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Denafrips ARES II USB R2R DAC Review

voodooless

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Do you know the input impedance of the Pre D90 ?
Seems to be quite low, read something of 1.4 to 2 kHz. For that, the thing should probably be disqualified..
 

MBL'er

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Seems to be quite low, read something of 1.4 to 2 kHz. For that, the thing should probably be disqualified..
In theory yes, as the preamp input impedance should be at least 10x the dac output impedance, or the bass performance deteriorates (as told by my friend amp designer).

In personal practice, I connected the Musician Pegasus (same output impedance as the Ares II) to my preamp trying both the 50K Ohm and the 10K Ohm single-ended inputs (the preamp has two different input boards) and could not detect any sound difference.
 

ohnonate

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Do you know the input impedance of the Pre D90 ?
Pre 90 - Input Impedance
Balanced
- 2,000 Ω
Unbalanced - 10,000 Ω

Denafrips Areies II Output Impedance
Balanced
- 2,400 Ω
Unbalanced - 1,200 Ω

so for best impedance matching you would need to connect it unbalanced from the Aeries II into the Pre 90. The input impedance is higher than the input impedance of the Pre 90.. would it affect the performance?

 

MBL'er

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Pre 90 - Input Impedance
Balanced
- 2,000 Ω
Unbalanced - 10,000 Ω

Denafrips Areies II Output Impedance
Balanced
- 2,400 Ω
Unbalanced - 1,200 Ω

so for best impedance matching you would need to connect it unbalanced from the Aeries II into the Pre 90. The input impedance is higher than the input impedance of the Pre 90.. would it affect the performance?

You are correct, best match is through unbalanced.

In theory, to perfectly match the Ares II the pre should have at least 24,000 Ohm on balanced input and 12,000 Ohm on unbalanced.

M
 

Lambda

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What the hell were they thinking?
No output Opamp/buffer saves a view $ and the fools will love it because they get "direct raw R2R sound"

In theory, to perfectly match the Ares II the pre should have at least 24,000 Ohm on balanced input and 12,000 Ohm on unbalanced.
What "theory" exactly is this bases on?


would it affect the performance?
Impossible to say in general without having knowledge about the exact schematics.
 

MBL'er

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What "theory" exactly is this bases on?

I have a friend who designs and manufactures tube amps. I got the info on impedance mismatch effects from him.

From what I understand on R2R designs, also having read some articles on Soekris site, it seems that the resistors rails have "voltage output", so they do not need the I/V stage. By directly routing the signal to the output there is no in-between component potentially adding noise, but that results in high output impedance.

Some member deeper than me - easy - into tech might add or correct.

The Topping D70S, which both I and my friend own (he dissected his sample) has no I/V stage at the dacs output, and that probably contributes to sound quality, but has op-amps in the output stage and a very low output impedance.

M
 

Lambda

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I have a friend who designs and manufactures tube amps. I got the info on impedance mismatch effects from him.
This is not a Theory.
You just quote a rule of thumb you heard somewhere without knowledge if this as any relevance in this cases.
 

MBL'er

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This is not a Theory.
You just quote a rule of thumb you heard somewhere without knowledge if this as any relevance in this cases.

"in theory" does not mean that there is a formal theory, but rathe "it should be like that"

Please do not get that literal path, I teached for 13 years business strategy and corporate finance at the Rome University ...
 

Killingbeans

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and that probably contributes to sound quality

I wouldn't bet the farm on it. Less is more doesn't apply indiscriminately. It all depends on what damage the individual stages does and what the total amounts to in the end.

If the AK4497 had current output, the added complexity of an I/V stage probably wouldn't amount to anything audible.
 

MBL'er

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I wouldn't bet the farm on it. Less is more doesn't apply indiscriminately. It all depends on what damage the individual stages does and what the total amounts to in the end.

If the AK4497 had current output, the added complexity of an I/V stage probably wouldn't amount to anything audible.
Likely.
 

ThomasMac

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I email Denafrips in regards to the Pre 90 and the Ares II and they even though the impedance of the Pre 90 is a bit low that it still should be fine. Just curious where you heard that from?
I emailed both Topping and Denaphrips. And they both didn't recommend it. Topping was especially more straight-forward with telling me no...which I found interesting since you'd figure they would want to sell me their product. I think Denaphrips adds some kind of buffer to all their dacs to compensate for the high impedance numbers. I did notice later that Denaphrips pre amps don't have particularly high impendance numbers...they are appx 10-12k...so, that makes me think it'll prob be ok to use the pre90. Idk much about this stuff. I'm curious...but just didn't want to spend the cash to just a/b test impedance matching.
 

ThomasMac

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Do you know the input impedance of the Pre D90 ?
1.5kΩ to 2kΩ I believe. The Ares 2 is appx 1.7k single ended 2.4k balanced. So, if u go by the 10x rule of thumb that a lot of people suggest...
That's a huge mis match.
 

ohnonate

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I email Denafrips in regards to the Pre 90 and the Ares II and they even though the impedance of the Pre 90 is a bit low that it still should be fine. Just curious where you heard that from?
Thomas your spot on. I emailed Topping and they said its not a good match and should be used with DACs with 200 or less ohms impedance.
 

giordy

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giordy

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I was referring only to the ratio of 1 to 10 on the output / input impedance from source to preamp
 

Lambda

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I was referring only to the ratio of 1 to 10 on the output / input impedance from source to preamp
And?
Because someone on the Italian internet is Referring to this made up 1/10 rule oft thumb it makes it more true?

  • Best condition - low output impedance - when the output impedance (Z OUT ) is less than the load impedance (Z LOAD ). This condition is better because most of the voltage (V SOURCE ) appears across the load and very little voltage is “lost” driving the output current through the output impedance.
Why should i care about energy loss?

Unsatisfactory condition - high output impedance - when the output impedance (Z OUT ) is greater than the load impedance (Z LOAD ). This condition becomes insufficient as only a small part of the source voltage (V SOURCE ) appears across the load, most of it is “lost” driving the output current through the output impedance.
And this is bad why?

Do you know about about Johnson–Nyquist noise?
 
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