Long interconnect - Bugle and Hagdac

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Long interconnect - Bugle and Hagdac
« on: 16 Dec 2006, 08:36 am »
Hi Jim,
Can Bugle and high-out on HAGDAC drive long interconnect around 5m to 7m ?
The other end would be integrated tube amp with 100K pot in the input.



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Re: Long interconnect - Bugle and Hagdac
« Reply #1 on: 16 Dec 2006, 10:12 pm »
Both of these machines have a very solid output drive.  The opamps make good line drivers.  I do decouple them from the cables a bit with 300 ohm series resistors.  This does two things.  First, it keeps the cable capacitance (for those long runs) off of the feedback, thus keeping the opamp unconditionally stable.  No odd loading glitches or slew rate limiting (a nasty form of distortion).  Second, it ends up rolling off any residually amplified RF.  The opamps are reasonably wideband and can push out MHz stuff at low amplitudes. 

Ok, so say you have 10 meters of cable, that's probably 1000pF load.  With the 300 ohm drive you get a high frequency rolloff of about 500kHz.  This is reasonable, as it has virtually no effect on the audio band with minimal phase shifts, yet tends to eliminate unwanted RF hash.

jh :)