Resistors and preamps

I'm building the 312 preamps and I was wondering if I have to use 1/4watt 1% resistors or if I could use 2% without any problems?

maybe the 2% tolerance will get it closer to that "vintage" sound???

I'm a complete newbie when it comes to this stuff....I basically can solder pretty well and follow directions.

What role does the tolerance play in sound and functionality?

I'm building the 312 preamps and I was wondering if I have to use 1/4watt 1% resistors or if I could use 2% without any problems?

Click to expand...

yes unless it's stated otherwise like in 48v resistors for example.

the tolerance is how close to the actual value the resistor will be - 2% is still pretty good. Most consumer electronics use 10% or 5% - 1% should be dead on for every single unit in the batch - 2% is close enough for me, considering most of my stuff has 5%.

http://www.aikenamps.com/ResistorColorCode.htm for reference...

Are you building the op amps themselves, or just the support circuit for something off the shelf?

A bunch of the 70s British gear that I've seen naked has %2 metal film (4 band color code with a RED tolerance band) which I'm assuming are probably +/-100ppm or worse. I take this as justification to use a lot of modern metal film resistors with the same specs in the gear I build. The Dale CCF07 series, for example. Mouser sells them really cheap. I think they're made with basically the same composition as they were two or three decades ago.

To answer the question, %2 should be fine for most, if not all, of the support circuitry. If you're wiring up stereo pairs and want them to be identical then I would use %1 resistors for the input pad (or anything else pretaining to balanced input) sensitivty switches, the feedback network, and parts of the discrete amp sections. If you don't care about .25dB-.5dB of error here and there then just use %2 (or even %5) throughout. One thing to keep in mind is the lower the resistor value, the more of an effect that tolerance is going to have.

Above all, just make sure your phantom power application resistors are 0.1% (buy precision or get a meter good enough to measure from a batch of %1) for good common mode rejection.

Some of the old timers used to play games with different resistors, using their differences in temp coef to keep things stable, so you can outsmart yourself sometimes. But this is probably rare. I mean how many times do you see a mix of resistor types? The only time I have seen it is in those discrete VCA's, made by the guy to your left.