Infinity SM-152 Questions

[nwsalmon]

Hello all,
I just picked up beautiful pair of Infinity SM 152’s. They are in near mint condition in their original boxes. After placing them on my family room carpet I noticed they are far from being stable. I ordered a set of Dayton spikes from Parts Express to solve this problem. After reading the spike installation directions I’m going to need to get inside the cabinet to install the spikes. I’m new at this so any input would be appreciated before I make a newbie mistake.

Looking at the cabinet it appears I’ll need to remove the 15” woofer to gain access. Also, while I’ve got it apart I’d like to add some bracing and damping material.

So, some questions:

1) Is there another way to get inside the case besides removing the woofer? It seems like the entire front panel should come off somehow but maybe not.

2) What kind of damping material should I use and how much?

3) Anything in particular I should know about installing the bracing?

4) Is there anything else I should do while I have the case open?

I’m going to take pictures while I’m doing this and will post them when I’m done. Thanks in advance for your input.

 

[TLS Guy]

Hello all,
I just picked up beautiful pair of Infinity SM 152’s. They are in near mint condition in their original boxes. After placing them on my family room carpet I noticed they are far from being stable. I ordered a set of Dayton spikes from Parts Express to solve this problem. After reading the spike installation directions I’m going to need to get inside the cabinet to install the spikes. I’m new at this so any input would be appreciated before I make a newbie mistake.

Looking at the cabinet it appears I’ll need to remove the 15” woofer to gain access. Also, while I’ve got it apart I’d like to add some bracing and damping material.

So, some questions:

1) Is there another way to get inside the case besides removing the woofer? It seems like the entire front panel should come off somehow but maybe not.

2) What kind of damping material should I use and how much?

3) Anything in particular I should know about installing the bracing?

4) Is there anything else I should do while I have the case open?

I’m going to take pictures while I’m doing this and will post them when I’m done. Thanks in advance for your input.

No, you will have to remove the woofer. You will need a soldering iron.

It is not really possible to add effective bracing. Braces need to cover a large area and be grooved into the panels. You can actually make things worse.

Are the speakers ported or sealed? If they are ported do not add fill, you will kill the resonance. If they are sealed they should have a heavy fill with Polyfill available at Walmart.

Those speakers are very old, and date before computer assisted crossover modeling came of age. If you want some old "thumpers" they will be fine.

 

[nwsalmon]

Are the speakers ported or sealed? If they are ported do not add fill, you will kill the resonance. If they are sealed they should have a heavy fill with Polyfill available at Walmart.

The speakers have a port in the back.

I read some posts about adding bracing which is why I was considering doing that.

Thanks for the response!

 

[TLS Guy]

The speakers have a port in the back.

I read some posts about adding bracing which is why I was considering doing that.

Thanks for the response!

The only thing you might do, is check the caps in the crossover. In those days non polarizing electrolytic caps were popular. If it has those caps they will be nowhere near the values they started out, and should be replaced with modern polypropylene caps of the same value.