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I picked up two of these mono kits.they look simple as all hell to assemble. now, anyone care to recommend a different opamp or other parts?looks like its a socket style system so you can pop them in/out w/o any soldering.http://www.velleman.be/fr/en/product/view/?id=8897I'm thinking two of them together in a dual mono setup.I'll either design a step up VR for the 10v requirement, or I'll just use 18v.any thoughts ?
its just another excuse to spend time in the basement burning my fingers.
Quote from: Nick's Picks on March 02, 2008, 07:42:28 AMluckily, the opamp supplied can be replaced...and I've all ready got the replacement picked out.less gain, but much better. Gain in an opamp circuit is set by the resistors/pot in the feedback loop. The opamp itself does have a maximum gain, dependent upon frequency, which is listed in the specs as "gain bandwidth" or GBW. But any better opamp you go to will almost certainly have better GBW than the one in the kit. There is also the issue of headroom, but that is mostly a function of the power supply voltage, and secondarily the ability of the opamp to be driven to its rails.Apart from that, the only considerations are quality of the components (read: replace those caps) and especially the quality of the power supply. If you intend to run this off a battery, you need to create a virtual ground reference. That may be what a couple of those resistors in the circuit are doing, it's hard to tell. Otherwise, you need to construct it. Assuming your intended load is 1Kohm, a voltage divider with two 10Kohm resistors, and filter caps from + to virtual ground to -.Next, you will probably want to add a small value cap in the feedback loop, something like 10-100pF. Also, you should have filtration very close to the opamp's supply pins, I typically use a 0.1uF film cap. I don't know if one of the electros on that board is a power supply filter or not.If you want to get really fancy, a single channel opamp usually has a pin for DC offset adjustment . . . I typically use dual opamps and live without it. A good opamp's offset should be small enough so as to not cause trouble.After that, you could replace the trimpot with a more useful pot . . . something that mounts on whatever chassis you select. The circuit will need to be shielded to be quiet. I would add an impedance balanced output as well.As for people that think all opamps sound like crap . . . I find it amusing that they think they can DIY a circuit with 4 transistors and beat a TI or AD chip that has 40 . . . I mean, sure there are people who can build an excellent 20 transistor discrete stage, but those usually aren't the people saying bad things about opamps . . . especially since such circuits are often discrete opamps.
luckily, the opamp supplied can be replaced...and I've all ready got the replacement picked out.less gain, but much better.
again, your showing your cluelessness.
ok, you guys are ruining this for me.the chip replacement I have planned is the NJM5534I think it will just drop into place ?