Plug port of Dynamo 500 with tennis balls?

MartinLogan Audio Owners Forum

Help Support MartinLogan Audio Owners Forum:

This site may earn a commission from merchant affiliate links, including eBay, Amazon, and others.

mpitogo

Member
Joined
Jan 4, 2015
Messages
8
Reaction score
0
Location
NJ
A free Dynamo 500 sub came with some speakers I recently purchased. I put it in as SUB2 in a 7.2.2 Marantz 7009 system opposed to SUB 1 a Polk DSW microPRO 3000. Audyssey calibrated while plugged with tennis balls and both combined help give more depth to the sound. Without taking any measurements, balls in sounds much better and less boomy than with it ported. While its not a Dynamo 700, is there any harm in plugging the ports? Also, because of dual SUB, the volume of both have been tuned well below 50% and shouldn't be over driven as a single sub would be. I know a dense foam plug would be better but the tennis balls were something quick easy and perfect fit with just the right amount of friction.

Any thoughts or concerns? Has anyone tried this? I was thinking could have been better to pay the $200 difference and gotten the Dynamo 700 but not sure if they would have given me the $500 credit for the Dynamo 500 because it was a bundled deal.
 
Sealed is much better than ported. If the woofers can withstand the extra power and extra excursion required to still have a decent bass response, then it should be OK to block off the ports. But I would be careful turning it up to max...
 
Generally, a "ported" sub allows for lower frequency response with the possible trade off of speed and articulation of its operating bandwidth. It, in theory should be more "efficient" requiring less power to produce the same output level at lower frequencies.

I'd check with ML but it doesn't surprise me that blocking the port produces a cleaner, better defined sound. If you can live with this attenuation at the bottom of the frequency range and ML indicates it shouldn't be a problem, go for it. It's a better mousetrap.

GG
 
Thanks. The Polk DSW microPRO (10" sealed with a passive radiator rated 1000w RMS and 2000 peak) is doing most of the heavy lifting while the Dynamo is next to the listening position and providing support and more coverage. While playing at moderate volumes there's very little discernible stress. Will ask ML but not sure they will respond positively. The two Dynamo looks to be designed differently, the 500 is ported and only rated 125w RMS while the 700 is rated at 300 and true acoustic suspension.
 
Be careful what you call "sealed," as a woofer with a passive radiator is just a small step away from a ported box.
 
Be careful what you call "sealed," as a woofer with a passive radiator is just a small step away from a ported box.

A yes true. At least I didn't call it an acoustic suspension.
 
Sealed is wrong term, bass reflex and passive radiators are called "tuned".
 
Aren't acoustic suspension boxes also tuned? But mainly for a specific volume because enclosure volume/driver interaction affects frequency response?

Anyway... the Dynamo 500 with tennis balls... I think its worth experimenting. It came free and I purchased a 4 year extra protection plan (total of 7 years) for an extra $19.00. I purchased an SPL meter for my iPhone 6 but I don't think its worth the .99 cents its decent for test tones of full range speakers but not so good for bass as it doesn't give the correct readings (proly iPhone 6 mic is not up to it). The Polk was setup using its own calibration (PRO - Polk Room Optimization) and both the ML and Polk together where finally setup with Audyssey XT32. So far the sound from the ML is a bit more balanced, before, I had too much boom. For 2 chan listening I toggle between sub on and sub off but both cases with Audyssey dynamic EQ set to L/R bypass to the ML Motion 40.
 
"Tuned" is used for a resonance tuned suspension where as sealed is more or less matched to driver suspension but this is just playing with words, I'm sure we all in this forum know and understand these principles :cool:
 

Latest posts

Back
Top