Quote:
Originally Posted by Sword in Hand
So Paul, let me completely understand what you're saying... by asking more questions.
Example 1:
Let's say I sent a keyboard signal, that was extremely hot going into the pre, and I turned the pre input and output levels to a nice level. The pre in and out meters are comfortably in the green, but I still hear distortion. Is this potentially damaging the pre/transistors?
If the input and output meters are not showing red - there shouldn't be distortion. If there is distortion then this isn't a great amp and/or it's being overloaded internally without telling you on the meters? If you have reduced the input level to a legal value (i.e. meters show green), then normally it shouldn't do damage - however with the distortion you describe, something somewhere is suspiciously unhappy. I would worry about this :-(
The only way to be sure if you are damaging the amp is to compare the output level from the keyboard with the specified max input level quoted for the mic amp.
Quote:
or
Example 2:
Let's say that the keyboard's output is lowered to a comfortable level. I then turn the input gain to where the input meter is pegging the red, and the output trim is still metering in the green. Is this potentially damaging the pre/transistors?
No this should be ok. It is now clear that what you call an input meter is in fact an internal intermediate level (maybe the output level of the front end amp). In other words you can clip the output of the actual mic amp (within the box) and then reduce it with the trim after the event and end up with a distorted signal even though the final output is not overdriven? I despair - what is the use of an output trim after the mic amp if the mic amp itself has already saturated?! If this is so it's a bad and confusing design, but you shouldn't be able to damage the amp by clipping the output of the first mic amp stage. The key here is that you have had to increase the gain to get the input red light(?) - so the input level must be within the expected legal range?
Quote:
or
Example 3:
Same as #2 except, the pre's input gain is in the green and the output is pegging the red. Is this potentially damaging the pre/transistors?
No - this definitely should be ok. It shouldn't be possible to damage the amp by clipping it's final output.
A word of advice - with this amp leave the output trim flat out (and never reduce it) and adjust the mic amp gain to get the required output level. If the amp had a proper gain trim (rather then just a volume control after the mic amp before the output), none of this confusion would have ever occured.