Tuning bass reflex port

[beamnet]

Oh, there must be a hundred threads covering this, yet a half hour search did not come up with anything.

So i'm lazy and open a new thread

I am making a big tube amp. Needed something to test it on and bought two speakers for $20

They are old philips speakers, unmistakably from the late eighties, by their looks.

They sound pretty decend.

They are a little bright now and then, but still..

I listen to them witg a +6dB gain at 70hz on the equalizer.

That way it performs good.

Now there's a large diameter vent directly behind the driver. It's covered with cloth.

At large Basses, the cloth vibrates and wit an amplitude of at least 0,5 cm

Can i tune the ports for deeper/stiffer bass? Will removing the cloth help?

The speakers state "Power monitor 100"