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Topping A50s Headphone Amplifier Review

milosz

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For those who wonder what the power-hungry 'phones are:

HiFiMan HE-6 planar needs around 2.0 watts​
AKG K1000 I heard they need about 5 watts​
Audeze planar need close to 1 watt (maybe this has changed, I dunno. My LCD2's needed almost 1 watt.)​
 

JohnYang1997

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To avoid confusion about power levels.

using the D50s DAC (2.0V 0dBFS) and the amp on high gain at max. volume setting (+6dB = 2x) in SE mode (6.3mm TRS) = 4V out.

32 Ohm = 0.5W
50 Ohm = 0.3W
120 Ohm = 130mW
300 Ohm = 50mW
600 Ohm = 25mW

using the D50s DAC (2.0V 0dBFS) and the amp on high gain (+6dB) at max. volume setting in Balance mode (Pentaconn) = 8V out

32 Ohm = 2W
50 Ohm = 1.28W
120 Ohm = 0.5W
300 Ohm = 200mW
600 Ohm = 100mW

(all rounded off numbers)

Max power when using a DAC with higher output voltage (> 3.8V) S.E. out = 7.4V

32 Ohm = 1.7W
50 Ohm = 1.1W
120 Ohm = 450mW
300 Ohm = 180mW
600 Ohm = 90mW

Max power when using a DAC with higher output voltage (> 3.8V) Balanced out = 14.8V and assuming no current limiting

32 Ohm = 6.8W (may be less due to current limiting ?)
50 Ohm = 4.4W (may be less due to current limiting ?)
120 Ohm = 1.8W
300 Ohm = 700mW
600 Ohm = 360mW
3437736.jpg
 

raif71

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To avoid confusion about power levels.

using the D50s DAC (2.0V 0dBFS) and the amp on high gain at max. volume setting (+6dB = 2x) in SE mode (6.3mm TRS) = 4V out.

32 Ohm = 0.5W
50 Ohm = 0.3W
120 Ohm = 130mW
300 Ohm = 50mW
600 Ohm = 25mW

using the D50s DAC (2.0V 0dBFS) and the amp on high gain (+6dB) at max. volume setting in Balance mode (Pentaconn) = 8V out

32 Ohm = 2W
50 Ohm = 1.28W
120 Ohm = 0.5W
300 Ohm = 200mW
600 Ohm = 100mW

(all rounded off numbers)

Max power when using a DAC with higher output voltage (> 3.8V) S.E. out = 7.4V

32 Ohm = 1.7W
50 Ohm = 1.1W
120 Ohm = 450mW
300 Ohm = 180mW
600 Ohm = 90mW

Max power when using a DAC with higher output voltage (> 3.8V) Balanced out = 14.8V and assuming no current limiting

32 Ohm = 6.8W (may be less due to current limiting ?)
50 Ohm = 4.4W (may be less due to current limiting ?)
120 Ohm = 1.8W
300 Ohm = 700mW
600 Ohm = 360mW

Any example dacs with 3.8V? I know mojo in DAC mode has 3V output
 

Atanasi

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If you'd use a simple cable, definitely yes. just the XLR voltage cut into two.
There isn't a single cable that works from a balanced output to an unbalanced input.

An ordinary cable shorts ground and cold, which isn't allowed with some outputs or increases distortion. With those, RCA ground should be connected to XLR shield and XLR cold left floating, which halves the voltage.

A cross-coupled or transformer-balanced output supports shorting cold to ground, and retains full voltage.
 

raif71

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There isn't a single cable that works from a balanced output to an unbalanced input.

An ordinary cable shorts ground and cold, which isn't allowed with some outputs or increases distortion. With those, RCA ground should be connected to XLR shield and XLR cold left floating, which halves the voltage.

A cross-coupled or transformer-balanced output supports shorting cold to ground, and retains full voltage.
What about this one ?

https://www.amazon.com/4-4mm-Balanced-Headphone-Adapter-Silver/dp/B07WSR5M3J
 

solderdude

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For those who wonder what the power-hungry 'phones are:

HiFiMan HE-6 planar needs around 2.0 wattsAKG K1000 I heard they need about 5 watts

correction:

If you want to reach loud levels (say 110dB peak) the (original only) HE-6 requires 12.5V = 3.6W in 43 Ohm
The K1000 requires 9.5V = 0.6W in 150 Ohm.
 

mcdn

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There isn't a single cable that works from a balanced output to an unbalanced input.

An ordinary cable shorts ground and cold, which isn't allowed with some outputs or increases distortion. With those, RCA ground should be connected to XLR shield and XLR cold left floating, which halves the voltage.

A cross-coupled or transformer-balanced output supports shorting cold to ground, and retains full voltage.

This is true between active devices. To passive devices such as headphones why wouldn't you run XLR HOT to RCA SIG and XLR COLD to RCA GND? The 'phones only care about the voltage difference anyway, and it's not like they have a ground connection.
 

solderdude

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There isn't a single cable that works from a balanced output to an unbalanced input.

An ordinary cable shorts ground and cold, which isn't allowed with some outputs or increases distortion. With those, RCA ground should be connected to XLR shield and XLR cold left floating, which halves the voltage.

A cross-coupled or transformer-balanced output supports shorting cold to ground, and retains full voltage.

You could use a DI box like the Millenium DATI going XLR in (4V) from a balanced DAC and then RCA out (also 4V) but would be pointless as the distortion will be much higher than the A50s;)
 
Last edited:

Veri

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There isn't a single cable that works from a balanced output to an unbalanced input.
Wellllll, theoretically a floating one will carry over half the voltage without shorting issues right? Worst case there can be grounding noise picked up. https://benchmarkmedia.com/products/benchmark-xlrfm-to-rca-adapter-cable-pin-3-floating

So definitely possible unless you mean, to carry over both hot and cold in one cable that would be impossible. Which was my point in my previous point :D sorry to derail the thread about this stuff but I think it's worth mentioning as to not confuse people....
 

raif71

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Any value for the headphone output impedance for this amp? Thanks
 

ninetylol

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So Topping A50s vs L30.

L30 for high ohm HPs and A50s for low ohm HPs?
 

solderdude

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SE out-> L30
BAL out -> A50s

but only when it concerns max. output power with 2V FSD output sources.
A50s has balanced out and is DC fed (easier to buy)

Both will be usable with a wide range of headphones in real life and 'normal' listening levels. ;)
 
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