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Haufe RK-736 transformer and Vout dacs
Haufe RK-736 transformer and Vout dacs
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Old 21st July 2014, 02:24 PM   #1
terranigma is offline terranigma
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Default Haufe RK-736 transformer and Vout dacs

Hi guys,

I purchased this transformer for use at Vout of DAC. According to seller it was 750ohm 1:1 transformer. I recently found its datasheet which specifies its impedance as 5K ohm @ 1 khz. I wonder if this higher impedance value degrade the performance of DAC (say AK chip with ~120ohm output impedance).

Datasheet attached. It is German.
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Last edited by terranigma; 21st July 2014 at 02:33 PM.
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Old 21st July 2014, 03:09 PM   #2
Ken Newton is offline Ken Newton  United States
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Quote:
Originally Posted by terranigma View Post
Hi guys,

I purchased this transformer for use at Vout of DAC. According to seller it was 750ohm 1:1 transformer. I recently found its datasheet which specifies its impedance as 5K ohm @ 1 khz. I wonder if this higher impedance value degrade the performance of DAC (say AK chip with ~120ohm output impedance).

Datasheet attached. It is German.
The 750 ohm load specification you mention (which I did not notice on the datatsheet) probably refers to the driving and load impedances which the tramsformer's design has been optimized for. That assumes, that the driving amplifier will not experience performance degradation when driving an 750 ohm load. In general, the higher the load impedance seen by an Vout stage of an DAC, the better. Raising the load impedance tends to decrease harmonic distortion.

The 5K ohms @ 1KHz specification may be the primary load impedance with the secondary open, indicating the core inductance as seen in to the primary. The working primary load seen by the DAC's Vout pins will equal the load on the secondary side of the transformer in parallel with the inductive reactance of the core - ignoring the parasitic impedances.

Last edited by Ken Newton; 21st July 2014 at 03:13 PM.
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Old 21st July 2014, 08:10 PM   #3
terranigma is offline terranigma
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Quote:
Originally Posted by Ken Newton View Post
The 750 ohm load specification you mention (which I did not notice on the datatsheet) probably refers to the driving and load impedances which the tramsformer's design has been optimized for.
750 ohm was seller's claim. I acquired its datasheet later that showing an impedance value of 5k which I'm not sure what kind of specification it is. I see everyone suggesting 600 ohm 1:1 transformer for voltage output DACs then I purchased this one according to seller's sketch. Probably it is a reasonable fit for my needs for reasons that you mentioned.

DC resistances are low and casing is not so small. These may indicate for something good too.

Seller's sketch is flipped. It is showing two windings at secondary but they are primary windings according to datasheet (0.5+0.5:1.07).

Thanks.
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Last edited by terranigma; 21st July 2014 at 08:34 PM.
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