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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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  • 1 month later...

I somehow missed this reply completely.  The issue with these is that they are in no way Stax compatible.  Sure the bias supply might be 600V but for this driver design it should be far higher.  Even with the Carbon CC (so more power than you can throw at any one set of headphones) it starts to compress and act up which are the tell tale signs of trying to compensate for a lower bias voltage with the drive voltages.  It creates and odd effect so yeah... can't really recommend an amp for these. 

I need to do a follow up really as there is so much oddity here.  I cracked open the supplied headphone cable and wow... it is so weird. Think Hifiman cable but worse...  Then we have the energizer which I just rebuilt to my SRD-7 spec.  It is just weird, channels swapped and the wiring made no sense at all.  Nice transformers but the rest is just utter crap, also unsafe as only the back panel is actually earthed.  All 6 panels which make up the chassis are tied to the corner posts, which are made out of plastic so non conductive. 

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  • 2 months later...

Ahhh yes, the age old "ohh this model is way inferior to the others"... despite it having the same driver setup.  The issue isn't down to voicing, it is the fundamental setup of the drivers, they just don't work.  They are simply not stable so when you try to compensate for the lower sensitivity with more drive voltage, it all falls apart.  Plenty of others have compared them in the Mafia and yeah... there are no favorable reviews to be found. 

One thing that should also be clear, none of these are actually amps, they are basic speaker amps driving the same transformers across the range.  The transformers are ok, nothing more than that but the rest is just a dumpster fire.  Now let's start with the truly dangerous stuff, none of the chassis is actually earthed or uses proper high voltage parts.  Sure the back panel is earthed but the other 5 chassis panels are in no way electrically connected to it.  Since they like to run non isolated bias a fraction of a millimeter away from the front panel... yeah this is a big problem.  Then we have the whole fake XLR's from China being asked to carry 600VDC and high voltage AC though a cable which is a bad joke.  It's actually worse than the Hifiman one and that says a lot...  I can't remember if I ever posted a picture of it but I'll try to do that later. 

Reading something on HF?  No... I don't waste my time on that unless there is solid technical background.  Impressions are all but meaningless. 

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2 hours ago, voja said:

There is no point in sharing an opinion if you are going to have someone push yours away just because you published your impressions to a website and have no technical background. What's next? You will not listen to someone because they are not a measurement microphone? Sound like heavy bias to me, and that's something that I have no interest in. Everyone should be free to share their opinion and have a healthy debate or disagreement...

There are opinions and then there are technical facts. Spritzer used plenty of safe design practices facts (non-earthed chassis panels, improperly spec'd connectors, non-isolated bias close to (non-earthed) panels, etc.). Terming these as "opinions" is disingenuous.

The more you argue, the more it appears you have a real hard on for this company, and are acting as a shill.

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It's pretty absurd if you think what's inside a product doesn't somehow reflect on the reputation of a company

You can't fault other people for making educated assessments just because you don't understand the technical aspects of the design- having a high word count isn't going to make up for that, this isn't headfi

Edited by nopants
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I've seen detailed internal pictures of both of the other units and yeah... pure utter trash.  Every corner has been cut, product which springs for ChangX capacitors... yeah they really care about quality.

If I'm so wrong, post internal pictures and tell me how wrong I am using actual facts, not feelings. 

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The point is that things can potentially SOUND good, but if corners are cut there may be issues with usage and/or longer-term reliability.

Some prime examples of this have been HiFiMan (QC issues with many of their phones but often sounded good; and "production" models VERY quickly upgraded to v2 or higher, which tends to mean the product wasn't even a fully finished product to start on first introduction), Cavalli (similar QC type issues and possible design shortcuts), and as an extreme example, Single Power (parts used that aren't in spec for voltages present, poor construction that could literally cause fires and failure; but boy they sounded great).

This is not your normal forum, and while it's good to learn about new things there are colleagues in here that can tell many aspects of design and construction quality based solely on the pictures of the innards.

So while your opinions on sound are worthwhile in some aspect, it is tempered by build quality questions; so many decide not to move forward and blindly accept sound impressions without more technical info. It could save $ and aggravation in the long run.  The argument is that both go together, sound and design/build.  So if one is clearly not up to par, then the other doesn't matter - at least to people here.  I'm in no way saying these products are like Single Power, but a LOT of people got burned by him/that company.

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I tried to read that article... holy crap do you honestly believe those cables and idiotic footers make a difference?  For fucks sake...  Also first good point is build quality... sure. 

Thanks for the internal pics though as this thing sure is a hot mess.  So you have a tube amp... and you could use that to directly drive the stators but nope, they went the worst of all worlds.  They take a push pull amp, step that down to speaker level and then step it back up for the electrostatics.  WHY!!!??  In what universe is that a good design choice, double up the transformers and cram it all in a small chassis... right next to the power transformer and the inductor.  You would be much better off with a cheap tube amp off ebay (the China specials) and a SRD-7.  That way there is at least some isolation. 

Same bias supply as the transformer box, despite this being a tube amp and thus safe, high voltage AC being present which is easy to step up.  Hell, a dedicated tap off the transformer would suffice. 

I just love that one nut in the back right hand corner just not fully fixed.  Shows the amount of care. 

All the same earthing issues as the other amps as it uses the 3D printed corner pieces which don't conduct. 



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While I'm at it, here is the cable they use:


Just took some quick picks with the phone, can't be arsed to spend any more time on this:



So those are the cheapest XLR's money can buy and possibly the oddest cable I've ever opened.  The signal is carried on those thin wires but the bias is on a massive copper mesh for some reason.  Now somebody spent a lot of time making this but that doesn't mean any of it is a good idea.  First off, the teflon is clearly very thin when the proper 600V stuff is not and in what world is it a good idea to have the highest current capacity for the bias wires?  The bias supply is tied directly to the mains, if the bias resistors fail and all hell breaks loose... you don't want what is essentially a mains cable coming up to your head. 

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I think you are seriously missing the point. The big problem with the transformer box is potential SAFETY issues. When spritzer talks about the construction not being up to code, what he is talking about is construction standards that are designed to protect the user from being SHOCKED, or worse, ELECTROCUTED. For example, he mentions that the XLR connectors are not spec'd for the voltages they are intended to carry, which is not aa good thing. The metal panels on the box are not all connected to ground which means that if a wire inside the box should somehow break and touch an ungrounded panel, and you then touch that panel, you would get a shock. That is why all modern appliances (including amps) with metal boxes have their outsides electrically connected to the ground wire on your three wire power cord, for your protection. You admit that you are not a technical person, so you should pay attention to someone like spritzer, who is. It doesn't matter a bit if the headphones sound absolutely perfect, if they could injure or kill you. End of discussion.

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i have bigtime problems with their cables.  for cables with a cable shield the shield has to be at ground potential, not 580vdc.

with 2 wires on each stator, the cable is double the capacitance that it needs to be. really messes with the frequency response and high frequency load presented to the amplifier.

6aq5 output tubes paralleled, so maybe 5 watts into 8 ohm speaker tap.

e180cc as input tube. medium gain.

circuit highly similar to early dynaco, pentodes driven as tetrodes with ultra linear transformer taps.

unregulated power supply is a bad joke.

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51 minutes ago, voja said:

I don't see the reason behind all the little personal jabs.


Where's the reasoning behind all the inappropriate comments? Or are these sorts of comments acceptable here? Never seen this way of communication anywhere else.

This ain't just any ol' audio forum. Should have done your research before cross posting from HF, etc.  Enjoy the ride!

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Bon Voyaje!

5 hours ago, voja said:

Did I ever claim to possess any sort of a technical background? No.

I will press the founder about them and encourage him to change the design if the concerns are valid.


How will you press the designer if you don’t understand the technical issues? 

Edited by luvdunhill
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Indeed, you have no clue what you are talking about and you come to us... and expect what exactly?  This isn't Head-fi where nobody has a clue what the hell they are looking at, we spot BS from miles away and shills as well.  You may think this stuff is as good as it gets but for me that just points to inexperience more than anything else.  Nothing wrong with that, everybody starts somewhere but barging in and claiming you have a clue what is going on... it's not a good look. 

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