Noise floor of BeePre

[xjb123]

Hi, I have a question - my Foreplay III is dead quiet running into my 2A3 Paramounts driving 100db speakers. The BeePre, however; has a *very* slight 60Hz background hum coming through the speakers - not noticeable when music is playing, but detectable on silent passages with nearfield listening. Is this normal operation of the BeePre or could it indicate a wire routing problem with my build?

The hum is very slight and does not get louder if I turn up the volume controls and it is the same amount on both channels.  I tried disconnecting the input leads - so it is not a problem with my interconnects.  If I didn't directly compare it to my Foreplay III, then I probably wouldn't have even noticed the issue. So I'm just wondering if this is normal and expected from the BeePre circuit design or if there is a chance for me to improve it a bit...

By the way, the microphonics of the 300b are pretty crazy! Really different experience from the 12AU7 of the Foreplay. I'm going to try adding the recommended flask weights on top of the tubes to see if I can tame things down a bit, but in my opinion it's a small price to pay for the great sound of the BeePre.

[Paul Birkeland]

The BeePre is not quite as quiet as the old Foreplay, but there is certainly a way to improve upon things a bit.  Since you have the BeeQuiet, what would you say is the maximum amount you have the BeePre cranked up?  If there's some room in the attenuator, then you can add a resistor to each Paramount to pad down the input a little bit, which will reduce the apparent noise from the BeePre and also reduce the microphonics a bit at the same time.

-PB 

[xjb123]

Thank you for the great idea. I still have plenty of headroom so it should be no problem padding down the Paramounts a bit. Also thanks for confirming my suspicion the BeePre has a tad bit more noise compared to the Foreplay - I'm relieved I won't need to poke around inside the BeePre trying to track down the source of noise!

[Paul Birkeland]

If you let me know how high up on the controls is the highest listening level, I can help you determine the correct resistor value to add to the Paramounts.

-PB

[xjb123]

Hi Paul,

Can you please re-post your last response with the recommended resistor values and installation photo? I saw it last week, but then it seems to have disappeared since then! I want to make sure I install the new input resistors correctly in my Paramounts. (I'm trying to reduce input sensitivity by 9db.)

Thanks!
Anthony

[Paul Birkeland]

I'm on vacation and that image is on a machine at home, but here's the idea.  I lowered the resistance values a little bit as well IIRC.

[xjb123]

Perfect - Thank you!!!