WooAudio WA6 vs. Yulong A18
- Thread starter PaulyT
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Spent some time this morning doing an initial audition of the A18 that arrived yesterday. I say initial, because I'll be doing at least a few more rounds of this in the near future. First, I'm using an RCA/unbalanced connection between the DAC and the amp. I've heard it said on Head-Fi that there's some (slight) sonic differences between that and the XLR/balanced inputs of the A18; my DAC does have XLR out, as does the DA8 that's coming, I just don't (yet) have the cables for it. I'll repeat this later with XLR, just to see if there's any truth to that.
Also, I'm using my beloved modded Denons still. I will repeat this yet again when I get the T1 next week. And then there will be different DACs... The problem with so much gear is that there are a gazillion different combinations of components, and I don't have the time or patience to evaluate every single combinatorial possibility.
I'm not going to go through a track-by-track commentary on this comparison. Mainly because I'd end up saying a lot of the same things over and over. Rather, I'll just provide general comparisons, with the occasional reference to particular tracks if need be. I'm using the track list I posted earlier:
:text-link:
Complete signal path for this round is: FLAC -> squeezebox -> optical/toslink -> M-Audio SuperDAC 2496 -> RCA/unbalanced -> WA6 or A18 -> Denon D5000
FYI the WA6 is $699 new, plus >$200 more for the tubes I've got. The A18 was $899 new, though it's been discontinued. I got both of these used, so I didn't pay that much, but I mention this mainly to indicate that the price range we're talking about is similar for the two.
So... maybe now you'd like to hear something about the sound...
:happy-smileygiantred:
Well, let me start by saying that the Yulong A18 is the best solid state amp I have personally owned and carefully evaluated. Y'all know I'm biased towards tubes, as I generally feel that solid state often has a dry, somewhat harsh and fatiguing sound compared to tubes. I got this A18 specifically because of claims (again on Head-Fi) that it has a "tube-like" sound. And... I agree. This is the first SS amp I've found that I can listen to for hours without experiencing fatigue. I could definitely use this amp for everyday listening.
So the big question... is it better than the WA6? Well, yes and no. There are some things I like a lot about it, and some things I like more on the WA6 still.
Strengths of the A18 in comparison: firstly, the bass is a little better controlled. Not that it's necessarily louder or lower, but tighter - maybe better damping, not sure what the right word is. And it's not an enormous difference, but I think it's there. Secondly, the sound across the entire frequency spectrum is more consistent when the music is very loud and full and covering a broad range of highs, mids, and lows. That is, sometimes with the WA6, there's a very slight "thickening" or echo or something in the midrange when, say, a full orchestra is playing all-out (like in the Stravinsky tracks). With the A18, I don't hear that. The response is smooth and natural across the whole spectrum even in these louder moments. And I don't mean just turning up the volume, although that maybe does a little of the same thing. I don't tend to listen at ear-splitting volumes. But if you've ever heard a live orchestra up close, it can be pretty damn loud, and I like to listen at "realistic" levels.
Strengths of the WA6: precision of imaging and soundstage. By this I mean the apparent breadth - and even depth - of the stereo "landscape" of sounds, and how precisely localized a given sound appears to be. The A18 is pretty good in this regard - noticeably better than the Meier I reviewed recently. But the WA6 still takes the cake here. It has a way of presenting a depth (front and back) when there's a lot going on in a recording, many instruments layered into the mix, like the Rodrigo y Gabriela track. Or the Bob James, where with the WA6 I get the sense that the horns are behind the piano. While the left/right imaging is pretty good with the A18, I don't get that depth, at least not as much.
So overall, if I had to pick one or the other, I'm pretty sure I'd still go with the WA6, mainly because a good soundstage presentation is my #1 personal goal. I'm very curious to see if the XLR connection to the A18 makes any difference in this (though I'm skeptical), or, especially, whether going to the Beyer T1 headphones will change or reinforce this opinion.
FYI there's a tiny bit of hiss in the A18 when I turn the volume all the way up but nothing playing. It's very slight, and you need to be in a quiet room to hear it. Certainly not an issue when listening at normal levels; kind of like hiss from a speaker when you put your ear right up to it. In comparison, the WA6 has a tiny bit of a hum, but totally independent of the volume setting. I guess just a residual thing from the tubes. But again it's tiny, you can only hear it in a quiet room by pulling the headphone plug in and out of the jack. You'd never hear it under any music.
Also, I'm using my beloved modded Denons still. I will repeat this yet again when I get the T1 next week. And then there will be different DACs... The problem with so much gear is that there are a gazillion different combinations of components, and I don't have the time or patience to evaluate every single combinatorial possibility.
I'm not going to go through a track-by-track commentary on this comparison. Mainly because I'd end up saying a lot of the same things over and over. Rather, I'll just provide general comparisons, with the occasional reference to particular tracks if need be. I'm using the track list I posted earlier:
:text-link:
Complete signal path for this round is: FLAC -> squeezebox -> optical/toslink -> M-Audio SuperDAC 2496 -> RCA/unbalanced -> WA6 or A18 -> Denon D5000
FYI the WA6 is $699 new, plus >$200 more for the tubes I've got. The A18 was $899 new, though it's been discontinued. I got both of these used, so I didn't pay that much, but I mention this mainly to indicate that the price range we're talking about is similar for the two.
So... maybe now you'd like to hear something about the sound...
:happy-smileygiantred:
Well, let me start by saying that the Yulong A18 is the best solid state amp I have personally owned and carefully evaluated. Y'all know I'm biased towards tubes, as I generally feel that solid state often has a dry, somewhat harsh and fatiguing sound compared to tubes. I got this A18 specifically because of claims (again on Head-Fi) that it has a "tube-like" sound. And... I agree. This is the first SS amp I've found that I can listen to for hours without experiencing fatigue. I could definitely use this amp for everyday listening.
So the big question... is it better than the WA6? Well, yes and no. There are some things I like a lot about it, and some things I like more on the WA6 still.
Strengths of the A18 in comparison: firstly, the bass is a little better controlled. Not that it's necessarily louder or lower, but tighter - maybe better damping, not sure what the right word is. And it's not an enormous difference, but I think it's there. Secondly, the sound across the entire frequency spectrum is more consistent when the music is very loud and full and covering a broad range of highs, mids, and lows. That is, sometimes with the WA6, there's a very slight "thickening" or echo or something in the midrange when, say, a full orchestra is playing all-out (like in the Stravinsky tracks). With the A18, I don't hear that. The response is smooth and natural across the whole spectrum even in these louder moments. And I don't mean just turning up the volume, although that maybe does a little of the same thing. I don't tend to listen at ear-splitting volumes. But if you've ever heard a live orchestra up close, it can be pretty damn loud, and I like to listen at "realistic" levels.
Strengths of the WA6: precision of imaging and soundstage. By this I mean the apparent breadth - and even depth - of the stereo "landscape" of sounds, and how precisely localized a given sound appears to be. The A18 is pretty good in this regard - noticeably better than the Meier I reviewed recently. But the WA6 still takes the cake here. It has a way of presenting a depth (front and back) when there's a lot going on in a recording, many instruments layered into the mix, like the Rodrigo y Gabriela track. Or the Bob James, where with the WA6 I get the sense that the horns are behind the piano. While the left/right imaging is pretty good with the A18, I don't get that depth, at least not as much.
So overall, if I had to pick one or the other, I'm pretty sure I'd still go with the WA6, mainly because a good soundstage presentation is my #1 personal goal. I'm very curious to see if the XLR connection to the A18 makes any difference in this (though I'm skeptical), or, especially, whether going to the Beyer T1 headphones will change or reinforce this opinion.
FYI there's a tiny bit of hiss in the A18 when I turn the volume all the way up but nothing playing. It's very slight, and you need to be in a quiet room to hear it. Certainly not an issue when listening at normal levels; kind of like hiss from a speaker when you put your ear right up to it. In comparison, the WA6 has a tiny bit of a hum, but totally independent of the volume setting. I guess just a residual thing from the tubes. But again it's tiny, you can only hear it in a quiet room by pulling the headphone plug in and out of the jack. You'd never hear it under any music.
Let me add, I did have one rare "OH WOW!" moment when listening to the A18 this morning. That was with the Rachmaninoff Vespers choral track. I can't explain why exactly, but when I heard that start to play, I immediately had an audiogasm. 
Well ok... but still, there was that jaw-dropping initial reaction that you (or at least I) only get rarely but maybe some of you have experienced, with certain recordings on certain gear. It's one of those events that makes all of this so much fun. Anyway, the choir just sounded BIG; and even more, the sense of it being a group of individual voices, like you're standing right up near the stage with the choir spread out before you, where the sound is huge but if you concentrate you can still sometimes hear individual singers, was stronger with the A18 than I've ever heard. And this is a recording I've owned for 20 years and have listened to countless times. I think maybe it's related to the "strengths of the A18" paragraph above, where when the choir goes into a big crescendo (that means "gets louder" for you musical novices ), with the WA6 it gets a little ... congested ... in the midrange, like there's a little resonance somewhere that's displeasing. The A18 didn't do that, it was smooth all the way across even in the fuller parts.
Why this would be so apparent to me in this one track compared to all the others, even the others that are pretty loud/full, I have no idea. But it was cool.
Well ok... but still, there was that jaw-dropping initial reaction that you (or at least I) only get rarely but maybe some of you have experienced, with certain recordings on certain gear. It's one of those events that makes all of this so much fun. Anyway, the choir just sounded BIG; and even more, the sense of it being a group of individual voices, like you're standing right up near the stage with the choir spread out before you, where the sound is huge but if you concentrate you can still sometimes hear individual singers, was stronger with the A18 than I've ever heard. And this is a recording I've owned for 20 years and have listened to countless times. I think maybe it's related to the "strengths of the A18" paragraph above, where when the choir goes into a big crescendo (that means "gets louder" for you musical novices ), with the WA6 it gets a little ... congested ... in the midrange, like there's a little resonance somewhere that's displeasing. The A18 didn't do that, it was smooth all the way across even in the fuller parts. Why this would be so apparent to me in this one track compared to all the others, even the others that are pretty loud/full, I have no idea. But it was cool.
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Part One or Part Two?PaulyT said:
I like to wear dark clothing with Part One and less sombre tones with Part Two. It changes the soundstage appreciably.
Switched to XLR interconnects between DAC and A18 this morning, and repeated the evaluation. Yes, there was a difference. It's a little bit brighter sound, a bit more detail in the high end, which I like. Slightly better soundstage breadth and depth. Not an enormous difference, but enough that I want to go back now to the WA6 and compare again, that'll be next, when I get a chance.
One obvious difference though was in the volume level. Yeah, pro audio (XLR) line level voltage is a lot higher than consumer audio (RCA). That may account for most of it, though you'd think the design of the two inputs would take this into account... Anyway, with the XLR interconnects, the volume knob on the A18 needed to be a lot lower, such that I was probably using only the bottom ~1/4 or less of the full dial. It also makes the volume adjustment a lot more sensitive, which is mildly irritating. I don't know, though, whether this is just an issue of the A18, or the DAC, or both, because of course I'm changing two variables here: different input on the A18, but also different output on the DAC.
There's definitely more noticeable noise with nothing playing and the volume turned all the way up, when using the XLR. But this is attributable to the DAC, because if I turned off the DAC or disconnected it, most of that noise disappears. There's still a tiny bit, which I noted above when using RCA inputs. So clearly the XLR out on my DAC isn't particularly good; I need a better DAC. Good thing I have one coming.
One obvious difference though was in the volume level. Yeah, pro audio (XLR) line level voltage is a lot higher than consumer audio (RCA). That may account for most of it, though you'd think the design of the two inputs would take this into account... Anyway, with the XLR interconnects, the volume knob on the A18 needed to be a lot lower, such that I was probably using only the bottom ~1/4 or less of the full dial. It also makes the volume adjustment a lot more sensitive, which is mildly irritating. I don't know, though, whether this is just an issue of the A18, or the DAC, or both, because of course I'm changing two variables here: different input on the A18, but also different output on the DAC.
There's definitely more noticeable noise with nothing playing and the volume turned all the way up, when using the XLR. But this is attributable to the DAC, because if I turned off the DAC or disconnected it, most of that noise disappears. There's still a tiny bit, which I noted above when using RCA inputs. So clearly the XLR out on my DAC isn't particularly good; I need a better DAC. Good thing I have one coming.
XLR is a mess for consumer devices. Some manufactures add XLR but keep the gain at -10dB while others accommodate Pro levels with XLR interfaces designed for +4dB. It sounds like your source is putting out a pro-audio level of +4dB ref while the amp is expected -10dB ref.
While not likely, it is possible you are getting a bit of clipping from this mismatch which would sound more shimmery and bright, in many cases, due to the harmonics it generates.
While not likely, it is possible you are getting a bit of clipping from this mismatch which would sound more shimmery and bright, in many cases, due to the harmonics it generates.
Went back to the WA6 this morning. Early morning is a good time for me for this stuff, as the rest of the family isn't up yet so the house is quiet, and I'm rested and relaxed.
Anyway, I'm solidifying my opinion that with my current setup - M-Audio SuperDAC 2496 + Denon D5000 - I like the WA6 better for a lot of things. Generally, imaging is more precise, soundstage wider, resolution of individual instruments better. (I believe all these are connected.) Acoustic instruments and vocals are smooth and natural - meaning not overly dark or bright, a good balance. The layering of multiple sounds in Hanuman (Rodrigo y Gabriela with the Cuban band) is really terrific.
("Layering" to me means how well you can distinguish details and placement of individual instruments, both left/right and even (to some degree) perceive front/back, when the mix is thick.)
Where I like the A18 better is when there's a lot of bass in the mix - like in the Bromberg acoustic bass track, or the pipe organ, or one place in the Beth Hart track where there's a low tom drum that comes in (not the kick drum) when there's a lot of other stuff going on. The WA6, as I mentioned earlier, has a tendency to get a little congested when the bass is strong. Meaning, the other sounds in the mid+treble range tend to get narrowed in the soundstage and less well resolved. My theory - and of course this is only speculation - is that with my low-impedance headphones I'm pushing the current output limits of the tubes when bass is strong, leading to some distortion. This doesn't happen with the A18; the resolution of mid+treble sounds on top of a full bass is unaffected.
I'm very curious to see if this same phenomenon happens with the high-impedance T1s.
Anyway, I'm solidifying my opinion that with my current setup - M-Audio SuperDAC 2496 + Denon D5000 - I like the WA6 better for a lot of things. Generally, imaging is more precise, soundstage wider, resolution of individual instruments better. (I believe all these are connected.) Acoustic instruments and vocals are smooth and natural - meaning not overly dark or bright, a good balance. The layering of multiple sounds in Hanuman (Rodrigo y Gabriela with the Cuban band) is really terrific.
("Layering" to me means how well you can distinguish details and placement of individual instruments, both left/right and even (to some degree) perceive front/back, when the mix is thick.)
Where I like the A18 better is when there's a lot of bass in the mix - like in the Bromberg acoustic bass track, or the pipe organ, or one place in the Beth Hart track where there's a low tom drum that comes in (not the kick drum) when there's a lot of other stuff going on. The WA6, as I mentioned earlier, has a tendency to get a little congested when the bass is strong. Meaning, the other sounds in the mid+treble range tend to get narrowed in the soundstage and less well resolved. My theory - and of course this is only speculation - is that with my low-impedance headphones I'm pushing the current output limits of the tubes when bass is strong, leading to some distortion. This doesn't happen with the A18; the resolution of mid+treble sounds on top of a full bass is unaffected.
I'm very curious to see if this same phenomenon happens with the high-impedance T1s.
Doing some googling, it seems the A18 has an output impedance of ~2.2ohm, whereas the WA6 has an output impedance of ~14ohm. So the damping factor (ratio of load impedance to source impedance) is substantially higher with the A18. That could well explain at least some of what I'm hearing in these comparisons.
Interestingly, Ken Rockwell - yes THAT Ken Rockwell - has detailed measurements of the WA6SE. Didn't know he was an audio geek.
:text-link:
:text-link:
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I wonder how true that really is.PaulyT said:
In speakers it's important because of the moving (mostly woofer) mass involved, but in a headphone?
Also, how much of the stated impedances is resistive? How do headphone amps (and headphones) compare to "normal" power amps and loudspeakers in that regard. I suspect there might be an apples and bananas situation - but don't know for sure.
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Yes but with relatively low moving mass. In loudspeakers damping factor is important primarily with respect to woofers - whose moving mass is many times larger (even orders of magnitude) than the moving mass of the drivers in most any headphones. I've never heard of damping factor mentioned in relation to headphones. But then again I readily admit to not hanging around the likes of head-hi etc. where perhaps such issues take on great import.PaulyT said:
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Don't you mean backwaters?Botch said:JeffMackwood said:
Damn backwoods Canucks.... :teasing-tease:
malsackj
Well-Known Member
I feel the damping factor is important in both areas. Clipping some notes from Crown power amps.
Though technically more complex than this, Damping factor is usually thought of as an indicator of how tight an amplifier will sound when powering bass speakers. A speaker's driving motor is a coil of wire (called a voice coil) mounted within a magnetic field. As this coil of wire moves within the field a voltage will be induced in the voice coil. If resonant motions of the speaker are not sufficiently short circuited by the amplifier, the speaker output can have an over accentuated or "boomy" bass sound.
From a technical measurement stand point, Damping factor is the ratio of the rated speaker impedance to the amplifier's output impedance. Low output impedance is the consequence of the amplifier having substantial negative voltage feedback taken from its output terminals. Properly designed negative feed back not only corrects for output voltage errors induced by the speaker but also produces other benefits:
and from the pro sound
http://www.prosoundweb.com/article//wha ... factor_df/
When I played with the Yamaha Sub Kick to do some recording, I compared the wave form on the DAW with the signal from a microphone. The speaker in the Sub Kick had a signal with two full cycles of audio, the microphone had one cycle. This is telling me that the physics of the speaker being used as a microphone was ringing and creating one extra cycle.
The size of the diaphragm, weight, spring and such (basicly the physics) will determine how much amplifier is needed to control the springing of the diaphragm. Most people will agree that the smaller headphone or IEM type diaphragms will have such a small level that no one will hear the problem and it would take a sensitive device to even detect the problem.
Though technically more complex than this, Damping factor is usually thought of as an indicator of how tight an amplifier will sound when powering bass speakers. A speaker's driving motor is a coil of wire (called a voice coil) mounted within a magnetic field. As this coil of wire moves within the field a voltage will be induced in the voice coil. If resonant motions of the speaker are not sufficiently short circuited by the amplifier, the speaker output can have an over accentuated or "boomy" bass sound.
From a technical measurement stand point, Damping factor is the ratio of the rated speaker impedance to the amplifier's output impedance. Low output impedance is the consequence of the amplifier having substantial negative voltage feedback taken from its output terminals. Properly designed negative feed back not only corrects for output voltage errors induced by the speaker but also produces other benefits:
and from the pro sound
http://www.prosoundweb.com/article//wha ... factor_df/
When I played with the Yamaha Sub Kick to do some recording, I compared the wave form on the DAW with the signal from a microphone. The speaker in the Sub Kick had a signal with two full cycles of audio, the microphone had one cycle. This is telling me that the physics of the speaker being used as a microphone was ringing and creating one extra cycle.
The size of the diaphragm, weight, spring and such (basicly the physics) will determine how much amplifier is needed to control the springing of the diaphragm. Most people will agree that the smaller headphone or IEM type diaphragms will have such a small level that no one will hear the problem and it would take a sensitive device to even detect the problem.
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Which pretty much supports what I said in my complete post before Botch's.
ps. The first of your cut and paste quotes is not entirely accurate. In calculating damping factor I believe that you should only use the resistive component of the impedances - which I think I also mentioned in a previous post.
ps. The first of your cut and paste quotes is not entirely accurate. In calculating damping factor I believe that you should only use the resistive component of the impedances - which I think I also mentioned in a previous post.
Sure, with a smaller driver, the amount of current generated by the driver's movement through the voice coil is less than with a full size speaker driver. But the amount of current generated by a headphone amp is also proportionally smaller. There's nothing in the physics that says this is only valid for a "large" system.