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Soltanus Acoustics Euridiche electrostatic headphones


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I've had my eye on these for the last year or so but waiting for a cheap set to come up.  There are three versions they sell and I found the cheapest one for sale, brand new in the box with the transformer adapter.  I'll take some pics of the system tomorrow (shortest day of the year here so... yeah not great for photos) but I've at least a pic of the headphones and the internals of the transformer box. 


Here they are and I quite like the looks and the build quality.  They are using mini XLR's which is not ok but questionable connector choices are a theme here.  The stock cable is beyond crap (more on that tomorrow) so I'm using a Stax PC-OCC off my RR-1's.  They feel substantial but also light and fit my head snugly at the largest extension. 


Carbon Fiber headband and the leather is nice.  On their site they claim the Minima is supposed to have pleather earpads but these are clearly genuine leather. 


These look very similar to earpads I've bought from China in the past and nothing wrong with the quality.  I shone flashlight through the driver to you all could see the structure, very unusual drivers here.  Now onto the adapter box... yeah this is not good.  


That's it... and yeah there are so many issues here.  Let's start with this gem:


It's hard to capture on "film" but the IEC input and the fuse holder are completely uninsulated and mere millimeters from the metal frame of the transformers.  Thankfully the chassis is earthed but yeah, this is not to code and an instant CE violation there. 

In the first picture you can also see there is no protection for the transformers at all and we will get to why that is an issue.  Now the active parts:


The bias supply is driven directly off the mains, no isolation between you and the wall.  Now this was commonplace in the 70's but now... I'm not sure this meets any modern standards.  The bias supply is a simple voltage doubler and for 117V they just add another doubler on top.  There is then a 600V zener clamp to make sure the bias doesn't rise above that threshold.  None of this has the elegance of the Stax bias supplies and frankly this is just sad.  For instance the LED for power indication is driven directly off the mains, through one tiny resistor. 

Now you might notice those 3 pin XLR's there and yup, they are the stock outputs for the Euridiche, the Stax output is just for convenience.  One of my biggest gripes is with using XLR's as they are in no way rated for these voltages, especially the cheap, no-name, units they are using.  Also check out the clerances on that PCB.. bias and high voltage signals less than 1mm apart.  Then we have what scares me the most, see those traces which go right to the edge of the board and into pin 3 of the XLR's...?  Yeah that is the bias so 600V is sitting there, pressed right up against the chassis with exposed solder connections.  Sure this is after the ballast resistors (one 4m7 for the Stax and separate 10M units for each side of the XLR's) but still... They have a lot of faith in the powder coating on the chassis. 


Finally the Stax socket, 3D printed and fed directly off the XLR sockets.  Almost no way to actually cram a Stax plug in there but you know, I almost had to use a hammer.  😉

Then we come to the final issue, on paper these appear to be Stax compatible despite the stupid XLR connectors and similar bias supply but nope... they are so inefficient that my usual test amp (Icepower 50 module with a preamp tacked onto it) was at max volume to get these to my normal listening level.  I plugged in my test SR-207's as well and they were at half volume using this transformer box.  As seen in the first pic, I've fitted them with a Stax plug but they make the Carbon CC work for its pay so yeah, you need a very powerful amp to drive them. 

Now finally, how do they sound... pretty damn nice actually.  🙂  This is off the Carbon CC prototype in my rig right now and they are very balanced sounding, slightly dark sounding but very mellow and open.  They are not overly forward or bright, unless when called to be and I can listen for a few hours with nothing bad to say really.  Bass is plentiful and deep, midrange has a nice presence to it and the soundstage is pretty good.  Top end is a tad dark but it is very mild and they make for a relaxing and pleasant package.  

So TL;DR... great headphones that are let down by being too inefficient, frankly unsafe transformer box and stupid cable/connector choices.  Change the cable to Stax and drive them off a powerful amp and the sound is great. 

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I've spent some more time with the headphones now (when I really should be testing out the new CRBN) but I like these a lot.  They really do nothing wrong, soundstage is a bit flat (flat earpads though) and they aren't great with small detail retrieval but other than that they are neutral, honest sounding and I can spend hours listening to them. 

Now for the wanky things (besides that name, seriously... anus in your company name can never be a good idea ;) ) such as the box these ship in:


Almost Voce bad but at least it is well made, unlike the Mr. Speakers box. 


Here is the silly dual cable for these, male 3 pin XLR's on one end 3 pin mini XLR's on the other.  It feels terrible and I'll rip it apart later. 


What truly bothers me is this shit, these are cheapest XLR's you can buy short of the knock off Neutriks and they are pushing 600V bias and 200Vrms through this?  Yeah it's not ok... 

I'm thinking about what I'm going to do with that energizer as the transformers seem to be pretty decent.  Probably just fit my own PSU to it and change it to three Stax sockets that the headphones actually fit into. 

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The model I own is their top of the line Euridiche which is supposed to sound a bit better (despite using the same drivers) and has the added benefit of a treble adjustment switch.   

I really like these headphones, but don't know how they stack up against similarly priced Stax offerings.  Reading between the lines it sounds like these might have more bass, body and perhaps a more natural treble than a typical Stax?

Given their signature and inefficiency, what would be the best estat amp or energizer to use with these?  Soltanus Acoustics made me an adapter to facilitate using with a standard Stax Pro bias connector, but I also would love to try with other cables. 


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