[Dailydrive]

I'm 99% sure there's no difference between the XLR and speaker inputs, although I've only used the latter. Both connect directly to the transformer primaries AFAIK.

From iESL manual on Balance Headphone Amplifier Input:

"..... It is recommended that amplifier should be able to deliver at least 10V into 64Ω, as much as 28V/64Ω are permissible."

I wonder how it's translate to layman perspectives (?) in comparison to it's loudspeaker input which stated as :

"Rating below around 10 Watt/8Ω may not deliver satisfactory playback"

 

[BassicScience]

From iESL manual on Balance Headphone Amplifier Input:

"..... It is recommended that amplifier should be able to deliver at least 10V into 64Ω, as much as 28V/64Ω are permissible."

I wonder how it's translate to layman perspectives (?) in comparison to it's loudspeaker input which stated as :

"Rating below around 10 Watt/8Ω may not deliver satisfactory playback"

P = V**2 / R = 10**2 / 64 = 1.5625 W @ 64 ohms

Power roughly doubles with each halving of the load impedance, so this equates to 12.5 W @ 8 ohms. The specs are roughly the same for both inputs.

 

[Dailydrive]

P = V**2 / R = 10**2 / 64 = 1.5625 W @ 64 ohms

Power roughly doubles with each halving of the load impedance, so this equates to 12.5 W @ 8 ohms. The specs are roughly the same for both inputs.

Thank you, 10Q.
Seems like a rms 2.3watt 4Ω (or 8?) output into iESL BAL headphone input hardly suffice

 

[iFi audio]

I'm 99% sure there's no difference between the XLR and speaker inputs,

There isn't. It's just a matter of signal routing from one or the other, but the same circuit handles both.

 

[goldwerger]

Fantastic! Look forward to your feedback on hookup to iESL speakers input.

I’m looking at a preloved 2004 SE84CS Zen. With its basic design remains, i hope it doesn’t differ too much to latest ufo2.

The speaker to 4-pin XLR look like this, which I saw locally, as alternative to iESL bal input

ok I have just tested this and it is extremely surprising - and may have wider interest here for anyone who may be thinking about connecting a tube amp into the iESL (TLDR; it works)

I've just tested 3 things in parallel - both with the 007mk1 and X9000k (mostly with the latter):

(1) Mjolnir Carbon on its own - just as a reference point (with which I'm very familiar, and like a lot)

(2) iFi - powered by my Simaudio MOON 330A amplifier (spec'ed 125W at 8 ohm)

(3) iFi - powered by Decware Taboo SE84TS+ (spec'ed 8W, at 8 ohm afaik) + an OTL tube pre


The surprise - all provided about equal power and headroom.

(1) and (3) provided a classic contrast of SS vs. Tube amping, with the Carbon offering fast attack and a crisp voicing, and the Decware providing a hologrpahic sweet tube voicing.

In fact, this may be my favourite X9K setup right this second as I listen to it for the first time. It's super fresh, so I may revert or change my view naturally but, off the cuff, it's super viable and potentially great.


Note - I used the XLR in, based on iFi's direct input above that the speaker taps and 4-pin XLR are the exact same balanced inputs ino the iFi with just a change in convenience factor which plugs are used (I had a speaker-to-XLR cable on my Decware, with another XLR-to-XLR extension cable I added to it to reach the iESL, which let me quickly conenct and test; this cable setup can be further improved)


(note - if you are buying an even older Taboo than my model, check the wattage. I recall they made a switch from 2 watts to 6 watts at some point in their history prior to my (already rather old) model, and I think the lower wattage would not work)

 

[BassicScience]

ok I have just tested this and it is extremely surprising - and may have wider interest here for anyone who may be thinking about connecting a tube amp into the iESL (TLDR; it works)

I've just tested 3 things in parallel - both with the 007mk1 and X9000k (mostly with the latter):

(1) Mjolnir Carbon on its own - just as a reference point (with which I'm very familiar, and like a lot)

(2) iFi - powered by my Simaudio MOON 330A amplifier (spec'ed 125W at 8 ohm)

(3) iFi - powered by Decware Taboo SE84TS+ (spec'ed 8W, at 8 ohm afaik) + an OTL tube pre


The surprise - all provided about equal power and headroom.

(1) and (3) provided a classic contrast of SS vs. Tube amping, with the Carbon offering fast attack and a crisp voicing, and the Decware providing a hologrpahic sweet tube voicing.

In fact, this may be my favourite X9K setup right this second as I listen to it for the first time. It's super fresh, so I may revert or change my view naturally but, off the cuff, it's super viable and potentially great.


Note - I used the XLR in, based on iFi's direct input above that the speaker taps and 4-pin XLR are the exact same balanced inputs ino the iFi with just a change in convenience factor which plugs are used (I had a speaker-to-XLR cable on my Decware, with another XLR-to-XLR extension cable I added to it to reach the iESL, which let me quickly conenct and test; this cable setup can be further improved)


(note - if you are buying an even older Taboo than my model, check the wattage. I recall they made a switch from 2 watts to 6 watts at some point in their history prior to my (already rather old) model, and I think the lower wattage would not work)

At which setting do you have the Impedance switch on the iESL? Note that with a lower-powered amp, a lower impedance setting will give you more effective gain from the iESL at the expense of a bit of linearity (although the sonic difference is fairly minor, in my experience).

One can also try different settings on the AC Termination switch, although (again) I've never found them to make much of a difference in practice.

 

[goldwerger]

At which setting do you have the Impedance switch on the iESL? Note that with a lower-powered amp, a lower impedance setting will give you more effective gain from the iESL at the expense of a bit of linearity (although the sonic difference is fairly minor, in my experience).

One can also try different settings on the AC Termination switch, although (again) I've never found them to make much of a difference in practice.

I've tried all impedances and all worked well. The effective gain difference was easily compensated with a small volume change on the preamp. But I've settled on the 16 ohm one since, with the X9k, it simply sounded the most hologrpahic and pleasing (I didn't have enough time with it though)

 

[goldwerger]

I just did one more experiment. Connected the Auris Nirvana 4-pin XLR out to iFi 4-pin XLR-in. In comparison with Decware/OTL combo, the Nirvana had a much deeper and authoritative bass (making the X9K decidedly bassy) and warm sound signature, while the Decware offers less bass but more balance and a more holographic presentation.

These are all superficial observations at this point - but I'd say this: it's really worthwhile experimenting with tube amps (speaker/integrated/powerful headphone amps), as the combination of that upstream with the estat headphone on the other end creates some really delightful options

 

[Miiksu]

I've tried all impedances and all worked well. The effective gain difference was easily compensated with a small volume change on the preamp. But I've settled on the 16 ohm one since, with the X9k, it simply sounded the most hologrpahic and pleasing (I didn't have enough time with it though)

Changing bias makes bigger difference to the sound. I liked high bias with tube amp.

 

[goldwerger]

Changing bias makes bigger difference to the sound. I liked high bias with tube amp.

Any risk in damaging the headphones in going too high or too low bias vs their spec?

 

[Miiksu]

Any risk in damaging the headphones in going too high or too low bias vs their spec?

If you have pro bias e-stat HP you can go up to 640V. If you go too low it just sounds bad lose sensitivity.

 

[aokman]

You can apparently short and burn out the diaphragms if the bias is too high, no idea what the limits are as Spritzer talks about going quite high… Your risk to take going beyond spec…

I would imagine using a low bias could lead to excessive power going into the stators trying to get the same volume as when I tried normal bias on my old SRD it was just quieter.

 

[goldwerger]

You can apparently short and burn out the diaphragms if the bias is too high, no idea what the limits are as Spritzer talks about going quite high… Your risk to take going beyond spec…

I would imagine using a low bias could lead to excessive power going into the stators trying to get the same volume as when I tried normal bias on my old SRD it was just quieter.

yes it seems risky, I'm inclined not to do that unless I'd know for sure it were safe..

 

[Dailydrive]

Thank You, Goldwerger.
Just read your feedback and it's a delight.
Sound like the 2.3w Decware I'm eyeing a little underwhelming for iESL, or maybe I'll lookout for the Taboo SE84TS+ instead. decware may have made a switch from 2 to 6 watts sometime in their history, but it seems their latest ufo2 is back to rms 2.3w again.
Overall, set my sight on triode Zen or other SET, and probably the last tube amp I'm trying. Sometimes ago, when I'm on T1.1 600, I have feliks n bottlehead otl but enjoy it best with Beyer A20, due to otl artificial (may not be right word) forward colouring imo.
I think you maybe better served with DAC directly or (neutral) SS pre into Taboo as tube output instead of adding a otl as pre, at least not 2 diff tube type cocktail, to get the true SET favour. Just a humble suggestion

 

[goldwerger]

Thank You, Goldwerger.
Just read your feedback and it's a delight.

My pleasure, and so happy this may be of small benefit.

I think you maybe better served with DAC directly or (neutral) SS pre into Taboo as tube output instead of adding a otl as pre, at least not 2 diff tube type cocktail, to get the true SET favour. Just a humble suggestion

I know exactly what you mean.. but the specific two tube compoents I'm playing with happen to have a very specific synergy that works (I tried each with other pres and amps, both SS and tube, and it's just a specific thing with that setup that works well. Sometimes there is a clear reason to the what and why. And sometimes, you just stick the cable in and see what happens and find out..