Speaker designs using Purifi drivers

[AnalogSteph]

Any takes on the medium stroke (fs = 33 Hz) and midrange (fs = 55 Hz) varieties yet?

 

[FeddyLost]

And it has to be crossed low (1900 Hz is about it) in a 2-way

To get decent off-axis responce or to still have very low distortion?

 

[Dennis Murphy]

To get decent off-axis responce or to still have very low distortion?

No--it sinks like a rock above 2 kHz when measured from the tweeter axis, which is what you would hear in most designs.

 

[Rick Sykora]

Any takes on the medium stroke (fs = 33 Hz) and midrange (fs = 55 Hz) varieties yet?

Just got a couple of the new aluminum cone ones in and they are in the queue to be tested with Directiva r1.

 

[Rick Sykora]

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.

Both Purezza and Directiva cross over above 1900 Hz and both measure well and get good reviews. The target for Purifi was to reduce IMD, which independent testing has validated.

Are you claiming the Scan Speak is comparable in respect to IMD?

 

[Holmz]

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.

I heard the March Audio Sointuva a few weeks ago and it was pretty good.
It has two of the Purifi passives on the back, and the bass was surprisingly more than I expected it to be.

I have no easy way to tell how good it was as it was a new room, new amp driving it, sighted, etc… But I would not hesitate to try it at home, and the looks would make it easier to sneak past the Mrs. guarding the door.

 

[Savi]

Both Purezza and Directiva cross over above 1900 Hz and both measure well and get good reviews. The target for Purifi was to reduce IMD, which independent testing has validated.

Are you claiming the Scan Speak is comparable in respect to IMD?

Indeed, hificompass measurements suggests that it could be cross maybe to 2.3kz with LR4

 

[Dennis Murphy]

Both Purezza and Directiva cross over above 1900 Hz and both measure well and get good reviews. The target for Purifi was to reduce IMD, which independent testing has validated.

Are you claiming the Scan Speak is comparable in respect to IMD?

1900 is where I crossed--so I'm not sure whether you're agreeing or disagreeing with me. I don't know how Scan does on IMD, or how audible any differences would be. I'm just saying the Scan gives me much more flexibility as a designer to choose crossover points and slopes. As for sonics, the Scan sounds great to me. The Purifi sounds great to me.

 

[Dennis Murphy]

Indeed, hificompass measurements suggests that it could be cross maybe to 2.3kz with LR4

View attachment 170071

But you have to take into account the response vertically at the listening axis. That of course depends on the woofer-tweeter spacing, which was quite wide on the design I did. Anyhow, 1900 Hz seems to be the sweet spot with a LR4.

 

[VintageFlanker]

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This site sets the new world record for audio advertising. I cannot even see what I've been looking for in the first place.

 

[NTK]

Oh my...

This site sets the new world record for audio advertising. I cannot even see what I've been looking for in the first place.

Yeah. In retrospect, I should have just posted pictures of the speakers instead of just the web page.

 

[Rick Sykora]

1900 is where I crossed--so I'm not sure whether you're agreeing or disagreeing with me. I don't know how Scan does on IMD, or how audible any differences would be. I'm just saying the Scan gives me much more flexibility as a designer to choose crossover points and slopes. As for sonics, the Scan sounds great to me. The Purifi sounds great to me.

Thanks Dennis! Was looking for why you made the claims you had (despite my contrary personal experience) and you clarified in the next post. Your distance between drivers was different.

Have not used or heard the Scan Speak, so can only go on the data. Agree the Purifi is a bit of a diva and you pay extra. The hificompass site (cited earlier) tested comparable versions of the drivers being discussed. Measured frequency response for the 2 drivers is a wash IMO (they both rolloff comparably around 2 kHz just as you might expect for drivers of their size). IMD is allegedly more audible than HD, but not sure on the bounds for it...

As for the IMD measurements, the Revelator is not in the same league as the Purifi, but the 8545 Scan you used in the BMR monitor is much more comparable (and cheaper!). As for looks, the 8545 is easily the ugly sister IMO though.

 

[Dennis Murphy]

Thanks Dennis! Was looking for why you made the claims you had (despite my contrary personal experience) and you clarified in the next post. Your distance between drivers was different.

Have not used or heard the Scan Speak, so can only go on the data. Agree the Purifi is a bit of a diva and you pay extra. The hificompass site cited earlier, tested comparable versions of the drivers being discussed. Measured frequency response for the 2 drivers is a wash IMO (they both rolloff comparably around 2 kHz just as you might expect for of their size). IMD is allegedly more audible than HD, but not sure on the bounds for it...

As for the IMD measurements, the Revelator is not in the same league as the Purifi, but the 8545 Scan you used in the BMR monitor is much more comparable (and cheaper!). As for looks, the 8545 is easily the ugly sister IMO though.

I'm getting confused. When you say "hificompass...tested comparable versions of the same drivers being discussed"...what's the second driver? Not the 7" revelator--it's practically flat on axis out to almost 10 kHz. With some baffle step compensation, it could be used as a full range driver in the nearfield.

 

[Savi]

But you have to take into account the response vertically at the listening axis. That of course depends on the woofer-tweeter spacing, which was quite wide on the design I did. Anyhow, 1900 Hz seems to be the sweet spot with a LR4.

I agree. I was just trying to find the highest XO possible. If I had to play with it, I would start at 2 kHz in vituixcad.

 

[Rick Sykora]

I'm getting confused. When you say "hificompass...tested comparable versions of the same drivers being discussed"...what's the second driver? Not the 7" revelator--it's practically flat on axis out to almost 10 kHz. With some baffle step compensation, it could be used as a full range driver in the nearfield.

Unless you have some newer Revelator, may be is not what hifi compass has posted. Yes, on-axis, the Scan is a little better out around 10k Hz, but both rolloff off-axis comparably at 2 kHz (where it matters most).

Am reluctant to cross post their images as am not sure how the hicompass folks feel about it (hard to get a account registration or any response from them). but here are the links:

Revelator: https://hificompass.com/en/speakers/measurements/scan-speak/scanspeak-18w/8531g00

Purifi: https://hificompass.com/en/speakers/measurements/purifi/purifi-ptt65w08-01b-ptt65x08-nfa-01

If you disagree about the off-axis rolloffs being comparable (looking at the normalized FR off-axis curves), can do some overlays as am judging by sight.

 

[Dennis Murphy]

Unless you have some newer Revelator, may be is not what hifi compass has posted. Yes, on-axis, the Scan is a little better out around 10k Hz, but both rolloff off-axis comparably at 2 kHz (where it matters most).

Am reluctant to cross post their images as am not sure how the hicompass folks feel about it (hard to get a account registration or any response from them). but here are the links:

Revelator: https://hificompass.com/en/speakers/measurements/scan-speak/scanspeak-18w/8531g00

Purifi: https://hificompass.com/en/speakers/measurements/purifi/purifi-ptt65w08-01b-ptt65x08-nfa-01

If you disagree about the off-axis rolloffs being comparable (looking at the normalized FR off-axis curves), can do some overlays as am judging by sight.

The measurement axis makes a big difference. Here's my measurement of the Purifi and the Revelator in two different versions of my BMR monitor. They both are mounted in the same position below the small BMR midrange and the RAAL ribbon tweeter. First the Purifi, then the Revelator:

On Axis, both woofers would be more extended. But strictly from a frequency response standpoint, I would rather work with the Revelator. I don't know quite what to make of the IMD results. There may or may not be a clinically significant difference between the two woofers. As I said, both drivers sound great to me.

 

[nc42acc]

I am starting to think the purifi woofers were built with measurements in mind and not ease of implementation for speaker builders. Maybe with time and feedback from builders they will build a driver that breaks new ground.

 

[Rick Sykora]

@Dennis Murphy I see your point, but your charts are not normalized and hificompass ones are.

Without normalization, a sighted comparison becomes even more problematic. Since I have given attribution, here is what I mean from the hificompass measurements:

Purifi first...

and now the Scan Revelator...

So, based on these measurements and a crossover around 2 kHz, am not seeing a major deal breaker here.

Both are good drivers and so agree with you on that. If I was doing a value-focused, 2-way passive design, I'll concede I would use the Revelator (or more likely the 8545).

 

[Dennis Murphy]

@Dennis Murphy I see your point, but your charts are not normalized and hificompass ones are.

Without normalization, a sighted comparison becomes even more problematic. Since I have given attribution, here is what I mean from the hificompass measurements:

Purifi first...

and now the Scan Revelator...

So, based on these measurements and a crossover around 2 kHz, am not seeing a major deal breaker here.

Both are good drivers and so agree with you on that. If I was doing a value-focused, 2-way passive design, I'll concede I would use the Revelator (or more likely the 8545).

I think it's pretty clear without normalization which is the smoother driver. But either driver can be made to work in a 2-way crossed low and steeply. The Scan just gives you more options, particularly on slope. I wouldn't necessarily prefer the 8545--been there, done that. Even crossed at 800 Hz in a 3-way, you can't make second order slopes work, and that forces you to go with a lower sensitivity design. And in a 2-way, you have to throw a lot of components at it to smooth out the cone-surround resonances.

 

[Rick Sykora]

I am starting to think the purifi woofers were built with measurements in mind and not ease of implementation for speaker builders. Maybe with time and feedback from builders they will build a driver that breaks new ground.

That is not an unfair conclusion. This is just a first generation driver and some of the more established competitors have refined their offerings over many years. Also more volume would (hopefully) help make them a better value too...

If you have a tweeter preference or insist on a passive speaker, it may or may not be a good choice. Along with the commercial speakers discussed thus far, there are some interesting DIY ones too. Heissmann, Troels, and hificompass have all used the Purifi woofer. Without being too immodest, the Directiva r1 is pretty good too!