Skylab
Reviewerus Prolificus
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.
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
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.
