REVIEW: Head-direct.com HiFiMan EF2 tube Hybrid Amp with USB DAC
Jul 8, 2009 at 6:00 PM Post #33 of 1,326
I've done a little bit of reading on the LittleDot I+ tube rolling thread, and now I'm getting more excited about the possibility of getting my first tube amp!
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A few questions for you HeadphoneAddict, if you have a moment:

1)
I'm curious about the Raytheon 6AK5 replacement tubes you used. Are they military grade tubes? I've been looking at tubes on eBay (sold by one of the popular sellers that tests and matches), and I found that the military grade versions cost nearly twice as much. On the EF2, is it worth going for the military grade (or otherwise high-end version such as Sylvania Gold etc)?

2)
I read your review for the Travagans Red/Green/White, and I'm curious if you have an impression of the White DAC performance vs the EF2 DAC since they use the same BurrBrown 2702. Since you no longer have the White, and you can't exactly evaluate the EF2's DAC directly, I know this may be a tough question. But do you have an impression of how these two units compare to each other?

I was originally thinking of getting the White for a simple office DAC/amp unit. However, now I'm thinking of getting the EF2 and using some of the money I save to buy a pair of upgrade tubes.
 
Jul 8, 2009 at 6:19 PM Post #35 of 1,326
Most definately, as most consider the new iphone to better or be exactly like a d2
 
Jul 8, 2009 at 6:23 PM Post #36 of 1,326
thanks for the response, im very tempted to order this and sell the d2 boa

im hoping it'd pair well w/ my RE0 since they're both HiFiMan products
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hopefully OP can chime in with his opinion too
 
Jul 8, 2009 at 6:43 PM Post #37 of 1,326
Quote:

Originally Posted by FullTwisting /img/forum/go_quote.gif
I've done a little bit of reading on the LittleDot I+ tube rolling thread, and now I'm getting more excited about the possibility of getting my first tube amp!
smile_phones.gif


A few questions for you HeadphoneAddict, if you have a moment:

1)
I'm curious about the Raytheon 6AK5 replacement tubes you used. Are they military grade tubes? I've been looking at tubes on eBay (sold by one of the popular sellers that tests and matches), and I found that the military grade versions cost nearly twice as much. On the EF2, is it worth going for the military grade (or otherwise high-end version such as Sylvania Gold etc)?

2)
I read your review for the Travagans Red/Green/White, and I'm curious if you have an impression of the White DAC performance vs the EF2 DAC since they use the same BurrBrown 2702. Since you no longer have the White, and you can't exactly evaluate the EF2's DAC directly, I know this may be a tough question. But do you have an impression of how these two units compare to each other?

I was originally thinking of getting the White for a simple office DAC/amp unit. However, now I'm thinking of getting the EF2 and using some of the money I save to buy a pair of upgrade tubes.



1) I don't recall if the tubes are military designated or not. Can't read them while they are in the amp, and they came two to a single box with no print. I think I paid $25 for the tubes.

2) I would say that the White's DAC is on par with the EF2 DAC. It is a bigger guess on my part to say that maybe the White with a pair of OPA627 opamps on a 2:1 "over/under" adapter would sound somewhat similar. (about $340 for both amp and opamps after shipping).
 
Jul 8, 2009 at 6:58 PM Post #38 of 1,326
Quote:

Originally Posted by koven /img/forum/go_quote.gif
Thanks for the review, not sure how long it's been since you've used a D2 boa but would you say this is an upgrade from the d2 boa?


Assuming the EF2 is fully burned-in, yes, it is better than the D2 Boa, no question - while the D2 Boa isn't bad it just isn't as enjoyable as the EF2. It's probably on about the sound quality level of the 3MOVE or XM5 with upgraded opamps and BUF634 buffers, but with a bit more power than the XM5 and a little more euphonic sounding than either (with stock or rolled tubes).

The D10 and Pico, while having less power for 300 ohm headphones, will be more detailed and spacious - but the Pico is not quite as warm and mellow and romantic sounding as the EF2, especially with the Raytheon 6AK5 tubes. I haven't listened to the stock D10 for a long time, but I would say it sits between the D10 and EF2 in warmth when using the Raytheon tubes (maybe closer when using the stock tubes).
 
Jul 8, 2009 at 7:11 PM Post #39 of 1,326
Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif
1) I don't recall if the tubes are military designated or not. .


Yes, the Raytheon tubes Larry got from me are military tubes.
 
Jul 8, 2009 at 7:19 PM Post #40 of 1,326
Quote:

Originally Posted by HeadphoneAddict /img/forum/go_quote.gif
1) I don't recall if the tubes are military designated or not. Can't read them while they are in the amp, and they came two to a single box with no print. I think I paid $25 for the tubes.

2) I would say that the White's DAC is on par with the EF2 DAC. It is a bigger guess on my part to say that maybe the White with a pair of OPA627 opamps on a 2:1 "over/under" adapter would sound somewhat similar. (about $340 for both amp and opamps after shipping).




Thank you very much for the reply.

I thought that for the price, your tubes may not have been military, but I see that Skylab just posted that they are. Nice buy!

Also, I really appreciate your opinion on the White. If I had purchased the White, I would likely have eventually looked into the opamp upgrade you mentioned.

Right now, it seems like the EF2 is a win all around (for my price range and needs anyway). I'm running out of excuses to order one. My wallet doesn't seem as scared of me as it was a week ago.
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Jul 8, 2009 at 7:22 PM Post #41 of 1,326
Seems I must snatch some tubes here
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Jul 8, 2009 at 7:25 PM Post #42 of 1,326
Quote:

Originally Posted by Skylab /img/forum/go_quote.gif
Yes, the Raytheon tubes Larry got from me are military tubes.


Thanks for the update Skylab. The military grade NOS/tested/matched tubes I found on eBay are about twice the cost of regular tubes. If you have more for that price, I'd be interested too.
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Jul 8, 2009 at 7:42 PM Post #43 of 1,326
Yeah, I gave Larry a good deal - those Raytheons tend to go for $40-60/pair.

But you can get NOS Sylvania military 6AK5's for $5-10 each, and NOS Western Electric military issue for $15 each on eBay easily - just search 6AK5.
 
Jul 8, 2009 at 7:50 PM Post #44 of 1,326
Quote:

Originally Posted by Skylab /img/forum/go_quote.gif
Yeah, I gave Larry a good deal - those Raytheons tend to go for $40-60/pair.

But you can get NOS Sylvania military 6AK5's for $5-10 each, and NOS Western Electric military issue for $15 each on eBay easily - just search 6AK5.



Yeah, I thought that was probably the case.
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I'm a bit nervous about buying the tubes from eBay, so I was looking at one particular seller that seems to have a good reputation here on head-fi. I have no equipment to test them, so I'd rely on the seller to test and match them. That's going to (understandably) bump my cost up.
 
Jul 8, 2009 at 8:01 PM Post #45 of 1,326
Quote:

Originally Posted by Skylab /img/forum/go_quote.gif
Yeah, I gave Larry a good deal - those Raytheons tend to go for $40-60/pair.

But you can get NOS Sylvania military 6AK5's for $5-10 each, and NOS Western Electric military issue for $15 each on eBay easily - just search 6AK5.



Thanks again! You really wanted this amp to get a good review for Fang, eh? Nah, you just wanted me to enjoy it more and were being nice to me.
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