Hiss on laney A1

I would check C37 & C38. If one is loose or bad connection, there will be 100/120HZ noise.

I am no expert about such things but the electric guitar pickups work with steel strings, wouldn't work if the strings weren't steel - the pickup is a coil of wire and the vibration of the steel string generates an output in the coil the amplifier can work with.

The pickups of the acoustic guitar are presumably glorified microphones that would usually work in a similar fashion to the above, by generating an output but if they are active devices they will need a power supply in order to generate an output, something a standard amplifier input will not provide.

An active device either needs an independent power supply to make the device work like a radio needs a battery or the device will create the output by varying the current flow of the voltage applied across it.

Bad connection? Loose fittings? I used to get a crackle from my amp when I turned the volume or balance knobs. A quick spray of WD 40 down the shaft after removing the knobs fixed it.

If possible, use MORE gain from the guitar and LESS at the input of the passport system to get better signal-to-noise ratio.

Some hiss at high gain settings is normal. If you get objectionable hiss at 1 o'clock settings of gain, that is too high. Electronics has noise that is "statistical" in nature due to physics that we can't get around in design. Most hiss is created in the preamp area and swapping tubes in the first stage might help. By varying the volume controls and observing the level of the hiss, we may be able to analyze the offending staage of amplification. ALso turning up the treble controls will increase the hiss, as it is mostly in the higher pitches.

It sounds like somehow the pre-gain is very high while the volume or post-gain is very low. Try turning the volume high on the effects unit and the gain low, and don't have the amp volume too low either.

If this ties to a keyboard, make sure the keyboard and this are BOTH plugged into the same receptacle. You should send a higher level from the keyboard (turn volume up to around 70% or so) and use less volume at the input gain of this amp. Use more at master volume if the amp has one if needed. If the hiss is there with NO input cables plugged in and input gains at 50%, that is objectionable, the amp probably needs servicing. Unused channel gains should be clear down.

Make sure the master volume is turned up and the inout gain is down some.

All of the electronic devices suffer from the statistical noise within the amplifying components. Keeping the inour gain down some tends to limit the gain where the hiss is most sensitive, that is the high gain in the "front end" or preamp section.

A "ton" is not a MEANINGFUL measure of the loudness of the hiss.

A meaningful measurement would be the Db relative to the normal program material.

Test with no devices plugged into it as the preamps in guitars can create hiss too. The hiss should be barely perceptable at 5 feet from the amp.

If trim controls or gains are set near maximum, HISS is normal as electronics generates a thermal type noise.

If gains are set in normal operating area, the noise SHOULD be minimal.

Other sources of interference like nearby radio transmitters, welders, arc lights, etc. can create noise.

Start with ALL gains turned down and find which if any cause the noise to be unacceptable.

MAKE SURE all power to this and ALL the other connected equipment come from a single receptacle to avoid ground loops.