It's generally a good idea to pull needed stops out all the way in order to supply sufficient air to reeds so that they don't sound flat. If your harmonium is loud that is a function of it's overall design. DMS and BINA harmoniums are much louder than Surokars or Paul & Co. which have have breathier softer tone. This is partly because of the way Calcutta reeds breathe and also because the Delhi style harmoniums tend to be much more air-tight. If your harmonium is too loud - trying experimenting with laying different materials across the top to muffle the sound. I've known folks to get varying results using sheets of rubber carpet liner material across the top. It's definitely not good to play with the stops half-closed because by restricting the passage of air you are placing more stress on your bellows and seals than they were designed for. Peace, KD
Well I think this will depend on the make of the harmonium you are useing, I use a Pakrashi scale cahnger it doset require any pull or push its just ready, but as you sai correctly Delhi made instruments are louder.
If you dont pull out the stops completely and try to reduce the volume by adjusting the stops. Two things will happen for sure in any harmonium: Most importantly- Tuning of the harmonium will go flatter by a few cents. This means if the harmonium is tuned on A-440, it might not sound on it with stops partially opened. Secondly some of the air stops in the harmonium also provide air to the drone reeds. If full air is not supplied to it, then these will also sound flat and sometimes may not even produce any sound. By the way.. what model do you have? If your model is with a cover like the delhi models are, then perhaps you can use the cover itself on the top half folded to reduce the volume. Otherwise the best thing is a towel. Though this will make the sound more heavier.