Infinity SM-152

I had a pair of SM-152's, and I loved the sound. But! I did have an intense dislike for the cabinet build quality. I found it irritating that they put that vinyl shit over the MDF. I also felt they were not deep enough (dimension wise), and that if you had them on carpet, with out spikes installed, they tended to teeter.

Otherwise I loved the sound, the quality of the drivers and the crossover controls.
 
MaxSeven speaks true! On carpet, they were an inverted pendulum, always in jeopardy of falling. Mod the box, and they get even better.

Doesn't anyone know the crossover points?? Purty please??
 
I suggest to the original poster that if they sound great to you then well they sound great. Mine do and I don't give a rats a$$ if someone else says something else is better, I'm sure it is but it's not in my house so it doesn't really matter.

Turn up the music.

Bob Brown

You are correct Sir! There are some who don't like them (their opinion) which is there right and adds to a good discussion. But by the same token those that love them shouldn't care nor be offended by someone elses opinion, we all don't hear things the same way :thmbsp:
 
Can't help on the crossover points, but there's a bit more to it than that. The crossover points are impedance dependent. And that's a moving target with infinity as the impedance swings a fair amount based on frequency. Since they won't divulge the Thiel/Small parameters for any of their drivers, it gets a bit complicated. GordonW can build you a first class crossover, but he has been using (and working on) Infinity speakers for years. Puts him a bit ahead of us :)

The best bet is to post a question with the crossover diagram (from Infinity.DE) and ask if anyone can decipher it. That question will get more responses on the general speaker forum.

But, I think the factory crossovers are capable of being overhauled. I did mine in the RS3000's and will be doing the ones in the RS5000's this summer. It takes a bit of patience to open them up. Denatured alcohol will soften the hot melt glue. Then a carefully applied razor knife will separate the last of it.

All you need to do is replace the caps. The coils are OK and so are the load resistors. If they are working, they are in spec. Caps age and loose electrolyte of time. They change with age. I clipped mine out and soldered in new extended leads from the pads on the main board, then added the bigger poly caps to the leads and hot-melt glued them to the back of the existing assembly so they would go back in through the same cut-out. Worked out quite well. Just looked bad starting in :)
 
THANK YOU, brocluno!!

I may attempt to do it myself, it just seemed rather daunting. Hey, if I screw it up, I can plead for GordonW to build some custom ones. I'm sure it would sound fabulous.

As one of the woogers are kaput, it may be awhile. About to get back my 9090db, overhauled ECHOWARS style!:banana::banana::banana:


I'll just bet there will be a thread about that in the next week or two...:scratch2:
 
I had a pair SM 150 speakers and a Pioneer M90 amp I like the sound good bass I got a pair later. put on a nakamichi PA7 MKII did not like the sound

Darren
 
I have owned Infinity SM 12' and 10" three ways since the 80's. The factory literature packed with mine claimed 750 and 5000. Every reference I have seen on all of the SM series state the same specs. One reviewer claimed that the woofer was being seriously taxed trying to reproduce up to 750. I'm pretty happy with them after bracing the cabs and extending the ports slightly. The Polycell tweets can become a little fatiguing when cranked up hard, they start beaming some, but at normal (for me) listening levels I am quite happy. They are (dare I say it) very revealing speakers. A poorly mastered record sounds just like a poorly mastered record. A really good recording can be amazing. I also like high efficiency speakers. They sound good with a 30 watt amp. I am currently driving them with an old 60 watt Harman Kardon. Replace the surrounds, fix the cabs and tune the port and they are not at all bad for the money invested. My oldest pair probably need to be recapped. I am always amused by the people on these forums posting about how terrible they are. Definitely not Infinity's cream but better than a lot of speakers I've listened to.
 
I have owned Infinity SM 12' and 10" three ways since the 80's. The factory literature packed with mine claimed 750 and 5000. Every reference I have seen on all of the SM series state the same specs.

The SM-152 used a 15" woofer (looks very big for such a shallow depth box) The SM series were started in the mid-1970's and the 3 ways used 10" 12" and 15" woofers and a variety of combinations of mids and tweeters. Consequently a correspondingly varied range of crossovers.

The German Infinity Classics Site (which in my limited experience has pretty good information) has a list of the range at :

http://www.infinity-classics.de/infinity/models/Monitor-series-1975/index-Monitor.htm

Lots of info is missing but strangely none of them have 750 - 5000 crossovers listed.

Anyone know the answer to this riddle??


- Neil
 
The series has been around THAT LONG?? Damn!

Got mine in '89, and just NOW gotta refoam.

Those who lengthened the port....you gotta be getting close to the back of the box. How much did you lengthen, and what did you use, as that is a 6'' hole, I think.
 
and how is it with the same size box (only 1 inch difference) and the SAME 15'' driver, that the SM155 goes down to 27 hz, and the 152 only to 44 (which is bunk. Mine go QUITE low, at least to 35 or so)

Yet another quandry.
 
27 hz is definitely where a well vented 15" should be getting down to -or even further. Only thing I can think of that would make that much difference (besides very different measuring methods) would be a much better designed port which hits the resonance "sweet" spot.

Even a 1cm change can make this difference in resonance - makes the cubic volume change a lot more. Changing port length in yours may well get you down there. If someone has a pair of 155s perhaps you can compare dimensions?

- Neil.
 
I don't know about the SM-152 model, but the owner's manual for my SM-150's say the crossover frequencies are 500 and 5500 Hz. I found info somewhere that said the SM-152 had the same crossover points.

As far as the enclosure being shallow, yes it's only 12 1/2 inches deep, but isn't the important thing the volume? And the inside dimension of the box is about 36" high and 17" in width. With a interior depth of 10", that's about 3 1/2 cubic feet.
 
As far as the enclosure being shallow, yes it's only 12 1/2 inches deep, but isn't the important thing the volume? And the inside dimension of the box is about 36" high and 17" in width. With a interior depth of 10", that's about 3 1/2 cubic feet.

For vented enclosures the important thing is the relationship between the volume of the box and the volume of the port and the Thiel/Small parameters of the woofer.

The only reason I mentioned the shallowness is that it looks unusual for a vented box - most you see are a lot closer to square in cross-section. I think the reason for this is to decrease flexibility of the panels - a squarer design will lessen the possibility of resonance in wide panels. But you don't get it exactly square or you get a whole lot of other resonance problems.

It looks more like a typical sealed design from the 70's - perhaps they included the port as an afterthought in the design?

Then again - maybe I'm just used to seeing my 15" drivers in boxes that look like this :

Model19_72dpi.jpg
:D:D

- Neil.
 
My neighbor up the street has a pair o SM152's in black, or it is the SM155's. I can't remember. I just know they are black with two mids and a poly tweeter. I'll see what I can find out.

Did you guys use 6 '' pvc?? Now I'm itching to have mine refoamed!!!! :nutz:
 
For vented enclosures the important thing is the relationship between the volume of the box and the volume of the port and the Thiel/Small parameters of the woofer.

The only reason I mentioned the shallowness is that it looks unusual for a vented box - most you see are a lot closer to square in cross-section. I think the reason for this is to decrease flexibility of the panels - a squarer design will lessen the possibility of resonance in wide panels. But you don't get it exactly square or you get a whole lot of other resonance problems.

It looks more like a typical sealed design from the 70's - perhaps they included the port as an afterthought in the design?

Then again - maybe I'm just used to seeing my 15" drivers in boxes that look like this :

Model19_72dpi.jpg
:D:D

- Neil.

Don't tease with 19's in a SM-152 thread!!!:D:D:D I saw a pair at the swap a few days ago but didn't have enough folding cash to buy them.
 
Back
Top Bottom