Better woofer for Optimus STS-620

johnr66

Well-Known Member
I have a set of these speakers I bought 12 years ago or so. The sound a little boomy/boxy to my ears. It has a 6-1/2 woofer. I measured the cabinet to be .41 Cu/ft internal and has a 2" dia port that is 2" long in the back.

I have some experience tweaking large speakers, but not these smaller ones. Can I expect much by installing a better woofer and maybe closing or modding the port? If I can flatten out the response and maybe extend the bass a bit, I'd be happy.

sts620.jpg
 
I have a set of these speakers I bought 12 years ago or so. The sound a little boomy/boxy to my ears. It has a 6-1/2 woofer. I measured the cabinet to be .41 Cu/ft internal and has a 2" dia port that is 2" long in the back.

I have some experience tweaking large speakers, but not these smaller ones. Can I expect much by installing a better woofer and maybe closing or modding the port? If I can flatten out the response and maybe extend the bass a bit, I'd be happy.

sts620.jpg
Better? Not necessarily. Porting might be the issue, based on how you describe the sound. Try stuffing a sock or something that allows less air (manner of speaking) to escape. Sometimes plugging the opening entirely produces results people enjoy. Negative side? May loose some bass extension and some efficiency. Won't hurt anything to try. If that don't work, then look into other drivers. Oh, check to see what kind of crossover is used, if any. That may shed some light on things.
 
Okay, I stuffed socks into the ports. It sounds about the same without the bass extension. I decided to remove the woofer. It is direct driven and the the tweeter has a very small cap. I can't read its value because of the way it is glued down.

The woofer has a decent sized magnet, but not as big as some of the better ones. I'm told smaller magnets will mean a higher Qts value and this can be problematic for smaller enclosures.

I'll have to try my hand at matching drivers for these small enclosures.
 
Okay, I stuffed socks into the ports. It sounds about the same without the bass extension. I decided to remove the woofer. It is direct driven and the the tweeter has a very small cap. I can't read its value because of the way it is glued down.

The woofer has a decent sized magnet, but not as big as some of the better ones. I'm told smaller magnets will mean a higher Qts value and this can be problematic for smaller enclosures.

I'll have to try my hand at matching drivers for these small enclosures.
Find out what an inexpensive xover runs. What you have now is totally inadequate as the woofer is being permitted to extend into the range of the tweeter which will create overlap that is out of time and produce and un-natural openess, or in your case boomy.

Also, what is the stuffing like, if any? Adding insulation makes a huge difference. I may do the same with my JBL's as I feel they are a little on the boomy side.
 
Is there any baffling in the enclosure? You might try stuffing the box to try to eliminate the "boomy" sound. Keep the port open if you use it ot try blocking it entirely. Adding batting makes the box behave as if it is bigger and maybe it will sound better with the port closed. The speaker is what it is and you will not get it to sound like a speaker with a large woofer but you might improve it a little.
 
Well the mark of the unobservant is upon me. I began taking the tweeter and woofer out of the cabs and just as an above post stated I found a tiny 2.2Uf cap behind the terminals on the speaker. I did not expect to find it there and now I know to be more attentive. Thanks to all.
 
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