jma790
500+ Head-Fier
- Joined
- Jan 31, 2008
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Hi! Today I’ll be reviewing the Head Direct EF1 Hybrid Headphone Amp; manufactured and sold by Head Direct, and hand assembled in China. This is a full sized amp, but it has a pretty small footprint, so it doesn’t take much space.
Head-Direct is a small company which carries a lot of audio equipment; you can get headphones, amps, cables and many other things from their site. The company is ran by Fang, who is a great person to deal with. The company is constantly introducing new products to their line, as well as distributing many nice products from many other companies (Yuin, Darkvoice, etc). They always try to achieve a good price performance ratio, and that’s why their products have won some praise around here.
The Specs of the amp, per Head-Direct’s site are:
Opamp: OPA275
Tube: Sylvania 12AU7 (CONN branded)
Frequency Response: 20-30K Hz
THD+N: less than 0.2%
S/N: more than 95dB
Input impedance: 50K Ohm
Output impedance: 2–2K Ohm headphones
Output signal strength: up to 15 Volts at 32 Ohm
Input: RCA*1
Output: 1/4 headphone jack*1
Dimension: 110mm(W)*50mm(H)*270mm(D),
or 4.33inch(W)*1.97inch (H)*10.63inch (D)
Weight: 750g (without power supply)
Accessory: 12AU7 tube, 18V AC power supply
The OPA275 and the Sylvania 12AU7 are the stock configuration of the EF1. The newest version of the amp comes with socketed opamp, as well as a socket for the tube, so there’s a big potential for tube/opamp rolling which I’ll explore later.
I was interested in the amp for a really long time before getting it, due to all the positive comments. That’s why I contacted Fang more than a month ago and asked him if he had a B-Stock unit that he could sell to me. He told me that he had one lying around and he could sell it to me. I agreed happily, and told him that I would do a review as a little way of saying thanks; but that doesn’t means that I’ll give it a positive review if I don’t like it. After all, I am paying for it.
I’ll post my impressions of the amp, and I’ll try to compare it with other amps that I had owned before, although I haven’t tried that much amps.
Reviewing Equipment:
- Sony Discman D-311 PCDP (the best source that I own right now).
- Sony PFR-V1’s/ Sennheiser PX100/ Grado SR-80 (for a week) headphones.
- Custom made mini to RCA cable, using 4 strands of Vampire Copper Wire (2 strands per channel), and Switchcraft plugs on both ends.
- RCA 12AU7/JJ ECC82 tubes.
- OPA275/(2)AD743JN (mounted on 2:1 adapter) opamps.
•Everything has been burned in for a minimum of 50 hours; the V1’s have more than 100 hours on them. The amp and the RCA tube have a lot more (I don’t know exactly how much).
The looks:
This little amp looks really nice. It’s small, and very well built, giving it a very professional look. The black aluminum chassis is really sturdy, and looks like it could stand a bit of abuse. The top is composed of a long plate of plastic (?) with a small hole for the tube. It has some lettering on it, but it seems like newer EF1’s don’t come with it. On the back there are the RCA jacks, and a jack for inserting the transformer plug. At the front, there is one ¼” output jack, an on/off switch, and the volume pot.
The interior of the amp looks really good, and shows a very clean component layout. From there you can see the opamps as well as the tube. There are also a lot of resistors, caps, etc.
The transformer included with the amp is quite big, being almost of the same size of the amp. It supplies 30 W to the amp, and you need to order a different one depending if you use 110 or 220 V.
I love the small form factor of the amp, as I can have it over my bedside table, and it doesn’t takes much space. It looks really good on there too. I thought that the amp was bigger, and I was surprised when I saw its small size.
Overall, I think that build quality is really good for the price. I would change, however, the plastic cover on top, and replace it with one without the lettering (although it doesn’t bother me), or with a better glass cover.
The sound:
This is the most important part of the review, so I’ll try to be as clear as possible.
I didn’t try the amp when it was brand new and unused, due to the amp being a B-Stock unit it already came with many hours on it. I put even more hours on it, so I can’t give any “first impressions” of the amp. Everything that I say will be based on the fully burned in state of the amp.
First, I want to describe a bit about the volume control. The volume pot is really good (and big); it gives you a nice feeling on contact, and it’s easy to regulate. It doesn’t show the irregular volume changes that cheaper pots tend to give.
There has been some talking about the fact that there is a lot of noise at the lowest volume settings when there’s no music, due to the active volume control that the amp uses. However, at least with the headphones that I tried with, I couldn’t hear any of that noise. I don’t know if I am not hearing well (maybe), but I wasn’t able to pick that noise neither when I tried the OPA/RCA nor with the AD/JJ combo.
The pot is supposed to show a scratchy sound when regulating it, but again, I couldn’t hear that. Maybe I am not blessed with that golden ears that some people have
. I guess that this noise might be more noticeable when using IEM’s, but I won’t be able to test that if that’s the case. The only time when I was able to notice some noise was when I had the AD opamps installed, but only at times (maybe it was due to static? When I get closer while the noise is there, it gets worse, so that may be it).
I’ll post my impressions comparing both opamp/tube combos at the same time, trying to say the differences that I hear between them.
Be aware that the headphones sound signature is really important when testing the amp, as different headphones will yield different impressions, so I’ll try to be a bit explicit about those differences.
Across the Sound Spectrum:
I’ll start with the highs. The V1’s are supposed to be quite similar to the ER-4P’s in their sound spectrum, and that means that they may show a bright treble. That was something that I could notice with the RCA tube installed. Don’t get me wrong, I don’t feel that it’s bright, but when you compare it to the JJ tube, it may sound a bit bright. It wasn’t bad at all though, as it’s really detailed, and never harsh. Fortunately, the JJ tube gets you a more neutral treble, remaining detailed at all times.
The second part would be the mids, which are beautiful. I do understand now why so many people (like Skylab and others) love the tube sound so much. The mids are really good, even while some people say that the EF1 doesn’t have a totally tubular sound. Voices sound great, especially female ones. Sharon Den Adel’s (Within Temptation) voice sounds great on many tracks from the albums “Mother Earth” and “The Silent Force”. I loved her voice before, and now I love it even more. Dolores O'Riordan (The Cranberries) voice in the compilation album “stars” also sounds great. Many other voices sound really good like that of Vibeke Stene (Tristania), Diana Krall (her voice… ‘S Wonderful
), Ailyn and Fabienne Gondamin (both from Sirenia), Kai Hansen (Gamma Ray), Hansi Kürsch (Blind Guardian), among many others. All of them sound really good. Instruments in this range also sound great, with great definition and speed; it’s enjoyable and detailed at the same time. Guitars sound great, as well as sax, drums, pianos, etc. This may be due to the good synergy between the V1’s and the EF1. Both combos sound great here, with not many noticeable differences.
Finally, we have the bass. First, I want to say that I am not a basshead. I prefer a neutral bass over an imposing one, and I don’t care if the bass is ultra deep and makes your head shake. I wouldn’t stand something that only gets in the way of the other frequencies. After saying that, I have to say that the EF1 has a great bass. Pretty neutral, and detailed, with great speed and definition. Maybe it’s lacking for bassheads, but it may be enough for most persons. It goes pretty low, and it’s really deep. And that’s what I hear with the V1’s, which are supposed to lack a lot of bass. Turning on the bass boost from the D-311 only gives better presence to the bass. While it may not make your head shake, it has a nice character on some tracks that are really well mastered. The bass from Tristania’s “World Of Glass” sounds really good, going deep and with a great presence, but never getting in the way of other sounds. Many tracks from the Cranberries as well as Diana Krall also show a great bass. Again, I couldn’t notice big differences between both combos.
I need to make an special mention to the Trance genre. It sounds “delicious” with this headphone/amp combo, many live discs from Armin Van Buuren, DJ Tiësto and Paul Van Dyk sound extremely good, making me toe tap at times (not something easy to make me do). Another thing that I would like to mention is the fact that many things sound very “organic”, with a really nice and enjoyable sound. Versus my old iBasso D2 Viper, voices have a more lifelike feeling, and the sound has a better presence and decay. Everything is more detailed and fuller. Definitely, a nice upgrade, although not a night/day difference.
I get the feeling that the amp aims to a pretty neutral sound. And it's not so colored, so it might be close to that. It does have those beautiful mids and that great bass though, so you are the judge about that neutrality here.
Soundstage and Imaging:
This may be a strong point of this headphone/amp combo. It’s really really good! Almost everything that I threw at it sounded great, with great positioning, and with a good size for the soundstage. Everything is out of your head at almost all times. Live music sounds extremely good, and you get a lifelike feeling of the music at times. This is something that I couldn’t achieve with the D2 Viper. While it had a nice soundstage size, the EF1 simply beats it at size and imaging (positioning). The sound is so greatly separated. You don’t feel like if everything were congested at some point in your head. You can concentrate on something that you want to hear, because while the soundstage is big, everything remains very well defined, without losing details. The sound is always clean and clear, with a really nice feeling. I think that the width is better than the depth. The 3 dimensions are good, but not on the same level. This might be as well due to the headphones.
Here’s where the tube/opamps combo have a noticeable difference. The AD/JJ combo shows a better imaging and soundstage that the other one. While it’s not a night/day difference, it’s a nice upgrade, and I prefer to keep it this way.
For me, soundstage is one of the most important things when looking for headphones, not the most important though. And I just have to say that I love the soundstage that I am getting out of the combo. The fact that the chorus is in one place while you hear the singer is in another one, and also the fact that voices remain distinct and separate. It sounds simply amazing.
I was willing to try this headphone/amp combo just because someone recommended it to me for the great soundstage, and he didn’t deceive me. I do feel that it gets a bit smaller at times, but that may be due to the mastering of the music. Maybe getting a better source might also help with that. I’ll try to explore that in the future.
Other thoughts:
I thought that, given that the V1’s have fairly low impedance; I wouldn’t notice much difference when going from my portable D2 Viper to this full sized amp. I was a bit wrong with that, as almost all the sound coming out from this headphone got a lot better. I would surely recommend getting a full sized amp from now on, if portability isn’t a critical factor. It may be a bit more problematic to carry from one place to another, but it’s a much better sound, for almost the same price.
I like the idea of the hybrid between solid state and tube sound. It gives you the beautiful mids of tubes, and the clean output of solid state. Thanks to this, I didn’t felt a radical change in sound signatures. Instead, I just got a sound with nicer and more enjoyable characteristics, and I think it’s worth to try and see if you like it.
Also, I want to say that I don’t like Grado’s. Not that I have anything against their sound, but rather that those headphones (at least the cheaper ones) hurt my ears a lot, and I can’t stand that. However, I noticed that the synergy between the SR-80’s and the EF1 was really good. With a deeper bass than that of the V1’s. Soundstage also got bigger. Overall, the sound got a great boost.
I need to mention the fact that the tube gets really hot after using the amp for a while. And I mean, really hot. Enough to make the cover on top and the volume knob to get hot too! It happens a lot more with the RCA tube, as the JJ remains a little more cooler even while used for the same time. Be careful with this, as you may get burned
.
Another thing would be the fact that the blue LED at the inside is not so powerful to allow you to regulate the volume adequately in a dark room (to know if you are going deaf). It makes the amp look really cool, but due to the positioning, and the fact that the volume knob is totally black, it’s not much of a help.
Finally, I think that there might be much better amps out there (obviously, otherwise, why pay +$1000 for another amp?), but I also think that the EF1 would make for a great starter home amp. It offers a great sound at a really affordable price. Compared to many portable amps in a close price range, it goes all over them without much effort. The fact that it has much more power for headphones makes it an obviously better option for hard to drive cans. It might not be the best amp out there, but it may be good enough for many people. I think that I can finally stay with it, and upgrade other parts of my rig. I really want to do this, as I want to see how well the amp and headphones upgrades when I upgrade my source. I also want to try other headphones with the amp, so I’ll explore that later.
Conclusions:
I want to close this little review with my conclusions:
- The amp is really good looking, and offers a great sound.
- It’s a great bang for the buck options versus some amps in a close price range.
- The small footprint makes it easy to carry and store at many places at home, but it’s not a portable amp!
- It would make for a better option over portable amps if portability is not an important thing for you; especially if you want to use it with hard to drive cans.
- Care needs to be taken when manipulating tubes and opamps, as they can get damaged if done improperly.
The review ends here. I hope that you enjoyed reading it. I try my best when doing this, so if you like it please tell me so. If you didn’t like it or have any recommendations, please tell me too, because that way I can get better at this. Please forgive me for any typos or redaction errors that you may find. I’ll try to add more info to the review in the future, if I feel that it’s worth to do so.
Like always, everything is IMO, so please forgive me if it doesn’t match yours.
I hope to see you around again, and if you have any questions, please do not hesitate to ask.
Have a great day/afternoon/night.
Regards,
Head-Direct is a small company which carries a lot of audio equipment; you can get headphones, amps, cables and many other things from their site. The company is ran by Fang, who is a great person to deal with. The company is constantly introducing new products to their line, as well as distributing many nice products from many other companies (Yuin, Darkvoice, etc). They always try to achieve a good price performance ratio, and that’s why their products have won some praise around here.
The Specs of the amp, per Head-Direct’s site are:
Opamp: OPA275
Tube: Sylvania 12AU7 (CONN branded)
Frequency Response: 20-30K Hz
THD+N: less than 0.2%
S/N: more than 95dB
Input impedance: 50K Ohm
Output impedance: 2–2K Ohm headphones
Output signal strength: up to 15 Volts at 32 Ohm
Input: RCA*1
Output: 1/4 headphone jack*1
Dimension: 110mm(W)*50mm(H)*270mm(D),
or 4.33inch(W)*1.97inch (H)*10.63inch (D)
Weight: 750g (without power supply)
Accessory: 12AU7 tube, 18V AC power supply
The OPA275 and the Sylvania 12AU7 are the stock configuration of the EF1. The newest version of the amp comes with socketed opamp, as well as a socket for the tube, so there’s a big potential for tube/opamp rolling which I’ll explore later.
I was interested in the amp for a really long time before getting it, due to all the positive comments. That’s why I contacted Fang more than a month ago and asked him if he had a B-Stock unit that he could sell to me. He told me that he had one lying around and he could sell it to me. I agreed happily, and told him that I would do a review as a little way of saying thanks; but that doesn’t means that I’ll give it a positive review if I don’t like it. After all, I am paying for it.
I’ll post my impressions of the amp, and I’ll try to compare it with other amps that I had owned before, although I haven’t tried that much amps.
Reviewing Equipment:
- Sony Discman D-311 PCDP (the best source that I own right now).
- Sony PFR-V1’s/ Sennheiser PX100/ Grado SR-80 (for a week) headphones.
- Custom made mini to RCA cable, using 4 strands of Vampire Copper Wire (2 strands per channel), and Switchcraft plugs on both ends.
- RCA 12AU7/JJ ECC82 tubes.
- OPA275/(2)AD743JN (mounted on 2:1 adapter) opamps.
•Everything has been burned in for a minimum of 50 hours; the V1’s have more than 100 hours on them. The amp and the RCA tube have a lot more (I don’t know exactly how much).
The looks:
This little amp looks really nice. It’s small, and very well built, giving it a very professional look. The black aluminum chassis is really sturdy, and looks like it could stand a bit of abuse. The top is composed of a long plate of plastic (?) with a small hole for the tube. It has some lettering on it, but it seems like newer EF1’s don’t come with it. On the back there are the RCA jacks, and a jack for inserting the transformer plug. At the front, there is one ¼” output jack, an on/off switch, and the volume pot.
The interior of the amp looks really good, and shows a very clean component layout. From there you can see the opamps as well as the tube. There are also a lot of resistors, caps, etc.
The transformer included with the amp is quite big, being almost of the same size of the amp. It supplies 30 W to the amp, and you need to order a different one depending if you use 110 or 220 V.
I love the small form factor of the amp, as I can have it over my bedside table, and it doesn’t takes much space. It looks really good on there too. I thought that the amp was bigger, and I was surprised when I saw its small size.
Overall, I think that build quality is really good for the price. I would change, however, the plastic cover on top, and replace it with one without the lettering (although it doesn’t bother me), or with a better glass cover.
The sound:
This is the most important part of the review, so I’ll try to be as clear as possible.
I didn’t try the amp when it was brand new and unused, due to the amp being a B-Stock unit it already came with many hours on it. I put even more hours on it, so I can’t give any “first impressions” of the amp. Everything that I say will be based on the fully burned in state of the amp.
First, I want to describe a bit about the volume control. The volume pot is really good (and big); it gives you a nice feeling on contact, and it’s easy to regulate. It doesn’t show the irregular volume changes that cheaper pots tend to give.
There has been some talking about the fact that there is a lot of noise at the lowest volume settings when there’s no music, due to the active volume control that the amp uses. However, at least with the headphones that I tried with, I couldn’t hear any of that noise. I don’t know if I am not hearing well (maybe), but I wasn’t able to pick that noise neither when I tried the OPA/RCA nor with the AD/JJ combo.
The pot is supposed to show a scratchy sound when regulating it, but again, I couldn’t hear that. Maybe I am not blessed with that golden ears that some people have
I’ll post my impressions comparing both opamp/tube combos at the same time, trying to say the differences that I hear between them.
Be aware that the headphones sound signature is really important when testing the amp, as different headphones will yield different impressions, so I’ll try to be a bit explicit about those differences.
Across the Sound Spectrum:
I’ll start with the highs. The V1’s are supposed to be quite similar to the ER-4P’s in their sound spectrum, and that means that they may show a bright treble. That was something that I could notice with the RCA tube installed. Don’t get me wrong, I don’t feel that it’s bright, but when you compare it to the JJ tube, it may sound a bit bright. It wasn’t bad at all though, as it’s really detailed, and never harsh. Fortunately, the JJ tube gets you a more neutral treble, remaining detailed at all times.
The second part would be the mids, which are beautiful. I do understand now why so many people (like Skylab and others) love the tube sound so much. The mids are really good, even while some people say that the EF1 doesn’t have a totally tubular sound. Voices sound great, especially female ones. Sharon Den Adel’s (Within Temptation) voice sounds great on many tracks from the albums “Mother Earth” and “The Silent Force”. I loved her voice before, and now I love it even more. Dolores O'Riordan (The Cranberries) voice in the compilation album “stars” also sounds great. Many other voices sound really good like that of Vibeke Stene (Tristania), Diana Krall (her voice… ‘S Wonderful
Finally, we have the bass. First, I want to say that I am not a basshead. I prefer a neutral bass over an imposing one, and I don’t care if the bass is ultra deep and makes your head shake. I wouldn’t stand something that only gets in the way of the other frequencies. After saying that, I have to say that the EF1 has a great bass. Pretty neutral, and detailed, with great speed and definition. Maybe it’s lacking for bassheads, but it may be enough for most persons. It goes pretty low, and it’s really deep. And that’s what I hear with the V1’s, which are supposed to lack a lot of bass. Turning on the bass boost from the D-311 only gives better presence to the bass. While it may not make your head shake, it has a nice character on some tracks that are really well mastered. The bass from Tristania’s “World Of Glass” sounds really good, going deep and with a great presence, but never getting in the way of other sounds. Many tracks from the Cranberries as well as Diana Krall also show a great bass. Again, I couldn’t notice big differences between both combos.
I need to make an special mention to the Trance genre. It sounds “delicious” with this headphone/amp combo, many live discs from Armin Van Buuren, DJ Tiësto and Paul Van Dyk sound extremely good, making me toe tap at times (not something easy to make me do). Another thing that I would like to mention is the fact that many things sound very “organic”, with a really nice and enjoyable sound. Versus my old iBasso D2 Viper, voices have a more lifelike feeling, and the sound has a better presence and decay. Everything is more detailed and fuller. Definitely, a nice upgrade, although not a night/day difference.
I get the feeling that the amp aims to a pretty neutral sound. And it's not so colored, so it might be close to that. It does have those beautiful mids and that great bass though, so you are the judge about that neutrality here.
Soundstage and Imaging:
This may be a strong point of this headphone/amp combo. It’s really really good! Almost everything that I threw at it sounded great, with great positioning, and with a good size for the soundstage. Everything is out of your head at almost all times. Live music sounds extremely good, and you get a lifelike feeling of the music at times. This is something that I couldn’t achieve with the D2 Viper. While it had a nice soundstage size, the EF1 simply beats it at size and imaging (positioning). The sound is so greatly separated. You don’t feel like if everything were congested at some point in your head. You can concentrate on something that you want to hear, because while the soundstage is big, everything remains very well defined, without losing details. The sound is always clean and clear, with a really nice feeling. I think that the width is better than the depth. The 3 dimensions are good, but not on the same level. This might be as well due to the headphones.
Here’s where the tube/opamps combo have a noticeable difference. The AD/JJ combo shows a better imaging and soundstage that the other one. While it’s not a night/day difference, it’s a nice upgrade, and I prefer to keep it this way.
For me, soundstage is one of the most important things when looking for headphones, not the most important though. And I just have to say that I love the soundstage that I am getting out of the combo. The fact that the chorus is in one place while you hear the singer is in another one, and also the fact that voices remain distinct and separate. It sounds simply amazing.
I was willing to try this headphone/amp combo just because someone recommended it to me for the great soundstage, and he didn’t deceive me. I do feel that it gets a bit smaller at times, but that may be due to the mastering of the music. Maybe getting a better source might also help with that. I’ll try to explore that in the future.
Other thoughts:
I thought that, given that the V1’s have fairly low impedance; I wouldn’t notice much difference when going from my portable D2 Viper to this full sized amp. I was a bit wrong with that, as almost all the sound coming out from this headphone got a lot better. I would surely recommend getting a full sized amp from now on, if portability isn’t a critical factor. It may be a bit more problematic to carry from one place to another, but it’s a much better sound, for almost the same price.
I like the idea of the hybrid between solid state and tube sound. It gives you the beautiful mids of tubes, and the clean output of solid state. Thanks to this, I didn’t felt a radical change in sound signatures. Instead, I just got a sound with nicer and more enjoyable characteristics, and I think it’s worth to try and see if you like it.
Also, I want to say that I don’t like Grado’s. Not that I have anything against their sound, but rather that those headphones (at least the cheaper ones) hurt my ears a lot, and I can’t stand that. However, I noticed that the synergy between the SR-80’s and the EF1 was really good. With a deeper bass than that of the V1’s. Soundstage also got bigger. Overall, the sound got a great boost.
I need to mention the fact that the tube gets really hot after using the amp for a while. And I mean, really hot. Enough to make the cover on top and the volume knob to get hot too! It happens a lot more with the RCA tube, as the JJ remains a little more cooler even while used for the same time. Be careful with this, as you may get burned
Another thing would be the fact that the blue LED at the inside is not so powerful to allow you to regulate the volume adequately in a dark room (to know if you are going deaf). It makes the amp look really cool, but due to the positioning, and the fact that the volume knob is totally black, it’s not much of a help.
Finally, I think that there might be much better amps out there (obviously, otherwise, why pay +$1000 for another amp?), but I also think that the EF1 would make for a great starter home amp. It offers a great sound at a really affordable price. Compared to many portable amps in a close price range, it goes all over them without much effort. The fact that it has much more power for headphones makes it an obviously better option for hard to drive cans. It might not be the best amp out there, but it may be good enough for many people. I think that I can finally stay with it, and upgrade other parts of my rig. I really want to do this, as I want to see how well the amp and headphones upgrades when I upgrade my source. I also want to try other headphones with the amp, so I’ll explore that later.
Conclusions:
I want to close this little review with my conclusions:
- The amp is really good looking, and offers a great sound.
- It’s a great bang for the buck options versus some amps in a close price range.
- The small footprint makes it easy to carry and store at many places at home, but it’s not a portable amp!
- It would make for a better option over portable amps if portability is not an important thing for you; especially if you want to use it with hard to drive cans.
- Care needs to be taken when manipulating tubes and opamps, as they can get damaged if done improperly.
The review ends here. I hope that you enjoyed reading it. I try my best when doing this, so if you like it please tell me so. If you didn’t like it or have any recommendations, please tell me too, because that way I can get better at this. Please forgive me for any typos or redaction errors that you may find. I’ll try to add more info to the review in the future, if I feel that it’s worth to do so.
Like always, everything is IMO, so please forgive me if it doesn’t match yours.
I hope to see you around again, and if you have any questions, please do not hesitate to ask.
Have a great day/afternoon/night.
Regards,
