WolfX700 Measurement of Topping A90 Headphone Amp

[poimandres]

Congratulations John, the A9 appears to be designed very well. Looking forward to the release and price.

 

[JohnYang1997]

+15dB on balanced is pretty high lol. But hmm, so no 0dB/unity gain for balanced in final design?

6db is essentially the unity gain. It's inherent in the balanced topology. It will have double the voltage than unbalanced.

 

[August]

Long time no see, and congratulations!

 

[Veri]

6db is essentially the unity gain. It's inherent in the balanced topology. It will have double the voltage than unbalanced.

Right. Thanks for clarifying =). Can you share something about the power supply? How did you get noise so low?!

 

[JohnYang1997]

Right. Thanks for clarifying =). Can you share something about the power supply? How did you get noise so low?!

Nothing special about power supply. Mr wolf tested XLR input so no issue regarding PS noise. In terms of the overall noise, just use low value resistors and make it stable.

 

[Matias]

Linear power supply or switching mode?

 

[ThomasXia]

Good job

 

[JohnYang1997]

Linear power supply or switching mode?

SMPS

 

[Veri]

SMPS

Considering ADI-2 DAC, THX 789/887 etc all use SMPS I see no problem with a good SMPS, as can be seen here with these stellar measurements!

 

[JohnYang1997]

0.37R for BAL

Alright. Changed cable connection to minimize cable interference to the measurements. The balanced output impedance is 0.135ohm. The extra impedance must be the cable impedance from the phone out to the load.

 

[WolfX-700]

1M FFT

 

[digicidal]

That's just ridiculously good. I'm not that into headphones so it's of limited value personally (at the moment)... but it's always nice to see just how fantastic modern equipment can be when competently designed. Nearly as good as megabuck diagnostic equipment... now if Topping could build an ADC with this level of perfection, we could all measure relatively pedestrian gear with similar accuracy to an APx555 for 1/25th the price!

 

[boXem]

@JohnYang1997 I guess it's a little early to ask, but ... topology?

 

[JohnYang1997]

@JohnYang1997 I guess it's a little early to ask, but ... topology?

Composite + feedback. Basically the same as everyone else.

 

[Veri]

Composite + feedback. Basically the same as everyone else.

But still better. apparently

 

[Koeitje]

That is an impressive piece of kit.

 

[maxxevv]

Very impressive results!

The way I see it, this will serve very well for people who own both headphones and speakers, especially active/powered speakers !

Connected to equally competent DAC's such as the D90 and say the X-Sabre, there really isn't any reason to look at any form of upgrade for a long, long time. Maybe just the transducers and that's about it!

Awesome stuff!

 

[Matias]

Very nice indeed!

What is the output impedance on the line level XLRs and RCAs?

 

[Sydneysider]

John Thanks - great work.
Is there a timeline for a 90 series dac/headphone amp all in one?

Thank you Vincent

 

[WolfX-700]

Very nice indeed!

What is the output impedance on the line level XLRs and RCAs?

41 XLR 20.5 RCA