I've got an OLD pair of JBL L40's - I want to plug the port. (1 Viewer)

[John Pine]

I doubt anyone else will admit to still using these "dinosaurs" but I'd like to experiment with the "low bass" response. What material do you suggest for these (front-ported) speakers? Any downside to plugging the port?

 

[Kerry Hackney]

John, toy rubber balls work well or even Nurf footballs. There is no harm in experimenting with plugs. You should see less bass extension but the remaining bass may be somewhat better controlled. There is no way it will harm the speakers that I am aware of.

 

[John Garcia]

Try an old CLEAN sock rolled up. I tried some foam that was not in there tight, and it got blown out.

 

[John Pine]

Thanks for the suggestions guys! I'll try it out and post my results!

 

[Tom Brennan]

John---There are lots of people into old JBLs, a cult one might say. They have many virtues depending on the model. Go to www.audioheritage.org for a website dedicated to the history of JBL and Altec-Lansing speakers. There's a message board there too. This is IMO the best audio site there is.

 

[John Pine]

Tom: Thanks for the great link! I only wish the forum had a search function.

 

[John Pine]

OK guys I got them plugged. I think I really like the change! The bass is not boomy but nice and tight now. I have noticed that now I have to resist the urge to turn the bass up though. To be expected it's also changed the "color" of the upper bass and midrange sound. Mid-range and vocals are a little "warmer" now. The only thing that I don't like is I can tell it's put more stress on my new Yamaha RX-V530. After an hour or so of listening at -25 & -20 levels I can tell my Yammi is running warmer than before. It's not hot, but definitely warmer than before. I would think that's because a port speaker is easier to drive than a sealed one. I had both of these speakers re-coned last year, I guess we'll see how good a job they did.

 

[John Pine]

Problem came up this morning! While I was listening to SRV at concert level(-20 to -15)I noticed a faint buzzing coming from the recessed speaker connection posts on one of the speakers. The buzzing was following the kick bass part so I'm almost certain it's an air leak. Any suggestions on a material to seal it "air tight"? At this point I have to ask again if this is safe for the speakers?

 

[Kerry Hackney]

I have used a product from Home Depot made by FrostKing. It is a "rope caulk" that comes in a roll. It stays pliable, is not adhesive like tube caulk and is in general very easy to work with.

I am curious why your receiver is working harder to drive the speakers now vs ported. Same drivers, same crossover. There may be a change to system impedence curve due to the alignment but if anything, i would think the impedence would be less demanding??? Hopefully, a "guru" will chime in and straighten me out.

 

[John Pine]

Kerry: Thanks for the "caulking" suggestion, I'll pick some up tomorrow. I know it's not my imagination, the receiver is running very slightly warmer. I don't know much about audio physics but I thought a sealed "acoustic" unit was harder to drive than a ported one. Maybe someone will clear it up for us.