What ?

If you're talking about a soundcard. Check the voltage rails +12v,-12v, +5v & -5v and also check any coupling capacitors on the soundcard itself, ie capacitors between the outputs of the soundcard and the soundcards own amplifier IC.

No soundcard. Talking about output on Roland MT-32 older old one 823364 serial number.
Sorry looking that this is emulation thread.

HiroSK wrote on 2023-11-16, 18:24:

Hello, I have old model 823364 without headphone output. When connecting headphones to outputs it is very quiet and only with active speakers on maximum volume it is relative loud. It is OK? Shouldn't be loud also on headphones? Volume knob control is still on 100 - maximum value...

Hey, Hiro-chan. The MT-32 is a very quiet synth, one of the quietest in terms of output volume I've owned. However I don't recommend plugging headphone into output, that would be extremely loud @ 100 volume.

If plugging headphones in isn't giving volume, have you tried routing the MT-32 audio into a sound card and seeing what the levels are like, or something similar?

I went looking for a schematic and found the first edition here on vogons MT-32 Service Notes 1st Edition

If caps C1, C7, C11 &or C16 have degraded that would also cause low output volume.

This appears to be normal behaviour- the original MT-32 was designed to be connected to the line input on an amplifier, mixer or tape recorder. When directly connected to a passive device such as a set of headphones, the maximum output volume will be very dependent on the impedance of the connected device, and would usually be too quiet for acceptable listening.

Connecting the MT-32 through a headphone amplifier should resolve the issue.