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Review and Measurements of Topping DX7s DAC and Headphone Amp

amirm

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#21
Good news, bad news on headphone out.

Bad news is that the output impedance is the same as DX7 at 10 ohms. Good news is that it has more juice! :)

upload_2018-2-21_18-50-33.png


It has a full volt higher unloaded voltage at 7 volts vs DX7 (blue bar). Loaded is about 0.7 volts higher than DX7 (orange bar).

So there is more power here to drive inefficient headphones.
 
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#22
Good news, bad news on headphone out.

Bad news is that the output impedance is the same as DX7 at 10 ohms. Good news is that it has more juice! :)
What about that idea you had of modding it to reduce the output impedance? Have you tried it already?
 

Jimster480

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#23
Good news, bad news on headphone out.

Bad news is that the output impedance is the same as DX7 at 10 ohms. Good news is that it has more juice! :)

View attachment 10836

It has a full volt higher unloaded voltage at 7 volts vs DX7 (blue bar). Loaded is about 0.7 volts higher than DX7 (orange bar).

So there is more power here to drive inefficient headphones.
Still pretty overkill power lol, I've never used my DX7 past -30...
Even with 300 ohm headphones on balanced output its fine at -32db.
 

amirm

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#24
What about that idea you had of modding it to reduce the output impedance? Have you tried it already?
Not yet. Too much in the measurement pipeline. :) Stay on top of me and I will get it done.
 
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#25
Good news, bad news on headphone out.

Bad news is that the output impedance is the same as DX7 at 10 ohms. Good news is that it has more juice! :)

View attachment 10836

It has a full volt higher unloaded voltage at 7 volts vs DX7 (blue bar). Loaded is about 0.7 volts higher than DX7 (orange bar).

So there is more power here to drive inefficient headphones.
Interesting results. Topping may have increased the voltage gain to the headphone amp. I wonder if the noise floor or thd+n increased at all at the headphone output. From my experience, too much voltage gain makes it hard to use with sensitive and low impedance headphone's. They should have made the amp with multiple gain setting with a selectable switch like on the A30. Thankfully the performance of the dac and addition of the balanced output makes it worthwhile to pair with a external headphone amp.

At $499, the price is getting up there. Add another $100 to $300 for a headphone amp and you are reaching a higher price point. The last massdrop price of $380, Imo is a good deal.
 
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#26
I might end up selling or trading mine if I end up satisfied with the Topping NX4 DSD that is coming to me soon. Since they share the same DAC chip and I don't have a balanced setup anyway, I suspect the measurements will be close enough that it's not worth the extra $230.
 

Jimster480

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#27
Interesting results. Topping may have increased the voltage gain to the headphone amp. I wonder if the noise floor or thd+n increased at all at the headphone output. From my experience, too much voltage gain makes it hard to use with sensitive and low impedance headphone's. They should have made the amp with multiple gain setting with a selectable switch like on the A30. Thankfully the performance of the dac and addition of the balanced output makes it worthwhile to pair with a external headphone amp.

At $499, the price is getting up there. Add another $100 to $300 for a headphone amp and you are reaching a higher price point. The last massdrop price of $380, Imo is a good deal.
That is possible too.
I do have a DX7 with an O2, I paid $275 for the DX7 on promo and ~120 for the custom O2. Pretty hard to beat for $400.
 
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#28
I might end up selling or trading mine if I end up satisfied with the Topping NX4 DSD that is coming to me soon. Since they share the same DAC chip and I don't have a balanced setup anyway, I suspect the measurements will be close enough that it's not worth the extra $230.
The equivalent of the DX7(s) unbalanced would be the D50. Even with comparable performance (which I would love to see), they cater to different needs: one is portable, the other is robust (connection, longevity).
BTW nice job stealing the name, wonder what Topping would called themselves should they have a representative here :D
 

Jimster480

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#29
The equivalent of the DX7(s) unbalanced would be the D50. Even with comparable performance (which I would love to see), they cater to different needs: one is portable, the other is robust (connection, longevity).
BTW nice job stealing the name, wonder what Topping would called themselves should they have a representative here :D
They would be Mr. Topping or Topping Representative or Schiit_Destroyer.... who knows what they might choose!
 

Mad_Economist

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#30
What about that idea you had of modding it to reduce the output impedance? Have you tried it already?
Topping lists the headphone drivers as TPA6120A2 - if that is the case, the 10Ω resistors on the output are there to ensure its stability with load capacitance (see page 11 of spec sheet http://www.ti.com/lit/ds/symlink/tpa6120a2.pdf). Removing them could cause oscillation. Very unfortunate that they chose the TPA6120A2 - it is a good option for cheaper designs when very high current output is required (Monoprice's own budget DAC-amp, for example), but for a "statement" DAC-amp it would have been nice if Topping had used something better, perhaps the 1688 or 1622.
 

Jimster480

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#31
Topping lists the headphone drivers as TPA6120A2 - if that is the case, the 10Ω resistors on the output are there to ensure its stability with load capacitance (see page 11 of spec sheet http://www.ti.com/lit/ds/symlink/tpa6120a2.pdf). Removing them could cause oscillation. Very unfortunate that they chose the TPA6120A2 - it is a good option for cheaper designs when very high current output is required (Monoprice's own budget DAC-amp, for example), but for a "statement" DAC-amp it would have been nice if Topping had used something better, perhaps the 1688 or 1622.
I couldn't agree more. If you read my original review of the DX7 on headfi I actually went as far to say that the whole purpose of the DX7 made no sense since it was just a "D30 + A30" in a single box for a higher price with a remote.
I changed my mind about it in time, and thankfully it measured similar to how my ears thought (that it was actually better than the D30 in some cases) but the A30 uses the same Amp design.
 
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#32
The equivalent of the DX7(s) unbalanced would be the D50. Even with comparable performance (which I would love to see), they cater to different needs: one is portable, the other is robust (connection, longevity).
BTW nice job stealing the name, wonder what Topping would called themselves should they have a representative here :D
Was just too lazy to think of anything more original.

Now if only there were some headphone amplifiers reviewed, I would know what to get to compliment whichever Topping I keep.
 

Wombat

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#33

mindbomb

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#36
Certainly the performance of the dac part is really good. But it will be easier to judge the value of the dx7s when there are more headphone amp results. If it does well with 300 ohm sennheisers, that's good enough for many folks. But 20 ohm output impedance with the balanced connection is on the high side.
 

L0rdGwyn

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#37
Given the higher cost of DX7s, I am wishing the DX7 was still available and that would have been my recommendation.
Well, that is disappointing. A marginal increase in performance would have been a win, but the lack of remote, channel imbalance, and otherwise mixed bag on the other measurements feels like a loss, even if they are competitive with similarly priced DACs. Topping seems to only be competing with themselves in the entry to mid-level DAC market in terms of performance. The original DX7 is still available via AliExpress for $399.99 USD and free shipping, here.

Also, just wanted to point out that the Project Pre Box S2 Digital (what a pain-in-the-arse to type!) also exhibits what looks like an identical channel imbalance. Coincidence?
 

Veri

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#38
Well, that is disappointing. A marginal increase in performance would have been a win, but the lack of remote, channel imbalance, and otherwise mixed bag on the other measurements feels like a loss, even if they are competitive with similarly priced DACs. Topping seems to only be competing with themselves in the entry to mid-level DAC market in terms of performance. The original DX7 is still available via AliExpress for $399.99 USD and free shipping, here.
That is, if you don't end up having a "free upgrade" DX7s shipped to you. Chinese suppliers can be so unreliable.
 

stunta

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#39
That is, if you don't end up having a "free upgrade" DX7s shipped to you. Chinese suppliers can be so unreliable.
That is exactly what happened to me when I ordered via Newegg. Seller was Schenzen audio. I had to then get a universal remote and make it work.
 
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#40
So ... it looks like it's really "rev the unit so we can put ESS 9038" on the spec sheet deal.

Most of the changes from the 9018 series to the 9038 series, particularly with the Q2M and/or mobile parts, are about reducing power requirements and making them easier to implement in power/thermally constrained products. The 9038Pro series chips are a bit different in that regard, though the first unit using that converter that I tried would overheat/crash regularly.
 
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