Horning Eufrodites - help needed with boomy bass

These have been around for 15 years or more and they work.

MB Quart had them as well as Audio Concepts

http://www.gattiweb.com/images/dynaudio/variovent_data.pdf

Tom

Hi,

So further positioning trials have somewhat improved the boominess.
And then, following Duke's post, I stuffed towels into the woofers' ports and I think this is making an important contribution to the battle!
For sure, right now, I can listen to music and enjoy it.
Big step forward. Thanks a lot.

What material would be best to use for an appropriate stuffing?

Other than that, from the positioning trials I came to spread the speakers even further apart from each other which opened up the sound stage and brought in a lot of space between the instruments. So way to go for this collateral benefit.

Tom, how would you reckon the Variovent be installed in my speakers?
It seems that large speakers require a few of those. How would that be done, any idea?

Thanks a lot to all the contributors so far. It's helping a lot.

Regards from Paris.

Well there is a Paris Kentucky and I reckon the word reckon is used there many times a day as it is in Louisville, that other French name sake.

I'd have to ponder the variovent and how many and what size. That's probably more than just drilling a random hole I reckon. As far as material to place in the vent well that would be long hair sheep's wool.

Before you do any other mods you must mechanically ground your speakers. And after doing so the speakers and the grounding components will take a few days to settle in. There are several other enhanced grounding methods that could be applied to both the cabinet and the driver. All of which would improve performance and void the warranty. Tom

Tom, you reckon right, neither Kentucky nor Louisville is where base is.
Can you educate my layman self on what the mechanical grounding elements are?
Regards from the city of lights.

"What material would be best to use for an appropriate stuffing?"

I'm not sure. With the towel, what you did was add flow resistance to the port; you made it significantly harder for the low frequency energy to get out of the port. If the towel was filling the port completely, then you added a lot of flow resistance; the more airspace around it, the less flow resistance.

My suggestion is, trial and error. Bigger towel, smaller towel, see which is a step in the right direction. Maybe open-cell foam (when you "haaaaah" into the foam, can you feel the heat form your breath on the other side? If so, then it' open-cell foam), again I can't tell you how completely you should fill port, or how deep the foam should extend into the port.

Long-hair wool was mentioned. That's great for stuffing a transmission line, but imo the intention here is different - we're trying to reduce low bass output, rather than facilitate it. Unless you packed it tightly into a cloth bag and crammed it into the port - then, it would be behaving more as flow resistance than as gentle damping along the length of the line. Imo you can accomplish the same thing for less money with tightly packed polyester batting or fiberfill.

The variovent is itself a flow resistance device, and one with a rather strong flow resistance, maybe more like packing the port tightly with a towel than like open-cell foam. You'd want to turn the cabinet almost into a sealed box, with the only pathway between the inside and outside being through the variovent (which is dense fiberglass compressed inside a plastic housing that has airflow holes in it).

Duke