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Hi guys,as I added 2 Deephemp subs to my junior 8xrs I’m thinking about stuffing or exchange the ports for something like a variovent. Perhaps anybody has some insight as I already saw some people here stuffed their ports with nerf balls. So here is my thinking:I think the ports deliver lower deep end which I won’t need with the duo subs but have a slight trade of in accuracy (?)So my ports can go, now sealing the ports completely would lead to lower efficiency (afaik) which I don’t want, on the contrary more efficiency would probably help my set amp to work, and sealed speakers are normally not a good match for low watt triodes (afaik again ^^)So I ended up with the question if just stuffing the ports with some kind of material (material suggestions are super welcome) is the best way to do this or if exchanging the ports for something like a variovent would be even better.So if anybody has an insight on all this especially on variovent and materials would be super helpful. Otherwise I will just go down the rabbit hole of variovents and try things out. I just don’t want to mess up the frequency response or impedance curve.So any insight is much appreciated, greetings Oli
Dynaco used fiberglass sandwiched between steel mesh.Firstly, the vented box will not give you lower bass. It will produce a higher bass peak, but actually roll off below the tuning frequency more quickly. A sealed enclosure will not have as high a peak but will roll off much more gradually, often balancing room gain. An aperiodic enclosure is a lossy sealed box, making the box seem larger to the driver since internal box pressure is reduced by leakage from the resistive port. On the return stroke, the port actually slightly resists the driver movement. If we stuff the port of the existing speakers, we are creating a hybrid between aperiodic and vented. This can be used to our advanced to tune the enclosure.I would start by stuffing the port completely to se how it sounds sealed vs. vented. I would then remove the stuffing and slowly stuff a bit at a time until you like the tuning.Another option is to cover the vent tube from inside the cabinet with a resistive fabric. A square of fleece is stretched over the sport tube and held in place with a rubber band. Listen to the result and add additional layers until you get the result you want.
Have you considered emailing Louis directly and asking him what he thinks?
I simply stuff the ports with large tennis balls I found in a pet store. The simple conclusion is that bass (mid-bass) is tighter and more defined while unstuffed is looser bass. As I use Rythmik powered woofers and subs, both servo, the bass below the omegas is very tight and defined. Stuffing the ports makes for a good match and much better sound in the low end to my ears. It has also seemed easier to blend the bass units with the mains than when ports are open........Pete (who is about to pack up my system this week for a move to WA )
Variovens are a cheap-ass way to turn a box sort of aperiodic. They work OK but rarely real well.To push a vented box towards aperiodic, one can start adding some sort of damping to the vent. I ususally use fairly dense open cel foam, but drinking straws, polyfulff, fiberglass (will work but might puff out glass fibres — a variovent is simply some fiberglass squashed together by a mesh on either side.) even an old pai rof wool socks can be played with. Start will a little and add more until things are right. If you can measure impedance you are looking to suppress the system resonance. There is also GM’s clik test (you’ll have to google that).dave
