[ElectroCit]

Hi all! Just got my hands on a pair of ESP/950's.

They will definitely become a mainstay on my desk.

This is probably the only headphone I have ever tried that fully encircles my ears without pinching or rubbing any part of them. The long-term listening comfort is beyond compare, and that's why I do not intend to part with these headphones. I will definitely part with the stock earpads though. I DO NOT care for them.

When I set the headphones+amp up I quickly realized my current setup will probably have to change. I am outputting to the E/90 amp from the RCA monitor outs on a MOTU M2 audio interface. It's not a line-level out, and I can hear a ground loop noise when the interface is connected. It's very faint, and music easily overpowers it, but it's there. Funnily enough, if I put my thumb over the LED or the 3.5 jack socket of the E/90, the noise goes away. So I guess that issue must be resolvable. Just need to connect the E/90 to a source via unbalanced line-level outputs, and maybe get a better power supply.

Which brings me here. I don't know a whole lot about audio gear, and I am not exactly flush with cash, but I can afford gradual upgrades. My current plan is to start with simpler components and move on up to more complex upgrades.

1. Before I do anything else, I am ordering new earpads from Vesper Audio. Stock ones are objectively the biggest detriment to my listening experience right now.
2. Then I am going to get a decent 2RCA-2RCA shielded cable. I read that in some cases removing unwanted noise can be as simple as that.
3. Next, I'm going to look for a different audio interface. I want to use the ESP/950 with a PC and run some other audio gear out of that interface (a S/PDIF sound projector from Yamaha and an XLR condenser mic). So I guess I should be looking for something with low self-noise, an unbalanced line out, an XLR mic in, a S/PDIF out, and a USB in.
4. Finally, some folks here mentioned that a quality power supply does help the E/90 amp, so that should be worth the money. I could probably run both the amp and the audio interface out of the same power supply, and if it's wired right, it should not give me any ground loop noises. As far as I understand, that is something a good power supply can do.

Is my plan sound? Does anyone have any suggestions or pointers? Any input is appreciated.

P.S.: Before anyone suggests it, I cannot take advantage of Koss' limited lifetime warranty. Manufacturer no longer does any business in my country.

 

[Reticuli2]

if I put my thumb over the LED or the 3.5 jack socket of the E/90, the noise goes away

Does it occur even when the source is turned off but the E/90 is still on? That happened to mine I had way back that Tyll first measured before I returned it to Amazon.

The E/90 apparently measures comparable to a Stax SRM-323 amp, but the issue is the quality and durability of mostly the discrete components used on the Koss amp. They tend to be poor tolerance and prone to going bad over time. The warranty helps with that, but it's still a conundrum of decent enough sound when it's working properly but with a tendency to not work properly.

I also noticed that the system (or at least the amp) changes its sound as it's left on. The initial sound, the sound after about an hour or two, and the sound after a few hours more. This might be a result of discrete components inside being stretched to their limits and forced to operate at higher voltage and heat levels than normal for them. I'm not sure if this requires the amp to be in use to occur, or it's running class A in there at all and can be just left on to stabilize. Though, I must admit to preferring the initial and intermediate sound to the punchier, tighter, harder, crisper, more-U-shaped tone it gets at the end.

 

[ElectroCit]

Does it occur even when the source is turned off but the E/90 is still on?

I... haven't actually tried to listen for the sound in this configuration. It'll be a couple of weeks until I get back to my desktop setup, but I'll definitely try this.
I did hear the sound with the E/90 unit powered off and unplugged from the wall but still connected to the powered-on source via RCA.
Another observation about the noise: it's stronger when I just ran an aux cord from my laptop to the E/90.

I also noticed that the system (or at least the amp) changes its sound as it's left on.

There is some truth to that I suppose, but I'm still adjusting to the level of detail I have never heard out of my other headphones before. I can't rightly say where does my preference lie, but I think it's some hours into the listening session.

I have also looked into putting out a line-level signal through balanced outs of my audio interface. I checked the manual, and it is possible. But there is a caveat:

From MOTU M2 User Guide:
Note: the analog outputs are not cross-coupled. Therefore, when connecting them to an unbalanced input, use a TRS plug with the ring disconnected. Not floating the negative terminal will short it to the sleeve ground and cause distortion.

So that's going to take a special cable job. Not looking forward to that tbh. The RCA outs are also just supposed to mirror the jacks, so I think my connection is already as right as it can be, and the issue lies elsewhere.
I considered my options for an upgrade path and currently I'm looking at some second-hand Audient id22 audio interfaces. Straight upgrade to my current one across the board, and it has all the analog and digital i/o I need. Its analog outputs appear to be transformer-coupled, which I think means I can just run RCA-TS cables without causing any unwanted sound distortion.
I also found some mentions of a Line Level Shifter. It is a device that purports to do exactly what I need: eliminate ground loop hum and turn balanced output into unbalanced. Maybe I could start with that.

Honestly I don't even know if I want to jump through so many hoops to fix what is to me a non-issue. I just take the headphones off when I'm not actually listening. If I bought the headphones at retail price, then sure, maybe it'd bother me. But I got my pair second-hand for quite a nice discount so I'm willing to roll with some imperfections as long as they perform their primary function as intended, which they do.

Really happy with these headphones. Or, well, earspeakers, I guess.

 

[ElectroCit]

So I was in the middle of changing the earpads on my ESP/950 when I noticed that something's not quite right with the foam layer glued to the inside of the cup:

It's like it is stretched out and wobbly in the middle. The edges are glued up tight.
The Vesper Audio earpad (seen in the background of the shot) has this light mesh that pushes this spongy material down into the cup — I am a little concerned it could be touching the stator that way.

Do I need to fiddle with this foam business, or are my concerns misplaced? I reckon I can maybe peel it off, cut it down to size, and glue it back on.

 

[timb5881]

So I was in the middle of changing the earpads on my ESP/950 when I noticed that something's not quite right with the foam layer glued to the inside of the cup:


It's like it is stretched out and wobbly in the middle. The edges are glued up tight.
The Vesper Audio earpad (seen in the background of the shot) has this light mesh that pushes this spongy material down into the cup — I am a little concerned it could be touching the stator that way.

Do I need to fiddle with this foam business, or are my concerns misplaced? I reckon I can maybe peel it off, cut it down to size, and glue it back on.

I just replaced my pads, this time they are the Dekoni sheep skin. This makes a the fourth set since I purchased them 30 years ago. Leave the felt in place, it is for both protection and frequency adjustments.

 

[timb5881]

Since replacing the ear pads with Dekoni, I can honestly say that they are a big improvement. I also have been using them with the SRD-7 Pro and various power amps with them. When using my Aragon 8008, the ESP950 really takes a leap with firmer and deeper bass, and the treble is nice and clean. Even with the E/90, it is better.

 

[ANewtypeCentury]

Has anyone tried pairing either the ESP950 or ESP/95X with the new Topping EHA5 energizer? Really curious how it compares to the stock Koss, which I've been hearing for years is entry-level grade at best, hoping this new option is a cheap (for an electrostat) upgrade path.

 

[silent-circuit]

Has anyone tried pairing either the ESP950 or ESP/95X with the new Topping EHA5 energizer? Really curious how it compares to the stock Koss, which I've been hearing for years is entry-level grade at best, hoping this new option is a cheap (for an electrostat) upgrade path.

Most of the "serious" estat / Stax people are not fond of EHA5 and will probably just recommend you buy a used Stax unit. Seems like Topping cut quite a few corners with it.

 

[IBJamon]

Most of the "serious" estat / Stax people are not fond of EHA5 and will probably just recommend you buy a used Stax unit. Seems like Topping cut quite a few corners with it.

That's honestly quite surprising, given how well regarded most Topping equipment has become. Many of their 'normal' headphone amps have reference-level measurements.

 

[silent-circuit]

That's honestly quite surprising, given how well regarded most Topping equipment has become. Many of their 'normal' headphone amps have reference-level measurements.

Don't get me wrong - I love the G5 and D90/A90 stack, but it makes sense (unfortunately) that they built the energizer to a price point, not to be a top end product.

 

[timb5881]

While I do not own the EHA5, I feel it is getting a bad reputation before many people have even tried it. It is not the first amp of its type, with Stax SRD-X (and the pro version), being a portable amp with transformers. I would buy it, but I already have SRD-7 and a pro version as well, and I really would not gain anything with it.