Tempotec Sonata IDSD output impedance

[Skr1231]

Hello, everyone
I am new on this forum so don't be angry on me because i haven't got a chance to learn everything around here properly
I recently decided to purchase Sennheiser HD599,but I learned that these headphones are really sensitive to internal impedance of your DAC.I have got Tempotec Sonata IDSD DAC, this is a great DAC, however i didn't find anywhere information about its output (internal) impedance
Unfortunately,i don't have appropriate equipment and knowledge to find out this parameter by myself
So i am asking someone who owns this DAC to share its internal impedance with me
P.S. I tried contacting their official store on AliExpress but didn't get a decent answer since they(apparently) can't answer me understandibly in English
Thank you for attention,hope you can help me with that

 

[pozz]

Hi @Skr1231

Our member @solderdude has made tests of the HD599 to show the impacts of high output impedance: https://diyaudioheaven.wordpress.com/headphones/measurements/brands-s-se/hd599/

It is unlikely that the Tempotec's output impedance is as high as the 120 ohms whose effects were simulated measured in that graph. It's more likely that the Tempotec, because it was built with headphone use in mind, will have much lower measured impedance and the FR differences will be more subtle. But these are just guesses. You could send it for Amir to test, though hopefully someone else can provide you with exact data.

I looked it up online and found this page on the Hidisz site (not sure if it's the right unit): https://www.hidizs.net/products/serenade-idsd Their products have tested well in the past IIRC.

 

[solderdude]

The tempotech will have an output R below 10 Ohm
The output voltage will be 1.5V @ 32 Ohm.

Will see if I can get more info.

The 120 Ohm plot is not simulated though but an actual measurement with 120 Ohm output R.

 

[Skr1231]

@solderdude @pozz
That helps a lot, thanks!

 

[ZolaIII]

@solderdude @pozz
That helps a lot, thanks!

Nope, they are looking at wrong product (Serenade iDSD).
For Sonata iDSD output impedance should be below or around 1 Ohm (probably less) & it has just enough power to drive that Sennheiser (as it is for Superlux HD-668B which is slightly less efficient and 64 Ohms) good enough. That is if you are talking about Sonata iDSD not a Plus big brother balanced one.

Tho solderdude whosent all that far in it's calculation for Serenade for which this rewiev with some measurements would be interesting to you , especially comparation part with Sabaj DA3 (2 Ohm) with sensitive EMI's.

https://hiendportable.com/tempotec-serenade-idsd-english-review/

 

[Skr1231]

@ZolaIII that makes sense to me,however what makes you think output impedance is lower than 1 ohm?As far as i know no one measured and posted it in the Internet

 

[ZolaIII]

@ZolaIII that makes sense to me,however what makes you think output impedance is lower than 1 ohm?As far as i know no one measured and posted it in the Internet

It should be based on similar designs (ESS dac + same amp usually 06~07 Ohm's for instance DragonFly's [Red, Cobalt] all do that's terrible comparation but output impedance should be close).

 

[Skr1231]

Oh,thanks for your answer then

 

[ZolaIII]

TempoTec Sonata iDSD review, teardown with some measurements (should be taken with a grain of salt as neither he had good equipment, the data presented differs from graps which again are in horrible resolution, still better than nothing). Source is in Russian:
https://mysku.ru/blog/aliexpress/75563.html
The high quality disassembly picture's of prototype bord (not that anything changed with final & today's V 0.1) with significant components. Chinese source:
http://www.soomal.com/doc/10100006984.htm
I hope some day we will see proper measurements.

 

[solderdude]

What I found was the Tempotec Sonata IDSD DAC plus has 2 outputs. One 3.5mm TRS and a 2.5mm balanced.
In balanced mode the output = 150 mW/32 Ohm = 2.2V but this is only available on the Tempotec Sonata IDSD DAC plus version
In SE mode mode the output = 120 mW/32 Ohm = 1.95V
It looks like the output is current limited to 100mA (peak)

The Tempotec Sonata IDSD DAC = 75 mW/32 Ohm = 1.55V and is probably current limited to 70mA peak.

The max. output voltage of this device is probably not very high and may well top out at 1.6V or so.

The HD599 is 50 Ohm so the Tempotec Sonata IDSD DAC can deliver about 50mW into the headphone.
1.6V results in 109dB peak. This may seem like a lot but average levels may be a good 15dB below it.
So you can use it but if you want to listen at impressively loud levels it will come up short and starts sounding 'nasty'.

 

[ZolaIII]

What I found was the Tempotec Sonata IDSD DAC plus has 2 outputs. One 3.5mm TRS and a 2.5mm balanced.
In balanced mode the output = 150 mW/32 Ohm = 2.2V but this is only available on the Tempotec Sonata IDSD DAC plus version
In SE mode mode the output = 120 mW/32 Ohm = 1.95V
It looks like the output is current limited to 100mA (peak)

The Tempotec Sonata IDSD DAC = 75 mW/32 Ohm = 1.55V and is probably current limited to 70mA peak.

The max. output voltage of this device is probably not very high and may well top out at 1.6V or so.

The HD599 is 50 Ohm so the Tempotec Sonata IDSD DAC can deliver about 50mW into the headphone.
1.6V results in 109dB peak. This may seem like a lot but average levels may be a good 15dB below it.
So you can use it but if you want to listen at impressively loud levels it will come up short and starts sounding 'nasty'.

Sonata IDSD Plus is full balanced build (2x ES9018K2M and 2x Sabre9601K [each up to 75 mV @ 32 Ohm's]) while regular Sonata iDSD is just one of each. There's an audible difference when you push the volume all the way up & you certainly know if something can drive Superlux HD-668B satisfactory it can even better drive Sennheiser 599 as you have Superlux and Similar if not the same Senn. While it can drive it, it's optimal for up to 32~40 Ohm's earphones, actually as the Sabre9601k is very good amp it's also great for sensitive lo impedance one's.

 

[solderdude]

Sonata IDSD Plus is full balanced build (2x ES9018K2M and 2x Sabre9601K [each up to 75 mV @ 32 Ohm's])

Nope the data I wrote above is correct. The Plus has balanced and SE and is more powerful than the non plus version.

As the inquiry was about the non plus version the calculations are made for the non plus version and HD599 and output resistance because of the HD599 impedance peak. It looks like the output R is below 10 Ohm and this is what he wanted to know.
Not how it can drive headphones he doesn't own.

 

[Skr1231]

@solderdude @ZolaIII
Really appreciate the little research you did for me.Still waiting for someone who can directly measure the output impedance,though.Now it is just a matter of curiosity

 

[solderdude]

You could do this yourself but requires a soundcard and a tone generator (a 1kHz sound file placed on the player) to pull this off, and some guidance .

When you are up to it and have a soundcard with a line level input you could (indirectly) measure the output resistance of a source.
You will also need a 3.5mm TRS splitter (the ones used for connecting 2 headphones to one TRS output and a 3.5mm TRS to 3.5mm TRS (line input) of a souncard and something like audacity.

 

[ZolaIII]

You could do this yourself but requires a soundcard and a tone generator (a 1kHz sound file placed on the player) to pull this off, and some guidance .

When you are up to it and have a soundcard with a line level input you could (indirectly) measure the output resistance of a source.
You will also need a 3.5mm TRS splitter (the ones used for connecting 2 headphones to one TRS output and a 3.5mm TRS to 3.5mm TRS (line input) of a souncard and something like audacity.

Trying it right now with RMA, diged old comp from attic with old Audigy 2 ZS Platinum as I think it's sufficient for this but so far whosent able to adjust input levels as something is wrong with it. When I do I will proceed.

 

[solderdude]

The procedure is as follows:

1kHz file on the player.
Player output into a 3.5mm TRS splitter.
one output of TRS splitter directly into the line input of the sound card (USB or directly)
Set output volume of player about -6dB (so not full power)
Look at the meters of the input and note the value.
Plug in a headphone with a known impedance (the lower the better but not below 32 Ohm for this device)
See how much the input level of the sound card drops.

Than calculate the dB difference back to voltage difference.
From there on you can calculate the ratio between not loaded and loaded (with known impedance) voltages.
The relation from these voltages is the same as from the impedances involved (Z out and Z headphone)
At 1kHz most headphones are almost resistive and the nominal value.

The procedure above is for those not having a multimeter with 200mV AC setting and bandwidth of at least 1kHz.
Otherwise it would be simpler to do the same but measure the unloaded output with the output level set at 1V AC and then measure the voltage when the headphone is plugged in.
The ratio between R out and R load is the same as that of the measured voltages.

 

[Skr1231]

@ZolaIII @solderdude
Today i finally got an answer from the engineer of Tempotec.He claims that output impedance of Sonata IDSD is 0.2 ohm. That's a nice number though.Anyways, thanks again for your help

 

[solderdude]

It would not even matter if it was 1 Ohm or even 10 Ohm in your case. It's the low max. output voltage which is the limiting factor here.
More than enough to drive high efficiency low impedance headphones though.
Just enough for HD599 with normal to decently loud listening levels.
Enjoy the music ... worry free.

 

[ZolaIII]

@ZolaIII @solderdude
Today i finally got an answer from the engineer of Tempotec.He claims that output impedance of Sonata IDSD is 0.2 ohm. That's a nice number though.Anyways, thanks again for your help

I don't think so, couldn't do measurements myself (lost extension panel & damn thing only have input trugh it) but all do AudioQuest actually did everything wrong with complete DragonFly lineup (some of which developer community did menage to iron out but not pore design decisions) output impedance is something they did fairly right so it can be used hire for reference (06~07 Ohm's).

 

[ZolaIII]

It would not even matter if it was 1 Ohm or even 10 Ohm in your case. It's the low max. output voltage which is the limiting factor here.
More than enough to drive high efficiency low impedance headphones though.
Just enough for HD599 with normal to decently loud listening levels.
Enjoy the music ... worry free.

Yes that's why I highlighted him (2 vs 10 Ohm's on sensitive EMI's);
https://hiendportable.com/wp-conten...p-Kanas-Pro-iDSD-vs-Moodrop-Kanas-Pro-DA3.png