New project: 2way U18RNX D2604

[PKAudio]

For a long time I wanted to try one of Seas midwoofers, U18 seemed to be well balanced for midwoofer duty in 2way, though there was not many good measurements available from which I could judge the driver. D2604 limited edition discovery tweeters got to my hands, and I have to ay I like them a lot, at least the measured performance for now.
U18: I am very please with its FR linearity. It is very easy to work with a to make a crossover.
Initial crossover is attached, and in coming weeks I will optimize it and arrange the first listening tests.

More details: https://pkaudio.webnode.cz/u18d2604/

 

[wolf_teeth]

Great midbasses, loved them in my Drottnar build. Bass extension isn't the best, but the mids are smooth and easy.

 

[tktran303]

Nice preliminary design Petr!

That’s the the time I’ve seen some polar measurements of this woven polypropylene cone driver.

Interestingly the woven materials exhibit anisotropy. It looks like dual plane measurements might not be enough, after all.


References:
https://www.klippel.de/fileadmin/_migrated/content_uploads/KLIPPEL_Cone_Vibration_Poster_01.pdf

http://loudspeaker-research.de/Erweitertes Buendelungsmass.pdf


You should try some other woven materials when you have the opportunity. “old fashioned” Eg. Glass fiber, Kevlar

 

[hifijim]

I like the relative simplicity of the crossover, and I understand you are still optimizing it.

I have never worked with that midwoofer before, but I have often wondered about it. Polypropylene has good natural damping, and in theory by weaving fibers together, the damping is increased by internal friction, i.e. a lot of hysteresis. it is nice to see that the theory is validated. Truly a well behaved cone.

I am looking forward to your assessment of the finished speaker. As always, your cabinets look great.

 

[Nisbeth]

Never tried the U18 myself, but I noticed that https://ampslab-spk.com/hifi-drivers-2/ has a very positive review of it as well (and some designs with it).

 

[PKAudio]

Nisbeth: yes, Myna speakers series. Some of the U18 measurements show the dip at ~900Hz, so I was not sure what to expect. And no off axis measurements... Though I was pleased with the sound description.

Zaph's measurement show that dip as well.

Don's project convinced me to buy U18 and try it.
https://www.donhighend.de/?page_id=9543

 

[PKAudio]

You should try some other woven materials when you have the opportunity. “old fashioned” Eg. Glass fiber, Kevlar

I have already that experience with BW 802D2, yellow FST midrange. Peerless HDS drivers looked to be very good, unfortunately they are not available anymore.

I heard good reviews of U16, so I have good expectations from U18 as it is supposed to sound more lively compared to old P17 or SB MFC series.

 

[PKAudio]

I like the relative simplicity of the crossover, and I understand you are still optimizing it.

I assume I will end up with this simple LR2 crossover, though mild tuning of the values will be needed, based on listening tests.
I will try to model LR4 version as well, just for the comparison and to get experience...

 

[PKAudio]

Great midbasses, loved them in my Drottnar build. Bass extension isn't the best, but the mids are smooth and easy.

I studied your project as well, to get the feeling about U18 before I bought it. Interesting to see the dip ~3dB at 600Hz and you mentioned increased distortion in that area as well.

 

[wolf_teeth]

The measured dip Is closer to 900, and you can here that it is not as clean there. My Omnimic measurement is posted in the thread for verification.

The sim had a traced set of FR and I adapted them to the intended box, but I don't remember why the second dip at 600 was there for that part of the design stage. You cal also see the upperndip is closer to 1k than 900 in the sim.

 

[PKAudio]

I checked Idunn measurements and crossover. My measurements show resulting loudspeaker sensitivity ~85dB, and main woofer coil in the crossover ~2mH. I am glad to see it all matches Seas data. Not that I would not trust my work, it is just good to see my numbers are correct.

Seas Idunn:
https://www.seas.no/index.php?optio...d=380:idunn&catid=66:seas-diy-kits&Itemid=345

 

[PKAudio]

This weekend I connected the initial crossover and got a chance to listen to those speakers. After U22 experience I was curious to hear U18 and I had high expectations. Detail, midrange quality, sense of fast and light sound, and this all also at lower listening levels. Bass does not go low, but what is there is very good, no boominess, all is well textured and clear and basically fine for 6" 2way. I will keep in tuning, various port lengths and dampening material make the clear changes.
U18 would make excellent midrange in a 3way, hmmm SB34NRXL maybe.

 

[jerome69]

U18 would make excellent midrange in a 3way, hmmm SB34NRXL maybe

+1 Good idea !
Perhaps to have more bass you should increase the volume to a chebyshev alignment 24L@45Hz. 16L is a butterworth alignment.

 

[PKAudio]

U18RNX would be fine in volume upto ~24l as you suggest. In this project I used the cabinets I had already in hands.

 

[PKAudio]

So I got this project to the completion and I am very happy with the result. U18 is excellent midwoofer and after the tuning of crossover, dampening material and the port length the bass qualities are excelent, at least in 6" cathegory.

 

[Waboo]

PKAudio,

Gorgeous cabinet work.