[avitron142]

I didn't say there wasn't a difference, I just said not a big one. : p

Stay tuned for my B1 review for the details of the differences, but I do agree that the B1 does have a nice sound to it.

I'm not sure if it's only my unit, but there seems to be some sort of crossfeed-like effect, but not, for my B1. I think someone mentioned a channel imbalance somewhere.
It's hard to put into words, but when A/B-ed against my other amps, it is blatantly obvious to tell which one is the B1 and which one isn't because it places the left channel more on the left than the others. Even with just pink noise playing for volume-matching, I can hear that difference.

DAC is the Objective DAC in all of these tests. It's the only dedicated DAC I have. I could use the OPPO HA-2's line-out feature though if I wanted to.

Note to self: HE1000 unit is measured to be 31-ohms with the 3.5 mm cable (32 mW, 0.990 Vrms, 31.939 mA to reach 105 dB SPL).

Idk, I didn't get that effect at all. Musical, yes, but no channel imbalance on mine. I'm fairly sure of this because I've sent back units in the past that had channel imbalance and it turned out to be that they did, so I'm pretty cofident mine didn't have any. Another thing to note is Dergabe's clipping, it concerns me a bit that people with the B1 are having different problems. Same problems I can wrap my head around, but different ones... I'm confused 

 

[money4me247]

"Clipping" is caused by not having enough power. It affects the entire song throughout and every song. Commonly described initially as hearing 'roughness' or 'raspiness' at the edges of the sound. Or the music sounds more closed-in/congested. Spacing between notes not as clearly defined and individual notes do not sound as sharp and clear. Will not be isolated instances of distortion/noise. Isolated sections of a specific song where you hear distortion every single time at the same time segment of the track usually indicates another problem (usually source issue). Intermittent randomly occurring noise/crackling/static is a different issue as well (not related to clipping or source). It 'should' be relatively easy to distinguish what sort of issue you are running into through a few quick tests.
 
You will use this resource to calculate your headphone's power requirements: http://www.apexhifi.com/specs.html

1. For the Beyer T1, the maximum power you need is 200mW, 10.94V, and 18.2 mA to reach 125dB (loudness that begins to cause pain). That will cover more than enough headroom to cover any peaks. When using this headphone, you need to be in high gain mode as it has a 600ohm impedance. 
2. For the Shure SRH440 , you need 100mW of power, 2.1V, and 47.7mA to reach 125dB to reach 125dB.

 
**Note the amount of power needed to reach 125dB is a lot more power than you actually need for normal volume listening levels (60-98dB).
 
Ask Aune for the power ratings on their amplifier and you can see if the amplifier is not sufficient for your headphones. (you should really use 110-120 dB for real-world power requirements, 125dB is a lot more than required - I was just illustrating the extremes)
 
Hope this information is helpful!

 

[beeman]

Hi - very interestiing reading the thoughts and reviews on the b1. I was thinking about using the b1 with an iphone 4s (LOD) - does anyone use this combination and what are your impressions?

 

[miceblue]

Hi - very interestiing reading the thoughts and reviews on the b1. I was thinking about using the b1 with an iphone 4s (LOD) - does anyone use this combination and what are your impressions?

I'll have to do more listening today when I get back from work, but it sounded good to me!

 

[tretneo]

Really enjoying this amp, what a classy piece of equipment!

 

[zazex]

  So the Question should be, why is the B1 sometimes clipping at 20mA and not on 40mA. Anyone got an idea?

 
I'm hazarding a guess here based on high quality low power (speaker) amps
I've dealt with.  Sometimes they could play very loud without clipping due
to greater dynamic headroom (as it was explained to me).
 
So I'm thinking that similarly, the B1 may have greater headroom at 20
than at 40, and thus clips more readily at 40 than at 20.

 

[derGabe]

   
I'm hazarding a guess here based on high quality low power (speaker) amps
I've dealt with.  Sometimes they could play very loud without clipping due
to greater dynamic headroom (as it was explained to me).
 
So I'm thinking that similarly, the B1 may have greater headroom at 20
than at 40, and thus clips more readily at 40 than at 20.

You mean a greater headroom at 40mA, right? Because it's clipping at 20mA.

 

[miceblue]

I'm hazarding a guess here based on high quality low power (speaker) amps
I've dealt with.  Sometimes they could play very loud without clipping due
to greater dynamic headroom (as it was explained to me).

So I'm thinking that similarly, the B1 may have greater headroom at 20
than at 40, and thus clips more readily at 40 than at 20.

You have your numbers backwards, but that's a possibility. I don't hear any clipping with the HE1000 on any current mode and it requires much greater current than the T1 does.

Based on what Class A amplifiers do and the numbers from the official specifications, the Class A switch is just a current gain. Gain for amplifiers is usually mostly voltage gain and I've confirmed with Aune that the voltage output at the two gains is different. I don't think it's by coincidence that the 40 mA mode is also the maximum current output for the B1 at 16 and 32 ohm loads. Since Class A amps are biased 100% of the time, having two current gain modes is probably a smart design given the fact that the B1 is battery powered and battery consumption is determined by current draw.

 

[ESL-1]

You mean a greater headroom at 40mA, right? Because it's clipping at 20mA.

I agree with derGabe, at the higher current setting (40) you would have more headroom and be less likely to clip if playing loud with a less sensitive headphone. I found no problem at all driving my 600 ohm Beyer DT880 to a satisfyingly loud level with no issues. It will probably do even better with my T1 when I get to try it since the one Tesla rating makes it more efficient than the 880 even though they are both 600 ohms.

I have no issues with any sort of channel Imbalance, in fact no problems of any sort have shown themselves. I hope and expect to remain that way as I get to log more hours on the amp.

 

[zazex]

  You mean a greater headroom at 40mA, right? Because it's clipping at 20mA.

Yes, I erroneously reversed the numbers, sorry.

 

[miceblue]

Idk, I didn't get that effect at all. Musical, yes, but no channel imbalance on mine. I'm fairly sure of this because I've sent back units in the past that had channel imbalance and it turned out to be that they did, so I'm pretty cofident mine didn't have any. Another thing to note is Dergabe's clipping, it concerns me a bit that people with the B1 are having different problems. Same problems I can wrap my head around, but different ones... I'm confused 

I figured it out. I had the day off today so I basically did A/B tests all day between the B1 and the Objective 2, E12, OPPO HA-2, and JDS Labs C5/C5D; and with the OPPO PM-3, AKG K240 Monitor, AKG K701, and HIFIMAN HE1000 headphones.

I only really get that strange effect in the 40 mA mode. I actually prefer the 20 mA mode after listening really carefully between the A/B tests. It helped me at least for doing the volume-matched A/B tests because without a switch, you would have to turn the B1 off/on to listen for differences between the two current modes, and you could very easily forget how the music sounds in the few seconds you spend doing that. With the switch, you can do A/B switching for as long as you want to get a good idea of how the music sounds between the two amps, then go to the other amp while you switch the current mode on the B1, then switch back to the B1 to hear the differences if any.

From my listening sessions:
20 mA mode:

• Slight warmth in the bass/lower-midrange area
• Wide soundstage, little depth
• Decent center imaging

40 mA mode:

• More warmth, and a slight sub-bass boost
• Wider soundstage, more depth
• Lack of center imaging

These were just A/B tests mind you, not blind ones. If the B1 was in 40 mA mode on the other hand, I could probably easily pass an ABX test because the effect is so obvious for me. Just like how the AKG K701 is infamously known for having a wide soundstage with a lack of center imaging, the 40 mA mode sounds weird like that to me. It's really not a good pairing with the K701 nor HE1000 and I find the 20 mA mode to sound better in that regard.


All with low gain. I personally see no reason for the high-gain. Even with the AKG K240 Monitor at 688 ohms and 0.447 Vrms required to reach 90 dB SPL I never had to use the high gain mode.

 

[avitron142]

I figured it out. I had the day off today so I basically did A/B tests all day between the B1 and the Objective 2, E12, OPPO HA-2, and JDS Labs C5/C5D; and with the OPPO PM-3, AKG K240 Monitor, AKG K701, and HIFIMAN HE1000 headphones.

I only really get that strange effect in the 40 mA mode. I actually prefer the 20 mA mode after listening really carefully between the A/B tests. It helped me at least for doing the volume-matched A/B tests because without a switch, you would have to turn the B1 off/on to listen for differences between the two current modes, and you could very easily forget how the music sounds in the few seconds you spend doing that. With the switch, you can do A/B switching for as long as you want to get a good idea of how the music sounds between the two amps, then go to the other amp while you switch the current mode on the B1, then switch back to the B1 to hear the differences if any.

From my listening sessions:
20 mA mode:

1. Slight warmth in the bass/lower-midrange area
2. Wide soundstage, little depth
3. Decent center imaging

40 mA mode:

1. More warmth, and a slight sub-bass boost
2. Wider soundstage, more depth
3. Lack of center imaging

These were just A/B tests mind you, not blind ones. If the B1 was in 40 mA mode on the other hand, I could probably easily pass an ABX test because the effect is so obvious for me. Just like how the AKG K701 is infamously known for having a wide soundstage with a lack of center imaging, the 40 mA mode sounds weird like that to me. It's really not a good pairing with the K701 nor HE1000 and I find the 20 mA mode to sound better in that regard.

! I hope that you turned the B1 off before you switched the current; Aune specifically said that it could damage the amp if you don't. Regardless, great impressions! I'll see if my B1 has it from the reviews that the participants of the tour will publish. It could be your sample is faulty... bummer.

 

[miceblue]

Yup, of course I turned off the B1 when switching the current mode. That's why I mentioned why the A/B switch was important to me. I would just switch to the other amp while keeping the music playing in my ears, turn off the B1, switch the current mode after the relay click, switch the B1 back on, and turn the A/B switch back to the B1 to hear any differences between it and the other amp.

 

[avitron142]

Yup, of course I turned off the B1 when switching the current mode. That's why I mentioned why the A/B switch was important to me. I would just switch to the other amp while keeping the music playing in my ears, turn off the B1, switch the current mode after the relay click, switch the B1 back on, and turn the A/B switch back to the B1 to hear any differences between it and the other amp.

Ah, sorry, didn't realize. I would test my B1 for the same things you've found but it's on tour right now 

 

[Buhagim]

B1 Review, E12 comparison and

General ramblings  Part 1.

Read your comments and had a really good giggle. Loved the fleas and the pillow fight comment. Reminds me of similar claims from wine buffs. "this Xyz wine came from the south slope of the vineyard the year fungus improved the taste"

Just thought I'd say i loved the attention to detail and the quest for objectivity. Keep up the good work and as they say over here in brit land- "non carborundum illigitimae" (don't let the b**%%s%%ds grind you down"