Resistors, do I really need them?

Koda · 12113

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Offline Koda

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on: October 28, 2009, 05:50:57 AM
Besides the great sound, some of the things that I like about the Quickie would be that it has a pretty simple design and low parts count.
Those features helps me understand what each individual component contributes.

My next modification is to install transformer volume controls. What is the function of the 220 ohm carbon comp. resistors before the volume pots (also, they are not ahown on the schematic) and can they be eliminated when the TVC's are put in place?

And what about the 470K metal film resistor to ground on the output, can that go too?
If not, would changing it out for something else have a positive efffect on the sound?

Any other changes that come to mind for improving the Quickie? I have the chokes in place, as well as NOS tubes and Auracaps on the outputs... after the TVC transplant I want to install everything in a new case to match my other components.

  As always, suggestions are not only welcomed but encouraged. Thanks, K.



Kevin Erickson


Offline Paul Birkeland

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Reply #1 on: October 28, 2009, 07:29:48 AM
The 470k resistors at the outputs need to be there, otherwise there is nothing to stop the output side of the cap from drifting (you will get a spark/noise if you removed this resistor, powered on the Quickie, then plugged something into the output).  These resistors don't have much in the way of sonic impact IMO.

The 220 ohm grid stoppers are implemented as a preventative measure against oscillation.  You could probably get away without having them, but they do little harm being left in.

Just out of curiosity, which TVC's did you grab?

Paul "PB" Birkeland

Bottlehead Grunt & The Repro Man


Offline Koda

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Reply #2 on: October 28, 2009, 08:45:56 AM
Paul,
Thanks for the clear answer on the functions of the resistors, it sounds like they should stay in the circuit as is.

The TVC's I have are the Supermalloy 23 step models from DIY Hifi, they have the gray housing and not the models with nicer looking polished stainless steel cases... but I would think that both types sound about the same.

I also have the remote control for them, it takes 12 volts so I am thinking about using 12 volt sealed lead acid batteries for the preamp. Would 1.2 volt NiMH's be powerful enough to replace the D cells?
http://www.diyhifisupply.com/node/341
http://www.diyhifisupply.com/node/177

Kevin Erickson