easy ...

Salk's point around easy load was due to higher sensitivity. The impedance (no graph) is claimed to be 4 ohms. So reasonable for many amps.

Am more surprised he poked at others using passive radiators. After all, Purifi designed one specifically for their woofer. :confused:
 

TimVG

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There's thing weird thing

1638556565317.png
 

Dennis Murphy

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That looks like a big gap between the tweeter and lower woofer, is this really just a 2-way and not a 2.5-way?
Good observation and good question. It's a 2.0. That does make the listening distance a little more critical. If you listen at, say, 1 meter, there will be a dip around 2 kHz. At the design distance of 3 meters or greater, that smooths out. I've done 2.5's, and I've never been as happy with the midrange performance. They're certainly trickier to pull off than a simple 2.0.
 

nc42acc

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Good observation and good question. It's a 2.0. That does make the listening distance a little more critical. If you listen at, say, 1 meter, there will be a dip around 2 kHz. At the design distance of 3 meters or greater, that smooths out. I've done 2.5's, and I've never been as happy with the midrange performance. They're certainly trickier to pull off than a simple 2.0.
Dennis thanks for your time and reply. Are both the active woofers or is the bottom the Purifi passive radiator? If they are two active drivers do both see the same response from the crossover or is the bottom woofer crossed lower? Thanks
 

Dennis Murphy

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Floorstanding design allowed to make proper vertical port?
I'd like to see impedance graph or at least know impedance minimum. Pair of such powerful motors might malke this "easy load" not so easy ...
Jim used a very long, wide port, which the Purifi responds to well. The factory passive radiators tune too low with just one woofer, and get expensive with two woofers, since you may have to use as many as four of them. In any event, the impedance is an easy load for any amplifier designed for 4 Ohms.
BePure2 Impedance.png

Dennis thanks for your time and reply. Are both the active woofers or is the bottom the Purifi passive radiator? If they are two active drivers do both see the same response from the crossover or is the bottom woofer crossed lower? Thanks
Both woofers are active--it's a simple 2-way. No passive radiators involved--just the big port I mention in my other post.
 

nc42acc

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Jim used a very long, wide port, which the Purifi responds to well. The factory passive radiators tune too low with just one woofer, and get expensive with two woofers, since you may have to use as many as four of them. In any event, the impedance is an easy load for any amplifier designed for 4 Ohms.
View attachment 169975

Both woofers are active--it's a simple 2-way. No passive radiators involved--just the big port I mention in my other post.
Thank you Dennis. That explains the higher efficiency rating using two of the woofers.
 
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Rick Sykora

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Jim used a very long, wide port, which the Purifi responds to well. The factory passive radiators tune too low with just one woofer, and get expensive with two woofers, since you may have to use as many as four of them. In any event, the impedance is an easy load for any amplifier designed for 4 Ohms.
View attachment 169975

Both woofers are active--it's a simple 2-way. No passive radiators involved--just the big port I mention in my other post.

So, the box is tuned to 25 Hz. Impedance is 3 ohms from 150 to 500 Hz, so may be challenging for lesser amps/AVRs. If am spending greater than $6K, can probably afford a robust amp.

The port tuning appears even lower (off the graph)? With a long port, will be hard to avoid port resonance(s) without some tapering, lining, etc. Based on modeling, is still tricky tuning for bass reflex, but still should be better than SPK5.
 

Dennis Murphy

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So, the box is tuned to 25 Hz. Impedance is 3 ohms from 150 to 500 Hz, so may be challenging for lesser amps/AVRs. If am spending greater than $6K, can probably afford a robust amp.

The port tuning appears even lower (off the graph)? With a long port, will be hard to avoid port resonance(s) without some tapering, lining, etc. Based on modeling, is still tricky tuning for bass reflex, but still should be better than SPK5.
It's closer to 3.5 Ohms minimum, which is what you generally get running two nominal 8 Ohm speakers in parallel. The tuning point is pretty clearly 30 Hz, which is what we were aiming for. I checked for port resonances, and they're well down, and the port is on the back. There really aren't any issues here.
 

nc42acc

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It's closer to 3.5 Ohms minimum, which is what you generally get running two nominal 8 Ohm speakers in parallel. The tuning point is pretty clearly 30 Hz, which is what we were aiming for. I checked for port resonances, and they're well down, and the port is on the back. There really aren't any issues here.
So Dennis are the drivers as good as all the hype they have received?
 
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Rick Sykora

Rick Sykora

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It's closer to 3.5 Ohms minimum, which is what you generally get running two nominal 8 Ohm speakers in parallel. The tuning point is pretty clearly 30 Hz, which is what we were aiming for. I checked for port resonances, and they're well down, and the port is on the back. There really aren't any issues here.
Oops, misread the scale, the minima clearly is 30 Hz. See no point in hair-splitting over .5 ohm.

Sure you did your best and, as said earlier, would get my vote for best of the bunch!
 

Dennis Murphy

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So Dennis are the drivers as good as all the hype they have received?
Yes and no. They do what is claimed, but it's a highly specialized driver. It basically either needs a passive radiator in a bookshelf application, or a very large port in a tower. And it has to be crossed low (1900 Hz is about it) in a 2-way. And it's ugly. The venerable Scan Speak 7" Revelator is a much more versatile unit. It's high end response is much smoother and extended, it works with reasonable sized ports, and it's distortion is almost as low as the Purifi's at most volume levels. Plus, it's cheaper and more attractive.
 
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