DC-Protection (Tweaks)

by Bert @, Saturday, March 27, 2010, 10:57 (5142 days ago)

See picture and try to understand...

[image]

This schematic is just an example showing a passive line level crossover and how to block all DC flowing forth and back...apparently some amplifiers have problems if this DC "blocker" is not used.

Basically all switching amplifiers have this problem (NuForce as one example) but also tube amplifiers with an inferior bass amplifier connected (some plate amps but also commercial available integrated amplifiers) could have problems too.

Then DC is flowing back trough the tube amp's output transformers which could saturate them and loose transparancy...

So, if you do not have this extra capacitor in series with the signal and you do suspect problems (or if you are not sure) then please do add this extra part to protect you for possible problems.

The needed value depends on the input impedance of the bass amplifier (the lower the impedance the higher the value for the capacitor is needed).

Remember that this capacitor is basically a first order high-pass crossover, so if you do not want to loose quality and depth in the bass then be sure that the value is high enough (calculated 5 to 10Hz as -3db point usually works out well).

Basically this tweak should be used on all bi-amped systems...

Bert

--
BD-Design - Only the Best!

DC-Protection

by teigetje, Saturday, March 27, 2010, 21:04 (5142 days ago) @ Bert

Hi Bert,

Must be clear for everyone... What about the quality of the capacitor? Will a MKP capacitor do the job, or is a better quality capacitor necessary?

Greetz,

Frank

DC-Protection

by Bert @, Saturday, March 27, 2010, 23:18 (5142 days ago) @ teigetje

Hi Frank,

Must be clear for everyone... What about the quality of the capacitor? Will a MKP capacitor do the job, or is a better quality capacitor necessary?

Up to 300Hz even an MKT should do well (+200V DC type).

Bert

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BD-Design - Only the Best!

DC-Protection

by gary @, Thursday, April 01, 2010, 10:24 (5138 days ago) @ Bert

Hello Bert, are there other problems caused by this 'DC flow'? Regards Gary.

DC-Protection

by Bert @, Thursday, April 01, 2010, 14:38 (5137 days ago) @ gary

Hello Bert, are there other problems caused by this 'DC flow'? Regards Gary.

Besides the mentioned ones which are more related to the used principle for my designs I do read about switching amps that literary burn out subwoofers...

Bert

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BD-Design - Only the Best!

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