Author Topic: Killerdac Output Voltage and Impedance  (Read 5136 times)

Offline matt200sr

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Killerdac Output Voltage and Impedance
« on: July 29, 2016, 10:05:19 AM »
I have a question regarding the output parameters of my Killerdac

Can anyone tell me if the output will have an unusually low voltage or high impedance characteristics? Pardon my ignorance but how would I go about measuring these specific to my Killerdac?


Reason being is that I have previously tried my Killerdac with a new Naksa 125 with a simple Alps blue passive device in the middle and the sound was very compressed with no bass at all. An obvious impedance mismatch.

An active preamp in the middle "buffered" out the mismatch but I want to use a Bent Audio AVC-1 device which uses slagleformers  (see link below) which may even be more of a mismatch.

http://www.enjoythemusic.com/diy/0513/bent_audio_avc_1_autoformer.htm


Any help in understanding the logic around whether this would or would not work would be greatly appreciated.





« Last Edit: July 29, 2016, 01:41:38 PM by matt200sr »

Offline matt200sr

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Re: Killerdac Output Voltage and Impedance
« Reply #1 on: July 29, 2016, 10:20:11 AM »
One thing I forgot to mention and Hugh Dean has just confirmed us the at the Naksa Zin is 28k.

Offline zenelectro

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Re: Killerdac Output Voltage and Impedance
« Reply #2 on: July 31, 2016, 10:41:02 PM »
I have a question regarding the output parameters of my Killerdac

Can anyone tell me if the output will have an unusually low voltage or high impedance characteristics? Pardon my ignorance but how would I go about measuring these specific to my Killerdac?


Reason being is that I have previously tried my Killerdac with a new Naksa 125 with a simple Alps blue passive device in the middle and the sound was very compressed with no bass at all. An obvious impedance mismatch.

An active preamp in the middle "buffered" out the mismatch but I want to use a Bent Audio AVC-1 device which uses slagleformers  (see link below) which may even be more of a mismatch.

http://www.enjoythemusic.com/diy/0513/bent_audio_avc_1_autoformer.htm


Any help in understanding the logic around whether this would or would not work would be greatly appreciated.

To use a Slagle Autoformer vol control it would need to be driven from a buffer after the killerDAC.

It's not clear whether that Pre amp has a buffer in it.

The KDac wants to see very high impedance load >50k if possible.

cheers

Terry

Offline omodo

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Re: Killerdac Output Voltage and Impedance
« Reply #3 on: August 02, 2016, 01:49:19 PM »
hmm, isn't it the opposite?... seems like the perfect scenario/situation to use one.

with the autoformer following the kdac, for every 3db of attenuation the reflected load is halved (e.g. for the naksa, 28k -> 56k), at -12db the naksa would be a nice easy ~200k load

http://www.intactaudio.com/atten_FAQ.html


Offline zenelectro

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Re: Killerdac Output Voltage and Impedance
« Reply #4 on: August 07, 2016, 03:57:35 PM »
hmm, isn't it the opposite?... seems like the perfect scenario/situation to use one.

with the autoformer following the kdac, for every 3db of attenuation the reflected load is halved (e.g. for the naksa, 28k -> 56k), at -12db the naksa would be a nice easy ~200k load

http://www.intactaudio.com/atten_FAQ.html

Yes that is correct....... mostly but in an ideal world with an 'invisible' transformer.

There are a couple of real world mechanisms that can make things less than ideal.

Transformers have core losses and require magnetization current. For every halving of the frequency, the core magnetization level doubles.
This becomes very prominent at frequencies below a few hundred Hz and once you get below 100Hz can be clearly seen (and heard).

It depends a lot on whether the transformer is a high impedance type or low impedance type.  Low impedance types are the most
transparent but at low frequencies especially need to be driven from a low source impedance.

High impedance types have generally a bit more 'colour' (distortion) but are much less dependent on driving impedance.

The second thing is that at low frequencies this increased core magnetization current will impose a load on the Killer DAC's high
OP impedance.

So the bottom line is if the autoformer is fairly high impedance, ie lots of windings it may work reasonably well but
it is unpredictable what the outcome is.

If you were seriously considering this approach I'd shoot Slagle an email and ask the question.

T