7A - mid speaker moves like crazy

vernalbogneris

I've recently bought some 7A's. I'm not sure how old they are, but they have a single fuse. My question is this: The middle speaker really moves a lot, particularly when playing sound with very low frequencies (eg. an outdoor recording with some wind noise), much more than the woofer. Could it be that they've been modified and/or they're not sending the right frequencies to the right speaker? I doubt this since they don't sound especially strange -- not as bass heavy as I would like perhaps, but nothing obviously odd. (I'm using a Yamaha HTR-6190 amp.)

Just thought I'd pose the question nonetheless. Those mid speakers REALLY move a lot.

Nightfall

The bottom speaker is not a speaker, it is a passive radiator and the PR does not move like the MW.

agfrost

As nightfall says, the radiator doesn't move too much; it does in response to the movement of the mid woofer. As a test, gently press inward on the large radiator--you'll see the MW push out at you (and slowly return toward its resting place). When there's bass energy in the music (at healthy volumes), that MW will in fact be moving quite a bit.

Here's a clip of Lasareath blasting the ever-loving snot out his 1.2TLs which should look a lot like what you're seeing: http://www.youtube.com/watch?v=rHHLKERU0wo

TNHNDYMAN

Also could be the source material. Some turntables I've had can send some wicked rumble thru the woofers if you don't use the low cut filter...

westmassguy

agfrost wrote: »

As nightfall says, the radiator doesn't move too much; it does in response to the movement of the mid woofer. As a test, gently press inward on the large radiator--you'll see the MW push out at you (and slowly return toward its resting place). When there's bass energy in the music (at healthy volumes), that MW will in fact be moving quite a bit.

Here's a clip of Lasareath blasting the ever-loving snot out his 1.2TLs which should look a lot like what you're seeing: http://www.youtube.com/watch?v=rHHLKERU0wo

+1^^^^^^^^^
Check for air tightness. Press in on the passive radiator. If the driver returns to it's regular position in less than 3 seconds, you've got an air leak.

cnh

As mentioned the MW is the only "active" bass driver in that speaker. As such, you'd expect a LOT more movement from it than the Passive Radiator beneath it. Be CAREFUL NOT to CLIP your amp!

Weak bass could be:

1. You're a BASS HEAD, and normal bass sounds weak to you.
2. That Yamaha is not the most powerful or best receiver to power a set of 7s with.
3. There is actually leakage, as described above. In which case you need to reinforce the seals on the speakers to return the sealed integrity so that the PRadiator can do its job.

Only you can know which of the above is causing the problem. In the case of 1 and 2. The problem DOES NOT lie with the speaker.

Good Luck!


cnh

Msabot1

Make sure the wiring is in phase...a simple goof that happens sometimes!

boston1450

Welcome to Club Polk & enjoy those wonderful speakers - play around with your bass control & see if you hear much difference & put your ears to the test & tell us what ya think - there are lots of us here that enjoy the 7's ENJOY

vernalbogneris

Nightfall wrote: »

The bottom speaker is not a speaker, it is a passive radiator and the PR does not move like the MW.

Huh. How about that, eh? Thanks for the explanation.

westmassguy wrote: »

+1^^^^^^^^^
Check for air tightness. Press in on the passive radiator. If the driver returns to it's regular position in less than 3 seconds, you've got an air leak.

I'll give that a try as soon as I get home. Thank you (and agfrost) for the suggestion.

cnh wrote: »

Weak bass could be:

1. You're a BASS HEAD, and normal bass sounds weak to you.
2. That Yamaha is not the most powerful or best receiver to power a set of 7s with.
3. There is actually leakage, as described above. In which case you need to reinforce the seals on the speakers to return the sealed integrity so that the PRadiator can do its job.

I'd call myself a medium Bass Head. I'm not a techno/hip hop guy, mostly rock and experimental, jazz, african, reggae. My previous speakers were -- or are, just need to get a woofer fixed up -- my beloved Paradigm Titans which I bought circa 1995. They certainly were a bit more punchy in the bass department.

When I tested these 7A's in the used stereo store, I used an older less powerful Yamaha -- probably c. 2002 vs my 2008-ish HTR-6190. They sounded more bassy then, and they weren't snugged into a corner or anything. That amp was new enough to have HDMI but old enough to have actually bass and treble knobs. I don't trust digital interface tone controls!

Msabot1 wrote: »

Make sure the wiring is in phase...a simple goof that happens sometimes!

Definitely phased correctly. I'm quite careful about that, and I've been at others' homes and noticed by the sound that their speakers were out of phase. Not a bad tip though, thanks.