by bordonbert Mon May 29, 2017 12:51 pm
It's line level Syn666, but only in the sense that it is "a line" coming out and returning, but that doesn't really tell you anything. I could just say "Line level" and leave it at that but it would give you absolutely nothing real to work with in a practical sense.
What is their definition of line level? It isn't necessarily the same as everyone else's definition. There is no standard definition other than to say we use 1V as a reference and quote our own choice for line level with respect to that. That's what decibels are there for but that is too deep for most non-tech people to want to grasp naturally. The idea is simply that an instrument level signal is taken in at the front end where it goes through a few amplifying and processing stages. It then goes through the Fx Loop section at a higher level than at the input so it is less sensitive to noise which will get added. We would always want to get signal levels up higher where we can for that reason. My guess would be that the power amp wants to see about the level I quoted from the manual for full output so it is set to that to match. And as you can now guess, there is also no standard as to the input level for a power amp.
Likewise, instrument level is not defined anywhere, it just means the signal of that particular instrument. As a guide, guitar output can be anything from a few 10s of millivolts to about 1V.
And we haven't even considered the impedances the signal comes from and goes into which will change all levels drastically. Now that IS getting more technical than most people understand.
The best we can say is that if you put in 71mV from your guitar, (H&K's specified nominal input sensitivity), you would get 316mV out if you select the Clean channel with Boost off and keep everything else centred, and the amp would expect to see the same 316mV back at the return. Call those line level if you wish, they are within the ballpark to be considered standard as levels at preamp outputs and loops. These levels are all very rough as you have oodles more gain on tap and controls to take levels down where necessary. For example the Return would accept signals up to just over 5V before anything inside overloaded and you couldn't turn it down internally to prevent it.