Gyraf Pultec finished (Shopping list included!)

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I checked out the Metas, still a little unclear as to the fequency points of the Gyraf schematic. Isn't there a formula for choosing cap values based on the inductor present in the circuit? The thing is, i'm very picky about what Hz I want, since i'll be using this every day in practical apps... i'd like to plan out which caps i'll need beforehand if possible.

Thanks!
 
formula for resonance:



?=1⁄ 2 ∏ ×√ LC
L in henries, C in farads

Your formula approach will not match your actual results, but it will get you in the ballpark.
Having an exact frequency is tough due to the Q of the circuit.
Pick your cap values by ear. It is faster than formulas and gives real world results.
cj

if you manipulate that, you get

C = 1/ 4 ∏²?²L

where frequency and inductance are known.
 
Gotcha CJ... i suppose i'll design the front panel for the values I actually want, then experiment with the caps to reach those exact values. I'm a novice at this, but that makes sense. Thanks!
 
No problem.
That method also alllows you to try different kinds of caps.
I found the square WIMA's to work best in equalizers.
Manley uses them also in the Massive.
cj
 
[quote author="cjenrick"]No problem.
That method also alllows you to try different kinds of caps.
I found the square WIMA's to work best in equalizers.
Manley uses them also in the Massive.
cj[/quote]

Thanks... i'll try the WIMA's, as I certainly trust the Massive's design.
 
two soldering points blew up!

and i dont know why, maybe the tube, or the bridge rectifiers...?

the two points are: A1 pin from the tube and negative pole from the 4700 / 25v cap.

now i change the rectifiers, the tube, and the cap
and the 380v rectifiers are nearest to the 350v


any other idea why two soldering points blew up? no voltage was connected!
 
You have to discharge it. Use a resistor instead of a short from + to - terminals. BE CAREFULL.

Depending on the schem you could include a 220k resistor across the terminals for automatic bleeding when the unit is turned off.
 
thank you for your help

im using the gyraf pultec schematic... ehem...
and my english isnt that good to understand what a terminal for automatic bleeding is :oops:

can you explain how whre i have to put the 220k res?

thank you very much!!
 
[quote author="Brizco"]i have to connect the positive and the negative pole of a 220u cap? right?[/quote]

more specific it should be:

I have to connect the resistor to the positive and the negative pole of a 220µ cap.

Then the cap will discharge slowly on it's own.

Greets
 
thank you for your patiance!

i made it and it works! :thumb:

i can let these resistors connected everytime?

i will go testing the unit tonight in my studio! yippie!! :grin:

thank you very much!
 
I was wondering, you guys are using shorting or non-shorting 2x6 switches on the pultec ???
 
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