Explaining the Pultec Low Boost

[craigmorris74]

I'm a novice that understands a little bit of passive EQ theory. For example, I pretty much understand how the high boost of the Pultec EQP-1A works. I can't wrap my head around how the low boost works, though.

I've read this page on passive EQ:
http://home.online.no/~jaeioluf/sound/eqpassiv.htm

To me the Pultec low boost looks nothing like what is described here. What I see is turning the pot clockwise routes the signal through the one of the boost capacitors to ground, which looks like it would cut the signal.

Any help would be appreciated.

Thanks,
Craig

 

[solder_city]

it cuts the *high* frequencies, which means a relative 'boost' of the low.

when the pot is turned down all freqs are cut equally, when the pot is turned up the high freq cut remains the same but the low freq cut is reduced. so its a relative boost.

does that make sense?

 

[SSLtech]

[quote author="solder_city"]does that make sense?[/quote]
It's "New Jersey Logic"!

-How lose are you to Englewood, by the way?

"Which Exit"? :wink:

:green:

Keef

 

[solder_city]

which exit? hee hee- thats a good one

keef i am near paramus, also in north jersey (like englewood) but further inland

 

[craigmorris74]

totally makes sense, solder city. Thanks for the help.

 

[tv]

While pultec has totally different bridged configuration, I suggest you read this explanation - it's related to "james" styled tone networks (first top 3 pictures, but it's james-styled, not a genuine james), it's layed out so simple you will soon "feel" the way those networks work.

http://www.thermionic.info/tonecontrols/tone_control.html


Additionally, here's the DIY lowdown on "battery pow(d)ered" tube stages:

http://www.diystompboxes.com/smfforum/index.php?topic=63479.0


So you'll be able to have a Pultec-in-a-soapbox :wink:

 

[craigmorris74]

Thanks for the links, looks pretty useful!