The inputs on this commercial power amp has Balanced XLR inputs. They are the 3 prong connectors like on modern microphones. But there is also a barrier strip with 6 screws. (3 per channel). Each channel has GROUND, HIGH and LOW.
To connect a short distance cord with RCA plugs from a receiver preamp output, I know to use the GROUND for the outer shield, but do I use the HIGH or the LOW for the signal IN?
I know the XLR is used for long distance cables, such as the "snake" used by musical bands and theater systems. But I am not running that kind of system, and the receiver output is simply an unbalanced short run of cable (about 2 or 3 feet long).
I suppose I could just use the trial and error method without harming anything, but I thought I'd just ask and do it right.
The inputs on this commercial power amp has Balanced XLR inputs. They are the 3 prong connectors like on modern microphones. But there is also a barrier strip with 6 screws. (3 per channel). Each channel has GROUND, HIGH and LOW.
To connect a short distance cord with RCA plugs from a receiver preamp output, I know to use the GROUND for the outer shield, but do I use the HIGH or the LOW for the signal IN?
I know the XLR is used for long distance cables, such as the "snake" used by musical bands and theater systems. But I am not running that kind of system, and the receiver output is simply an unbalanced short run of cable (about 2 or 3 feet long).
I suppose I could just use the trial and error method without harming anything, but I thought I'd just ask and do it right.
Gareth's suggestion will probably work OK. If you experience any problem with hum or distortion, look for an adapter to convert between XLR's low impedance and your single-ended high impedance.
A family of such adapters is Shure's A95 series "Line Matching Transformers". The A95A or A95F may meet your needs, depending on the gender of your XLR connector.
Gareth's suggestion will probably work OK. If you experience any problem with hum or distortion, look for an adapter to convert between XLR's low impedance and your single-ended high impedance.
A family of such adapters is Shure's A95 series "Line Matching Transformers". The A95A or A95F may meet your needs, depending on the gender of your XLR connector.
This amp is strictly a power amp. I plan to get a mixer for it when I find one at a decent price. I dont really need a mixer, since I am using this for a home stereo, but a preamp appears to be needed, and even a small 4 or 6 channel mixer can and will provide that preamp.
On the other hand, maybe my receiver output will have enough preamp built into it (and I suspect it will). But I am aware that matching the impedense should be done. I knew they made such things, but I was not aware they could be purchased in the form of adaptors like these Shure ones. That should be real helpful.
I found out that the inputs are balanced 600 ohm. I am not yet sure what my receiver outputs in ohms. (Have to see if I can find a manual for it). I did however read about some of the (same brand) mixers that are often used with these amps, and they output 600 ohm balanced. Therefore that is a perfect match. One of those mixers, is a 6 channel unit which has 6 XLR connectors for microphones, but Two of those inputs also have a 1/4" jack, called AUX, and there is a switch to use either type (the XLR or the 1/4"). And there is also another switch to set either LOW or HIGH gain. So I'm guessing that those 1/4" inputs can be used to connect something with a high output, such as a receiver, or a DVD player or a Tape Player, etc. And I can only assume that this input can also be used for something like a guitar, when set to the HIGH gain position.
Until I get the XLR connectors I bought online, I cant do much, other than just patch things together. But yesterday I did connect the speakers and stick a direct probe into the XLR holes, connected to my audio generator. It worked like a champ, but I did have to turn the output up as high as it goes on that audio generator, which tells me that it does surely need a preamp.
But even with just a direct test lead jammed in the connector, there was no hum or unwanted noise, and I took it from 10cps all the way to
20Kcps, and it was clear as a bell. (At least from 30cps to 15Kcps). I dont hear above 15Kcps, and at 10cps it just made the speaker cones move and sound like a motor cycle engine.
This link PDF file is quite useful. But it dont specifically state what devices can be plugged into them. I know there are unbalanced microphones that have a 1/4" plug on their cord, and things like a guitar. But it does not specify if the preamp output from a receiver will match....
One question I have, is there some standardized output (in ohms) for things like the preamp output from a receiver, or the output from something like a DVD or Tape player, or even a small MP3 player? I assume all these devices have some sort of "standard" output impedence, or are they all different?
Most of the time I just hook the stuff up, and if it sounds OK, then I just use it. But I know this commercial equipment, with balanced inputs, is in a class of it's own.......
Impedances are guidelines. Not hard absolutes. Most (not all) equipment is remarkably tolerant. Commercial equipment is, typically, more tolerant than consumer equipment, if only because it will get harder use under a wider range of operating conditions.
Put another way, if it sounds good, and nothing gets hot - there you are.
There is little need to match impedances unless you need to maximize power transfer (for example, coax for radio equipment). Almost everything you run into with consumer audio equipment has hi-z inputs. The outputs are designed to drive those hi-z inputs (which is very easy to do as long as the outputs are lower impedance than what they are driving). The term for this type of signal is line level (as opposed to mics and guitars which can be much lower level). As you have discovered, professional audio equipment uses 600 ohm balanced lines in order to minimize hum and be able to handle longer runs of cable. Any preamp with RCA connectors for its output can drive the hi-z unbalanced input of your amp. If you want to use the 600 ohm balanced input, you need a preamp with that type of output of a converter, but the hi-z inputs (ie, RCA connectors) will work just as well in normal home use.
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.