Gauntlet throwdown for a maligned speaker - The Challenge

onwardjames

onwardjames

Hoardimus Maximus
Subscriber
I was ruminating about everything wrong with Infinity's approach concerning the SM series.

I have a pair of SM-152 speakers, the dual midrange, polycell tweet, 15'' woofer set that seemingly everyone hates.

I cannot disagree. It was a low quality offering from an otherwise great manufacturer.

My challenge - Since Zilch isn't here, who of you guys can think of a way to get better sound from these? I've braced the cabs, added some stuffing, but haven't done much else. These changes DID help.

I'm talking ANY DAMN THING goes. Since you cannot give these things away, could anyone come up with some implementation for the drivers?

Open baffle?

Some type of way of time-aligning? I'm thinking perhaps two square cutouts around the woofer to bring it out, and one for mids, then none for tweeters, a poor man's time-alignment.

Crossover mods, new points of crossover?

This is simply for fun, but I've got no issue changing these around, modding, whatever.

Again, anything goes. I know all of us have at some point either owned these, or found them for cheap. I cannot imagine there not being a better way to do these.
 
Sure... if I had a pair. Seems hard to believe you couldn't get something decent out of them, but need lots of measurements. Time-aligning doesn't help anything when the crossover wasn't designed for it in the first place (and if it accidentally helps, well, just tilt the speaker back a bit instead of hacking it up).

There's a refoamed pair for sale here for $250, too much for me to buy just for fun.
 
Replace the 15 with a nice coaxial driver? Or get some big horns/drivers to play on top of the 15s? Get some nice higher end dome midrange like Morel?
 
Upgrade the internal wiring, and solder it - it has worked wonders with some of my speakers.

Upgrade the crossover caps, and of course, solder them.

Consider upgrading the drivers. Fifteen-inch woofers are scarce, and good ones are scarcer still. Get my drift?

Find an amp which mates better with the speakers - I have found that to be nearly critical.
 
IMO the MAIN ingredient in a good speaker is down to the design/manufacturing Quality of the driver(s).
Boxes certainly help but mostly(invariably) below 200hz.
Crossovers, although much maligned are usually carefully tailored by their designers to get the very most out of their budget constrained parts.
Futzing about blindly rarely improves them.
Even so a full set of test gear is Mandatory...or it's just a wanking exercise imo.
Dunno What one can do to upgrade existing drivers: tighten mfg tolerances, stiffen cones, increase mag flux etc, etc.
Run what ya brung... basically.
 
I am surprised to hear that you think they suck. I have never heard them up close, but my neighbor across the street had a set. They sounded very loud and clear even from all the way over to my place. But who knows. Maybe they sound terrible up close.

What would you say the problem is? Overpowering bass? Boomy cabs?
 
What would Zilch have started with?

Measuring driver parameters
Modeling the crossover using the driver parameters to look for problems
Measuring on and off-axis response with a calibrated mic

At that point, things would ensue that to me were indistinguishable from magic, and an improved speaker would appear. :D
 
bare said:
IMO the MAIN ingredient in a good speaker is down to the design/manufacturing Quality of the driver(s).
Click to expand...
IMO (and IME), in order of decreasing importance:
1. crossover/EQ filter design
2. driver combination, i.e. they make sense to use together
3. cabinet design (primarily driver layout, baffle shape, etc.)
4. driver quality
5. nothing else matters very much unless it's just totally botched or inappropriate in some way.
 
Splatter Pak said:
Upgrade the internal wiring, and solder it - it has worked wonders with some of my speakers.
Find an amp which mates better with the speakers - I have found that to be nearly critical.
Click to expand...

Really? That's a new one, thanks! The wiring inside is pretty good, but I'll try it. Soldering was a new one, I mean.

CoogarXR said:
I am surprised to hear that you think they suck. I have never heard them up close, but my neighbor across the street had a set. They sounded very loud and clear even from all the way over to my place. But who knows. Maybe they sound terrible up close.

What would you say the problem is? Overpowering bass? Boomy cabs?
Click to expand...

I don't actually think they "suck" at all. I believe my problem is my tinnitus, which keeps getting worse. On the right amp, I really loved them, back in the day.

Get one set of Vandersteens, and your whole world changes.

I have batted the idea for this thread around for awhile. Seems they are abundant for most everyone, on the cheap.

Crossovers are a bit of a mess, sandwiched up pile of stuff. The pots are notorious for oxidizing, and I've already replaced them with NOS once. Wish I hadn't chucked the old ones, but pretty sure I did.

All input here is appreciated, and if Zilch were still around, I'm sure we could squeeze plenty of good sound out of these for not too much, and maybe have a good time in the process.

My gut feeling is that the two midranges (instead of one) is questionable, but I'm no expert.
 
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I do have a set of Morel MDT-37's. They may improve the sound over the polycells, which I've heard some good things about.

I think the crossover is a limitation. Especially those pots on the mid and highs which get noisy in just a few weeks of non-use.
 
You could line the inside of the cabinets with non drying modelling clay or if you want to spend more money with dynamat. You can also dampen the driver baskets with non drying modelling clay, blu tak also works (These mods are reversible)... You can stiffen driver cones with hodge podge (Not reversible!!)

How much of a difference any of this makes depends on what the main issue is with the speakers.
 
I don't think those Polycell tweeters are bad at all. Maybe some crossover work to tame any midrange peakiness?
 
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the thing stopping this is the quality of the components they used....it was a price point issue...

liking the sound of a speaker then making them better is much easier than starting with something that doesn't sound that good...

woofer is too big, slow and boomy...for starters...

good luck my friend...
 
Infinity SM152
Frequency Response 44Hz - 25kHz (+/-3dB)
Crossover Frequencies 500Hz, 5.5kHz
Sensitivity 102dB (1 watt/1 meter)
Power Rating 10 - 300 watts
Nominal Impedance 8 ohms
Woofer 15" (381mm) polypropylene coated
Midrange Driver TWO - 4.5" (114mm)polypropylene coated
Tweeter 1" (25mm) high-output polycell

In spite of the ever-present statements here that measurements mean nothing with regards to our equipment and how it sounds, I'd definitely want to see what their response curve looks like in the listening room before blindly forging ahead with changes.

Ar you able to do any analysis?
 
Never owned a pair of Infinity 'SM' series speakers. My opinion of them is that they were designed to compete with Cerwin Vega and JBL S-312. They are what they are.

Room placement (including trying stands) will yield greater results then tweaking. I am sure you have but if not read through this

http://www.cardas.com/room_setup_main.php

You may just have to shrug your shoulders and walk away when you have a chance : our demands, desires and taste change.


EDIT: Missed the part were this is just for fun. Have at it, I am sure the ride will provide knowledge.
 
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