AnalogSteph
Major Contributor
Any takes on the medium stroke (fs = 33 Hz) and midrange (fs = 55 Hz) varieties yet?
To get decent off-axis responce or to still have very low distortion?And it has to be crossed low (1900 Hz is about it) in a 2-way
No--it sinks like a rock above 2 kHz when measured from the tweeter axis, which is what you would hear in most designs.To get decent off-axis responce or to still have very low distortion?
Any takes on the medium stroke (fs = 33 Hz) and midrange (fs = 55 Hz) varieties yet?
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.
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.
Indeed, hificompass measurements suggests that it could be cross maybe to 2.3kz with LR4Both 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.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?
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.Indeed, hificompass measurements suggests that it could be cross maybe to 2.3kz with LR4
View attachment 170071
Oh my...JOACHIM-GERHARD-COLLECTION SURVEYOR MASTER SPEAKERS
Mono & Stereo High-End Audio Magazine: Magico - Nagra - Tidal Audio - Wilson Audio - MSB - Totaldac - Living Voice - Taiko Audio - Aries Cerat -Thraxwww.monoandstereo.com
Yeah. In retrospect, I should have just posted pictures of the speakers instead of just the web page.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.
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.
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.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 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.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'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.
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: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.
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.@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 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.