Bottlehead Forum

Bottlehead Kits => Legacy Kit Products => Smack => Topic started by: Dwight on July 22, 2012, 05:09:42 PM

Title: Smack WOT Load Impedance (input impedance of the amp)
Post by: Dwight on July 22, 2012, 05:09:42 PM

Hello Dear Bottlehead friends

I own a Smack and it is a really nice headphone amp. The best tube headphone amp I did ever hear.

Is anybody hear who can tell me the load impedance (input impedance of the amp) of the Smack. I need to know it because I have a crossfeed circuit Corda Cross 1 from Meier Audio (Jan Meier). To set it up perfectly I need to know the value.

Kind Regards and Thanks in advance

Philipp

Title: Re: Smack WOT Load Impedance (input impedance of the amp)
Post by: Paul Joppa on July 22, 2012, 05:50:43 PM

Stock, original Smack has a 100K pot at the input.

Title: Re: Smack WOT Load Impedance (input impedance of the amp)
Post by: Dwight on July 22, 2012, 07:53:46 PM

Hello Paul

Thanks for the fast info. Doesn't the amp input circuit add impedance to the 100K from the pot?

Sorry if it is a silly question, I'm not a pro.

Actually it does not really matter anymore, because at the Corda Cross there is only one setting possible for amps with an input impedance greater than 82K and the Smack definitely belongs to this range. But anyway it would be great to know if there something else (except of the poti) that determines the total input impedance of the amp.

In the course of this I have another question belonging to the pot. Can I use other values for the pot? Which values are allowed?

Kind regards

Philipp

Title: Re: Smack WOT Load Impedance (input impedance of the amp)
Post by: Grainger49 on July 23, 2012, 12:21:12 AM

Philipp,

If the wiper of the pot feeds the grid of the first stage then the impedance of the input might change the 100k of the pot by 1-100 ohms.  In other words, inconsequentially.