Purifi PTT6.5W04-01A 6.5" midwoofer

[Dennis Murphy]

Does anybody have the Purify driver at hand?

I have a pair coming from Madisound on Thursday. I'll try them in my 3-way BMR's and compare how they do compared with my BMR version with the Scan 8545 and the SB Acoustics 6" Ceramic. I'll probably hear a lot of port chuffing if I push it and will have to deal with that in the future, but I hope to get an idea of whether the bass sounds any cleaner or deeper at moderate volume. I understand that they're primarily intended for 2-way designs, but if the response is as smooth as Purifi claims in the upper midrange-lower treble, you have more flexibility in the choice of crossover points and slope order for the low pass filter. Because the SB Ceramic is so smooth in that region, I was able to switch from 4th order slopes for the Scan design to 2nd order (acoustic) for the SB woof and BMR midrange, and at a higher crossover point, which boosted sensitivity and took some load off of the little BMR driver at the low end. Anyhow, I'll give a full report in a few days.

 

[HooStat]

I'll try them in my 3-way BMR's

Just out of curiosity, when you do this, how to you account for the different cutout sizes? Or are all 3 drop in replacements for each other?

 

[Dennis Murphy]

Just out of curiosity, when you do this, how to you account for the different cutout sizes? Or are all 3 drop in replacements for each other?

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.

 

[GelbeMusik]

Are there any Klippel tests for this driver?

Klippel wouldn't help too much. The motor was tested ( https://hificompass.com/en/reviews/purifi-audio-ptt65w04-01a-midwoofer ): excellent! Suspension: not an issue due to general deliberations (While with the example given at the Purify site I clearly indentified the Ksm limitation.) Problem with me is the modulation of FM to AM (pun intended) within a reflective room.

 

[HooStat]

You obviously have never heard of masking tape or rope calk.

Actually, I am playing with the idea of dropping in some woofers and/or tweeters into existing boxes and was wondering what to do when drivers don't match up precisely. I have precisely NO experience with this so I wanted to pick your brain.

 

[McFly]

Are there any Klippel tests for this driver?

Would need some kind of complete reference build for it, maybe @amirm could track down one of the spk4/5 analysis models doing the rounds?

 

[Selah Audio]

Actually, I am playing with the idea of dropping in some woofers and/or tweeters into existing boxes and was wondering what to do when drivers don't match up precisely. I have precisely NO experience with this so I wanted to pick your brain.

Usually that doesn't work well because the box volume and tuning is wrong. It also changes the crossover - which may not be possible if the drivers aren't a good match.

 

[Selah Audio]

Would need some kind of complete reference build for it, maybe @amirm could track down one of the spk4/5 analysis models doing the rounds?

Sorry - I should have clarified - Klippel has a analyzer for drivers only. It's the system that first put them on the map.

 

[restorer-john]

Anyhow, I'll give a full report in a few days.

Should be interesting.

 

[McFly]

Sorry - I should have clarified - Klippel has a analyzer for drivers only. It's the system that first put them on the map.

Ahh now this would be cool

 

[dwkdnvr]

Details on the 4" are up on the site, and it shows up in the shop. At first glance doesn't seem quite as compelling as the 6.5".

 

[Dennis Murphy]

Details on the 4" are up on the site, and it shows up in the shop. At first glance doesn't seem quite as compelling as the 6.5".

Thanks. I'll have to check it out. I got my 6.5" woofs today. I flexed one for several hours with low bass test tones, but even out of the box it almost met its specs, and after the flex and cool-down, Fs was 29 Hz (vs 30 Hz Factory), and Qts was just a hair below the factory value of .29. Most woofers I've tested never come close to the quoted Fs--usually at least 5 Hz higher than spec--and Qts is sometimes double what it's supposed to be. So it looks like quality control is excellent and Claus is telling it like it is. I have to make a couple more measurements and then I'll plop it into my BMR, hopefully tonight.

 

[Matias]

There are now 3 drivers and 1 passive radiator in their website. Family is slowly increasing.

 

[DDF]

Details on the 4" are up on the site, and it shows up in the shop. At first glance doesn't seem quite as compelling as the 6.5".

I love that these drivers exist and push the driver state of the art, but to me they're a missed opportunity towards a real state of the art system.

A real start of the art system uses external subs (flexible placement for room modal control) and sealed boxes avoiding all the drawback of ports. Lets be honest, ports are cost reductions.

So, for commercial reasons, I get why they spec'ed these how they did, and watts are cheap. But I really wish they'd make a ~5" optimized for a small-mid sealed box with 80-100Hz f-3. That would have killer sensitivity, great power handling and max SPLs with amazingly low mid band distortion and killer directivity, in a reasonable box. The current designs are creme de la creme for an older school system design premise.

 

[Dennis Murphy]

Thanks. I'll have to check it out. I got my 6.5" woofs today. I flexed one for several hours with low bass test tones, but even out of the box it almost met its specs, and after the flex and cool-down, Fs was 29 Hz (vs 30 Hz Factory), and Qts was just a hair below the factory value of .29. Most woofers I've tested never come close to the quoted Fs--usually at least 5 Hz higher than spec--and Qts is sometimes double what it's supposed to be. So it looks like quality control is excellent and Claus is telling it like it is. I have to make a couple more measurements and then I'll plop it into my BMR, hopefully tonight.

I did a complete set of TS parameters and everything is dead on. The frequency response is also exactly as advertised--absolutely no breakup that I can see, and except for the baffle step it's flat to 4 kHz, after which it rolls off smoothly. I also measured distortion, and it also seems to be as low as the factory plots shows, although I don't know how accurate my OmniMic measurements are. The bass has great impact on bass transients, but there's a whole lotta port noise on steady tones down in the 30's even with my aggressively flared 2" Precision Port. And for correct tuning, I would have to increase its length, which would make the problem worse. I'll have to think about that one and see whether the passive radiator will be a necessity. Tomorrow I'll optimize my BMR crossover for the Purifi. It's currently designed for the SB Acoustics 6" ceramic, but it works surprisingly well with the Purifi. And then I'll listen carefully and compare it with the Scan 8545 to see whether all these great measurements really make an audible difference.

 

[HooStat]

But I really wish they'd make a ~5" optimized for a small-mid sealed box with 80-100Hz f-3.

Does anybody have one? Asking because that is my way of thinking as well. But I am not very knowledgable about drivers.

 

[DDF]

Does anybody have one? Asking because that is my way of thinking as well. But I am not very knowledgable about drivers.

I went with the W4-1720, it seemed the best candidate at the time, but it's break up requires some extra components in the crossover and I want to remeasure its mid range distortion. A Purify version would stomp it.

Here are the TS params I measured:
55.325 "Fs Hz"
4.100 "Re Ohms"
18.323 "Res Ohms"
2.308 "Qms "
0.516 "Qes "
0.422 "Qts "
0.149 "L1 mH"
1.007 "L2 mH"
1.515 "R2 Ohms"
0.227 "RMSE-load Ohms"
4.222 "Vas liters"
8.944 "Mms(Sd) grams"
925.213 "Cms(Sd) æM/Newton"
4.969 "Bl(Sd) Tesla-M"
83.242 "SPLref dB "
0.169 "Rub-index "

and small box I built:

 

[Dennis Murphy]

I love that these drivers exist and push the driver state of the art, but to me they're a missed opportunity towards a real state of the art system.

A real start of the art system uses external subs (flexible placement for room modal control) and sealed boxes avoiding all the drawback of ports. Lets be honest, ports are cost reductions.

So, for commercial reasons, I get why they spec'ed these how they did, and watts are cheap. But I really wish they'd make a ~5" optimized for a small-mid sealed box with 80-100Hz f-3. That would have killer sensitivity, great power handling and max SPLs with amazingly low mid band distortion and killer directivity, in a reasonable box. The current designs are creme de la creme for an older school system design premise.

I don't have a firm opinion on this, but I'm having trouble figuring out what question the 4" is an answer to. It isn't suitable as a dedicated midrange--the bass capabilities would be wasted and the sensitivity is really too low for commercial purposes. You can't use them in parallel because the system impedance would be too low. It would make a pretty expensive and low-sensitivity passive computer monitor. Maybe it would make sense to use it in an active mini where sensitivity wouldn't be an issue and the long stroke could make bass equalization viable That might make particularly good sense if it could be used sealed. The Qts is borderline for that (.37), but I haven't modeled it.

 

[VeerK]

I did a complete set of TS parameters and everything is dead on. The frequency response is also exactly as advertised--absolutely no breakup that I can see, and except for the baffle step it's flat to 4 kHz, after which it rolls off smoothly. I also measured distortion, and it also seems to be as low as the factory plots shows, although I don't know how accurate my OmniMic measurements are. The bass has great impact on bass transients, but there's a whole lotta port noise on steady tones down in the 30's even with my aggressively flared 2" Precision Port. And for correct tuning, I would have to increase its length, which would make the problem worse. I'll have to think about that one and see whether the passive radiator will be a necessity. Tomorrow I'll optimize my BMR crossover for the Purifi. It's currently designed for the SB Acoustics 6" ceramic, but it works surprisingly well with the Purifi. And then I'll listen carefully and compare it with the Scan 8545 to see whether all these great measurements really make an audible difference.

Thanks for sharing Dennis, good to see the Purifi is matching your expectations. I’m going to get the passive radiators with the purifi woofers when they show up on Madisound, so I’d be very curious to see your take on that combo.

 

[jhaider]

So, for commercial reasons, I get why they spec'ed these how they did, and watts are cheap. But I really wish they'd make a ~5" optimized for a small-mid sealed box with 80-100Hz f-3. That would have killer sensitivity, great power handling and max SPLs with amazingly low mid band distortion and killer directivity, in a reasonable box.

Put another way, you want an available version of the JBL 705i/P woofer.