RIGGED25 Posted February 18, 2007 Share Posted February 18, 2007 I'm thinking of purchasing a PA amp rated at 400wpc from a pawn shop for $200. One thing that struck me odd was the volume control, it's very sensitive. The slightest adjustment and it administers decibles one would hear at a concert. While I enjoy my music loud, I would like to have more control over the amount of sound that is blasted in my living room. This is the first time I've ever messed with pro equipment- is this normal? Thanks RIGGED Quote Link to comment Share on other sites More sharing options...
DrWho Posted February 18, 2007 Share Posted February 18, 2007 No, not normal at all... What kind of amp is it? There are a lot of crappy sounding pro amps out there... Quote Link to comment Share on other sites More sharing options...
RIGGED25 Posted February 18, 2007 Author Share Posted February 18, 2007 http://sanantonio.craigslist.org/msg/280250306.html The amp is made by Ross Systems. Here is the same exact one being sold on Craigslist. I hooked a cd player to the rca input and two Peavy speakers to the output. It just seem to go full throttle with the slightest adjustment. RIGGED Quote Link to comment Share on other sites More sharing options...
mas Posted February 18, 2007 Share Posted February 18, 2007 A little more information such as the make and model might help, but regardless of that, the gain controls should work essentially like 'any other' amplifier. They should rage from essentially 0 to maximum. They might possibly vary in terms of being logarithmic versus linear, but not knowing to what amp you refer it is hard to say. To the best of my recollection, the Crown and QSC amps all have linear gain controls. Sight unseen, it sounds like the one you are looking at may have a problem with the pot (potentiometer) gain control. This might be a very easy fix or it may indicate some other problem. You might see if you can have a local shop familiar with this type of amp take a look at it prior to purchasing it. If you need additional info, if you can provide more information regarding the make and model, I am sure that some of the folks here can help provide more information that might help you in your decision. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted February 18, 2007 Share Posted February 18, 2007 The controls you refer to as a "volume control" are actually gain controls. They differ slightly in operation. The pro amps are meant to be used with a device acting as a "pre" amp, thereby controlling the output of the amplifier. The gain controls set the voltage that is required in the amplifier inputs to achive full output. In other words, the actual voltage gain say 40x, is set and you cannot change that. If the gain controls are turned up, a small signal in the input will produce a large signal. In practice, you want as much voltage in the "pre" driver stages, this minimizes noise entry into the cabling, and being amplified. Having a preamp that can put out a good bit of voltage in the output stage is a good thing. You can turn down the gain control in the pro amplifier, enjoy reduced chance of noise and hum, and a maximized signal to noise ratio. Be forewarned that some pro amplifiers require more voltage ( into the inputs ) to produce full output than a normal home amplifer. This can be fixed with a device like the ART "cleanbox" sold at parts express. It converts the output of normal home gear to a larger ( still line level, but hotter ) signal needed to drive some pro amps. Also keep in mind that these pro amps sometimes have different connectors for the input ( XLR ) and outputs ( speakon ) than normal home equipment. There are many people here that can answer your questions. I own a QSC PLX II 3102 professional power amp, and have it hooked to my Marantz AVR, as a preamp. The Marantz controls the output of the QSC, and the gain controls are set at a static setting, they do not change. Quote Link to comment Share on other sites More sharing options...
michael hurd Posted February 18, 2007 Share Posted February 18, 2007 GUYS, read a little..."I hooked a cd player to the rca input and two Peavy speakers to the output. It just seem to go full throttle with the slightest adjustment." Yes it will, because the CD player is putting out probably 1volt RMS in the outputs.... there is no preamp stage, and yes this is normal..... Quote Link to comment Share on other sites More sharing options...
mas Posted February 18, 2007 Share Posted February 18, 2007 As Mike has mentioned, you need to use a pre-amp with any standalone amp (he said, making a very generic statement). A stand alone CD player is not sufficient to drive the unit in a manner that you are accustomed, and as Mike also said, the pre-amp is used to adjust the gain while the amplifier's gain controls are generally not touched once set. Assuming all is functioning correctly, you need a pre-amp that will interface with the amp with the appropriate levels and interface (balanced/unbalanced). Quote Link to comment Share on other sites More sharing options...
RIGGED25 Posted February 18, 2007 Author Share Posted February 18, 2007 See, I told ya'll I hadn't messed with pro amps before. lol Time to search for a pre-amp. Thanks for the wisdom fellas. RIGGED Quote Link to comment Share on other sites More sharing options...
michael hurd Posted February 18, 2007 Share Posted February 18, 2007 OK, my bad..... I replied before the picture went up.... in the thread, just took another look, and while I was typing up a response, there was a link posted with pictuers. What you are looking at is a powered mixer, not just an amplifier. As such, it takes signals from all devices, combines them into a common bus and amplifies them. You may need this if you are a weekend warrior in a garage band, but not for home, I would pass on that. Quote Link to comment Share on other sites More sharing options...
RIGGED25 Posted February 18, 2007 Author Share Posted February 18, 2007 OK, my bad..... I replied before the picture went up.... in the thread, just took another look, and while I was typing up a response, there was a link posted with pictuers. What you are looking at is a powered mixer, not just an amplifier. As such, it takes signals from all devices, combines them into a common bus and amplifies them. You may need this if you are a weekend warrior in a garage band, but not for home, I would pass on that. Now that you mention it, It will be located in my garage. I'm gonna try my hand at electric guitar at the tender age of 40. Quote Link to comment Share on other sites More sharing options...
mas Posted February 18, 2007 Share Posted February 18, 2007 I think we all replied thinking it was a stand alone amplifier. If you want a guitar amplifier, you should be able to pick up a good dedicated head for $200. I guess it all depends what you want to do with it.... Quote Link to comment Share on other sites More sharing options...
colterphoto1 Posted February 19, 2007 Share Posted February 19, 2007 Go ahead and get it, but get the guy to throw in that snazzy grill-guitar amp-stand! That's meant for PA, not directly playing guitar, it'll work but have that solid state sound that is not so popular with guitarists. Unless you desire an all in one that you can plug mic, keys, gtr into to really iritate your neighbors, I'd look for a used tube guitar rig. I keep thinking I will take up piano, my fingers are fast enough if I can learn the notes.... Michael Quote Link to comment Share on other sites More sharing options...
RIGGED25 Posted March 24, 2007 Author Share Posted March 24, 2007 Finally got the darn thing out of the pawn shop and I must say, it freakin rocks!!!! I hooked it up to the preamp and I'm only able to turn the dial up to 8 O-clock. I turn it to 9 and the wax in my ears melts. lol Now if I can only remember(after boozin it up) to keep the volume under 9. Very happy in Houston. RIGGED Quote Link to comment Share on other sites More sharing options...
NJbob Posted March 25, 2007 Share Posted March 25, 2007 turn the amp gain pots down untill you get full cotrol with the preamp volume control, then you get the most out of both units Quote Link to comment Share on other sites More sharing options...
Guest " " Posted March 25, 2007 Share Posted March 25, 2007 Sometimes the gain on these amps are not flexible enough. You can buy a passive pre-amp for a few hundred bucks or make one using a wall mount volume control that uses and autofomer. i made one for 10 bucks, that added some flexibility to one of my past projects. There was no detectable noise intorduced by the passive pre-amp. Wire it simular to the attached. Most of the wall mount autoformers have connection labels for input and output L and R, and use screw mount connection points. Quote Link to comment Share on other sites More sharing options...
Arky Posted March 25, 2007 Share Posted March 25, 2007 turn the amp gain pots down untill you get full cotrol with the preamp volume control, then you get the most out of both units Could someone explain this further for me. Quote Link to comment Share on other sites More sharing options...
NJbob Posted March 25, 2007 Share Posted March 25, 2007 you said you hooked up the preamp, start out with the amp gain all the way down, then turn the preamp volume all the way up SLOWLY turn the gain up on the amp untill its verry loud. then use the the preamp volume to what ever volume you like Quote Link to comment Share on other sites More sharing options...
Arky Posted March 25, 2007 Share Posted March 25, 2007 If that response was for me i'm not the OP. I assume that will work the same with my outlaw processor? Thanks Quote Link to comment Share on other sites More sharing options...
RIGGED25 Posted March 25, 2007 Author Share Posted March 25, 2007 Thanks for the advice. I find that with the amp gain at the 9 O'clock position gives me plenty of juice. It's amazing how much "fuller" the sound is with 400wpc. I know the dangers of playing with such high power can do so I make sure not to turn the preamp past the 9 O'clock position. RIGGED Quote Link to comment Share on other sites More sharing options...
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