Coax project using Radian 6CRS5130-R ribbon tweeter drivers

[smowry]

ppataki​

Frankly, I am impressed. For 'in room' with no correction, the response looks amazing to me! Your crossover seems to work very nicely. In addition, Radian hit the throat et al. design and the related low frequency and high frequency transducer acoustic coupling. However, the high frequency beaming could have been mitigated with a phase plug or some sort of acoustic lens. While the cone is the wave guide that should control the HF transducer's directivity and it seems to but only up to about 10K Hz.

Now with regards to cost vs value, that's subjectively personal or is it personally subjective? For example, in Thailand in addition the the transducer cost, there is shipping, 10% duty, 7% VAT, 2 - 3% Customs Broker fees, and there's an if the seller will even ship to Thailand. Radian offers no warranty for products shipped outside the USA. What's it like in Hungary?

Then having said all that, I purchased 2 x 6CRF5130 on Ebay from Utah, USA for list price but 1/2 typical shipping costs. They arrived in pristine condition with some of the best packing that I have ever seen. The carrier, DHL assessed an additional 19% on the declared value (list price). Then the KEF Q3 Meta loudspeakers (cannibalize the drivers from loudspeakers) costs more. The Tang Band W6-2313 costs about 25% less at Parts Express. I have purchased all three transducers and I have no experience(s) with the Sica coaxials and if they are even available in Thailand. However, with regard to the three coaxials that I purchased, there are things I like about each but my favorite is the Radian followed by the KEF Q3 Meta and then the Tang Band. I am happy I was able to get these bad boys or are they girls?

I plan to use the Radian 6CRF5130 in a ~0.6 m closed piece wise tapered PVC pipe that is treated inside and outside with a sand/AB epoxy mix with high pass above 400 Hz, similar the B&W 801D midrange. The pipe assembly will be composed of an inner (tapered) pipe and outer (not tapered - sand filled) 180 mm OD pipe. My point regarding value, the Radian is the best 6-inch coaxial that I can find but for me and maybe not everyone.

 

[DanTheMan]

I hate to say it, but I would return those while you can. It sucks to put all that work in, but something definitely appears to be wrong with the one tweeter.

 

[ppataki]

I hate to say it, but I would return those while you can. It sucks to put all that work in, but something definitely appears to be wrong with the one tweeter.

When crossed at 4kHz I do not experience any anomalies, neither by ear, nor based on the measurements
But I agree they indeed look funky below 2-3kHz

I am more worried about the distortion of the woofer, especially once all the corrections, etc. will be in place...

I hope this evening I will have time to further play with them - since Monday they have been running continuously to have some break-in

 

[ppataki]

What's it like in Hungary?

I have ordered them from TLHP, their terms & conditions shall apply here
I will decide whether to keep them or return them by the end of next week (I have 14 days of right of withdrawal, without any justification)

 

[smowry]

Here are the Radian and the KEF 6-inch coaxials. Note the DIY Nylon fastener with Cu fish tail lugs. The Tang Bands are in transit. I will get them next month.

If you are not satisfied with the Radians, the the KEF Q3 Meta's are only moderately more money. For me in Thailand, the Q3 Meta loudspeakers cost about US$15 more per unit or US$30 per pair. KEF products are sold locally, whereas the Radians came from the USA. The Tang Band's are a bit cheaper from Parts Express. An issue with the Tang Bands seems the be related to the crossover. In that case, I thought that if anyone can solve that riddle, it might be you! When Amar reviewed the KEF Q350, one thing stood out to me, excellent directivity! There were a few resonances that some thought were related to enclosure/port design. Anyway, all I will utilize from the Q3 Meta loudspeakers in my projects are the transducers. From an transducer engineering standpoint, it is implied by inspection that the KEF has a lot more development work and what I would call "meat" in their design/implementation.

 

[ppataki]

Here are the Radian and the KEF 6-inch coaxials. Note the DIY Nylon fastener with Cu fish tail lugs. The Tang Bands are in transit. I will get them next month.

View attachment 430152


If you are not satisfied with the Radians, the the KEF Q3 Meta's are only moderately more money. For me in Thailand, the Q3 Meta loudspeakers cost about US$15 more per unit or US$30 per pair. KEF products are sold locally, whereas the Radians came from the USA. The Tang Band's are a bit cheaper from Parts Express. An issue with the Tang Bands seems the be related to the crossover. In that case, I thought that if anyone can solve that riddle, it might be you! When Amar reviewed the KEF Q350, one thing stood out to me, excellent directivity! There were a few resonances that some thought were related to enclosure/port design. Anyway, all I will utilize from the Q3 Meta loudspeakers in my projects are the transducers. From an transducer engineering standpoint, it is implied by inspection that the KEF has a lot more development work and what I would call "meat" in their design/implementation.

Thank you for all these tips, much appreciated!

I am on the verge of sending them back actually.....the left tweeter started to have a fairly large dip in the frequency response at 5kHz and also a huge peak in the distortion curve at the same spot...... you were right @DanTheMan
And the right woofer has higher distortion than the left - probably due to air leakage in the center of the cone (I can totally hear it too)

By ear they sound pretty good but I am reluctant to keep two defective drivers for such amount of money....

I am now looking at these drivers as my next candidates to try: https://www.kartesian-acoustic.com/cox165-vpa

 

[ppataki]

OK, I have made my decision, I have initiated the return
Keeping two drivers with the above symptoms is not an option for 810 EUR (to me, at least)

I have three candidates on my short list:

1. https://www.kartesian-acoustic.com/cox165-vpa
This one has an alu compression tweeter and a carbon fiber woofer
On paper it looks quite good but somebody has published some measurements on diyaudio after buying a pair and those look pretty bad....

2. https://sica.it/prodotto/6-cx-2-pl/
This one has a polyimide (I guess kapton?) dome tweeter and paper woofer
Polar diagrams look really nice but when I simulated the woofer in BassBox Pro the result was really disappointing (F3 at around 300Hz....)

3. https://sica.it/prodotto/6-5-c-1-5-cp/
This is the bigger brother of the 5.5" version that I have already tried, so it shall be a similar ballgame but with a bit worse polar diagram

I would appreciate any comments folks, thank you in advance

 

[smowry]

OK, I have made my decision, I have initiated the return
Keeping two drivers with the above symptoms is not an option for 810 EUR (to me, at least)

I have three candidates on my short list:

1. https://www.kartesian-acoustic.com/cox165-vpa
This one has an alu compression tweeter and a carbon fiber woofer
On paper it looks quite good but somebody has published some measurements on diyaudio after buying a pair and those look pretty bad....

2. https://sica.it/prodotto/6-cx-2-pl/
This one has a polyimide (I guess kapton?) dome tweeter and paper woofer
Polar diagrams look really nice but when I simulated the woofer in BassBox Pro the result was really disappointing (F3 at around 300Hz....)

3. https://sica.it/prodotto/6-5-c-1-5-cp/
This is the bigger brother of the 5.5" version that I have already tried, so it shall be a similar ballgame but with a bit worse polar diagram

I would appreciate any comments folks, thank you in advance

The Kartesian's look interesting but I have no experience with them whatsoever.

Have you considered the Tang Band W6-2313?

This one is different from all the rest, in that the low frequency transducer motor is "Underhung". I only have Large Signal Parameters for the Tang Band 8-inch. They are the best I have found anywhere.

What amazes me is that the Tang Band has a surround similar to the KEF's which is geometrically asymmetrical and thus inherently has asymmetrical stiffness. However, the Tang Band suspension has no DC offset whatsoever.

Furthermore, the Bl(x) curve is truly linear like only underhung motor topologies can be. Any issues are again related to the tweeter and the crossover. The complete review of the Tang Band 8-inch is here (https://audioxpress.com/article/test-bench-tang-band-speaker-w8-2314-high-end-coaxial-driver). Here's a lengthy DIY project discussion of the 6-inch Tang Band Coaxial (https://www.diyaudio.com/community/threads/tang-band-w6-2313-sug2-25-based-project.406869/).

Cost is US$245/unit + shipping at Parts Express but they only have 10 left. The 8-inch Tang Band Coaxial is sold out and one must order at least 50 pieces at US$315/unit to make a purchase. Parts Express has a liberal 60 day return policy (https://www.parts-express.com/retur...IbnL3kzGGWP5CvQ0Knh4SYzk6fiqviLRl9kjtciDr1_mR). Finally, the Tang Band 6-inch Coaxial should be a geometric drop in for the round Radian 6-inch Coaxial.

Below is a Bl(x), Kms(x), Le(x) curves for the KEF LS50 transducer for example.

The LS50 parameters although good are not up to the Tang Band but KEF has the phase plug and optimized cone/waveguide geometry!

 

[ppataki]

The Kartesian's look interesting but I have no experience with them whatsoever.

Have you considered the Tang Band W6-2313?
View attachment 430615
This one is different from all the rest, in that the low frequency transducer motor is "Underhung". I only have Large Signal Parameters for the Tang Band 8-inch. They are the best I have found anywhere.

View attachment 430598

View attachment 430599

View attachment 430612

What amazes me is that the Tang Band has a surround similar to the KEF's which is geometrically asymmetrical and thus inherently has asymmetrical stiffness. However, the Tang Band suspension has no DC offset whatsoever.

Furthermore, the Bl(x) curve is truly linear like only underhung motor topologies can be. Any issues are again related to the tweeter and the crossover. The complete review of the Tang Band 8-inch is here (https://audioxpress.com/article/test-bench-tang-band-speaker-w8-2314-high-end-coaxial-driver). Here's a lengthy DIY project discussion of the 6-inch Tang Band Coaxial (https://www.diyaudio.com/community/threads/tang-band-w6-2313-sug2-25-based-project.406869/).

Cost is US$245/unit + shipping at Parts Express but they only have 10 left. The 8-inch Tang Band Coaxial is sold out and one must order at least 50 pieces at US$315/unit to make a purchase. Parts Express has a liberal 60 day return policy (https://www.parts-express.com/retur...IbnL3kzGGWP5CvQ0Knh4SYzk6fiqviLRl9kjtciDr1_mR). Finally, the Tang Band 6-inch Coaxial should be a geometric drop in for the round Radian 6-inch Coaxial.

Below is a Bl(x), Kms(x), Le(x) curves for the LS50 transducer for example.

View attachment 430606

View attachment 430608

View attachment 430611

The LS50 parameters although good are not up to the Tang Band but KEF has the phase plug and optimized cone/waveguide geometry!

Thank you for the tip - this Tang Band indeed looks very promising. I was searching for it here in Europe but could not find any on stock yet. But the bigger problem is that my better half does not really fancy their looks - and to be honest I also have a hard time imagining them in my sphere cabinets.
I know looks shall not matter but I guess this is yet another subjective area....

In the meantime I have done some simulations (in BassBox Pro) for the Kartesian and the Sica coax drivers above and I am not really happy with what I am seeing on the woofer front - all of them seem to start rolling off really early

Today I have accidentally stumbled upon this one here:

ESB 4.6C

6.5"/165 mm Coaxial

www.esbcar.com

(released in May 2024, pretty new!)

Yet another Italian company (like Sica) and both the graphs and the simulations look extremely good:

https://www.esbcar.com/_files/ugd/0bf3d1_3abb33ebd2a0438d8259225e34de27a0.pdf

I just put it here for reference, in case anybody is interested, the simulation of the Sica 6 Cx 2 PL vs the ESB 4.6C in my sphere cabinet:

At least the woofer of the ESB must be up to the game for sure!

And apparently I am not the first one to think about using these car speaker drivers at home:

As soon as my return process finishes I am going to order these drivers and will create a new thread to share my experience

 

[ppataki]

The new project thread is already available here:

Coax project using 6.5" car audio drivers ESB 4.6C

Here is the next step in my coax journey ;) Coax drivers have been pretty popular in car audio, so I thought I would take a look around to see if there are any manufacturers out there that publish T/S parameters and/or (relatively) meaningful measurements I have managed to find some...

www.audiosciencereview.com