Author Topic: OJ Squeezer replacement Jfets???  (Read 1179 times)

Evad Nomenclature

OJ Squeezer replacement Jfets???
« on: October 27, 2008, 01:18:28 AM »
Hey guys.

Was wondering if you thought about replacing the n5457 jfets in the OJ squeezer recipe with MPF102's.
I realized just as I was about to start building that I didn't have any, so I did pop them in (the 102's)  It works... but it seems like there isn't *that* much compression (when maxed)
No real squashy sound at all... there's definitely an audible compression but it seems pretty minor.  Notably though the compression was more pronounced on the bridge pickup of my strat when testing.

I don't really have any knowledge of the difference between one trans to the next... I just know how to put em in, what numbers they are and what my ears tell me so far. ^_^
Just wanted to know if you thought I should definitely get a different tranny than the 102's
yep!
Anyway thanks!
« Last Edit: October 27, 2008, 01:58:51 AM by Evad Nomenclature »
Evad Nomenclature III
Master of Dolphin Technologies

Zben3129

Re: OJ Squeezer replacement Jfets???
« Reply #1 on: October 27, 2008, 07:09:59 AM »
Hey guys.

Was wondering if you thought about replacing the n5457 jfets in the OJ squeezer recipe with MPF102's.
I realized just as I was about to start building that I didn't have any, so I did pop them in (the 102's)  It works... but it seems like there isn't *that* much compression (when maxed)
No real squashy sound at all... there's definitely an audible compression but it seems pretty minor.  Notably though the compression was more pronounced on the bridge pickup of my strat when testing.

I don't really have any knowledge of the difference between one trans to the next... I just know how to put em in, what numbers they are and what my ears tell me so far. ^_^
Just wanted to know if you thought I should definitely get a different tranny than the 102's
yep!
Anyway thanks!


Couple things. One is that the OS is very subtle by nature. You may be getting the full effect, as its subtle. You might not even know when its on sometimes, but you will sure know when its off  ;)

The second is that I use mpf102's a lot, and there is definitely a difference in some applications. I am about to use horrible terminology that I know isn't right that someone will correct me on when they read this, but it seems mpf102's have less "gain" than j201, 2n5457, 2n5485 etc. However, it looks like the JFETs are used to set some form of varying bias thingy to the opamp (I am assuming this is how the compressor works), so as they are not in the signal path I can't imagine much difference between 102's and 5457's in this case.

Just a possibly correct answer to hold you over till a smart person reads this  ;D

Zach

Gus

Re: OJ Squeezer replacement Jfets???
« Reply #2 on: October 27, 2008, 08:41:03 AM »
you need to look up the spec on the parts and compare the specs.
  With fets sometimes you need to select in the same part number brand and batch.  Look for the vishay app notes look at R.G.s site, google fets .................................................

mac

Re: OJ Squeezer replacement Jfets???
« Reply #3 on: October 27, 2008, 08:48:57 AM »
MPF102 did not work ok for me.
On the other hand, BF245A worked just fine. Also 2SK246 and 2SK117.
I guess that 102s higher Vgsoff is the problem.

mac
« Last Edit: October 27, 2008, 08:51:36 AM by mac »
mac@mac-pc:~$ sudo apt-get install ECC83 EL84

Evad Nomenclature

Re: OJ Squeezer replacement Jfets???
« Reply #4 on: October 27, 2008, 09:53:47 AM »
Got it guys.
Searched on NTE and the only thing I came up with was the nte457. 
Ran out and grabbed some early, popped them in and boom, compression!

Thanks muchos!
Evad Nomenclature III
Master of Dolphin Technologies