Bottlehead Forum

General Category => Technical topics => Topic started by: mcandmar on August 07, 2016, 12:01:55 PM

Title: Theory question: OP transformer grounding
Post by: mcandmar on August 07, 2016, 12:01:55 PM
Quick question i have been trying to find the answer too but cant seem to figure out the right key words to search for.

Take for example the S.E.X circuit where one end of the primary winding is connected to the cathode resistor and capacitor.  vs most other circuits where this connection is going directly to ground.  What are the pros and cons of each approach, i assume one or the other puts the cathode capacitor inside the current loop for the output transformer?

Cheers,

Mark

P.S. Any updates/teasers on a possible S.E.X. replacement?
Title: Re: Theory question: OP transformer grounding
Post by: Paul Joppa on August 08, 2016, 06:57:08 AM
Your assumption is correct.
Title: Re: Theory question: OP transformer grounding
Post by: mcandmar on August 09, 2016, 10:42:45 AM
Is there a name for this type of circuit, or is this a patented PJ design as i have only seen it done in your amps?

Cheers,

Mark
Title: Re: Theory question: OP transformer grounding
Post by: Paul Joppa on August 09, 2016, 04:22:27 PM
It goes back to Western Electric amps of the 20's, and is called by some the "WE connection." Here's a web page that Lynn Olson put together some 15 years ago.
:

http://www.nutshellhifi.com/library/Rosetta_Stone.html

Title: Re: Theory question: OP transformer grounding
Post by: mcandmar on August 10, 2016, 12:29:22 PM
Very interesting, i have found a few more examples as Western Electric layouts. Amazing to think all this was designed almost a century ago.  I have tried it on my quickie headphone amp and it does sound different connected to the cathode resistor/capacitor, not entirely sure what i am hearing at this stage, but it is different. More testing needed..

Thanks again,

Mark
Title: Re: Theory question: OP transformer grounding
Post by: Paul Joppa on August 10, 2016, 02:01:01 PM
Quote from: mcandmar on August 10, 2016, 12:29:22 PM
... Amazing to think all this was designed almost a century ago.  ...
In the twenties and thirties, airplanes and radios were the highest tech inventions around, and attracted the brightest minds. I think a lot of great ideas come out then, and some of them fell by the wayside when the "best and brightest" turned to computers for technological excitement.

My two cents.