Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › REVIEW: Head-Direct EF1 tube/hybrid headphone amp
New Posts  All Forums:Forum Nav:

REVIEW: Head-Direct EF1 tube/hybrid headphone amp

post #1 of 94
Thread Starter 
I received a PM from Fang at Head-Direct asking me if I would like to review his new headphone amp. Which of course I said yes to – I was actually very enthusiastic about this opportunity since I was intrigued to see what I would think of a hybrid amp, given my predilection for tube amps.

Pics:




The EF1 is a small tube amp using a 12AU7 for the input stage and an op-amp for the output. It uses an outboard power supply. The chassis is very sturdy and the Plexiglas top is a nice touch. The 12AU7 sticks out of the Plexiglas top. The internals appear neat and use some nice parts. Single pair of chassis-mounted RCA’s in the back, and a ¼” jack in the front. I was a little put off by the price of the amp at first - $400 for a small-ish tube-hybrid amp seemed high, given that you can get a WooAudio 3 or a Darkvoice 336SE for less. But I am happy to report that after listening to it, I think it’s absolutely worth the money.

The concern about hybrid amps is that instead of having the benefits of SS like easily driving low-impedance headphones with a bit of tube sound, that instead what you get is an amp that has to have its tubes replaced periodically (or is fussy about tube noise) and yet actually sounds too SS-ish. This was definitely my impression of the Bada hybrid amp – aggressive, even bright SS, and some weird tube reliability issues. The EF1, though, gets it right – easily drove my 25 oh Denons and 40 ohm Kenwoods, and yes did deliver just enough tube glow to make the overall sound very enjoyable.

About the tube – I’m not sure there is anything WORSE than cheap Chinese preamp tubes. I have heard quite a few and they all universally SUCK. Fang agrees with this, and does recommend using a NOS tube. I put in an RCA clear-top 12AU7, which sounds excellent. I also used a Tung-sol grey plate, but in the end preferred the RCA.

The EF1 is a little brighter than my other tube amps, but it does have that open, ultra-realistic midrange that I do believe comes only from tubes. I was worried that the SS output stage would eliminate this, but it doesn’t. The EF1 is not as warm overall as the Darkvoice 336SE, but the EF1 drives a wider variety of headphones than the DV amp, and is generally more transparent sounding. In fact, I preferred the EF-1 overall versus the 336SE. The EF1 has slightly deeper bass, generally cleaner treble, and almost as lush a midband. The 336SE does have the slightly lusher midrange, but it is less transparent sounding.

The 336SE has a less extended treble, and it has less treble detail, although the DV has the slightly silkier, smoother treble. There were a few times where the EF1’s more forward treble bordered slightly on too aggressive, but it never fully got there. I wouldn’t use the EF1 with already very bright headphones, just as I wouldn’t use the 336SE with overly warm headphones. For example, I prefer the DV336SE with the Beyer DT770/600. But I prefer the EF1 with the Kenwood K1000. In fact, the Kenwood K-1000 and the EF1 were a highly synergistic pairing. I would recommend that combo enthusiastically to anyone – it would be $750 that would be hard to beat in an amp-can combo. The EF1 also drive the Denon D5000, both stock, and Markl modded, very well.

The soundstaging was very good. It stops short of the truly holographic imaging I normally hear from my Extreme or MPX3, but the lateral placement was outstanding, and the soundstage felt very spacious. Depth was more convincing than width, but it was still quite good.

I also compared it to the identically priced Purity Audio KICAS (not the Caliente as mine is currently MIA ). This was a very tight contest. The amps actually sounded far more similar than I expected. The KICAS is very slightly more neutral, but the EF1 is just a little “prettier” to listen to. I will update this when I have my Caliente back, because I think the sonics between these two amps is remarkably similar.

Finally, I compared it to the $300 Travagan’s White. As good as the White is, the EF1 is easily better. I prefer it in almost every dimension. That said, the White is $100 less AND includes a quite serviceable USB DAC. Nice to have choices!

One small quirk: there is a small amount of sound that comes from the headphones even with the volume all the way down. For me this is of no consequence, but for some, it may be. According to Fang from Head-Direct, the reason for this is because they use an active volume control, which Fang says results a lot of sound quality benefit specifically from this design.


I don’t have a lot else to say. The EF1 succeeds in delivering a good hybrid solution – it may actually be the best of both worlds in its price class. No, it isn’t as good as the more expensive tube amps I own, nor is it as good as the higher-end SS amps I have heard. But it is DARNED GOOD – and gets a VERY enthusiastic recommendation from me.
post #2 of 94
I saw this in the sponsored thread section and was wondering how it sounded. Thanks again for another wonderful review. I really enjoy reading your stuff.
post #3 of 94
Thanks a lot for the review, a very interesting read!
post #4 of 94
Another great review Skylab. Did you get to try your ESW9s with it?
post #5 of 94
Thread Starter 
Yes. The ESW9 is a great match for the EF1, actually - the slight extra sparkle on top that the EF1 has suits the ESW9 very well.
post #6 of 94
I need to finish the review I started on this amp, so far I have only been able to make a few post w/ pics in the thread started by HiFlight.

I will echo what Skylab wrote, the amp is at its price a very nice sounding unit. I did not hear it being as energetic in the high end as Skylab and it may be due to the amount of burn in as well as differences between production models. BTW, my unit has about 350 hours of burn in or even the tubes we used.

The unit plays very nice via my Ultrasone PROline 2500 and the HFI-780. It also does very well w/ the AKG K701 and Grado RS-1. In a way I should not have been surprised since when I last heard this amp (CanJam 08) I felt that Fang had a winner.

The one area I am not 100% w/ Skylab or Fang is in the Chinese 12AU7. I actully think it does a very good job as compared w/ NOS JAN or GE tubes. Normally this would be a big deal because some NOS tubes have gotten so expensive that you have to really want them and you must have deep pockets. Fortunetly you can still get really good NOS 12AU7 tubes relatively cheap.

One area I felt this amp excelled at was in soundstage. I feel it is very wide and deep and it does this while retaining good bass impact.

If I was to make a recomendation to Fang it would be to:

1. Find a way to add vents to the plexiglass to help cool the amp.
2. Install vibration absorbing feet with sufficient height to separate the amp from the surface it lays on. I mention this because if you lay the amp on a CDP or an expensive piece of furniture the heat from the EF-1 will transfer and it could damage your fine piece of equipment or furniture.

Small and not to big a deal but it may be important to some. Anyways, I might as well add my pictures to Skylab's thread and thus not have to start another one.







I close saying thanks to Fang for the opportunity to audition this unit. BTW, I almost forgot the Yuin PK1 sound great out of the EF-1.

Edit 1: Like Skylab I also experienced:
Quote:
One small quirk: there is a small amount of sound that comes from the headphones even with the volume all the way down. For me this is of no consequence, but for some, it may be.
but for me it is not a big issue either.
post #7 of 94
Thread Starter 
Thanks for the pictures and comments, Miguel!
post #8 of 94
Thanks Skylab, I saw this on the Head-Direct website, glad you got to review one. Your comparisons to similarly priced amps you already own made the review all the more useful.
post #9 of 94
The second production run of the EF1 will have a socket to enable rolling the opamp. This should provide endless fun comparing various combinations of tubes and opamps.
post #10 of 94
Thread Starter 
I also need to add that there is a small amount of sound that comes from the headphones even with the volume all the way down. For me this is of no consequence, but for some, it may be. According to Fang from Head-Direct, the reason for this is because they use an active volume control, which Fang says results a lot of sound quality benefit specifically from this design.
post #11 of 94
This looks like a commercialized version of the SOHA
post #12 of 94
Quote:
Originally Posted by Mazuki View Post
This looks like a commercialized version of the SOHA
We can not agree with you. TOTALLY DIFFERENT DESIGN. We believe EF1 are better.
Reply
post #13 of 94
WoW Skylab, you're staying as busy as I am with reviews

Good job, attaboy, and keep it up!
post #14 of 94
As you've also reviewed (or are in the process of ) the Purity Audio amps, I can't wait to read your feedback about comparing them with the EF1
post #15 of 94
Thread Starter 
I did make comments about the EF1 vs the KICAS in my review above
New Posts  All Forums:Forum Nav:
  Return Home
  Back to Forum: Headphone Amps (full-size)
Head-Fi.org › Forums › Equipment Forums › Headphone Amps (full-size) › REVIEW: Head-Direct EF1 tube/hybrid headphone amp