[BassicScience]

I'm also happy to stand corrected here - I had the other supplies on hand, and didn't really expect differences - but I think I do hear them. I take your point about the capacitor bank and power supply designed to maintain the bias voltage. But electrostatic phones also require a balanced signal pair for each channel, to support push-pull action on the diaphragm. Each of those signals must be at much higher voltages than the signals supplied to dynamic phones, and work into much higher impedances. My thinking had been the iESL has a role here also - but precisely how that works is beyond me!

The signal voltages are stepped up by the iESL's transformers, which are passive components.

 

[jamesjames]

The signal voltages are stepped up by the iESL's transformers, which are passive components.

Yes, I now see your point - and on the face of it I can't see how the power supply could be producing the result I think I'm hearing. I'll need to go back and listen again - it wouldn't be the first time I've been the victim of expectation bias ...

 

[jamesjames]

No. iESL was designed to allow these cans to work with regular speaker amps.



The idea is old, but it all comes down to how it's implemented. E-stats are niche products so iESL, although successful, was nowhere near our top sellers. But who knows, perhaps one day we'll make an even better version of it.

Yes, I didn't mean to the suggest the iESL wasn't an impressive implementation - I happen to think it's one of the most elegant 'niche' implementations I've come across in audio (hence my disappointment that it won't be continued).

BassicScience made a good point in response to my suggestion about power supplies - and I now struggle to see in theory how changing the power supply could give an audible improvement (particularly as I think the standard iFi supply is excellent). Is this something you could raise with iFi, just as a matter of interest?

 

[jamesjames]

Just to complete this, I wanted to add that I lined up the supplies again, and listened at some length. And I've got to say, while I can't explain it, I hear subtle differences. This is inevitably impressionistic, but I find the result more 'effortless' with the Sbooster (but excellent with all). Obviously, this isn't evidence of any actual difference, just my report of my experience. I guess anyone interested in testing this might like to get hold of a cheap generic supply, to see whether it affects the result at all. If the result seems to be negatively affected, it would suggest a supply can affect the issue. I happen to have three very good supplies on hand, and I'm convinced by my test, so I haven't done that (and my report of that test wouldn't be any more 'reliable' in any case). That said, I would be surprised to find that it simply doesn't matter what supply is used ... I would certainly be interested to hear of any other experiments with supplies.

 

[iFi audio]

Just to complete this, I wanted to add that I lined up the supplies again, and listened at some length. And I've got to say, while I can't explain it, I hear subtle differences. This is inevitably impressionistic, but I find the result more 'effortless' with the Sbooster (but excellent with all). Obviously, this isn't evidence of any actual difference, just my report of my experience. I guess anyone interested in testing this might like to get hold of a cheap generic supply, to see whether it affects the result at all. If the result seems to be negatively affected, it would suggest a supply can affect the issue. I happen to have three very good supplies on hand, and I'm convinced by my test, so I haven't done that (and my report of that test wouldn't be any more 'reliable' in any case). That said, I would be surprised to find that it simply doesn't matter what supply is used ... I would certainly be interested to hear of any other experiments with supplies.

As a manufacturer we focus on making power suppies as quiet as possible, so their topology (linear or switching) doesn't mean as much as noise removal. But many folks on this forum reported their experiences with linear PSUs (just like your Sbooster) and very positive effects on a number of our DC-powered products. That said, power supplies can make a noticeable difference

 

[jamesjames]

As a manufacturer we focus on making power suppies as quiet as possible, so their topology (linear or switching) doesn't mean as much as noise removal. But many folks on this forum reported their experiences with linear PSUs (just like your Sbooster) and very positive effects on a number of our DC-powered products. That said, power supplies can make a noticeable difference

Many thanks for taking the time to respond. For anyone reading this, and interested in the set-up in which I tried the power supplies, here it is: Marantz SA10 balanced out (van den Hul Mountain) to Moon 430HA, balanced headphone out (Mogami 2534) to iFi Pro iESL (balanced in), to Stax SR-009S. Re Moon options: crossfeed 'on'. Re iESL options: Pro 580V bias; AC termination Pro bias 'on'; impedance 96 ohm. The power supplies in question are the iPower, iPower X and Sbooster MkII. I listen to classical music, and tested with orchestral and chamber music (including single instruments) at high res and CD quality. I would describe the perceived improvement with the Sbooster as increased 'calmness', striking me initially as slightly reduced energy which at first listening almost seemed to reduce detail. On further listening I perceived this as more natural, with better separation between instruments and reduced congestion. As noted above, I find the iESL to be a stellar performer with any of the supplies (which are all terrifically quiet). It's my preferred driver in combination with the Moon - to some extent, no doubt, because I prefer crossfeed (I also find the iFi iCAN and SPL Phonitor very good - they include analogue crossfeed circuits). I have used many conventional stat drivers.

 

[Miiksu]

I'm now testing how this works with dynamic headphones. I had some stupid problems. I bought a cable adapter for XLR output and it was incorrectly wired. I fixed the cheap China cable.

My first impression is it's very open and impressive dynamics when using lowest impedance but downside is if you use a lower than 64 ohm setting you hear a lot of noises from your tube amp and sound is bleeding even at 0% volume. If I hear correctly noises stop after u start to listen to something. Not a really good option for gaming.

 

[BTD1]

Over on the Susvara forum there is talk of the Susvara drivers being blown out by folks using speaker amps to power them. My question is does the iESL when used with a speaker amp and a headphone connected to the dynamic output offer inherent protections against damage to the driver of the headphone? I assume that the folks who blew out their drivers did something wrong or were unaware of the risk of connecting a headphone to a speaker amp. But since the iESL is such a well engineered device does it have built in protections against this kind of damage?

 

[ThanatosVI]

Over on the Susvara forum there is talk of the Susvara drivers being blown out by folks using speaker amps to power them. My question is does the iESL when used with a speaker amp and a headphone connected to the dynamic output offer inherent protections against damage to the driver of the headphone? I assume that the folks who blew out their drivers did something wrong or were unaware of the risk of connecting a headphone to a speaker amp. But since the iESL is such a well engineered device does it have built in protections against this kind of damage?

Unlikely.
You also really have to **** up your volume settings hard to blow a Susvara driver.
Those can take tremendous power until they blow.

 

[BTD1]

Does anyone know if you can plug a dynamic or planar headphone into the iESL at the same time a pro bias estat is plugged into the 5 pin output? Will the iESL output to both at the same time?

 

[Tachikoma]

Over on the Susvara forum there is talk of the Susvara drivers being blown out by folks using speaker amps to power them. My question is does the iESL when used with a speaker amp and a headphone connected to the dynamic output offer inherent protections against damage to the driver of the headphone? I assume that the folks who blew out their drivers did something wrong or were unaware of the risk of connecting a headphone to a speaker amp. But since the iESL is such a well engineered device does it have built in protections against this kind of damage?

Speaker amps can have quite a lot of DC offset. The iESL would block the DC offset, but the offset may also cause the transformer to saturate if it is sufficiently large.

Best to just make sure the speaker amp has little to no DC offset.

 

[BassicScience]

Does anyone know if you can plug a dynamic or planar headphone into the iESL at the same time a pro bias estat is plugged into the 5 pin output? Will the iESL output to both at the same time?

I'm pretty sure you can, but there's no practical way to control their volumes independently.

 

[etc6849]

Very nice! I also hooked an AHB2 to up to my iESL that iFi USA sent out and I just received.

This setup (DAC->HPA4->AHB2->iESL) drives my Sennheiser HD800S's really really well. Like the best I've heard them! Unbelievable bass with this combo. I didn't turn it up all the way, but seems I get more power than with the Benchmark HPA4's headphone amp (which is already a great headphone amp). I have turned up the HPA4's headphone amp all the way before, so I'm getting a lot more headroom with this setup, although I didn't measure to verify.

Question for @iFi audio and others:
However, I'm not getting the same loudness and bass quality when I tried my new Audeze CRBN's that just came (also months after ordering). I don't own any electrostatic amps and the lack of jaw dropping bass may very well be the electrostatic driver. That said if I try to get the same loudness by raising the volume on my HPA4 above 0dB (using it as a preamp not a headphone amp), a clip light comes on on the AHB2 at peaks when driving the CRBN's with the iESL. It seems I may actually need two AHB2's to drive some electrostatic headphones like the HPA4?!? I do have the ifi iESL on the lowest impedance setting (16 ohms), same setting I use when I have the HD800s' hooked up. Would be great if I could get the CRBN's as loud as the HD800's with this setup so I never have to increase the HPA4 past 0dB and can avoid clipping. Sounds to me like there's a 8-10dB volume difference between these headphones thru the iESL with the HPA4 set to 0dB. Could be due to the differences in efficiency between the CRBN's and the HD800's, something to with the the input impedance of the iFi iESL, etc... Not sure, but figured someone has ran into this here, so thought I'd ask.

Finally I was able to try this combination. The AHB2 has been proposed to drive the iESL before but I never saw anyone did so. For a speaker amp, the AHB2 is usually not considered the most powerful. Its specs (100W to 8ohm) seem to match the requirements of the iESL perfectly. My first impression was that it doesn't overpower a pair of headphones at all. However, I had a better perception of the meaning of power: those high notes immediately sounded more effortless without turning up the volume. Both AHB2 and iESL are compact and run very cool. I think the heatsinks are unnecessary for such an application. I've so far tried Hifiman Jade 2 and Audeze Sine. I'm hoping to do some more comparisons with different inputs and headphones.

 

[BassicScience]

Very nice! I also hooked an AHB2 to up to my iESL that iFi USA sent out and I just received.

This setup (DAC3-> HPA4-> ifi iESL -> AHB2) drives my Sennheiser HD800S's really really well. Like the best I've heard them! Unbelievable bass with this combo. I didn't turn it up all the way, but seems I get more power than with the Benchmark HPA4's headphone amp (which is already a great headphone amp). I have turned up the HPA4's headphone amp all the way before, so I'm getting a lot more headroom with this setup, although I didn't measure to verify.

Question for @iFi audio and others:
However, I'm not getting the same loudness and bass quality when I tried my new Audeze CRBN's that just came (also months after ordering). I don't own any electrostatic amps and the lack of jaw dropping bass may very well be the electrostatic driver. That said if I try to get the same loudness by raising the volume on my HPA4 above 0dB (using it as a preamp not a headphone amp), a clip light comes on on the AHB2 at peaks when driving the CRBN's with the iESL. It seems I may actually need two AHB2's to drive some electrostatic headphones like the HPA4?!? I do have the ifi iESL on the lowest impedance setting (16 ohms), same setting I use when I have the HD800s' hooked up. Would be great if I could get the CRBN's as loud as the HD800's with this setup so I never have to increase the HPA4 past 0dB and can avoid clipping. Sounds to me like there's a 8-10dB volume difference between these headphones thru the iESL with the HPA4 set to 0dB. Could be due to the differences in efficiency between the CRBN's and the HD800's, something to with the the input impedance of the iFi iESL, etc... Not sure, but figured someone has ran into this here, so thought I'd ask.

A couple quick questions:

1) I assume the iESL is actually being driven by the AHB2, at least when driving the CRBN cans? If not, it should be. In other words, your chain should be DAC->HPA4->AHB2->iESL, contrary to what you wrote.

2) Also, you've got the CRBN plugged into the Custom/Pro jack of the iESL, correct?

 

[etc6849]

Good catch on the typo. Meant DAC->HPA4->AHB2->iESL. Yep, the CRBN only plugs into the 5 pin pro jack (set to 580V).