Mismatched speaker performance (refoam consequence?)

[jharris]

Hi all,

I refoamed my first pair of speakers.. I'd have preferred a cheap set to practice but I got a pair of Ohm C2s on a budget and this was my trial by fire. Used a SimplySpeakers kit with their adhesive and directions.

I used less adhesive than recommended on the first woofer and also mis-centered it relative to the cone by maybe 0.5mm-- however, I used their hand-centering recommendations and also played a 30hz tone to help center everything before I glued it to the outer basket. Everything appeared good with test tones and music--there is no obvious buzzing or rubbing.

The second woofer was done with more adhesive and I was more careful to center it at first. Same technique with a louder 30Hz tone, as I was confident this worked and would make nasty noises if I did it wrong. No nasty noises happened and I believed both had gone well.

End result-- both speakers sound beautiful but the second has obviously more bass than the first. Alone, I'd say the first needs tweeters set -3db to match 0db setting of the other. But together, the high-frequency volume seems the same while the woofer is what's lower in the first speaker I worked on.

There is no obvious "rubbing" or buzzing. Any idea what could have gone wrong that could be blamed on my refoam?

I was pretty careful to get the speakers back in with red wire to positive and black to negative. This sounds like a phase issue but it probably wasn't in this case

 

[z-adamson]

One woofer may be a bit more compliant than the other.

Wait till they are both broken in and the compliance may even out between the two.

I am assuming that the problem is not amp/preamp/source related.

 

[jharris]

Thanks z-adamson! This was noticed when testing each speaker using the same amp/channel for testing purposes. Using my primary (DIY) amp it is less noticeable, which makes sense because stereo separation is supposed to matter less with bass frequencies than it does with mid/treble. However it's not very noticeable in use, and I am happy to give them a chance to break in!

 

[lab]

Any chance the spider is caved in on the quieter woofer. If stored on it's back for a considerable length of time the cone can sag inwards (or the opposite if stored on it's face). The result of either situation is the voice coil would be out of it's ideal location in the magnetic field and the volume would be reduced.

Just a thought.

 

[jharris]

Any chance the spider is caved in on the quieter woofer. If stored on it's back for a considerable length of time the cone can sag inwards (or the opposite if stored on it's face). The result of either situation is the voice coil would be out of it's ideal location in the magnetic field and the volume would be reduced.

Just a thought.

Thanks lab! This makes sense. Before I got the speakers I don't know how they were stored, it is 100% possible they were stored with the drivers up (or down) in a way that would affect the sound.

Could up/down (front/back in normal use) positioning have affected my refoaming job? It seems like left/right (radial) position issues are more likely to affect this... and also if the voice coil is not rubbing/scraping/buzzing I'm probably good... and I'm hoping all is well... but if I may I have done something wrong I'm ready willing to stop/undo/fix whatever problem I may have caused

 

[Justgotohm]

I received a set of NLA Advents that had new surrounds. The guy I traded with said he disliked the lowend performance, they had no bass. Upon inspection the polarity was reversed obviously by accident on one woofer.

 

[z-adamson]

Does it appear that one cone is further sunken in that the other or does it appear that both are level to each other?

 

[z-adamson]

I received a set of NLA Advents that had new surrounds. The guy I traded with said he disliked the lowend performance, they had no bass. Upon inspection the polarity was reversed obviously by accident on one woofer.

If this was the case, there would be no bass performance out of either woofer. In this case however one woofer performs well and the other does not.

 

[lab]

I was wondering if you had the two speaker cabinets in similar locations when you compared them. If the "louder" cabinet was on the floor or closer to a corner the bass would be perceived as louder than the "quieter" cabinet.

If I remember correctly this speaker is ported. Are both port tubes still glued in place ? Should one tube have come loose it's bass would be more boomy and less deep, which might make it sound louder.