Refoaming a midrange

markshan · Apr 20, 2014

I just did my first refoam using the 30Hz tone instead of shims. I LOVE this method. Quicker, cheaper, more ascetically pleasing and the results were perfect. :banana:

However, I have one cabinet where the mid needs refoamed. I assume you could adapt the same method but would love to hear from someone who has tried it. I say "adapt" because I was thinking that you wouldn't want to send a 30Hz tone to the coil of a mid (or maybe you would, that's why I'm asking). I was thinking that perhaps a 240Hz tone would be appropriate. That is at the bottom of midrange similarly to the way 30Hz is at the bottom of bass. Plus, it is exactly three octaves up from the 30, so I thought it might be a good way to go. Thoughts? Has anyone out there tried this? TIA

Bob Orme · Apr 20, 2014

markshan said:
I just did my first refoam using the 30Hz tone instead of shims. I LOVE this method. Quicker, cheaper, more ascetically pleasing and the results were perfect.

However, I have one cabinet where the mid needs refoamed. I assume you could adapt the same method but would love to hear from someone who has tried it. I say "adapt" because I was thinking that you wouldn't want to send a 30Hz tone to the coil of a mid (or maybe you would, that's why I'm asking). I was thinking that perhaps a 240Hz tone would be appropriate. That is at the bottom of midrange similarly to the way 30Hz is at the bottom of bass. Plus, it is exactly three octaves up from the 30, so I thought it might be a good way to go. Thoughts? Has anyone out there tried this? TIA

240 is just a little bit lower than middle C so you should be fine with that frequency for a midrange. Finding midrange surrounds can be a little difficult, depending on the mid.

fhawk618 · Apr 21, 2014

I would never recommend sending a 30 Hz tone to a midrange, since that is well out of their intended operational range, but you might want to look at the crossover specs to get an idea of the intended operational range of the midrange before even going as low as 240 Hz... 240 is still pretty low for the average midrange driver...

Most midrange surrounds can be found available from the speark repair houses like Simply Speakers...

markshan · Apr 21, 2014

fhawk618 said:
you might want to look at the crossover specs to get an idea of the intended operational range of the midrange before even going as low as 240 Hz

That would make sense if I had any specs. It's a generic 3-way that will end up in a give away system.

mech986 · Apr 21, 2014

I think 500hz - 750 hz would be fine for any midrange used in a 3 way system.

markshan · Apr 22, 2014

Okay, I'll go up another octave to 480.

Mystery · Apr 22, 2014

Yep, don't use too low tone on the mid range.
I was re-foaming an Infinity mid woofer using 30Hz tone (I should have known better) and I smelled something burning and then smoke came out from the voice coil

.
The mid woofer is no longer useful. My 1st and only messed up driver during re-foam.

dc270 · Apr 22, 2014

You have a mid tone generator, run a pink or white noise through your xover to the mid driver............
DC

ken kantor · Apr 22, 2014

Sorry... I have to say...

Please consider NOT refoaming your midrange(s). Refoaming something the size and frequency range of a mid is 100% guaranteed to totally mess up its response. And if you do a clean job, no one will know. Down the road, someone will audition the speakers and say, "Oh, I heard the blah blah and they totally suck." Or someone will scavenge and sell the mids to an unsuspecting restorer.

If you decide to go ahead with it, at least try to mark them as refoamed with some indelible method, such as a Dremel.

Thanks for your consideration.

-k

markshan · Apr 22, 2014

dc270 said:
You have a mid tone generator, run a pink or white noise through your xover to the mid driver............
DC

Seems a good idea.

markshan · Apr 22, 2014

ken kantor said:
Sorry... I have to say...

Please consider NOT refoaming your midrange(s). Refoaming something the size and frequency range of a mid is 100% guaranteed to totally mess up its response. And if you do a clean job, no one will know. Down the road, someone will audition the speakers and say, "Oh, I heard the blah blah and they totally suck." Or someone will scavenge and sell the mids to an unsuspecting restorer.

If you decide to go ahead with it, at least try to mark them as refoamed with some indelible method, such as a Dremel.

Thanks for your consideration.

-k

Is this based on a single incident or on many?

BTW, blah, blah, blah does suck. They are generic speakers that I am giving away in a starter system.

ken kantor · Apr 22, 2014

markshan said:
Is this based on a single incident or on many?

BTW, blah, blah, blah does suck. They are generic speakers that I am giving away in a starter system.

Many. Many many.

That's fine. You can, of course, use your discretion. But, they were worth fixing, no?

-k

tubed · Apr 22, 2014

A poor midrange refoam will cause one to despise piano passages, even ones favorites, from my experience.

Dennis Gardner · Apr 23, 2014

ken kantor said:
Sorry... I have to say...

Please consider NOT refoaming your midrange(s). Refoaming something the size and frequency range of a mid is 100% guaranteed to totally mess up its response. And if you do a clean job, no one will know. Down the road, someone will audition the speakers and say, "Oh, I heard the blah blah and they totally suck." Or someone will scavenge and sell the mids to an unsuspecting restorer.

If you decide to go ahead with it, at least try to mark them as refoamed with some indelible method, such as a Dremel.

Thanks for your consideration.

-k

I think the work I did on my mids turned out just fine.......

dc270 · Apr 23, 2014

dennis gardner said:
i think the work i did on my mids turned out just fine.......

rotflol..........................
Dc

fhawk618 · Apr 23, 2014

Watching the progression of this thread, ultimately, if they are "generic" speakers to give away for a starter system, you may just want to look at the Parts Express website and just buy a pair of new/cheap mids that fit the mounting holes and call it a day, instead of the cost and aggrevation of refoaming a midrange driver... because if you do one, you have to do both, or they will not sound the same. They may not sound identical to original spec, but they will be identical and new... and the cost of surrounds/glue/labor is probably more than the cost of some new mids from PE...

dc270 · Apr 23, 2014

I forgot the Infinity model, but it had those darn 3" poly cone mids, when I last looked I could not find a suitable replacement, which led me to having to refoam them. They came out sounding pretty good, but I did not have anything to compare them to a stock set.

I wanted to keep them as near original as possible- so necessity led me to inclution.. IT WAS a PITA to dance a small light weight foam with a glue bead around a stiff unforgiving cone. You learn to handle chop sticks real fast....buy extra foams too as you will be forced to ""practice". You'll also find yourself gritting your teeth in time to the back ground music..........just saying
DC

baco99 · Apr 23, 2014

i use a 400 Hz test tone for mids. I think that's an "A"

cablephil212 · Apr 23, 2014

ken kantor said:
Sorry... I have to say...

Please consider NOT refoaming your midrange(s). Refoaming something the size and frequency range of a mid is 100% guaranteed to totally mess up its response. And if you do a clean job, no one will know. Down the road, someone will audition the speakers and say, "Oh, I heard the blah blah and they totally suck." Or someone will scavenge and sell the mids to an unsuspecting restorer.

If you decide to go ahead with it, at least try to mark them as refoamed with some indelible method, such as a Dremel.

Thanks for your consideration.

-k

Well Ken, I understand and don't understand. :scratch2:

When re-foaming ANY driver, aren't things going to change anyway? The compliance of the new foam would be the major factor. What about the glue type? Dustcap replacement?

There's always a possibility of finding an OEM or used driver, but ..........
what if the driver is NOT replaceable? What's one to do? Have a set of speakers you can't use sitting in a closet or basement?

There's also the problem of keeping the speaker original. What would people think about a high quality (pick one) box with a different mid replacement? And what would be your response be when the potential buyer asks about the replacement? The foam was gone, so I replaced it with the closest thing I could find.

Even if you weren't in the market to sell the speakers, why would you alter them? Aren't different replacement drivers altering the sound also?

What's the lesser of two evils? Possible altered sound, of something totally different?

baco99 · Apr 23, 2014

How about this? New foam, see how they sound. if they sound good, then you are done. If they sound terrible, then find a replacement.

I have refoamed mids before with no ill effects.

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Refoaming a midrange

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