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Review and Measurements of Aune X7s and Arcam rHead Headphone Amps

Soniclife

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#61
Mine arrived yesterday, with my most sensitive IEMs I can hear hum when not playing music, it goes away when I touch any metal part of the case. Oddly it does not stop when you turn the volume knob to the standby position, and even odder it does not stop when you turn the power off with the physical switch on the back. Removing the power cord stops it.
I returned the Arcam, as well as the hum there was a scratchy noise on one channel. Both of these problems were only audible with my most sensitive IEMs (JH Audio 13 Pro custom) so I don't know if what I got was slightly faulty, or it's a very sensitive IEM thing, but they are silent when plugged into my laptop or phone at all times.
 
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#62
So I just got my D30 and X7S and tried them with my m50x and hd6xx single ended. At medium gain setting my m50x get pretty loud around 12 o'clock . with 6xx I have to go to 2 o'clock and I don't find the sound coming out from it satisfying. What can be wrong? Is it just my mind ? or what?
And also there is a notable hiss with quiet tracks with both headphones but it goes right away when I pause the track is it in the recording or the amp doing that?
 
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Sythrix

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#63
So I just got my D30 and X7S and tried them with my m50x and hd6xx single ended. At medium gain setting my m50x get pretty loud around 12 o'clock . with 6xx I have to go to 2 o'clock and I don't find the sound coming out from it satisfying. What can be wrong? Is it just my mind ? or what?
And also there is a notable hiss with quiet tracks with both headphones but it goes right away when I pause the track is it in the recording or the amp doing that?
How loud do you listen? Distortion does tend to go up with high power usage, as you can see from Amir's graphs... but that is at what should be really loud levels, given the power output. Are you listening at more that 110 dB? That's the only way I could see you hitting the kind of power levels that would cause the increased distortion with the HD 6XX.

Otherwise you may simply not like the amps signature or frequency response, with some part of your brain picking out things it doesn't like. If you can listen with your headphones on another adept source and do it soon enough to have a clear impression, you could find out if it's the same. Another, more grim, observation is that you may simply not like your headphones actual sound now that they are being powered properly. Depends on your prior experience with them.

Also, I might be wrong and someone correct me if I am, but as I understand it a Class A headphone amp (sort of an "always on" design) wouldn't be causing the hiss you are describing. The fact that it pauses along with the track is probably from the recording, not the amp. There are certain devices and amps (generally low quality, built-in type solutions) that hide hiss by only enabling the amp portion when music is playing, making it difficult to isolate.
 

amirm

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#64
So I just got my D30 and X7S and tried them with my m50x and hd6xx single ended. At medium gain setting my m50x get pretty loud around 12 o'clock . with 6xx I have to go to 2 o'clock and I don't find the sound coming out from it satisfying. What can be wrong? Is it just my mind ? or what?
And also there is a notable hiss with quiet tracks with both headphones but it goes right away when I pause the track is it in the recording or the amp doing that?
The gain switches are hard to flip. Push them band and forward again to make sure they are truly switched.
 
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#65
The gain switches are hard to flip. Push them band and forward again to make sure they are truly switched.
I am 100% sure they are flipped but did it again. My thought is that there is not enough power for the 6xx I will finish my balanced cable for them tommorrow will test again balanced. And what about the hiss(it's very suddle but it's there)? is it from recordings? I am using highest quality flac files that I can find.Maybe I need to burn in the amp for maybe 10 hours? To be clear with my m50x's I'd say sound is perfect (hiss is still there). With 6xx I wouldn't say that I am satisfied maybe because I was expecting too much. My last setup was fiio a3 straight fed from my crappy motherboard, maybe I was expecting too much. I just want to hear an educated opinion before my OCD kicks in.
 
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#66
I don't have HD6XX (rebranded HD650?), but HD600, the chain is Topping D30 -> Monoprice Desktop amp/dac (with 15v 3A power supply)-> HD600, low gain setting. Declared power output is 150mw at 300 Ohm, and with most recordings the pain threshold is well below 12 O'clock. I can't hear any background noise or distortion at any volume level.

Check your cabling and the computer volume levels, otherwise you may have a faulty unit. If you can, try other source instead of the D30, maybe the problem is not the amp.
 

PuX

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#67
can anyone explain what is the point of using XLR on rHead? let's say you have a balanced DAC and connect it via XLR, but the output is still an unbalanced headphone 1/4 or 1/8 jack. so what advantages are there? all I can think of is higher voltage vs RCA, but I don't really see why it would be necessary.
 

JJB70

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#68
can anyone explain what is the point of using XLR on rHead? let's say you have a balanced DAC and connect it via XLR, but the output is still an unbalanced headphone 1/4 or 1/8 jack. so what advantages are there? all I can think of is higher voltage vs RCA, but I don't really see why it would be necessary.
The SPL Phonitor Mini and a fair few of the Lake People amps do the same, XLR balanced in, single ended headphone out. To be honest I'm not convinced about the necessity of balanced interconnects. To me it just seems to be one of those things that is very happening, whether or not it really makes a difference is another question. I run the sound desk at a local church and for very long cable runs balanced lines do make sense and genuinely useful but I can't help thinking that for inter connects and headphone outputs it's answering a question that probably doesn't need to be asked and regular RCA connections and single ended headphones lines are perfectly adequate.
 

amirm

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#69
can anyone explain what is the point of using XLR on rHead? let's say you have a balanced DAC and connect it via XLR, but the output is still an unbalanced headphone 1/4 or 1/8 jack. so what advantages are there? all I can think of is higher voltage vs RCA, but I don't really see why it would be necessary.
Your headphones are always "balanced" since the signal is never referenced to ground.

Balanced outputs in headphone amps is a misnomer. It is there to provide higher output power or more channel separation due to not sharing the ground (both of which needs to be tested to be sure).

So back to your question, balanced input on the amp can deal with any ground loops that may be created using unbalanced connection.
 

PuX

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#70
Grace Design commented on their Standard DAC Balanced on Massdrop discussions with more or less the same point - balanced connection is there for avoiding ground loops, higher level etc.

what confuses me is that headphones typically use 3 wires and share ground like you said. I just don't fully understand why ground would be shared, it's not like it makes a cable much thicker. some of the cables secretly :D have 4 wires inside but the jack of course still has 3 contact points.

I guess it shouldn't matter too much anyway. maybe I'll try to compare RCA vs XLR sometime, but for now I only have a DAC with XLR output and no suitable amp.
 

Timbo2

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#71
I am 100% sure they are flipped but did it again. My thought is that there is not enough power for the 6xx I will finish my balanced cable for them tommorrow will test again balanced. And what about the hiss(it's very suddle but it's there)? is it from recordings? I am using highest quality flac files that I can find.Maybe I need to burn in the amp for maybe 10 hours? To be clear with my m50x's I'd say sound is perfect (hiss is still there). With 6xx I wouldn't say that I am satisfied maybe because I was expecting too much. My last setup was fiio a3 straight fed from my crappy motherboard, maybe I was expecting too much. I just want to hear an educated opinion before my OCD kicks in.
Do you have a multimeter? Pull the cord out off of the headphones and probe the voltage. Using a 1khz sine wave my non-RMS meter had me determine that 2V is generally plenty.

My O2 measured over 7V at on high gain (3.5x) and is painfully loud with the same HD6xxs on any “hot” music material.
 
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#72
can anyone explain what is the point of using XLR on rHead? let's say you have a balanced DAC and connect it via XLR, but the output is still an unbalanced headphone 1/4 or 1/8 jack. so what advantages are there? all I can think of is higher voltage vs RCA, but I don't really see why it would be necessary.
I guess you can run balanced cable from a DAC in another room to rHead?
 

PuX

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#73
I guess you can run balanced cable from a DAC in another room to rHead?
:D for what purpose? idk, maybe it would make sense in a studio or if you have one good dac and it's in your main system. otherwise it's better to use the shortest cable available.
 
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#74
:D for what purpose? idk, maybe it would make sense in a studio or if you have one good dac and it's in your main system. otherwise it's better to use the shortest cable available.
Well, people don't really always do the best things, do they? Also, there can be any number of reasons for someone to use a balanced connection. Depends a lot on their existing set-up and their use case. Only problem is when they start to claim it sounds better.
 

JJB70

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#75
Balanced cables, XLR connections and even balanced amplifier topologies aren't new. And if you look at professional audio equipment balanced cables and even good quality XLR connectors aren't expensive. A lot of professional audio equipment which uses balanced inputs and outputs is electronically balanced (but I suspect that may be true for a lot of balanced audiophile equipment) but it doesn't seem to add much to the price. When I look at audiophile products the presence of XLR connectors seems to be associated with a big price uplift in many cases. For many years hifi enthusiasts never knew they "needed" balanced interconnects and balanced amplifiers etc as regular RCA connectors worked perfectly well and it's perfectly possible to design and build amplifiers without balanced topology that work just as well and which are simpler. Then there is that whole debate about electronically balanced connections, most audiophiles see this as cheating and the work of Satan but pro-audio manufacturers such as SPL (who generally know what they're doing) happily use this technique and given that the main advantage of electrically balanced equipment is to reduce noise in cables the idea of just having electronically balanced connectors makes sense. However, it's obviously a very good marketing hook and magazines, reviewers etc are fully onboard. And that is without getting into the separate arguments about balanced headphones.
 

RayDunzl

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#76
what confuses me is that headphones typically use 3 wires
The stock cable for my HD650 has 4 wires, the cold side becoming common at the TRS connector.
 

PuX

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#77
The stock cable for my HD650 has 4 wires, the cold side becoming common at the TRS connector.
I know, that's because there is a balanced cabled for the same headphone for sale, only change being the connector.

it's less clear why HD595 has 4 wires inside.
 

RayDunzl

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#78
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#80
Do you have a multimeter? Pull the cord out off of the headphones and probe the voltage. Using a 1khz sine wave my non-RMS meter had me determine that 2V is generally plenty.

My O2 measured over 7V at on high gain (3.5x) and is painfully loud with the same HD6xxs on any “hot” music material.
I'm waiting @amirm to uncover the D50 equivalent for headamp that is able to power up a HD6xx haha
 
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