[duo8]

So the O2 is a good amp for HE-400i?
Will the O2 work well with IEMs? Especially BA hybrids.

 

[DavidA]

So the O2 is a good amp for HE-400i?
Will the O2 work well with IEMs? Especially BA hybrids.

The O2 is not an amp that I liked for the HD400i or HE400, I really didn't like it for any of the other headphones I had at the time due to slightly thin (some would say neutral) qualities of the O2 IMO, YMMV.
Sorry but I don't use IEM's

 

[ilmothedude]

Hum/hiss is almost always directly related to either ground loops or more likely high gain of the power amplifier. The easiest solution to reduce hiss is to make a resister network like the hifiman box before your headphone cable, reducing the load and power output.

I used this when I made mine:

https://robrobinette.com/HeadphoneResistorNetworkCalculator.htm

Thanks for the link, gotta build one resistor network adapter like that. I'm familiar with reducing hiss with resistor load, but that resistor network is new to me. I just need some higher wattage resistors, as all I have right now are just 1/4W resistors. I yesterday lubricated all pots and switches on signal path of my AKAI, allthough I had to do it a bit violently with switches as I had to crack their casing open as they are so closed design that I couldn't get any lube inside them without opening them.

 

[strango]

I'm familiar with reducing hiss with resistor load, but that resistor network is new to me. I just need some higher wattage resistors, as all I have right now are just 1/4W resistors.

hmm, I wonder why there is a recommendation to use 2W and 5W resistors while counted that dissipation is only a few mW..

Now we can also calculate the watts dissipated by R3 using the formula Watts = Amps^2 * Ohms = 0.0468amps^2 * 2ohms = .00438 watts. The watts dissipated by the headphones is: 0.00246amps^2 * 38ohms = 0.00023 watts (0.23 milliwatts).

 

[ilmothedude]

hmm, I wonder why there is a recommendation to use 2W and 5W resistors while counted that dissipation is only a few mW..

hmm, I was wondering the exact same thing, 1/4W resistors should be pretty adequate then.

 

[MrMateoHead]

So the O2 is a good amp for HE-400i?
Will the O2 work well with IEMs? Especially BA hybrids.

Short answer, Yes.

For IEMs, many of which needing little power, I would say it is but I would get "unity" gain (gain of 0X). For most listening, 2.5X gain is good IF you have a 2V source. for a 1V source, like a phone / Mp3 player, I would want a little more gain.

 

[MrMateoHead]

The O2 is not an amp that I liked for the HD400i or HE400, I really didn't like it for any of the other headphones I had at the time due to slightly thin (some would say neutral) qualities of the O2 IMO, YMMV.
Sorry but I don't use IEM's

What amp did you think sounded good with those thin-sounding headphones?

IMO the HE-400 sounded pretty bad until about 2 weeks in, when my ears adjusted. The amp had nothing to do with it except that I could go louder.

 

[Jazmanaut]

So the O2 is a good amp for HE-400i?
Will the O2 work well with IEMs? Especially BA hybrids.

I think, that my O2 works with 400i. Its very,very transparent and clean amp. In my books good amp just amplify signal and thats it.

Btw, now that i have read tons of comments and user experiences, mainly for seeking mods, and find that some people find that in many cases there is slight resonancepeak at around 9-10Khz in HE400i:s, and i just cant hear that, exept when boosting and searchin on that area with very narrow Q-band. Its there ok, but it has been tamed very good. My headphones are quite new, so i believe that they have found that and fixed the broblem at Hifiman at some point. It would be nice to hear some older models my self.
How old are 400i series?

 

[duo8]

Short answer, Yes.

For IEMs, many of which needing little power, I would say it is but I would get "unity" gain (gain of 0X). For most listening, 2.5X gain is good IF you have a 2V source. for a 1V source, like a phone / Mp3 player, I would want a little more gain.

I don't even have a dac actually, plan to just plug it in my laptop.

 

[MrMateoHead]

I don't even have a dac actually, plan to just plug it in my laptop.

In that case, I would probably do 1X gain for the IEMs and the 3.3X gain for less efficient cans. My computers have sounded really good, so the O2 will do its thing just fine. But I would note that the ODAC or an equivalent DAC definitely upgraded my sound nicely (I'd say 10% better though - not exactly night and day). IF you get a DAC down the road that puts out 2V know that you can clip the O2 at 3.3X gain. IF you think you might go that route, I'd do a 2.5X gain. That has generally been enough for me 90% of the time. ONLY when using a 1V source and listening to classical music / movies have I felt I needed the 6.5X gain.

 

[ilmothedude]

Well, I dared to try resistor network configuration with my normal 1/4W metal film resistors, and I find it working very well. If something, I believe resistors would heat up if watt rating weren't adequate, BUT I don't think resistors get even slightly warm at all, at least what my fingers could sense. I used 7.5ohm and 1ohm resistors which give 18.82db attenuation, which seems very optimal for my setup. Now backround is almost like dead-silent, no hiss, no hum, just clean and powerful audio. I'm very pleased with result, and didn't cost me any extra!

 

[strango]

Just one short question...
Is HE-400i worth buying at $199?

Currently use:
"Full" size: Sennheiser HD 228, cheap Superlux HD681, Superlux HD668B, KOSS UR20.
IEM (the best I have): kz zs5, Beyerdynamic MMX 100, 1more e1010.
DAC: xduoo x2, Shanling M1S (looking for M3S)
No AMPs or dedicated sound cards in my PC and laptop.

 

[DavidA]

What amp did you think sounded good with those thin-sounding headphones?

IMO the HE-400 sounded pretty bad until about 2 weeks in, when my ears adjusted. The amp had nothing to do with it except that I could go louder.

When I had the O2/ODAC I also had a Bifrost Uber, Modi, Magni, Teac UD-301, Asgard2 and Project Ember. Ember and headphone output of UD-301 were fuller sounding and were not sibilant to me but the O2 and Magni both had some sibilance while the Asgard2 has the full sound like the UD-301 and Ember it has some slight sibilance at times. I've since modded the HE400 so its no where close to the stock sound and it me its better than my HE560 in some ways for some genres of music.

@duo8 and @strango I think you might be on the wrong thread, this is the HE400 thread, not HE400"i" thread.
@strange, yes the HE400i at $199 is a good deal and worth it IMO.
@duo8, your laptop might or might not be able to power the HE400i depending on the built in amp of your laptop and the level at which you listen at.

 

[jay567]

Shame this thread is dead. The HE400 with silver cable and Jergpad is end game material to me. I have not found a pair of cans that perform much better than the HE400 honestly and I've auditioned majority of TOTL HPs.

 

[DavidA]

Shame this thread is dead. The HE400 with silver cable and Jergpad is end game material to me. I have not found a pair of cans that perform much better than the HE400 honestly and I've auditioned majority of TOTL HPs.

I'm still loving my modded HE400 but I don't think there are many still in use these days.