Bottlehead Forum

Bottlehead Kits => BeePre => Topic started by: Alonzo on June 29, 2018, 06:00:01 PM

Title: BeePre output questions
Post by: Alonzo on June 29, 2018, 06:00:01 PM
Okay, so it's time to change out some of my equipment (just cause it's been sitting comfortably too long).  So I have music playing (Bluesound to Gimby DAC to BeePre to Stereomour) and I start to unplug some of my equipment.   At the BeePre, when I get to unplugging the RCA's from my SS amp (Schiit Vidar) the Stereomour gets louder.  So I do the normal thing and plug it back (volume decreases), unplug (volume increases).  I repeat this with the Vidar inputs to all of the BeePre outputs ( I have 3) and it's the same.  The Vidar is 47K input impedance, is that driving down the output of the BeePre to the other outputs since they are tied together?  I do not have a balanced output, 3 unbalanced instead.  Anything I can do to fix this?
TIA,
Alonzo
Title: Re: BeePre output questions
Post by: Paul Birkeland on June 30, 2018, 05:20:17 AM
The output impedance of the BeePre is the upper leg of a voltage divider with the components it drives. 

The output impedance of the BeePre is about 600 ohms (603 when I last measured one), so we get:

BeePre driving Stereomour is a 600 ohm resistor in series with a 50K load, this causes 0.1dB of signal loss.

BeePre driving Stereomour (50K) and a Vidar (22K) in parallel will cause 0.33dB of signal loss.

There isn't anything to fix in this situation, this is just the way things work. 
Title: Re: BeePre output questions
Post by: Alonzo on June 30, 2018, 03:22:12 PM
Thanks for the lesson Paul.  Luckily there's plenty of range left on the volume knob.
Alonzo