Alternative to Loxjie A30 Amplifier

[cyp]

Hey guys, dear audio experts,

First time poster here.

I'm looking for a combi DAC / FDA or class D amp. I was very interested by the A30 following Amir's very positive review. The design, budget and features, not too much and not too few, it just looked too perfect to be true. And indeed it is, after reading all the 40+ pages of the review : the USB chip.

As my primary usage would be exactly USB (secondary RCA) out of my Mac mini, hence using the integrated DAC, it seems it kind of would defeat the purpose because of the cheap Realtek component through which only the USB is routed.

Last thing, the power isn't really relevant as it will drive 2 Klipsch RF82 II which are very easy to drive (98dB or something).

Is there any alternative in that 200-300 price range besides the A30 with a separate DAC ? I like to keep things simple and hence, the less devices the better...

 

[Hatto]

Topping MX3s (smaller, newer, affordable)
Topping MX5 (balanced)

 

[ppataki]

Sabaj A30A
It is a real FDA (unlike the Loxjie), so you don't need a DAC
It is in a different league though, both from a pricing and quality perspective
I have three of them, so far the best amps I have ever had (replaced Hypex Ncore with this)

 

[Hatto]

Sabaj A30A
It is a real FDA (unlike the Loxjie), so you don't need a DAC
It is in a different league though, both from a pricing and quality perspective
I have three of them, so far the best amps I have ever had (replaced Hypex Ncore with this)

@ppataki, may I ask, what does "real FDA" stand for?

 

[ppataki]

@ppataki, may I ask, what does "real FDA" stand for?

FDA stands for Full Digital Amp
It is a class D amp that gets the PCM signal via its digital inputs, converts it into PWM, amplifies it then converts it to analogue via a low-pass filter
So no classic DAC (PCM--> analogue) is involved in the signal chain
Loxjie is not an FDA since there is DAC in the signal chain

 

[Hatto]

FDA stands for Full Digital Amp
It is a class D amp that gets the PCM signal via its digital inputs, converts it into PWM, amplifies it then converts it to analogue via a low-pass filter
So no classic DAC (PCM--> analogue) is involved in the signal chain
Loxjie is not an FDA since there is DAC in the signal chain

How can an amplifier be "fully digital"? The main function of the amplifier (raising the voltage level in order to provide enough and controlled variable DC current to the transducer) is purely analog.

 

[ppataki]

Just explained it above, google for more info

 

[voodooless]

The USB DAC is not the limiting factor of tha A30, so don’t worry about it.

 

[Hatto]

Just explained it above, google for more info

You did not explain anything.

It is a class D amp that gets the PCM signal via its digital inputs, converts it into PWM, amplifies it then converts it to analogue via a low-pass filter

Amplifying PWM signal achieves nothing. PWM is a square wave modulation signal and modulation is independent of amplitude: It's normalized to 1, 0 or -1, that's it:

PWM amplitude can be 0.1V or 100V, (0.1V = 1 or 100V = 1) it makes no difference to the actual analog signal produced with it.

Stereo amplification is pure analog signal modification, therefore amplifier = analog. There can't be such a thing as a "fully digital analog".

 

[Kegemusha]

FDAs do not do digital to analog convertion before the amplification.
There is the Aiyima D03, not sure if it is better than the Loxjie.

 

[voodooless]

Stereo amplification is pure analog signal modification, therefore amplifier = analog. There can't be such a thing as a "fully digital analog".

The point is: here is no separate DAC and gain stage. The PWM output is at full rail voltage, and it’s generated directly from the digital input and a digital feedback signal sampled from behind the low pass filter of the amp.

 

[Hatto]

FDAs do not do digtal to analog convertion before the amplification.

How? PCM is a digital string, PWM is a continuous analog signal.

The PWM output is at full rail voltage,

Voltage of the PWM signal is arbitrary anyways.

and (PWM is) generated directly from the digital input and a digital feedback signal sampled from behind the low pass filter of the amp.

That is the definition of digital-analog-conversion isn't it? How is that different from any DAC?

In any case the amplifier has to produce an analog (variable DC) signal using PWM. It is all digital until PWM and all analog after PWM, my issue is with the term "fully digital".

 

[voodooless]

That is the definition of digital-analog-conversion isn't it?

I’m not disagreeing, just explaining how it works

How is that different from any DAC?

You can drive a speaker directly.

my issue is with the term "fully digital".

Call it a power DAC

PWM is a continuous.

It doesn’t have to be. It can be discrete as well.

 

[Hatto]

I’m not disagreeing, just explaining how it works

And I appreciate it, thank you.

You can drive a speaker directly. Call it a power DAC

Just like Loxjie A30 can. How is it different then?

It doesn’t have to be. It can be discrete as well.

If it's discrete it's a digital string.

 

[Overseas]

I know Lyngdorf amps are digital, no DAC chip inside, confirmed to me by manufacturer email.

 

[voodooless]

Just like Loxjie A30 can. How is it different then?

It’s not all in a single chip.. to be fair the class D drivers are also not in the Axign chip, nor is USB interface

If it's discrete it's a digital string.

It’s still PWM though.

Obviously by definition, if digital goes in, and analog comes out, it’s a DAC of some sort

 

[Hatto]

Obviously by definition, if digital goes in, and analog comes out, it’s a DAC of some sort

Exactly, it's a DAC nevertheless, just sounds more disorganized.

It’s still PWM though.

Well, to simplify, digital is 0 or 1, PWM is -1 or 0 or 1

It’s not all in a single chip..

And what do people have against single chips?

 

[voodooless]

Well, to simplify, digital is 0 or 1, PWM is -1 or 0 or 1

Not exactly. Digital generally just means things are discrete. PWM just means you have pulses with varying width. With digital PWM the pulse width is discrete, so can only have a fixed number of values. Analog PWM can have any arbitrary pulse width.

And what do people have against single chips?

No idea…

 

[Hatto]

Not exactly. Digital generally just means things are discrete. PWM just means you have pulses with varying width. With digital PWM the pulse width is discrete, so can only have a fixed number of values. Analog PWM can have any arbitrary pulse width.

Don't know much about discrete pulse width PWM but simplified digital has 2 dof (on and off) whereas PWM has 3 dof (increase, decrease and do nothing).

 

[voodooless]

Don't know much about discrete pulse width PWM but simplified digital has 2 dof (on and off) whereas PWM has 3 dof (increase, decrease and do nothing).

That’s just a special case of PWM, you can also have only two states: