WolfX700 Measurement of Topping A90 Headphone Amp

[MC_RME]

Why don't you measure the amplifier with real headphone load instead of resistive load?
You can read this article.
https://benchmarkmedia.com/blogs/application_notes/12838141-headphone-amplifiers-part-1

You could search this forum to find out that this is a useless endeavour...

 

[JohnYang1997]

When using pot to attenuate the input signal then the measurement is not comparable to all others so far done here. And the SNR that I calculated would not be available too, in that setting. Anyway, I don't want to cause the impression that I am critizing this development, so let's wait for your final numbers.

I think when measuring amplifiers, Amir and Wolf use pot if there's a pot. I am cool with all these questions. And I'll only discuss on the matter itself nothing more.
If I'm correct, the amplifier in adi2dac should have about 100dB SNR-50mV if measured alone.

 

[wje]

Congratulations JohnYang1997! Aka "The Destroyer," see this ASR thread: https://www.audiosciencereview.com/...review-another-champ.9438/page-12#post-249897

I am hoping the price will be $150 as projected by John , or at least no more than $300....

My mind is telling me something closer to $499.

Great review and thread. Impressive.

 

[evrial]

Any news on DX3/DX7 successors?

 

[railcannon]

You could search this forum to find out that this is a useless endeavour...

Thanks for reply.
But I can't understand that the actual load test is meaningless to the actual amplifier stability test.
Is the benchmark 's opinion on the actual headphone load wrong?

 

[777]

There will be any remote control ? I want to use it for my power amps like a pre-amp.

 

[JohnYang1997]

There will be any remote control ? I want to use it for my power amps like a pre-amp.

Sadly no. But there will be a dedicated preamp with remote.

 

[777]

Sadly no. But there will be a dedicated preamp with remote.

Mmm, very nice. I need a high performance and a powerfull pre-amp, for the power amps with 1kohm input impedance.

 

[Martin]

Sadly no. But there will be a dedicated preamp with remote.

Interesting... I was looking at the Gustard P26... Now I'll have to wait to see what the Topping preamp looks like (P90?). Based on the pricing differential between the D50/A50 pair I'm expecting the A90 to be between $475 and 499. I'd love to see a DX9 Pro to replace my DX7 Pro but just might jump on a D90/A90 pair.

Martin

 

[AudioJester]

@JohnYang1997 Congrats on your design!

So do you have and RME ADI-2 killer?
Have been using RME for years, but the new stuff is too expensive...

Also curious to see if Topping will come out with a power amplifier for speakers.

 

[VeerK]

Hmm, the A90 beats the 887 in two ways for me, matching the D90 aesthetics, and the extra XLR outputs for usage with speaker amps. Depending on the price, I may jump to this, exciting stuff. Hopefully the positive reception convinces Topping to start making ultra low distortion speaker amp modules

 

[Tks]

Wolfman is back! and he brought John Yang with him to smack THX in the face.

Goodness the performance of this thing.. Amps have finally superseded DAC's

All that's left now is for John to provide his insight and take down Benchmarks' Power Amp that's been king for at least half a decade.

Well done guys, and nice to see you back again Wolf, happy to know things are doing good.

 

[JohnYang1997]

Seems a little bit PS noise or interference through connections bled in. So I got roughly 104dB SNR with 50mV output.
Signal chain:
AP(5V output)-L30(attenuate to 50mV)-Noise amp(40dB amplification)-AP(unbalanced in)

PS: The picture is the noise amp not L30.

 

[jae]

Is that a 4.4 mm balanced?

 

[JohnYang1997]

Is that a 4.4 mm balanced?

yes

 

[Nango]

This is really a long and memorable vacation ...

Mainly for well-known reasons ... I haven't released any measurements for a long time

Logistics was completely stopped ... R & D and manufacturing were also completely halted ...

God ... this is really a boring holiday ... I have been bored to spend the whole week to adjust one of the equipment I made before (for example, to make the THD+N vs Freq curve of the left and right channels basically the same, and the harmonic components are also consistent)

For the coronavirus, I was almost 600km away from the center of the outbreak. In terms of government's epidemic prevention measures, in fact, I could hardly find anything to worry about-----Good social order and basically good supply in the supermarket-one thing to complain about is that Coca-Cola in the supermarket near my house is always in short supply


well, let's get back to business……

Before the Spring Festival, I knew that Topping was developing a new headphone amplifier and made an appointment with them for measurement.

The thing was finally mailed to me two days ago (thankfully they started working).

View attachment 53427

View attachment 53428

This is a compact unit. The workmanship is not exquisite, but there is nothing to complain about. Topping's family-style design (the size is the same as D90)

What I like very much is that the Power supply is built-in, making the whole system look simpler (it is always uncomfortable to hang a power adapter outside)

It's a headphone amplifier and preamp integrated product, this design may be very suitable for desktop users? (A small combination of active speakers and headphones)

First I will measure the headphone amplifier part:

I start with a medium gain, 4V input

View attachment 53449

View attachment 53450

Wow! ... I was a bit shocked ...

I feel that it is not the device under test that restricts the measurement results, but APX555.


In the case of 5V input / UNBAL output, I got 123 SINAD!

View attachment 53451

This is crazy!

For comparison, this is the AP Loopback:

View attachment 53453

How does THD + N change with frequency?
View attachment 53457
Attention! The bottom of this chart is not 0.0001% as usual, but 0.00001%!

Alright, let's get on the load! See the results under load!
SNR:
View attachment 53456

THD+N vs Level
View attachment 53454

View attachment 53455

I was having difficulty measuring the maximum output ... because the protection circuit is very sensitive, it cuts off all outputs at the moment of overload ...

I got a maximum output of 6.5W with 33R (BAL Out) in dashboard mode!

In this case, SINAD is still as high as 110db.

View attachment 53458

The results of the previous test were so crazy that it made me feel boring to release things like frequency response (such a device is almost impossible to have problems in this area)

View attachment 53460

Of course ... Since the volume is adjusted with a potentiometer, there must be some problems with channel balance.But it is said that the final version of the gain will be adjusted to -9 0 9 (the one I got is 0 6 12) should be able to adapt to various headphones.

View attachment 53461


End of headphone amplifier measurement ... output impedance（0.37R):
View attachment 53462

Preamp section: As good as the headphone amplifier section!

They built-in an AP short version inside to come up with these figures!

 

[LTig]

@JohnYang1997 Congrats on your design!

So do you have and RME ADI-2 killer?
Have been using RME for years, but the new stuff is too expensive...

Certainly not. To kill the ADI-2 it misses an excellent DAC and all the DSP features in this box.

 

[LTig]

This performance, ... WOW. There are less than 10 dB difference between THD of DUT and AP loopback so the results are limited by the AP. Incredible.

And with 6.5W @ 33 Ohm I'm speculating how much power it could deliver at 8 Ohm? Might be enough to feed very high sensitivity full range horn speakers - no need to buy an overpriced SET power amp.

 

[YSC]

Woo that’s an insane result! Any idea if it’s a op amp design or discrete? Really wonders how can they achieve that, any idea on potentiometer type/quality and pricing in final product?

 

[JohnYang1997]

Woo that’s an insane result! Any idea if it’s a op amp design or discrete? Really wonders how can they achieve that, any idea on potentiometer type/quality and pricing in final product?

Opamps
Customized rotary pot
I can't comment on pricing yet