A 'true' log response over the full range of perhaps 100dB is not really useful, because most of the time the gain is varied over a relatively small range. As many will have found out, this is rarely the case, and a pronounced 'discontinuity' is often apparent as the control is rotated.Īs with all pots used as volume controls, the first 10% of rotation causes a very large variation in level (essentially from 'off' to quietly audible). The theory is that between the two they will make a curve which is 'close enough' to log (or audio) taper. Unless you pay serious money, the standard 'log' pot you buy from electronics shops is not log at all, but is usually comprised of two linear sections, each with a different resistance gradient. A linear pot used for volume is quite unsatisfactory. In order to get a smooth increase in level, the potentiometer (pot) must be logarithmic to match the non-linear characteristics of our hearing. The volume control in a hi-fi amp or preamp (or any other audio device, for that matter), is a truly simple concept, right? Wrong. Extra cost doesn't necessarily get you an opamp that will sound 'better' than another, so use whatever you are most comfortable with. There are hundreds of different types, some outrageously expensive, others very cheap. The above isn't comprehensive, and is but a small group. LM4562 - One of the few that's actually better than the NE5532.NE5532 - Still one of the best audio opamps around.TL072 - FET input, cheap and cheerful, but they suffer an output polarity inversion if overdriven.Typical opamps that are commonly used for audio include. Some don't care for high loading (low impedances) and will show relatively high distortion, and others may be noisy. Differences are certainly measurable, but all standard opamps have response that's flat to DC.
Depending on your application, you'll use something cheap and cheerful (such as a TL072 for example), or you may want to go 'up-market' and use the LM4562, OPA2134 or something more exotic if it makes you feel better.ĭespite the many claims to the contrary, there are no opamps that will improve bass 'authority' (whatever that's supposed to mean), nor will they be bass shy, cause 'veiled' top end or any of the other rather remarkable claims you will see on the Net. Feel free to use the opamp of your choice in each case. No type number has been shown, but industry standard dual opamps are assumed for the pinouts.
Some of the following circuits use opamps. 2 - Further Ideas, Active Volume (Baxandall).1 - Better Volume Control ('Fake' Log Law).
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