Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Quickie => Topic started by: aragorn723 on March 21, 2014, 02:06:11 PM

Title: Quickie gain setting
Post by: aragorn723 on March 21, 2014, 02:06:11 PM

Hi,

Would it be possible to add a switch into the quickie that would allow gain changes on the fly?  I want to get better control of volume, but be able to switch between amps without unsoldering anything (in case I need the gain later).  Is this something easy to do?

Dave

Title: Re: Quickie gain setting
Post by: Paul Birkeland on March 21, 2014, 02:07:57 PM

This can be done by switching a pair of resistors in ahead of the volume pot, but it requires an extra switch and hole in the chassis.

Title: Re: Quickie gain setting
Post by: aragorn723 on March 21, 2014, 02:33:55 PM

Paul,

i'm guesing a dpdt switch would work for this?  My only concern in doing this would be degrading the sound, would it have a significantly negative effect?  This would mean one set of inputs and 2 sets of outputs-1 set of outputs would be un-padded, and the other set would have a resistor on each?  (just signal, not ground, right)?  Just wanted to make sure I got this right.  Would both left and both right wires go to the volume pot?

Dave

Title: Re: Quickie gain setting
Post by: Paul Joppa on March 22, 2014, 06:47:43 AM

You can place a resistor between the RCA jack and the selector switch. 100K gives 6dB reduction, 300K gives 12dB - to give you an idea of the range. That way, no new switch is needed.

Title: Re: Quickie gain setting
Post by: aragorn723 on March 22, 2014, 01:15:53 PM

Paul,

The reason I was thinking of adding another switch was to be able to switch gain on the fly (i.e. for future ability to adjust with different amps, or to adjust for different input levels (the macbook and a cd player have very different output levels).  Maybe 6 db is enough since volume is logarithmic?

Dave

Title: Re: Quickie gain setting
Post by: aragorn723 on March 23, 2014, 03:18:15 PM

What resistor wattage is needed for this?  I was thinking of using vishay-dales, like the ones in the kit..  Thanks

Dave

Title: Re: Quickie gain setting
Post by: Paul Birkeland on March 23, 2014, 06:44:11 PM

You need more than 1/1000th of a Watt. 

Title: Re: Quickie gain setting
Post by: aragorn723 on March 24, 2014, 10:54:55 AM

that should be easy to get, i'm guessing 1% tolerance is ok?

Title: Re: Quickie gain setting
Post by: Paul Birkeland on March 25, 2014, 06:33:50 AM

1% is good, 5% is probably OK.