Low volume from Fishman Loudbox Mini mic input, using brand new XLR cable and dynamic mic. Mic works just fine on instrument input using a Hi-Z cable so problem is not mik

Question edited for clarity and Capitalization.

Contact them direct and ask where their closest service centre is. Rechargeable items only last so many charge cycles.

Loudbox Mini Charge - Fishman

https://www.fishman.com > portfolio > loudbox-mini-c...
Rechargeable Battery Power (up to 18 hours); 60 Watts; 2 channels: Instrument & Microphone; Digital Reverb & Chorus; Bluetooth® 4.0 Connectivity.

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http://www.fishman.com/product/loudbox-mini

Are you trying to use the mic input on the back or plugging it into the instrument input on the front? If you use a low impedance mic with a quarter inch instrument input cord, you would need a transformer adapter to make the mic work on high impedance. Even if you put it on line in, you would still have to convert it. Only the XLR socket on the back will work on a low impedance mic.

Fishman iis you best bet http://www.fishman.com

You can download the user manuals, they do have a block diagram, but the scan is pretty bad.

It may end up the person looking at it is going to need to rely upon their general knowledge.

My own suggestion is to pull the chassis out so you can work on it while powering it. And then work your way through the amp with either a signal source plugged in at the input, and with high impedance headphones with test lead ends, go through each audio stage carefully. until the fault is isolated. If it is not caps or the rectifiers in the power supply, faulty ground connections to chassis or faceplate, a faulty 4558 is most probable. The headphone approach is the fastest way to address this last one. If a different series of preamp chip is used, a good source for the IC datasheets in general is Digikey http://www.digikey.com and parts too.

Greetings! Ok, your amp has an XLR (3-prong) Low-Impedance input on Channel 1 for a Mic. All the other inputs are 1/4" High Impedance inputs, which are for instruments and/or other High Impedance items including low quality High Impedance Microphones. The SM48S is a high quality Low Impedance microphone, so if you use it with a 1/4" plug, it will be in a High Impedance channel, and will be very LOW in volume in comparison with everything else. So, you must use an XLR (3 prong) cable from the Mic to the Channel 1 input on your amp. That will do the trick. Good Luck with your new amp and Mic!

You haven't told us what type mic you are using. If you are trying to use a condensr mic with this, you will need a preamp that supplies Phantom power to the mic. You haven't told us what cable you are using. Do check that you aren't using a condenser mic as there will be virtually no volume.

Does it make the noises at higher gains with nothing plugged in? If not, check your guitar cables and connectors.

You should be using Dynamic mics such as a Shure SM58. They go into the first FOUR channels and if there is excessive gain and distortion, push in thee Pad button below the connector for those four channels. Inexpensive consumer microphones used with some Karaoke home systems are not suitable for this unit. You should be using XLR cables on the mics (balanced lines). The Pad buttons reduce the gain by a fixed amount of -20 Db for mics that have too much output to be controlled by the gain controls right above the connector. Ideally those should be no less than 12 o'cloock for good signala to noise ratio. Additional channels beyond the first four do not have as much gain and they do not have the -20 Db pad option.

You should be using XLR to XLR cable, NOT a 1/4 inch cable. There is a problem of the 1/4 inch being the unbalanced version and is not compatible with this unit's input.

Use the XLR to XLR mic cable and it will work fine.

The cable you have would work for one of those cheap Karaoke machines...

Make sure you turn the Phantom power on the Mbox2 on as the Shure 87A requires it being a condenser mic.Make sure you use XLR mic cables. These are just things to check on.