Had anyone actually heard those Eton Arcosia drivers?

Nope, but they were expensive enough for Stereophile to finally give a DIY picture more than one sentence in their show coverage.

First Public Day at T.H.E. Show Newport | Stereophile.com

I'm with DCibel right now. Without a lot more and better information about them from the manufacturer, pulling that kind of money out of my pocket for them is out of the question.

As I've said before though, and the Stereophile post alludes to, the basic high-end calculation of MSRP to driver cost is about 20 or 30 to 1. So having expensive drivers like this is important if you plan on charging. Let's say you put together a 2 or 2.5 way with a pair of these in each speaker. Now you can justify a $30,000 per pair price tag, regardless of the sound quality. It works the other way as well. If you want to charge $100k per speaker pair, you have to find a way to spend $5k/speaker in drivers. Unless you are Wilson, then you can do $3k, they're at the high side of the scale.


IMG-1076.jpg - Google Drive

I recently built a pair of open baffle speakers with the Eton 4-318 ARCOSIA performing mid duty. It does sound fantastic. It has a very detailed and refined sound. Transients are fast and hard-hitting.

These ETON drivers are very easy to integrate into multi-way speakers because of their wide bandwidth. This allows me to use first order crossovers.

I have not heard the ScanSpeak Illumnators for comparison, but looking at the ScanSpeak frequency response they seem much harder to integrate, requiring more complex crossovers.

I would use the 4" again in future builds. I would also love to try the 7" Arcosia but the price on that one is really steep.
Eton arcosia in it's test enclosure
Certainly too expensive, for that you can get 2 Pufiri PTT6.5 drivers who are extensive tested and at least as good as those claim to be. And Scanspeak also delivers drivers like that for even less than half the price. But Eton drivers in general are not bad at all i hear (no personal experience altough).
And here is the measurement results (eton arcosia 4-218) Testbox was closed 5 liters. 30% filled by sonofil.
Measurement level is set to 87db (about 2.83V). Desibels measured by desibel meter at 1kHz tone.

Nearfield response and phase
arcosia near.png

Response (1 meter) and phase
arcosia resp1.png

Distortion 87db / 1 meter
arcosia distortion.png

And polar response. (there was little techical issues and level is not same in all measurements, but you can see directivity from this)
arcosia polar.png

Gating was 3,3ms, and No smoothing.

I listen driver at full range and it sounds quite good. Cone breakup is not sounding bad.
From the directivity measurements i think i can cross it about 3.0 - 3.5 kHz to T25B. (But this is another story)
  • Like
Reactions: 1 users
Arcosia 4-218 IMD measurements:

30hz + 255hz 4:1 (about 2mm cone excursion)
arcosia 30 255 2mm imd.png

This is interesting. IMA2 (255+30) is at higher level than IMA2 (255-30). Something similar i have seen in this forum by dayton epique.
IMA2(255+30) is about -33 db level. and other side spetrum is -43 db level. Not as good as PTT4.0 but better than seas W12CY006
IMA3(255+60) is very low level (cannot be seen). But IMA3(255-60) is shown here at -46db level. So IMA3 is not that good as W12CY006 but at in same level than PTT4.0

40+96 hz 1:1 70db
arcosia 40 96 70db imd.png

This clearly too much for a 4 inch cone. (maybe purifi can handle this) Driver is making huge excursion. more than xmax and IMD distortion is sky high.

50+210hz 1:1 70db
arcosia 50 210 70db imd.png

50+210hz arcosia can handle with very brilliant numbers. IMA2 is about -46db

50+210hz 1:1 80db
arcosia 50 210 80db imd.png

in the 80db volume highest distortion is 50hz 3rd harmonics. 210hz IMA2 is at -42db level. quite good for a IMD. IMA3 is showing here at -54 db level.

Overall arcosia driver is designed to have very low 2nd order distortion to achieve low IMD distortion. (you can see from seas W12CY006 measurements how driver makes 2nd order IMD, and 3rd order IMD is always much lower level) That's why this driver sound so good when listen. Also cone is finely damped and having very little of stored energy. Arcosia also have better effiency than W12 or PTT4.0