iFi Audio Pro iESL - The Official Thread
Jun 22, 2019 at 12:16 PM Post #181 of 336

frogmeat69

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My iFi iCan and iESL hanging with my RME ADI-2 DAC, makes the Koss 95X sound great. Will eventually be looking for some other ES 'phones to join the family.
 
Jun 29, 2019 at 1:42 PM Post #184 of 336

gordec

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I'm testing IESL fed from speaker taps of NAD M22 V2 speaker amp. Quick questions about operation of the IESL. Can I have both Susvara and Stax 009 plugged in at the same time without overloading the IESL? If I need to unplug either Susvara or 009, do I need to turn the unit off. I can't seem to find any info at that. Thanks.
 
Jul 11, 2019 at 4:25 PM Post #185 of 336
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I'm testing IESL fed from speaker taps of NAD M22 V2 speaker amp. Quick questions about operation of the IESL. Can I have both Susvara and Stax 009 plugged in at the same time without overloading the IESL?

Both can be connected, but since ESL headphones act as capacitors, having two headphones connected may affect high frequency response and thus perceived detail. We recommend to use only one headphone at a time.

If I need to unplug either Susvara or 009, do I need to turn the unit off. I can't seem to find any info at that. Thanks.

We would recommend turning the unit off, to be safe. However there should not be any damage if connecting/disconnecting while operating. If plugging/unplugging while operating it may be best to set AC termination to OFF during unplugging/plugging.
 
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Sep 6, 2019 at 4:24 AM Post #186 of 336

Soundwave76

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Sorry if this has been answered already, but does the ADI-2 DAC have enough amp power to be connected to the ESL and to drive Stax Lx00 models?

EDIT: I glanced through all the posts and it seems it does not. Too bad.
 
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Sep 28, 2019 at 10:00 AM Post #187 of 336

PolloLoco

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I've often read that going through other Energizers theres a trade off compared to using a dedicated stax amp. A great dac/amp through an Energizer will have better dynamics but less detail than a Stax amp. Is that still true here?

I'm getting a stax srm 353x, but I'm wondering if my next upgrade might be an IESL. Can anyone comment on whether or not I would lose any detail, if I use balanced connections?
 
Sep 28, 2019 at 7:12 PM Post #188 of 336

Zblarg

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I think it mainly depends on what amplifier you are going to use with the iESL.
My McIntosh MA6600 + little FX Audio tube preamp gives a better result than my 727. Same thing with my Viva Egoista 845.
I don't think I'm losing some details.
Well, my best results for my SR-007 and SR-009 are my KGSSHV Carbon CC + McIntosh C2300 tube preamp (with Tung sol 12AX7 tubes, inexpensive but wonderful), but this doesn't mean I couldn't get the same quality with the right amp + IESL.
I don't know the 353X which has quite a good reputation. But based on what I got with my 727 I think you can make a big step further with the IESL and the right amp. I love my 007 with the Viva Egoista 845 + IESL, superb midrange and soundstage. The bass is quite good too. I didn't have more details with my 727. On the contrary, things seemed more congested, especially in the highs.
Hope this will help.
 
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Sep 29, 2019 at 6:08 AM Post #189 of 336

analogsurviver

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I think it mainly depends on what amplifier you are going to use with the iESL.
My McIntosh MA6600 + little FX Audio tube preamp gives a better result than my 727. Same thing with my Viva Egoista 845.
I don't think I'm losing some details.
Well, my best results for my SR-007 and SR-009 are my KGSSHV Carbon CC + McIntosh C2300 tube preamp (with Tung sol 12AX7 tubes, inexpensive but wonderful), but this doesn't mean I couldn't get the same quality with the right amp + IESL.
I don't know the 353X which has quite a good reputation. But based on what I got with my 727 I think you can make a big step further with the IESL and the right amp. I love my 007 with the Viva Egoista 845 + IESL, superb midrange and soundstage. The bass is quite good too. I didn't have more details with my 727. On the contrary, things seemed more congested, especially in the highs.
Hope this will help.

Good observations. To put it extremely short - powered from a decent, ENOUGH powerful amp ( say 70+ W/ch/8 ohms/ and above ), Pro iESL is going to be an improvement in all cases ( driving electrostatics ) but with the most powerful aftermarket amps - and (maybe) latest/greatest/most$$$ Stax unit. You have correctly identified it is superior to most dedicated electrostatic amps in treble - no contest, only the most powerful aftermarket amps can hope to compete.

It takes POWER to drive ESLs in the treble - as they are essentially electrically a capacitive load, and the impedance falling proportionaly with the frequency. Meaning, sooner or later, in real world ANY amp will be running out of current with which to charge/discharge the load. Once even rather far removed from this "brickwall", audible distortion starts to set in. Stax amps ( used to ? ) have in their specs maximum frequency at which they are still capable of delivering full amplitude output into the load. None of the Stax units ( with the possible exception of the latesat/greatest/most $$$ I am not familiar with ) can not reproduce 20 kHz at full output - SRM1MK2/Lambda Pro can do it only to 4 kHz, for example. SRM1MK2 has power consumption below 40 W, meaning its output per channel must be below 20 W - even if assuming 100% efficiency, which Class A amp ( all ESL amps operate, by default, in Class A ) of course does not have. In theory, Class A efficiency is 50 % at best, meaning SRM1MK2 can put out below 10W into headphones proper.

A transformer has (almost) 100 % efficiency - and if well made as in Pro iESL, can actually deliver 70+ W/channel into headphones - provided the amplifier is up to the task. The deviation from totally linear response Pro iESL does introduce with various settings are, although ultimately audible, for all practical purposes without consequence. But once treble not limited by low power is heard, it is hard to go back from Pro iESL to a direct drive electrostatic amp not belonging to the most powerful group of very few indeed.

All it takes is a good recording from a decent soprano - not to mention large mixed choir.
 
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Sep 29, 2019 at 6:26 AM Post #190 of 336

PolloLoco

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Thank you both. I also received similar advice from a forum member via PM, who used to own an IESL, moved to a Carbon, and moved on. He said that in hindsight he might have kept the IESL for flexibility and gotten a more powerful amp.

Based on that, I'm going to see if I can find a good used IESL - and that might be my upgrade path after a 353X, or instead of it. Thanks again.
 
Sep 29, 2019 at 10:16 AM Post #191 of 336

saudio7

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Good observations. To put it extremely short - powered from a decent, ENOUGH powerful amp ( say 70+ W/ch/8 ohms/ and above ), Pro iESL is going to be an improvement in all cases ( driving electrostatics ) but with the most powerful aftermarket amps - and (maybe) latest/greatest/most$$$ Stax unit. You have correctly identified it is superior to most dedicated electrostatic amps in treble - no contest, only the most powerful aftermarket amps can hope to compete.

It takes POWER to drive ESLs in the treble - as they are essentially electrically a capacitive load, and the impedance falling proportionaly with the frequency. Meaning, sooner or later, in real world ANY amp will be running out of current with which to charge/discharge the load. Once even rather far removed from this "brickwall", audible distortion starts to set in. Stax amps ( used to ? ) have in their specs maximum frequency at which they are still capable of delivering full amplitude output into the load. None of the Stax units ( with the possible exception of the latesat/greatest/most $$$ I am not familiar with ) can not reproduce 20 kHz at full output - SRM1MK2/Lambda Pro can do it only to 4 kHz, for example. SRM1MK2 has power consumption below 40 W, meaning its output per channel must be below 20 W - even if assuming 100% efficiency, which Class A amp ( all ESL amps operate, by default, in Class A ) of course does not have. In theory, Class A efficiency is 50 % at best, meaning SRM1MK2 can put out below 10W into headphones proper.

A transformer has (almost) 100 % efficiency - and if well made as in Pro iESL, can actually deliver 70+ W/channel into headphones - provided the amplifier is up to the task. The deviation from totally linear response Pro iESL does introduce with various settings are, although ultimately audible, for all practical purposes without consequence. But once treble not limited by low power is heard, it is hard to go back from Pro iESL to a direct drive electrostatic amp not belonging to the most powerful group of very few indeed.

All it takes is a good recording from a decent soprano - not to mention large mixed choir.
I think your conclusions are wrong, Stax are driven by high voltage not current and this is biggest problem, as to play good they need peak to peak more than 1000V and very low current.
IESL use step transformers to drive Stax, what is needed is very fast amp, you don’t need high power.
 
Sep 29, 2019 at 10:40 AM Post #192 of 336

analogsurviver

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I think your conclusions are wrong, Stax are driven by high voltage not current and this is biggest problem, as to play good they need peak to peak more than 1000V and very low current.
IESL use step transformers to drive Stax, what is needed is very fast amp, you don’t need high power.

Nope. The problem is slew rate limiting. Current is required, not just voltage swing.

The most efficient subwoofer in the world would be electrostatic - almost 100% efficiency of transduction if designed properly. Not about 1% or so as in "average" dynamic speaker. But, it can only be built as a "ceiling" in situ - custom made to the room in question. Acoustic output around 10 W is possible - which is MORE than a symphony orchestra, for example. But, for BASS only - above say 100 Hz or so, the capacitance would become ever greater problem - by the time in treble, power requirements would strip anything considered still normal in audio - or possible to connect on normal household power line.

Please check any of the papers/book on electrostatic speakers and driving them - you will find it among the first obstacles to - at least try - to get in reasonable order. No way you can cheat on https://en.wikipedia.org/wiki/Electrical_impedance
 
Nov 10, 2019 at 9:30 AM Post #193 of 336

ahmedie

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I've often read that going through other Energizers theres a trade off compared to using a dedicated stax amp. A great dac/amp through an Energizer will have better dynamics but less detail than a Stax amp. Is that still true here?

I'm getting a stax srm 353x, but I'm wondering if my next upgrade might be an IESL. Can anyone comment on whether or not I would lose any detail, if I use balanced connections?

kgsshv or any srd7/iesl+amp(15k$$+) will out do 353x easily
 
Nov 11, 2019 at 8:32 AM Post #194 of 336

Zblarg

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I was wondering what was the output power of the XLR 4 pins output of the IESL (don't know if this applies for estats) ?
On most of the headphone amplifiers, we know what is the power of the headphone output (often something like a fraction of a watt, sometimes several watts).
Is this power always the same, and doesn't depend on the amplifier that is connected to the IESL, or does it depend on the amplifier?
I often use my IESL with my McIntosh MA6600 which provides 2x200 watts (and it works wonderfully). I like very much to listen to my Audeze LCD-4 or my JPS Labs Abyss through this system.
But I guess the IESL doesn't give an output of 200 watts to my headphones...
 
Nov 11, 2019 at 9:22 AM Post #195 of 336

analogsurviver

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I was wondering what was the output power of the XLR 4 pins output of the IESL (don't know if this applies for estats) ?
On most of the headphone amplifiers, we know what is the power of the headphone output (often something like a fraction of a watt, sometimes several watts).
Is this power always the same, and doesn't depend on the amplifier that is connected to the IESL, or does it depend on the amplifier?
I often use my IESL with my McIntosh MA6600 which provides 2x200 watts (and it works wonderfully). I like very much to listen to my Audeze LCD-4 or my JPS Labs Abyss through this system.
But I guess the IESL doesn't give an output of 200 watts to my headphones...

It does... - or, if you were really heavy with volume, it - at least - could.

The power for electrostatics is required for high frequencies - and the perfect amp for electrostatics would have infinite power. That is because electrically electrostatic driver is >>99% pure capacitance. https://en.wikipedia.org/wiki/Electrical_impedance#Capacitive_reactance
Sooner or later, the power available will be too small in order to drive capacitor correctly at the required frequency. With typical capacitances involved with headphones ( around 150 pF +- a few tens of pF according to the brand/model), that means for decent performance in the treble at least about 70 W are required at the electrostatic driver terminals - regardless of whether it is a direct drive high voltage amp or regular speaker amp plus step up transformer like in iFi Pro iESL. The later is safer - as there is no DC with any dangerous current ( bias voltage is by very definition VERY high impedance, incapable of delivering any current worth mentioning ) levels present at the electrostatic drivers ( i.e - listener's head ).

Regardless of what are you driving ES headpohones with, it is not something recommended to use with wet or still damp hair after a shower ...
 

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