I know these were probably one of Inifinity's worst models, but I was wondering if anyone who has/had this or any model in the "SM" series, removed the wooden base attached to the bottom of the speaker? It appears they're glued on rather than attached with screws so I'm hesistant to really mess with them. I've seen some comments in previous posts that this model is rather unstable and from what I can tell it's mainly due to this wooden base which has a smaller diameter than the speaker itself. I think they'll be much more stable without the wooden bases attached.
Thanks for any advice!

If they're unstable it is because they don't have any weight to them.
Sell them if you can.

Bully speaks with straight tongue. There's a serious lack of cabinet heft to the entire SM line until you get down to the little bitty SM-80's and 60's which I think morphed into the 82's and 62's. They sounded MUCH better than the big brothers, probably due to the fact that they couldn't get as loud.

I had two pairs of these. I talked by future brother-in-law into buying one pair (he's mad at me now and won't talk to me) and kept the good pair for myself. I've almost tried to give them away with no takers. They look nice enough. I am curious to know if stuffing the boxes with fiberfill would help them any :scratch2: ?

Thanks for the advice guys. I know I'm probably wasting my time but I'm going to try and at least give these speakers a chance. Fortunately, I only paid $50 for them. Probably $45 too much I guess.
One thing I'm wondering, these SM-120's weigh about 50lbs each. As far as weight/heft goes, isn't that a decent amount? I think they weigh about as much as my HPM-100's.

$50 isn't a bad price for a pair of SM-120s. I've seen them regularly sell for more than $200 on that auction site. Though, that price has probably been driven up by those seeking these speakers to relive their dorm days as is happening with more than a few more popular '70s speakers. 50 lbs is light for a floor-standing speaker, so maybe more bracing and fibrefill could make for a significant improvement. Go ahead and try them out, they could very well sound just about as good as the HPM-100s and you may like them even more.

- JP

Things that make SM120s sound better:

Take the base off, and replace it with a base made of layered MDF, and put spikes in the base.

Put cabinet braces from from the front baffle, just above and just below the woofer, to the rear panel of the cabinet. 2x2 lumber works very well for this.

Put 4" thick fiberglass insulation (WITHOUT paper backing) inside the cabinet, lining all of the cabinet panels, except the front baffle.

Replace the port tubes... keep the same diameter, but increase the length by about 25% (tune the box lower, to get rid of some of the midbass boominess). You can use PVC plumbing pipe for this, though you will have to trim the holes in the baffle to a slightly larger size (the PVC pipe has thicker walls). Just make sure the vent pipe doesn't go back, to closer than 3" from the rear wall... and leave an open spot in the fiberglass insulation on the rear wall, to avoid blocking the port.

Should make quite a difference...

Regards,
Gordon.

Thanks JP! I'll definitely give the fiberfill a try. Can you give me some idea of how to go about using the fiberfill and how much to use?
As far as the bracing, I was thinking of adding a section of wood to the wooden base attached to the bottom of the speaker. I was thinking of using a piece of walnut about two inches thick or so and the same diameter as the bottom of the speaker. This way the speakers are a little more stable. Any other suggestions as far as bracing?
Macaltec- I'll let you know how the fiberfill works out.

Things that make SM120s sound better:

Take the base off, and replace it with a base made of layered MDF, and put spikes in the base.

Put cabinet braces from from the front baffle, just above and just below the woofer, to the rear panel of the cabinet. 2x2 lumber works very well for this.

Put 4" thick fiberglass insulation (WITHOUT paper backing) inside the cabinet, lining all of the cabinet panels, except the front baffle.

Replace the port tubes... keep the same diameter, but increase the length by about 25% (tune the box lower, to get rid of some of the midbass boominess). You can use PVC plumbing pipe for this, though you will have to trim the holes in the baffle to a slightly larger size (the PVC pipe has thicker walls). Just make sure the vent pipe doesn't go back, to closer than 3" from the rear wall... and leave an open spot in the fiberglass insulation on the rear wall, to avoid blocking the port.

Should make quite a difference...

Regards,
Gordon.

Thanks alot. Now I have another projects to eat up my money.

Thanks for the tips Gordon!

Thanks alot. Now I have another projects to eat up my money.

You're quite welcome. Glad to help! Anytime! :D :D :D

Gordon- Any idea how the wooden bases come off? I don't see any screws so I'm guessing they're glued on. The layered MDF should be the same diameter as the bottom of the speaker right? Does the thickness matter?
Where do you get the spikes?
Would you mind going into more detail regarding the bracing? Where exactly should the wood 2x2's be placed? Do they go horizontal from the front of the cabinet to the rear of the cabinet?
Thanks again for the help!

You're quite welcome. Glad to help! Anytime! :D :D :D

How much better are we talking? Worth the time, effort, and money?

I have a set of 122's (same junk), read this thread a couple of days ago and tried a couple of Gordons mods, I removed the base, simply glued on, you will tear up the veneer a little but you are going to cover it anyway, I replaced it with 4 pieces of 3/4 MDF laminated together, installed spikes, braced the cabinet as per Gordon's instructions, installed the fiberglass, did not change the port yet, Sounds much better almost like a real speaker :thmbsp: I am a woodworker so I am considering just building new cabinets for these drivers, wondering if anybody has tried this, might have more invested in lumber than the speakers are worth, Thanks for the help, I have learned more in the last two weeks on this forum than than I have in years.

I have learned more in the last two weeks on this forum than than I have in years.

Very cool, that's what it's all about.

I just replaced my SM-122's with HPM-100's. Perhaps the reason SM's are so wooden sounding is because the particle board is approximately 3/4 inches thick. Good luck with your 120's.

Just an update, I built some stands to raise the speakers 6 inches off the floor (recommended in the owners manual), also angled them at about 3 degrees,
How much better are we talking? Worth the time, effort, and money?
Total cost of these mods around $30, well worth it, I found these at a thrift shop for $40 they are now a decent sounding speaker for a total of $70.
the fiberfill however does decrease the efficency a little I notice I have to turn them up a little more than I used to
:music:

...I am a woodworker so I am considering just building new cabinets for these drivers, wondering if anybody has tried this, might have more invested in lumber than the speakers are worth...

If you're going to go to that much trouble, time and expense, and have the cabinet know-how, I'd suggest starting a thread here on "What Infinity to Build". There'll be a lot of suggestions, and you'll wind up with something really good!

If you're going to go to that much trouble, time and expense, and have the cabinet know-how, I'd suggest starting a thread here on "What Infinity to Build". There'll be a lot of suggestions, and you'll wind up with something really good!
Still considering it however I would probably have another $100 to $150 invested, I'm just not sure that these drivers and xovers are worth the time and investment, would like to hear some opinions on this, if it looks worthwhile I would be happy to post pics and go through it step by step (with the help of the knowledgable folks here).

I have a pair of Infinity SM-152's.....Gordon, or whomever, should I do this to mine as well?? Plus, with the weight and my wooden floors, would spikes be the way to go, or should I get some rubber feet from Wallyworld or somewhere??

Do you simply glue the two two by 4's to the back wall??

I realize Infinity cut corners with these speakers, but they aren't THAT bad, at least not to my ears.

I realize Infinity cut corners with these speakers, but they aren't THAT bad, at least not to my ears.

I guess that it would matter what you have to compare them with.

I have a pair of Infinity SM-152's.....Gordon, or whomever, should I do this to mine as well?? Plus, with the weight and my wooden floors, would spikes be the way to go, or should I get some rubber feet from Wallyworld or somewhere??

I have no experience with wood floors so I cannot help you there, although I am sure someone here does.

Do you simply glue the two two by 4's to the back wall??

I ripped the 2x4s down to 1 1/2 X 1 1/2 then simply glued them on the sides from front to rear to support the front baffle, one on each side just above the woofer and one on each side just below the woofer. I found that getting them up of the floor and getting some insulation in them did more than any thing else :thmbsp: IMHO with a few mods they will sound pretty decent.

Divotdog, thanks for the advice. Shall do that first opportunity..

To not have fiberfill inside a ported box is a travesty, I will admit. To have nearly NO bracing is another travesty. But I still contend that the drivers aren't that bad. Can't even START to touch my Marantz, but better than most of the Black Plastic Crap out there.

I was 17 or so when I had them auditioned to me at Poston's in Bowling Green Ky. Had never heard anything worth a flip, so I got them. Promptly had a woofer blow on me when I made a beer run and my "friends" decided to play some Public Enemy. A#@holes left as soon as I got back, before I had a chance to turn the stereo on and find out what happened. :pistols:

Argh.

Still, since hearing all the various speakers since I've gotten into this foray, I've had nagging doubts about these large things ever since. Well, time to fire up the bandsaw.

:lurk:

Keep us posted. :thmbsp:

Definitely let us know how it works for you, I was very pleased when I finished mine, if I can figure out how to post pics I will put some up of the stands, as they classed up the speakers quite a bit and helped with the sound tremendously :music: I am with you I believe them to be an excellent sounding mass produced speaker, Far better than some that I have listened to.

The SM152's are currently on a rather weak Onkyo black plastic crap HT. When paired with my Sansui AU-G99x, they are delightful. I have the day off tomorrow, and fully plan on doing the bracing and the fiberfill. Anyone have any opinion on what is the best (styrofoam sheets/fiberfill/insulation) and approximately how much should I use...

Seems real easy to take r-13 or something, glue it paper down inside the cab... would that suck?? The fiberfil in my Marantz is the thickest stuff I've ever seen.

As for the stands, just a chisel and a hammer and beat the old ones off?? They are just held on with some tiny nails I think. Perhaps this has been covered, I'll have to reread the thread...

More to come....

Okay, never mind. As usual, GordonW has already laid down the law, step by step, earlier in the thread. Thanks GordonW. :thmbsp:

Okay, better late than never.

First, sorry to resurrect this thread, but after blowing one of the woofers' surround CLEAN OFF, I realized I hadn't "kept ya posted".

I will agree, these speakers are maligned for a reason. But after ripping two by fours, glueing in place, stuffing much insulation, etc...

they sound MILES away from their original sound.

Still haven't adjusted the port. MUST do that.

I gotta refoam the blown one ( a 160 watt shot of Kings X "Dogman" did it in!) but to be honest, I been blasting these since 1989.

I have HPM-100's, Epicure 20's, DCM CX-27's, the list goes on and on. But when it comes time for Jazz/Classical or my IASCA car audio finals cd, the Infinity's are top dog. If I can tame that tubbiness a bit more (hoping the port will do it..) I will never get rid o' them. Parental h.s. grad gift. But the sound is 100% better after the mods.

Gotta find those surrounds!

Almost forgot...

Gordon, need ur knowledge...

I'm gonna rebuild the crossovers with better caps. The ones in here are CLAYTON. WTF??? I figure after 20 years they could use it.

Prob is, the crossover is mickeymouse, and so I thought I might just rip it off, salvage the l-pads, and get one of those prebuilt ones from Parts Express. Bad idea?? Any idea of the crossover points on the SM-152 crossover?? Or could I solicit your work? If so, PM me.