I just bought a 2 channel Xtant 202M amp rated at (50x2 @4 ohms) or (100x2 @ 2ohms) or (200x1 @ 4.) I am running at 4 ohms 2 channels, so my gain should be set at 14.13V per channel, right? Ok, so when I do that, I get the right channel dialed in just right, and the left channel is at 13.46V. Is it normal to see a .5V difference between 2 channels? There is selectable input gain by moving jumpers at (-20,-10,0,+10,+20), and the adjustable output gain with the usual potentiometer. The i/p gain is set at +10, which is what the manual says the default setting from the factory is.
I can't really hear any difference, but I just want to know if this is normal or if I should I send it back while I still can?
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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."
Yeah, I think that is normal, at least from my experience. Set at the highest number, so that one channel doesn't go into clipping at full volume. Just for the helluvit, switch the RCA input wires and see if the difference remains at the same channels. Another thing, try a variety of frequencies if you have them available, that correspond to the type of speaker the amp is powering...and find the freq that provides the highest number. Set with that one to be on the safe side. But I recall 50Hz being the loudest when I adjusted mine.
As far as the input jumpers go, does your manual give you any details about why the setting should be changed?
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Build the box so that it performs well in the worst case scenario and, in return, it will reward you at all times.
Thanks for the ideas. As for the manual, it's out in the truck, so I'll post what it says in the morning when I get a chance to try switching the RCA's. I did set it as you mentioned, with the higher channel at the 14.13, and man, it sounds great, but as I said I just want to be sure.
Thanks,
Matt
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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."
O.k. I got off my lazy a$$ and got the manual, and here's what it says on the input gain:
Input sensitivity is adjustable in 10dB steps via the Input Gain Select Jumper located above the Balanced Input Mode Jumper. Each of the 5 jumper positions correlate to a specific range of input signal levels. The chart below details the relationship between the jumper position and input signal level
Adjusting Input Sensitivity
Input Jumper Signal Level
-20dB = 10 to 17 Volts
-10dB = 3 to 8 volts
0dB = 1 to 3 volts
+10dB = 300mV to 1 volt
+20dB = 100 to 300mV
The amplifier is shipped with the input gain set at the +10dB position. If you do not know the output signal level of your head unit and you want to change the factory setting, simply move the jumper to the +20 dB position to increase the gain. Move the jumper to the -, -10, -20dB positon to decrease the gain.
The input circuitry operates similar to a line driver by increasing the signal level when placed in the +10 and =20 postions. The following chart illustrates this function:
Input Voltage Multiplying Factor
Input Jumper Multiplying Factor
+20dB = 10
+10dB = 3
0dB = 1
-10dB = .3
-20dB = .1
(i.e. A head unit with 300mV output with input jumper @ +20dB = 3 Volts input)
The input stage may be over-loaded by a high level signal if the input gain is set too high. If this should occur, simply reduce the input sensitivity setting.
Whew! Sorry for the long post - just didn't want to miss anything. I do have the Balanced Line Input Enabled. The head unit is an Alpine CDA-7893. It is advertised as a 4 Volt sub pre-out (yeah I do know it won't really put out 4 V untill it's almost at meltdown) and I really don't know what the other 2 pre outs are rated at. How can I test this? Just probe the center and sheild of the RCA? This amp is connected to the Front pre out. I included the subs pre out also as this info also pertains to my 121m sub amp. Also, in the last paragragh from the manual above, when it says that the input stage may be overloaded - how would I know if it's overloaded or not? Clipping?
Thanks again!
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You'd better get me out of this lord... or else you'll have me to deal with. -- Hunter S. Thompson "F.A.L.I.L.V."