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Head-Direct EF-1

post #1 of 348
Thread Starter 
Today I received my EF1 from Head-Direct. I had first heard the amp at CanJam2008, and was quite impressed with the prototype.

The amp is a hybrid that utilizes a single 12AU7 tube.

Although I have only accumulated about 3 hours listening time, I did try most of my phones and a variety of different genres of music.

The amp sounded superb with everything I threw at it, even with a brand new tube and virgin componentry.

Soundstage is very large and realistic, bass is deep and tight, and highs smooth and detailed. Tonal accuracy of individual instruments is outstanding, even with very large orchestral recordings. Background is dead silent with no input.

The power supply provided with the EF1 is a hefty regulated source that outputs 18vac. There should never be a lack of current to provide all the headroom one could ever need.

The clear acrylic cover allows one to see the innards, which give all appearances of a superb circuit layout. There is plenty of heatsink to dissipate the heat generated by the tube circuitry.

My only disappointment was that the opamp was soldered to the circuit board, rather than being socketed. I will probably at some point install a socket so as to be able to match opamp with tube.

I look forward to hearing how this amp matures with additional burn-in. I will post further impressions and comparisons with some of my other amps after I have enough time accumulated to feel that the amp has reached its maximum potential

Fang is to be commended for continuing to provide such fine equipment at prices WAY below their performance level.
post #2 of 348
Got mine too today, but you are ahead of me in the listening business (won't be connecting it until the weekend!).

Questions for you:

1. Does your acrylic have the lettering/message: "Hello Head-Fi'er / If it were not for you we would not be here". Mine does, and while I appreciate the thought, I think it detracts from the look. Maybe Fang has totally clear covers?

2. Mine came with a new 12AU7 from China, and an older RCA (as promised on the web site). Which did you use? Are you thinking about getting a better NOS tube? Which one?

3. What warm-up time does the amp need do you think? You plan to shut it off after each use, yes?

TIA!
post #3 of 348
Thread Starter 
Quote:
Originally Posted by wavoman View Post
Got mine too today, but you are ahead of me in the listening business (won't be connecting it until the weekend!).

Questions for you:

1. Does your acrylic have the lettering/message: "Hello Head-Fi'er / If it were not for you we would not be here". Mine does, and while I appreciate the thought, I think it detracts from the look. Maybe Fang has totally clear covers?

Yes, mine has the lettering. It would be a very simple matter to have a local plastic fabricator clone a new one, less lettering. I was also thinking of one in smoke color.

2. Mine came with a new 12AU7 from China, and an older RCA (as promised on the web site). Which did you use? Are you thinking about getting a better NOS tube? Which one?

I am using the RCA that was included. I have some other tubes from my other amps that I might try at some time in the future, but I would first like to get familiar with the "stock" sound. I have not found the Chinese tubes to sound as good as the NOS tubes.

3. What warm-up time does the amp need do you think? You plan to shut it off after each use, yes?

Most tube amps take about 30 minutes or so to stabilize. I am not sure that I can hear much difference after 5 minutes...
I have been leaving my Earmax on continuously, and will probably do the same with the EF-1. Probably more to condition the tube than for any other reason. I personally think that tubes last longer when left on continuously, but it would be difficult to prove that point.

I will, more than likely, remove the opamp from the circuit board and install a socket so I can try some different opamps.


TIA!
Ron
(HiFlight)
post #4 of 348
Glad you both have received your amps. Mine should be here shortly (in transit). The good thing about the 12AU7 is that there are many out there and should be inexpensive.

I concur w/ Ron on the 30 minutes of warm up to let the amp stabilize. As far as burn in I would give it 200 hours just to make sure, although changes after the first 100 hours should be subtle.

Does the power cord from the PSU to the amp have an RFI magnet core? Thanks.

Good luck!
post #5 of 348
Quote:
Originally Posted by mrarroyo View Post
... The good thing about the 12AU7 is that there are many out there and should be inexpensive....Does the power cord from the PSU to the amp have an RFI magnet core? ...
Yep, the cable on the DC side has a ferrite bead (as they're called ... a friend of mine sells them for a living). The PSU seems to have a beefy enough transformer (from the weight), misspells the word "transformer", and has the cord on the AC side permanently attached (I prefer a standard power cord). The molded strain reliefs seem OK.

As you say, the ferrite bead controls RFI emission; added to pass certification. Why do you ask? These degrade signal quality on audio cables, but that's not an issue here. Are you worried because it gets too close to signal cables (I worry about that too, but a small air gap is all you need, no?).

I am a newbie wrt 12AU7's ... some NOS on the web are quite expensive. Should I pay $15, $25, $50, $75, or $250???

Thanks!
post #6 of 348
I have quite a bit of experience with the 12AU7. The RCA "clear-top" ones are excellent, as are the Tung-Sol JAN-CTL grey-plates. These can be had for $30 or less. The Tung-Sol black-glass are also supposed to be wonderful but they are quite expensive. The Chinese tube isn't worth trying at all.

Interesting looking amp, I will await the reviews. It does seem a little expensive for a single-tube, op-amp based hybrid amp, to me, but if it's wonderful sounding, then great!
post #7 of 348
Has anyone tried their cables? I'm curious about the DW12 for Senn:

Head-Direct.com
post #8 of 348
Congrats on the amps. One little question, how does it handle low impedance cans ? Is there any hiss at all ??? Thanks...
post #9 of 348
Quote:
Originally Posted by Skylab View Post
I have quite a bit of experience with the 12AU7. The RCA "clear-top" ones are excellent, as are the Tung-Sol JAN-CTL grey-plates. These can be had for $30 or less. The Tung-Sol black-glass are also supposed to be wonderful but they are quite expensive. The Chinese tube isn't worth trying at all...
Thanks for the advice, I will follow it!
post #10 of 348
Ron & Miguel. I'm very disappointed that these amps came after our Mini-Meet. Looks like we may have to get together again sometime soon!
post #11 of 348
Thread Starter 
Quote:
Originally Posted by Downer View Post
Congrats on the amps. One little question, how does it handle low impedance cans ? Is there any hiss at all ??? Thanks...

I hear no hiss or hum at all with any of my phones, low impedance included. I hear hum when connected to my iRiver H120 and it is turned off, but that is normal and is the same with all of my amps. As soon as the source boots, the hum disappears completely.
post #12 of 348
Quote:
Originally Posted by illkemist View Post
Ron & Miguel. I'm very disappointed that these amps came after our Mini-Meet. Looks like we may have to get together again sometime soon!
I agree, I am trying to get Ron (HiFlight) to host the next meet. Similar to the way Nick20 did it. Come on Ron, you can do it!

Note I received my unit today and it is burning in.

Downer, w/ no signal being fed into the unit and w/ 15 minutes out of the box w/ the chinese tube I could hear a bit of his at about 3:00pm w/ either an Ultrasone HFI-780 or a Senn PX-100. But there is no way I would use that amp w/ the volume at 3:00pm or I would go deaf in no time. At normal volumes (for me it would be at +/-9am or less) there was no noise/hiss w/ either of the two cans I mentioned.

I am excited w/ this unit and I have already identified three tweak! Elastomer feet for the PSU and the amp to help w/ vibration, Herbie's Halos for the tube, and a second rfi blocker to the cable providing the power to the amp. If I get adventurous I may even try a new plexiglass top w/ more vent holes.

Meanwhile I have high hopes for this unit. It is the perfect size for a discrete office or night stand service. The psu is quite hefty.
post #13 of 348
Has anybody hooked up a AKG K701 up to this amp yet? If so, how do they sound?
post #14 of 348
Miguel you know what I am going to say - you simply must try a better tube than that Chinese one. Chinese preamp tubes like that are universally awful. Send me a PM, I will send you something, I owe you a tube

I also will be getting a EF-1 to review it looks like. Looking forward to it.
post #15 of 348
Quote:
Originally Posted by Skylab View Post
Miguel you know what I am going to say - you simply must try a better tube than that Chinese one. Chinese preamp tubes like that are universally awful. Send me a PM, I will send you something, I owe you a tube

I also will be getting a EF-1 to review it looks like. Looking forward to it.
THANKS for the Tube!

To be honest I do not find the Chinese tubes as objectionable as others. Sometimes I actually think they sound very nice. But change and diversity spices life in general, so having other tubes to have would be great. PM coming your way.

Note:

I just took a quick pick using a V3 APureSound re-cabled HFI-780. I am using a Philips DVP and the artist was George Shearing. The amp has just about 24 hours of burn in w/ the Chinese tube and it is interesting how burn-in removes the rough edges of an amp's presentation. This is typical whether SS or Tube, the closest analogy would be polishing a blade. I will continue the burn-in process and hope to post at the 100 and 200 hours.
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