Hifiman EF2C

[TeoS]

An update of the ef2a , seems they changed the volume pot to a stepped one . Does somebody know more? Some mods in the DAC section? They did changed a bit the specifications , also .

 

[fjrabon]

I just ordered one.  I'm quite confused by the stated output impedance, but I assume it works well enough with their own headphones, and it will mostly power my HE400i.  It will be at the Atlanta meet this saturday, if anybody wants to try it.
 
It definitely seems that the big issue was fixing the volume pot, which was by far my biggest issue with the old EF2A.  It was unusable for any high efficiency headphones.  I actually briefly owned the EF2A and had to return it because of this issue.  

 

[fjrabon]

They apparently did change the DAC chip.  Just got an email back from HiFiMan, now they are using; CM102S USB DAC chip.  They previously used Burr Brown PCM2702.  Can't find much on the CM102S.
 
So, we are up to two known major-ish changes 1) improved volume pot to a step potentiomenter and 2) different DAC chip.  Seems like HFM were listening, as the volume pot and DAC were always the biggest complaints on the EF2A.
 
Edit: it's the same DAC chip as used in the EF100, so reviews on the DAC section of the EF100 would probably also apply here.  Biggest issue most will have is lack of jitter control, I'd guess, compared to high end DACs.

 

[fjrabon]

so, just got mine in.  I can't tell if the DAC is this bad or if the DAC on mine is faulty.  It just sounds really wonky, like it has some sort of crazy phase issues (though I don't think that's it).  However, when I used the m9XX as a DAC, the amp portion sounded great.  
 
I think somehow the DAC is causing clipping.  When I turn the volume to half in iTunes and just turn the amp up, the problem is solved.  However, turning the system volume down doesn't solve the problem(which does control the DAC output volume on the EF2C, unlike most DAC/Amp combos, which only allow for physical knob volume control, disabling the system volume controls).  Turning iTunes volume down is a workable, though far from ideal solution (if for no other reason than it causes non-iTunes system noises to be crazy loud, "YOU HAVE AN EMAIL, SORRY TO BLOW YOUR EARDRUMS OUT LETTING YOU KNOW!"  The DAC still isn't great even when this solution is implemented, but it's passable/good.  
 
But when sourced with the m9XX, the amp is powerful, crisp and dynamic.  They really solved the volume pot issue on the old EF2A, as I'm sitting exactly halfway up the dial with the HE400i.  No hint of channel imbalance or excessive crosstalk.  by 2 O'clock it's unlistenably loud, so it seems to have juice to spare.  Turning the Grace down to 60 (90 is unity gain, and what I would normally run it on), I can run it wide open max volume and it's still very clean, though you can maybe hear very small amounts of clipping on particularly hard bass transients.  Which, to me is very good for a hybrid amp being run wide open, even if at lower input levels.  I obviously would never run it that way, but I can't listen to it at max power any other way without completely blowing my ear drums out.
 
I'd say it has very good treble extension and bass tightness.  Like most hybrid amps it probably sounds 2/3 solid state and 1/3 tube.  Very good dynamics, yet smooth.  Transients are punchy without being overly dry.
 
Overall I'm a fan of the stepped volume control, especially being familiar with the volume control on the old EF2A.  However, there are times when I wish it had a half click between detents.  So, this is the limitation of a volume stepped analog pot, giving the range maximum usability or having fine control.  

 

[12many]

That's funny. 
 
Interesting about the DAC.  Seems like that part is easier to get right as it is mostly 'in-chip' operations.
 
Would you say it has a tube sound or colors the music to a softer, less analytical sound as compare to a pure solid state ($200 amp) ?
 
How do you compare it to your Grace?  Obviously not as good, but softer and warmer? 
 
From your review it sounds like the amp pairs well with the impedance of the HE-400i, which is expected since it is made by HIFIMAN.
 
I am on the lookout for a ~$200 tube amp for my 400i's but want something 'tubey' if that is a word. 

 

[fjrabon]

  That's funny. 
 
Interesting about the DAC.  Seems like that part is easier to get right as it is mostly 'in-chip' operations.
 
Would you say it has a tube sound or colors the music to a softer, less analytical sound as compare to a pure solid state ($200 amp) ?
 
How do you compare it to your Grace?  Obviously not as good, but softer and warmer? 
 
From your review it sounds like the amp pairs well with the impedance of the HE-400i, which is expected since it is made by HIFIMAN.
 
I am on the lookout for a ~$200 tube amp for my 400i's but want something 'tubey' if that is a word. 

I wouldn't call it "tubey"; it has some tube like characteristics.  Like I said earlier, I'd maybe say it sounds 2/3 like a solid state amp and 1/3 like a solid state amp.  As the tubes get warmed up, maybe I'll change that to 1/2 tube and 1/2 solid state as far as sound goes.  In a lot of ways it sounds very similar to the Schiit Vali.  It doesn't have the rolled off highs or mid-bass hump that I think people mean when they say they're looking for "tube warmth"  But it is a punchy amp in the lower regions.
 
The biggest difference I notice between it and the m9XX is the m9XX is more dynamic and lively, it handles congested passages better.  My guess is that this is due to the m9XX doing a bit better job damping, so I'm guessing the EF2C is around 3 ohm output impedance.  The EF2C isn't bad in that regard, by any means, but the m9XX squarely beats it.  The m9XX just sounds much more transparent too, with a more black background.  While you pay the penalty with congestion and lack of absolute transparency, it does make for a very smooth, rich listen.  Kick drums have a very pleasant weight and decay to them.
 
Right now I'm pairing it with my old Hot Audio HotUSB1 DAC and it's a very solid mid-fi sound.  
 
I'd say it's overall a pretty neutral amp, especially for a hybrid.  It's got a fun, smooth sound to it, but lacks a little bit in terms of dynamics in heavy passages with a lot going on.  It's maybe a touch on the U-Shaped/warm side, but not as much so as tube amps that are know for being warm.
 
Regarding the DAC, it just seems like it's somehow getting additional gain, so that any source that's got a bit of energy throws it into clipping at the DAC stage.  And DAC stage clipping is ugly sounding as all get out, I'm like 99% certain that is what this is, but until now I had never heard a DAC clip before, so I can't really say for absolute certain that's what it is, but the fact that turning down iTunes fixes it, makes me pretty confident..  THe DAC chip is something changed from the old EF2A, so I'll be interested to see if this is just an issue with my unit or endemic to the way they wired the DAC up.  Again, I have a spare DAC just lying around, and this isn't a portable amp because of the tubes, so it's not the biggest deal in the world, but it would be nice if it worked properly.
 
It's a good amp, and worth the price as an amp alone, especially if you want to play around with tube rolling.  But don't expect it to "fix" issues with bright headphones.  It's hard to not be disappointed with the issues with the DAC, but 1) I didn't buy it for the DAC, it's clearly an amp first with a DAC just thrown in, as an almost afterthought.  and 2) even if the DAC was ripped out, it would be worth its price.

 

[fjrabon]

Just ordered a pair of matched Mullard 8100 and a pair of matched Voshkod 6ZH1P to do some tube rolling.  Sad they won't be here by the meet up on saturday.

 

[Skycyclepilot]

  so, just got mine in.  I can't tell if the DAC is this bad or if the DAC on mine is faulty.  It just sounds really wonky, like it has some sort of crazy phase issues (though I don't think that's it).  However, when I used the m9XX as a DAC, the amp portion sounded great.  
 
I think somehow the DAC is causing clipping.  When I turn the volume to half in iTunes and just turn the amp up, the problem is solved.  However, turning the system volume down doesn't solve the problem(which does control the DAC output volume on the EF2C, unlike most DAC/Amp combos, which only allow for physical knob volume control, disabling the system volume controls).  Turning iTunes volume down is a workable, though far from ideal solution (if for no other reason than it causes non-iTunes system noises to be crazy loud, "YOU HAVE AN EMAIL, SORRY TO BLOW YOUR EARDRUMS OUT LETTING YOU KNOW!"  The DAC still isn't great even when this solution is implemented, but it's passable/good.  
 
But when sourced with the m9XX, the amp is powerful, crisp and dynamic.  They really solved the volume pot issue on the old EF2A, as I'm sitting exactly halfway up the dial with the HE400i.  No hint of channel imbalance or excessive crosstalk.  by 2 O'clock it's unlistenably loud, so it seems to have juice to spare.  Turning the Grace down to 60 (90 is unity gain, and what I would normally run it on), I can run it wide open max volume and it's still very clean, though you can maybe hear very small amounts of clipping on particularly hard bass transients.  Which, to me is very good for a hybrid amp being run wide open, even if at lower input levels.  I obviously would never run it that way, but I can't listen to it at max power any other way without completely blowing my ear drums out.
 
I'd say it has very good treble extension and bass tightness.  Like most hybrid amps it probably sounds 2/3 solid state and 1/3 tube.  Very good dynamics, yet smooth.  Transients are punchy without being overly dry.
 
Overall I'm a fan of the stepped volume control, especially being familiar with the volume control on the old EF2A.  However, there are times when I wish it had a half click between detents.  So, this is the limitation of a volume stepped analog pot, giving the range maximum usability or having fine control.  

So, do you have a recommendation in the same price range for a really good, one piece desktop amp/DAC?  I'm considering the Oppo HA-2 portable because of all the excellent reviews, but would go with a desktop unit if it were 1) just as good as the HA-2, and 2) less expensive.

 

[fjrabon]

So, do you have a recommendation in the same price range for a really good, one piece desktop amp/DAC?  I'm considering the Oppo HA-2 portable because of all the excellent reviews, but would go with a desktop unit if it were 1) just as good as the HA-2, and 2) less expensive.

What headphones? And how loud do you listen?

 

[Skycyclepilot]

What headphones? And how loud do you listen?

HE400i headphones...  I listen to classical at realistic levels, but occasionally jam out on classic rock at fairly high levels.

 

[fjrabon]

HE400i headphones...  I listen to classical at realistic levels, but occasionally jam out on classic rock at fairly high levels.

I honestly like the Schiit Fulla quite a bit. Though that depends a lot on how good your computers USB port is. After that I don't have a ton of experience with combo units. Audioengine D1 DAC is great, but the amp isn't a great match with the HE400i

 

[Skycyclepilot]

I honestly like the Schiit Fulla quite a bit. Though that depends a lot on how good your computers USB port is. After that I don't have a ton of experience with combo units. Audioengine D1 DAC is great, but the amp isn't a great match with the HE400i

I'll check out the Fulla.  I'm leaning toward the Oppo HA-2 at this point.

 

[fjrabon]

So, I got an email from HiFiMan that this is a known issue with their DAC implementation, that the DAC will clip at full line levels.  It's certainly annoying, and I don't really understand how it happened, and made it to production this way.  But, again, I wasn't planning on using it as a DAC to begin with, and it is "workaround-able" by lowering the volume within iTunes, so it's hard to be too annoyed about it.  But yeah, this is HiFiMan.  They can put out some of the most incredible sounding gear in the world, and then they do stuff like this.  
 
I wonder if they will eventually release a fixed version, or if they plan on just rolling with this.

 

[aharitt]

  So, I got an email from HiFiMan that this is a known issue with their DAC implementation, that the DAC will clip at full line levels.  It's certainly annoying, and I don't really understand how it happened, and made it to production this way.  But, again, I wasn't planning on using it as a DAC to begin with, and it is "workaround-able" by lowering the volume within iTunes, so it's hard to be too annoyed about it.  But yeah, this is HiFiMan.  They can put out some of the most incredible sounding gear in the world, and then they do stuff like this.  
 
I wonder if they will eventually release a fixed version, or if they plan on just rolling with this.

 
I just got mine today, and have listening it for about 2 hours.  My first impression was "what a crap!" It sounded so bad. I thought the tubes may need some time. When I tried it second time, it sounded much better. However, it gets muddy again. I noticed that EF2C sounds better when the sound is not crowded (e.g., solo violin), but gets muddy when there are many sounds. I don't have the issue with Audioengine D1.
 
Your explanation about their DAC implementation matches my experience. It is too bad because I am going to use it as DAC/amp for my work environment. I reduced output from my laptop. Still there are times when the sounds get muddy. I wish I can find a good setting, because I want to like this amp.  

 

[fjrabon]

   
I just got mine today, and have listening it for about 2 hours.  My first impression was "what a crap!" It sounded so bad. I thought the tubes may need some time. When I tried it second time, it sounded much better. However, it gets muddy again. I noticed that EF2C sounds better when the sound is not crowded (e.g., solo violin), but gets muddy when there are many sounds. I don't have the issue with Audioengine D1.
 
Your explanation about their DAC implementation matches my experience. It is too bad because I am going to use it as DAC/amp for my work environment. I reduced output from my laptop. Still there are times when the sounds get muddy. I wish I can find a good setting, because I want to like this amp.  

reducing the output from your laptop itself won't solve the problem at all (as that will simply lower the DACs output, since this turns the DAC into your soundcard, and the issue with the DAC is the levels going *in*, not the levels coming out of the DAC, you have to lower the volume from within the player), you have to reduce the volume within the player you use on your laptop.  ie if you're using iTunes, you have to turn down the volume within iTunes.
 
Yes, this is a stupid problem, especially if you're using it as HiFiMan markets the thing, as a DAC/Amp that will be "all you need for computer listening."  Like I said, I never really intended to use the DAC all that much.  But I still can't believe that HiFiMan let this pass through.