I have almost exactly the same dilemma... have the 2 x 315hf on hand. I am trying to decide which Purifi driver to mate with them... I would likely use either sealed, and cross actively, obviously higher to the midrange variant.
I do wonder, if one doesn't need the extra sensitivity, what benefit is there to the 6.5M over the 6.5NAA (once the resonances of the latter were passively notched out.) Has anyone compared both?
The X, vs W vs M dictates how low you want (or need) to go.
The cone diameter ie. 10", 8", 6.5", 6.5" or 4" dictates how low, but also how high you want (or need) to go, and the largest size cabinet you can bear.
Until there's one driver that does DC to 20Khz with 120dB@1m and completely omnidirectional (I'm not holding my breath), we have to make those trade-offs in system design.
The cone diameter ie. 10", 8", 6.5", 6.5" or 4" dictates how low, but also how high you want (or need) to go, and the largest size cabinet you can bear.
Until there's one driver that does DC to 20Khz with 120dB@1m and completely omnidirectional (I'm not holding my breath), we have to make those trade-offs in system design.
Any chance of a shallow 4" for automotive use one day? The depth is about 25mm too much for most doors. Guessing not since there's a reason for the performance, but one can dream
.And the implementation is the most important.
More the amount is huge and more I have time, more I hesitate.
It's very difficult to directly compare the sound of different drivers and the potential match.
However if some people know them, advices are welcome.
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Well yes, I do understand the naming convention, and the physical differences between the units. And I know there is no perfect driver, and understand the tradeoffs inherent in different driver sizes and strokes.
What I'm asking about specifically is the difference between the 6.5M and 6.5NAA. The M model is optimized for midrange duty, has different cone material and geometry, higher sensitivity, and less stroke. There are other differences in the soft parts that I don't fully understand. Possibly differences in the motor as well?
The midrange optimization gives you better sensitivity. But looking at the datasheets and the hificompass reviews, it looks like the directivity is very similar (as would be expected, cone size dominates, geometry only affects this so much), and once notched, the NAA can be used as high or higher than the M. The distortion on both is impressively low, though if I read the graphs right, it seems like the M may be slightly cleaner >200hz, and stay cleaner to a higher output level. I'm not confident in my ability to critically analyze the IMD/CSD plots.
So in an application where the extra sensitivity doesn't help, box size is flexible, and you could cross in the 150-200hz range, is the M driver still the better choice for a mid playing unusually low? Are there technical advantages that I may be missing (in which case I'd love to learn)? And ideally, what do the differences translate to subjectively, especially if someone has had a chance to play with both?
Is this a clean slate design or do you already have some drive units you are already using?
Looks like you are looking for help with a purchase decision.
X series make most sense in a 2 way; because it gives excellent clean bass down to 50Hz that no other 6.5” can do. And it has a much smoother upper response than many other metal cone midwoofers. Eg. SS 18WU/4747
The reason for the development of the W and M is because because the market wants some higher sensitivity drivers. By shortening the voice coil and reducing the moving mass the sensitivity goes up.
1. Yevgeniy’s review is thorough and excellent
https://hificompass.com/en/reviews/purifi-ptt65m08-nfa-01a-65-true-midrange
2. JonMarsh over at HTGuide is working on a 2 way with the RSS315HFA-8 in pairs with the PTT 6.5M as mid and T34A/B tweeter.
The main reason to use it is that you need the extra sensitivity
And in terms of directivity and distortion what your drivers below and above need.
Eg. 18” to 6.5” to 4” to tweeter
120hz/800Hz/3Khz crossover points- use W
Dual 12” to 6.5” to tweeter
300Hz/2500Hz crossover - use M
The cone material: well that’s everyone’s favourite topic how does it sound?
I was hoping to do a lil type experiment where a 2-way with the NAA and NFA would be made with the exact same CTA2034A measurements (horizontal /vertical off axis), and have Erin do a little listening test and report back; but that might have to wait whilst he’s taking a short break.
Hope that helps
Looks like you are looking for help with a purchase decision.
X series make most sense in a 2 way; because it gives excellent clean bass down to 50Hz that no other 6.5” can do. And it has a much smoother upper response than many other metal cone midwoofers. Eg. SS 18WU/4747
The reason for the development of the W and M is because because the market wants some higher sensitivity drivers. By shortening the voice coil and reducing the moving mass the sensitivity goes up.
1. Yevgeniy’s review is thorough and excellent
https://hificompass.com/en/reviews/purifi-ptt65m08-nfa-01a-65-true-midrange
2. JonMarsh over at HTGuide is working on a 2 way with the RSS315HFA-8 in pairs with the PTT 6.5M as mid and T34A/B tweeter.
The main reason to use it is that you need the extra sensitivity
And in terms of directivity and distortion what your drivers below and above need.
Eg. 18” to 6.5” to 4” to tweeter
120hz/800Hz/3Khz crossover points- use W
Dual 12” to 6.5” to tweeter
300Hz/2500Hz crossover - use M
The cone material: well that’s everyone’s favourite topic how does it sound?
I was hoping to do a lil type experiment where a 2-way with the NAA and NFA would be made with the exact same CTA2034A measurements (horizontal /vertical off axis), and have Erin do a little listening test and report back; but that might have to wait whilst he’s taking a short break.
Hope that helps
@tktran303
Very interesting read.
I just ordered 6x PTT6.5M08 NFA01 for 3x inwall WMTMW LCR. What Q would be recommended to get the best sound quality out of these midranges?
Very interesting read.
I just ordered 6x PTT6.5M08 NFA01 for 3x inwall WMTMW LCR. What Q would be recommended to get the best sound quality out of these midranges?
where are you planning/guessing you'll crossover? It probably wont matter much depending slightly on where you crossover. I would shoot for anywhere between .5-.7 qts.
I'll use 200Hz as recommended. I was planning on using a Qts slightly under 0.7 but if 0.5 would allow these mids to "breathe" a bit better I'd definitely choose that value.
I'm also researching for the best midrange enclosure shape and damping material but there are enough topics to read on this forum discussing this matter.
Now thats an LCR i'd like to hear!
Anywhere from .5 to .7 as suggested would be fine. Its more likely going to bother your crossover level/phase matching more than sound quality.
just wondering why use purifi speaker as a dedicated bass woofer in WMTMW ? what does it lack compared to those tried and ture 12, 15 inch bass driver (especailly with the ones that are high effecicy). The only downside I can see with purifi driver is they cant perform in low power amp like SET amp or first vfet mk3
These purifi PTT6.5M08 will be used as mid from 200Hz to around 1500-1800Hz. The woofers will be dual 15" PHL 6201MNd in sealed boxes and the tweeter the inevitable Bliesma T34B. I'll use the Hypex Fusion FA253 (or FA503 if better) for amplification and active filtration except the Bliesma which will be protected with a 2nd order passive HPF. It's a long term project though as I first need to build 4x LLT subs that'll be hidden behind this in-wall AV/stereo system.
Thanks! Yes the filtering will become the most difficult part. I'm going active for the most part so it should be easier to get decent results in a relatively short time. Making it awesome is the true challenge.
What's the estimated time frame? I have patience...rather 1.25"