Topping DX7s Balanced DAC/Amp Discussions | Drop

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Topping DX7s Balanced DAC/Amp

Audiophile

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Sinery

Feb 5, 2018

"Output impedance: <20 ohms" Amazed they listed that, for some godawful reason Aune and Topping love that output impedance.

Feb 5, 2018

npc2

Feb 5, 2018

SineryWhat a lot of recent DAC+AMP and DAP have in common is using the TPA6120A2 which causes them to have the high output impedance (which would be double for balanced compared to single ended). It is unclear whether this model has the same part given the claim of higher output power.
Edit: revised for clarity

Feb 5, 2018

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DarknessAngel

Feb 5, 2018

SineryBased on NwAvGuy as long as your headphones are 8x that amount your fine. Wont cause any issues with 80 ohm or greater on SE and 180 ohm or greater on Balanced. Would have to keep this in mind if its good for your headphones now and will it be good for any headphones you purchase in the future.
source: http://nwavguy.blogspot.com/2011/02/headphone-amp-impedance.html

Feb 5, 2018

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npc2

Feb 5, 2018

DarknessAngelWhat's interesting is that the TPA6120A2 and parts with similar high impedances are often used in DAPs and IEMs would be generally much less than even 80 ohm. It is also true I suppose that not every driver or crossover has the same FR changes when the source impedance varies so I am not sure the 8x rule always applies.

Feb 5, 2018

DarknessAngel

Feb 5, 2018

npc2I agree, but i'd definetly lean more on the side of caution unless you know otherwise from testing the possible drivers you would use. If i'm diving into something having not used it, i'd rather be on the safe side. He uses it as a rule of thumb to rule out the possibilities of downfalls due to the output impedence.

Feb 5, 2018

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npc2

Feb 5, 2018

DarknessAngelAgreed. I think the rule is generally warranted as I have seen reviewers comment that products like those DAPs did affect the sound depending on the load impedance and I have personally observed it with one of my more sensitive IEMs (probably due to the crossover in it rather than the BA drivers).

Feb 5, 2018

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DarknessAngel82

Feb 5, 2018

npc2Curious from someone who's heard how it affects drivers what did you notice?

Feb 5, 2018

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MooTaters

382

Feb 5, 2018

DarknessAngelAm I missing something here? Based on OP, npc2 and your first post, 8x would be 160ohms SE, and 320ohms on balanced. "Output impedance: <20ohms" npc2: "which causes them to have high output(which would be doubled for balanced)." DarknessAngel: "Based on NwAvGuy as long as your headphones are 8x that amount you're fine"

Feb 5, 2018

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DarknessAngel82

Feb 5, 2018

MooTatersHe actually says your output impedance of your amp should be 1/8th of your cans. So reverse that would be x8 of the amp output impedance. Amp specs are less <10 for SE and <20 for SE. How much lower who knows so calculate it off the best known. 10x8 is 80 20x8 is 160. 1/8 of 80 is 10 and 1/8 of 160 is 20 unless my math is off lol

Feb 5, 2018

MooTaters

382

Feb 6, 2018

DarknessAngel82Yeah, looks right then...though I assume you meant balanced for <20. It certainly had me thinking 320ohms would be exceptionally high.

Feb 6, 2018

npc2

Feb 6, 2018

DarknessAngel82Depends on the scenario. The most striking example I have tried is the NuForce Primo 8 which already sounds like the treble falls of cliff without any help (see https://www.innerfidelity.com/images/NuForcePrimo8.pdf). Connecting it to a Matrix M-Stage HPA-1 at 10 ohms instead of from Grace Design m9XX (0.08 ohms) the trebles rolls off much more (it does vaguely seems to follow the huge fall in impedance). To be fair part of this is that the M-Stage HPA-1 is not neutral and is warm with roll off at the top (purchased for the benefit of HD 800) but the effect is less dramatic than what I hear with the Primo 8. The same issue also occurs with the Primo 8 and a 3DS (45 ohms by someone's claim) or the output of my desktop's MB sound compared to using adding an old FiiO E5/17 as a buffer amp. My guess is different headphones will have different results (I suspect the Primo 8 is particularly finicky) and I am not sure how much to read into the impedance curves. (I will have try some experiments with something like a k7XX or LCD2C at a moderate 70 ohm but then again, it is hard to say if results would translate to the DX7s).

Feb 6, 2018

Jimster480

395

Feb 6, 2018

SineryThats only for balanced. Its 10 for SE. But the DAC itself is awesome and you can connect it to any balanced Amp and it will just kick ass. Topping themselves will have some newer Amps this year, so look out for one that has a 0 ohm output impedance. They told me they were working on products with lower output impedance when I emailed them about this a few weeks back.
So maybe a second Amp that will plug into this unit will deliver lower output impedance for those like me that need it.
For now my I use my DX7 with a o2Amp on my low impedance headphones.

Feb 6, 2018

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