Purifi PTT6.5 vs PTT4.0 as a (possibly dipole) Midrange.

PaulEbert

I am considering picking up a pair of PTT6.5s in the group buy here:

https://www.diyaudio.com/forums/group-buys/348234-purifi-ptt6-5w04-01a-woofer-buy.html

These would be used as midranges with the Transducer Labs N26MGR-A and (probably) the CSS SDX10. However, my preference would be for a smaller mid such as the not yet released PTT4.0 (or even better, a 5" version).  I can save a few hundred dollars going with the group buy which makes it barely within my budget.

I might like to go open baffle for this mid.

So, given all that, what would you do?  Should I jump on the PTT6.5 deal or be patient and hope something works out for a smaller Purifi driver?

ani_101

My opinion only, but if you are looking for a mustang, b then you are sorry of wasting the best stent of the pride, which is go low in a small box and be that ultimate tm or tmm bookshelf. If you are going to pair with the sdx, I would choose a low point and use the sdx as subwoofers crossing over at 80 or so. 

Would it sounds good in a miserable sure, you are removing the stress of lfe from it, but then you are ignoring it's best parts....

I am also waiting for the 4" mid. Maybe they're will be another group but or we can setup one in here.

Wolf

I don't know if using it as a mid actually is ignoring its best parts. If this is engineered for the ultra-low IMD and HD as it is supposed to be, it SHOULD also make a great midrange.

PaulEbert

I should have added some details. This will be a small(ish) floorstanding TMW for music use only. I don't often listen too loudly, but my music is very dynamic and full range (think Mahler symphonies).  I intend it to be passively crossed over and driven with my Spectral DMA-50 amp.  The amp is rated at 80 watts into 8 ohms.  The space is a medium sized family room with cathedral ceiling.

Before the Purifi drivers became available, I planned to use the Satori WO24 as my woofer and have a (probably single) sub. Going with a Purifi driver as a mid requires foregoing the separate sub and swapping the WO24 with the SDX10 to meet my budget.  I figure the SDX10 will be a good match anyway, though I'm somewhat concerned about it being able to go high enough to meet the PTT4.0.  Also, if anyone has a HD plot for the SDX10, I'd love to see it.

So, yes, the PTT6.5 seems designed for a TM, but as Ben said, its IMD and HD between (say) 100 and 2000 Hz, in addition to what seems to be very usable FR, should make for a state of the art mid.  At least that's the hope. I suppose I could go with the PTT6.5 in a TM and a single sub (perhaps the SDX12?).  I'll have to give that some thought, but for some reason, I like the idea of using SDX10s as (sub)woofers better.

But the PTT4.0 might allow for a higher crossover point to the TL and a smoother power response.

Another consideration is that I am not sure the PTT4.0 would be well suited to dipole use given its small diameter and relatively large magnet diameter. Perhaps making it difficult to get good air flow out the back?  That said, a dipole mid isn't at the top of my design priorities.

rjj45

Paul, that sounds like a beautiful design, and a high dynamic range / low distortion 3 way can deliver impact and realism that I don't find in a TM (Although a PTT6.5 might be close...). Although those CSS drivers leave nothing on the table, I started thinking about swept volume and using a 12 or even a 15 on the bottom. That might help with your budget also.
I wasn't that happy with my mini-statements, but a lot of folks like open back mids. If you want to go that direction, I'd use a Heil tweeter also. 

dcibel

As a dipole midrange you can EQ the low end considerably to extend down to the 120Hz or so that you'd need to cross to a dipole bass, you won't be doing that passively though. If you're not doing dipole bass then it really doesn't matter, might as well cross higher up 300Hz or so. On the top end, you're limited to about 1500Hz dipole response due to driver size. Of course if you just want open baffle and not necessarily a true dipole then you can cross over higher.

PaulEbert

rjj45 said:

Paul, that sounds like a beautiful design, and a high dynamic range / low distortion 3 way can deliver impact and realism that I don't find in a TM (Although a PTT6.5 might be close...). Although those CSS drivers leave nothing on the table, I started thinking about swept volume and using a 12 or even a 15 on the bottom. That might help with your budget also.
I wasn't that happy with my mini-statements, but a lot of folks like open back mids. If you want to go that direction, I'd use a Heil tweeter also. 

Is there a specific 12 or 15 (sub)woofer you'd recommend?  It would need to be very low distortion and, potentially, usable up to 400 hz.

I see that Parts Express no longer carries the ESS Heil products. Did they go out of business?

rjj45

Paul, 
ESS Heil folks had an inventory blowout sale last year and I (foolishly) bought 2 pairs.
They are total monsters, about 16 pounds apeice. Still in the boxes on my shelf.
The sound is legendary, and a great solution for a dipole or OB build. Price is not too bad at all, IMHO.
http://esslabsusa.com/heil-amt/

NavyGuy

Given how low the TL tweeter can cross, you should have no problem matching to the 6.5"

Ed_Perkins

rjj45 said:

Paul, 
ESS Heil folks had an inventory blowout sale last year and I (foolishly) bought 2 pairs.
They are total monsters, about 16 pounds apeice. Still in the boxes on my shelf.
The sound is legendary, and a great solution for a dipole or OB build. Price is not too bad at all, IMHO.
http://esslabsusa.com/heil-amt/

Let me know if you want to unload  a pair.    With that weight it would be best if we could meet at a DIY get together.  I usually attend the Iowa and South Dakota events, but plan on making my 1st MWAF this year too.

rjj45

PaulEbert said:

rjj45 said:

Paul, that sounds like a beautiful design, and a high dynamic range / low distortion 3 way can deliver impact and realism that I don't find in a TM (Although a PTT6.5 might be close...). Although those CSS drivers leave nothing on the table, I started thinking about swept volume and using a 12 or even a 15 on the bottom. That might help with your budget also.
I wasn't that happy with my mini-statements, but a lot of folks like open back mids. If you want to go that direction, I'd use a Heil tweeter also. 

Is there a specific 12 or 15 (sub)woofer you'd recommend?  It would need to be very low distortion and, potentially, usable up to 400 hz.

I see that Parts Express no longer carries the ESS Heil products. Did they go out of business?

I got a pair of these last year on a DOTD blowout, and plan to use them on an upcoming high efficiency 3 way, quite possibly with a Heil AMT. The efficiency is too high for your passive build, but they would be awesome on an OB with active crossover.
https://www.parts-express.com/dayton-audio-pn395-8-15-neo-series-pro-woofer-with-4-voice-coil-8-ohm--295-044

rjj45

Ed_Perkins said:

rjj45 said:

Paul, 
ESS Heil folks had an inventory blowout sale last year and I (foolishly) bought 2 pairs.
They are total monsters, about 16 pounds apeice. Still in the boxes on my shelf.
The sound is legendary, and a great solution for a dipole or OB build. Price is not too bad at all, IMHO.
http://esslabsusa.com/heil-amt/

Let me know if you want to unload  a pair.    With that weight it would be best if we could meet at a DIY get together.  I usually attend the Iowa and South Dakota events, but plan on making my 1st MWAF this year too.

I'm thinking very hard about attending MWAF for the first time this year, and the car will be loaded with drivers I need to unload... So maybe....

ani_101

10mm of linear travel fs of 30hz sounds good and I was interested to pair with the PR but a single PR would which run out of steam and two is pretty expensive.

@PaulEbert let me know how you are proceeding with these, I might just be able to get in on the GB. I still don't have any alignment or tweeter picked out, will decide after getting actual measurements.

PaulEbert

I decided to go with the 6.5s. I don't particularly want to use them ported due to port length or with the multiple (or very large) PRs that they would require. I am leaning toward running them sealed (F3 around 70 Hz).  I'll have to decide where to cross them over to the (sub)woofer.