Removed speaker internal foam

[karatestu]

Hello, me again

Decided to take the internal foam out of my B&W P4 speakers. They are 2 way floorstanding transmission lines from 1996. The xover is one inductor in series with mid/bass (6.5" Kevlar) and 3rd order electrical high pass filter on the tweeter (25mm metal dome).

The foam came out quite easily, just a few dots of glue here and there. I have left the wool in the transmission line as I gather this is quite important.

I am definitely not putting it back in. The sound has tightened up a fair bit and I like it. A bit more detail also.

Stu

[karatestu]

Also after removing the foam and listening i have experimented by taking the ferrite core inductor on the mid/bass out of circuit. This is easy for me to do as years ago I removed the xover from the cabs and put them right behind my amps.

Well, I cannot say that it sounds brilliant without the inductor. There is too much mid frequency going on but that is to be expected with the two drivers summing too much in the mid. There is still bass but it is lower in the mix. I suppose a little less bass from these TL's is no bad thing but not this much less !

Doping the 6.5" Kevlar mid/bass would be the obvious thing to do now to bring the levels to my liking - who gives a feck if it's not the same as before , it is my ears that count not a graph.

Removing the foam is a winner though

Stu

[karatestu]

Not my image and mine are in darker rosewood finish.

Trying to get some Visaton tweeters in these is almost impossible as the tweeter cut out would have to enlarged and the Visaton have face plates which might not fit on the baffle.

stu

[Dr Bunsen Honeydew]

Just dope the bass drivers. You wont be able to steel line a transmission line, or seal the cabinets, BUT do an experiment for me stuff the port as full of socks and cloth things as much as you can and push the cabs further back to the wall. Mid range will still be forward though until you dope the bass cone.

[Dr Bunsen Honeydew]

Speaker foam is daft and I think is just put in automatically as it is convention to do it.

[karatestu]

Just dope the bass drivers. You wont be able to steel line a transmission line, or seal the cabinets, BUT do an experiment for me stuff the port as full of socks and cloth things as much as you can and push the cabs further back to the wall. Mid range will still be forward though until you dope the bass cone.

Ok, i will give that a go and put them right against the wall.

Stu

[karatestu]

Bit more messing about here.

I have pushed some smelly socks in the ports and reintroduced the LPF inductors for now. Have not pushed them back to the wall yet but will do once I have listened some more in their original positions.

I have 56 lbs (1 Bushell) steel weights used on the farm in the olden days to weigh produce on top of the speakers at the moment.

Bass is obviously a bit light as they are 40cm (16") from the wall but what is there is much less thick? or bloated if you like. I can feel the cabinets vibrating much more now than when the vent was open.

Going to move them back soon - after I have lifted the 56lbs weights off.

Anyway Doc, as far as not being able to steel line them - I will have a bloody good go. The top of the cabs are no problem as access is good through the mid/bass cut out. I can gain access to the very bottom through the old crossover cut out which I previously made bigger (many years ago). Crossover is no longer in there. The problem will be the transmission line part of the cab although I might be able to get access to some of it. Might even try blocking it from the top near the drivers with a steel plate (reversible) .

Stu

[karatestu]

How about blocking the port and filling the transmission line part with concrete poured in from the mid/bass cut out ?

Stu

[Dr Bunsen Honeydew]

go for it if you want. But remember concrete is wet, it will soak into the wood.

[karatestu]

go for it if you want. But remember concrete is wet, it will soak into the wood.

You are quite right of course and the thought did occur to me later, after writing the post. I work with cement (when added to sand, gravel and water = concrete) as part of my job. When bags of dry cement (usually a fine powder) are left for a while with exposure to moisture in the air, they eventually go rock solid (and I mean rock solid).

I reckon I could pour in a whole 20kg bag of dry cement in to the transmission line part of the speaker. That would result in a heavy speaker especially if the top part where the drivers are, are steel lined.

This idea probably reads as extremely wacky. I am nuts ? Probably

Might make a box out of MDF, fill it with dry cement and see what happens.

Stu