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Messages - Guitarist

#1
Hello Gerry man. Howard M. Berlin's "Design of Active Filters: With Experiments" is a good book. It will give you a good understanding of filters and expand your knowledge of clever ways of using them. It covers analog filters based on the 741. These days other opamps such as the TLO72 will yield even better results. Knowing this will also give you a better understanding of using digital filters. Keep in mind that filters are't just tone controls, and can be used for envelope shaping, amplifier control, even control of other filters, or for that matter even control of lights. From there, your imagination can take over. It is remarkable what effects you can make with creative use of filters. Have fun.
#2
Amplifier Discussion / Re: Laney Pro-Linebacker PL100 Twin
September 27, 2010, 07:39:31 PM
I'm with DJPhil, You can try to clean them. Often times with older pots, cleaning just isn't enough, you have to replace them. If you can open them, you may be able to bend the wiper a little to apply more presure but if it is scratchy after cleaning it likey needs replacement.
#3
Preamps and Effects / Re: what exactly is a preamp
September 27, 2010, 07:09:30 PM
You have three basic types of amplifier. Where you draw the line is a little arbitrary but this is the idea. You have:
Pre amp
IPA Intermediate Power Amplifier
PA Power Amplifier
With audio, IPAs are not necessary. Neither is power transfer. With modern electronics, for audio we are concerned only with Voltage transfer. Hence, matching impedance is totally unnecessary unless you are making a telephone system with miles of wire.
So, given that we are talking guitar amps, the Pre amp purpose is to raise the voltage of the source (in this case a guitar pickup) to a leval useful to the Power Amp.  We have then raised the Voltage but have not yet given the ability to provide current at the voltage to develop useful power. It is easier and cheaper to add equalization and effects at low power so manufactures alway put equalization and effects in the preamp. It could be added in the power amp but would result in unecessary expense. Now that we have adequate voltage and all our equalizing and effects, we need power. So, we feed the output of the Pre Amp to a Power Amp. The Power Amp usually does not increase voltage but at unity voltage gain (ie no increase in voltage) adds the ability to supply current sufficient to drive a speaker (Typically 4 or 8 Ohm) If you try to drive a speaker with the output of a Pre Amp, the Pre Amp will be unable to supply the current to maintain the Voltage and hence the Voltage will drop and little or no sound will come from the speaker. The final Pre Amp stage may even overheat and destroy itself. This is why we have both Pre and Power Amps. Intermediate Power Amps are typically used in Radio where not only are we transfering voltage but indeed power.
#4
Preamps and Effects / Re: guitar mixer schematics help
September 27, 2010, 06:51:11 PM
This is really easy to do. You need only a follower with three resistors to the input. Each guitar or bass connects to one resistor and that is it. The question is do you really want to. If you do that, each guitar connected will contribute to feedback and noise unless you turn the volume down on each one that is not currently in use. It may be altogether easier to continue with your abc switch. If I can figure out how to post a schematic, and you still want it, I will draw one up and there you go.