Bottlehead Forum

Bottlehead Kits => BeePre => Topic started by: rockpassion on February 08, 2016, 03:11:35 PM

Title: Wire for External Capacitor
Post by: rockpassion on February 08, 2016, 03:11:35 PM

Hello All,

At some time in the future I will be trying some Russian Capacitors in my BeePre.  Boy are these puppies big.  Anyway, I plan on mounting them external to the BeePre box.  One of the capacitors I could probably fit, these are the coupling capacitors. So, will I or should I use a shielded wire when mounted externally.  The capacitors could be as much as 18 inches from the BeePre.  I am going to try and keep the distance to about 6 - 9 inches if possible. 

I will be replacing both the coupling caps and the output caps.  Any help would be appreciated.

Thanks

Title: Re: Wire for External Capacitor
Post by: Paul Joppa on February 08, 2016, 03:33:00 PM

The only caps in the signal path are the output caps (10uF). What "coupling" caps are you referring to?

Title: Re: Wire for External Capacitor
Post by: rockpassion on February 08, 2016, 07:20:01 PM

Paul,

The two large 10uf Caps  between the 300b sockets and the Selector/Volume controls.  I was told these are coupling caps.  If these are not coupling caps what are they called.

Thanks

Title: Re: Wire for External Capacitor
Post by: Paul Joppa on February 09, 2016, 11:18:45 AM

Well, they are the output caps - I suppose you could call them "output coupling caps". So, what are the other caps you are talking of?

Title: Re: Wire for External Capacitor
Post by: rockpassion on February 09, 2016, 02:22:39 PM

Paul,

The two large caps on top of the balanced output and rca connector at the back of the unit.  They are also 10uf 250 V rated.

Thanks

Title: Re: Wire for External Capacitor
Post by: Paul Joppa on February 09, 2016, 05:02:09 PM

Ah! Thanks, now I understand.

Those caps by the XLR are not in the circuit unless you are using balanced output. They exist only to make the impedance-to-ground the same for + and - of the XLR output. If you ARE using those outputs, you want the caps to be as identical as possible to the output caps.

Title: Re: Wire for External Capacitor
Post by: rockpassion on February 09, 2016, 05:43:34 PM

Paul,

Thanks for the info.  On the other caps should I be using a shielded wire since the run length could be pretty long or will normal wire be ok. 

Additionally, I will probably buy an enclosure for the Caps so the terminals are not exposed to an accidental touch. 

Thanks

Title: Re: Wire for External Capacitor
Post by: Paul Birkeland on February 10, 2016, 01:47:20 PM

To make this as safe as possible, using a deeper base and keeping the caps inside the chassis is your best option.  If you short out the cap lead carrying the high voltage, considerable damage to your preamp (and your body) could occur.