diyAudio

diyAudio (http://www.diyaudio.com/forums/)
-   Pass Labs (http://www.diyaudio.com/forums/pass-labs/)
-   -   Tricky little problem with Z4 component (http://www.diyaudio.com/forums/pass-labs/19181-tricky-little-problem-z4-component.html)

Buhl 19th August 2003 03:14 PM

Tricky little problem with Z4 component
 
Hi there !

This is a little embarressing, but when i ordered the parts for my dual bridged Z4, i couldent get fixed value 5 pF capacitors, so i ordered variable 5-15 pF. Fine enough, but how do I check i witch of the outer positions (the lowest 5 pF one) those trimmers has to be in ?

I have no scope to measure the square wave as mentioned by
nelson in the article, only a "standard multimeter that can measure volts, amps, resistance and diode function.

Can I do this without a capacitance-meter ?


Cheers !

Hans Houmøller

Netlist 19th August 2003 03:39 PM

Hans
You should definitely try to buy a scope.
As for the cap, only with a scope it will be possible to trim a square wave up to it's nicest shape.
You could also buy 2 10pf caps and solder them in series.
If you get some decent caps (silver mica) it will improve the sound as well. I'm not claiming I would hear the difference but a trimming cap is probably not the best sounding device to put in a feedback loop.
Without a scope, my guess is that it will be difficult to measure
the trimming position with such low values.
Maybe others know how to do this...

Greetings

/Hugo :)

Buhl 19th August 2003 08:58 PM

Quote:

Originally posted by Netlist
Hans
You should definitely try to buy a scope.
As for the cap, only with a scope it will be possible to trim a square wave up to it's nicest shape.
You could also buy 2 10pf caps and solder them in series.
If you get some decent caps (silver mica) it will improve the sound as well. I'm not claiming I would hear the difference but a trimming cap is probably not the best sounding device to put in a feedback loop.
Without a scope, my guess is that it will be difficult to measure
the trimming position with such low values.
Maybe others know how to do this...

Greetings

/Hugo :)



Thnx for the advice Hugo - Ill try and persuade someone with a scope to measure a squarewave for me. No harm will come to the amp or speaker though if operating for a short while in the 15 pF mode instead of 5 pF - just in the power-up period ?

Cheers !

Hans Houmøller

Nelson Pass 20th August 2003 07:37 PM

This is not a critical thing. When I want 5 pF, I twist 2
pieces of wire wrap wire (the teflon insulated kind) together
for about an inch.

eLarson 21st August 2003 01:15 AM

A teflon trimmer capacitor that anyone could afford! How cool is that?

Erik

Buhl 21st August 2003 03:10 PM

Thanx for the replys, but I actually came across 4 pcs. of 5 pF at my local electronics shop, that normally have everything but the partsI need, but in this case - they had what I couldnt find on the web......

Another thing, I very soon about to fire up my Z4 - can i run two boards supply from the unregulated supply in parallel ? Simply connecting board two to the same supply + and - as board one ?



/cheers !

Hans Houmøller


All times are GMT. The time now is 01:21 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright ©1999-2014 diyAudio


Content Relevant URLs by vBSEO 3.3.2