A quick PMC question

[admin_exported]

The port bungs on the DB1is, are they designed to stay in the speaker or are they removable?

 

[MattSPL]

That is part of the special acoustic absorbent foam used in all of PMC's transmissionline speakers and must not be removed.

It absorb's any unwanted mid and midbass frequencies radiated from the rear of the mid bass driver and only allows deep bass to pass through.

You will notice it flaps slightly when you play at high volumes : )

 

[Andrew Everard]

Indeed. Not port bungs at all.

 

[Anonymous]

Cheers, I thought as much.

 

[Anonymous]

MattSPL:
That is part of the special acoustic absorbent foam used in all of PMC's transmissionline speakers and must not be removed.

It absorb's any unwanted mid and midbass frequencies radiated from the rear of the mid bass driver and only allows deep bass to pass through.

You will notice it flaps slightly when you play at high volumes : )

Actually that's not quite true. The foam that you can see at the end of the transmission line is purely there to cover up the hole and prevent you seeing or putting things into the loudspeaker cabinet, it doesn't have any specific acoustic properties to speak of and is purely cosmetic. This is quite clearly highlighted by the fact that the end of the transmission line on the Fact8 and Fact3 speakers from PMC is a perforated metal grille instead of the foam cover.

However, there is a special foam lining that runs the length of the transmission line inside the PMC speakers that's purpose is to absorb the rearward radtion from the drive unit in the mid and mid-bass frequencies, this foam is a different composition to the one used at the end of the transmission line.

I hope this clears things up a bit.

Regards,

Chris.