Iinfinity Speakers

Which speaker system? Can you supply a photo? Do you have technical specs for the drivers?

What's wrong with the speakers? If it's the surrounds you can do it yourself. If you have the skills to remove and replace the speakers you have the skills to refoam them. Check YouTube. There's a How-To for anything.

William Sommerwerck submitted this idea :

RS4

They look like the photo except the pop-off cloth cover is on mine.

Come on over and give me a hand.

Whether this is going to work (at all, or with reasonably good results) is going to depend a lot on the speaker system design. Since you haven't provided the speaker model number I can't say for sure.

The best case is probably "acoustic suspension" systems (woofers in sealed cabinets). Drivers made for acoustic-suspension use have a range of cabinet sizes (internal volumes) into which they work well, and it's possible to "tune" the cabinet's effective internal volume to some extent by changing the amount of foam, wool, or fiberglass with which these cabinets are usually filled.

Ported / vented / "bass reflex" systems are trickier. These systems depend on a resonant "tuning" relationship between the woofer's mass, its compliance (springiness), the volume of air inside the cabinet, and the length and diameter of the port or vent. This tuning relationship can be fairly critical - changes of a few percent in any of the parameters can result in an un-even frequency response. So, for these systems, replacing the woofers with any that aren't nearly identical may not have good results.

With either type, you're also going to need to deal with the speaker's impedance curve ("8 ohm" is a nominal number - it's actually frequency dependent) and sensitivity. It may be necessary to change some of the components in the crossovers to adjust for differences in the woofers.

If you want a successful refurb, you're going to need to research the original design, and then see if you can buy woofers whose physical parameters are close enough to the originals. If not, you'd actually be looking at a "re-design" project.

As far as where to get replacement drivers - the source I usually use is Madisound - they carry a lot of the better brands and they do cater to home-builders. Zalytron is a similar outfit - haven't bought anything from them myself.

MCM Electronics also carries speaker drivers.

All else being equal, I'd suggest buying woofers with rubber surrounds. Foam-based surrounds deteriorate and fall apart after a decade or two (I've heard various stories as to why - "ozone" and "attack by fungus" are two), while high-quality rubber surrounds seem to have a very long lifetime.

There's a pair of RS-4 up for sale on eBay (item 131202124777). The photos don't show anything that appears to be a port or vent, on either the front or rear. This is good news, I think, as it probably means they're acoustic suspension, which means that the driver-to- cabinet-volume matching might not be super-critical.

So, what you'd need to do is estimate the internal volume of the main cabinet (exclusive of any space set walled off for sub-compartments for the midrange and tweeter), divide by 2, and then look for woofers which are 8" nominal diameter, 8 ohms, and which are designed to work with a cabinet volume of about that amount (half of the total cabinet volume).

With luck, you may be able to compensate for sensitivity and frequency-response differences between the new woofers and the originals, just by fiddling with the existing midrange and tweeter level controls.

These are polypropylene drivers with foam surrounds. Unless you've abused them by driving them at excessively high levels, the most-likely thing wrong is that the foam has gone bad.

These are probably very good speakers (I owned RS-4.5s and have kicked myself a hundred times over for selling them) and are worth repairing. I'm sure someone can refer you to a source of replacement surrounds.

There is a problem (of course). Hardly anything sticks to polypropylene, and you'll need an appropriate adhesive.

And, if you don't care for the risk of doing the work yourself, they seem to offer a repair service. Take out the drivers, ship 'em, and for $44 each they will replace the surrounds and gasket themselves, test the drivers, and give you a 7-year warranty on the work.

That's still gonna be cheaper than replacing the woofers with anything of decent quality.

I just checked and those got pretty good reviews.

We NEED to know teo things.

One, does it use Watkins woofers ? I looked at a page or two on it and some one said they thought no. I am not sure exactly how to tell, but if there i s a capacitor in the crossover like 1,000 uF or more, they probably are. Wh at this means is by not using the exact replacements, they will not sound t he same. Probably will lack that bottom octave.

I would suggest a phopen call to these folks :

If they ARE Watkins woofers, refoaming is the very best option as long as t he motor and xcone are still good. The place at the link above charges $65 each, which is a piece of change but way cheaper than replacing Watkins woo fers. If you look at the procedure on youtube, the one with the complete j ob of aligning the voicecoil and not hoping for the best, and the cost of t he new surrounds, the price really isn't all that bad.

If they aren't Watkins wookers and they are otherwise damaged or blown, rel acemetn can be had that will sound so close (or even on a very slim chance a bit better but not much), that it will be worth it.

The second question is whether the boxes are ported or not, or have any pa ssive radiators. If it is a sealed box it takes one kind of woofer, if port ed or usin a passive radiator it takes a different kind of woofer.

An explanation of this is available at :

It's called Thiele small parameters. If it is a sealed cabinet, for example you want a higher Qts. If you can get the BL figures on the replacements, the higher the better. Actually that is probably true in all cases, but is more critical in a closed system. You don't see that parameter on alot of t hem out there.

Another parameter is Re, which is the DC resistance of the voice coil. Whil ie it is related to impedance, it is not the last word. Some have more turn ss of heavier wire and others have fewer turns of thinner wire. In my opini on, the heavier wire ones with higher inductance usually souind better but are not well suited for a two way system. Of course this is not a tewo way system so lower is better to a point.

These speakerds are probably below eight ohms and newer junkphonics amps do n't take too kindly to four ohms. We just sold one of those old big ass Ken woods to someone who said they were buying it because they have four ohm sp eakers. We understand, I have heard the difference.

So, to proceed we need whether they are blown or not, if the cabinet has a port or radiator and try to determine is the woofers are in parallel or ser ies.

the bottom one just as a woofer. AM examination of the crossover should rev eal that.

If you cannot tell for whatever reason we will go from there by getting mor e detailed info on the net somewhere, or you could most likely find out fro m the Watkins people. their phone number is on the website at the watkinsst ereo link up there.

The Watkins woofer had two voice coils, with different crossover elements. The principle was that the second coil had a relatively low impedance at the resonance of the main coil. This allowed the driver to pull more current from the amplifier in that region. You weren't getting something for nothing. Rather this arrangement allowed the speaker to take better advantage of the power the amplifier could supply.

How did you come by this knowledge ? I have been looking for details on thi s for years now. Thanks.

I do believe I saw one a long time ago. It was kinda wierd, disconnecting o ne coil lost all the low end but the other one disconnected seemed to make it a subwoofer only.

Normal woofers take advantage of the constant voltage nature of amplifiers and when they pull more current at lower frequencies it TENDS to make up fo r the fact that the radiating surface is so much smaller than the wave to b e radiated.

Actually in selecting woofers, this is why I tend to prefer the ones with a lower Re which is DC resistance. Without a shitload of equalization, how else does one squeeze out that bottom octave ?

Of course alot of wimpy amps do not like this. The whole industry makes mor e money because of the lack of a solid low octave and underbuilding (IMO) t he output stages of these amplifiers.

I've been doing a little vintage audio lately, and my pardner has this Sans ui AU-9500. I think the thing is great. Really. Iopens it up and looks at t he transformer and heat sinks and think "Hmm, what is this about 200 a chan nel ?". Nope SIXTY FIVE ! (or something like that).

Older, quality amps, were built to work into the lower impedances. They exp ected it. They KNEW woofers were inductive BECAUSE THEY WERE. Back then.

OK they still are, but it is still less turns of thinner wire to get the sa me "impedance".

Anyway, enough of my treatise here, just agree, disagree, respond, call me a nut or an old fogie, but back to the Watkins. I saw one, or one of its cl ones a long time ago and got the idea. It is an enhanced woofer, the voice coils are probably of different impedances. (enlighten me if...)

Then I hear of them in the manual for the Phase Linear 400, that the extrem ely high value cap in the crossover causes an anomoly when the Phase Linear shuts down. I forgot what the fix is, but what I remember is that there wa s a fix.

I have many questions about this. For example, is it special wound to avoid mutual inductance and/or coupling between the two voice coils ? Or is that just dealt with some other way ? If that huge capacitor is acroos either v oice coil, doesn't it at least damp the cone in the expected way ?

All in all, it doesn't seem like a very efficient system, but then if effic iency was the prime directive of course, we would have, well, what we have today. Speakers that can claim to handle 100 watts at 8 ohms, but are not i nductive. Amps that can claim 100 watts, into a resistor, but into a REAL s peaker would choke. Either the protection would kick in or it would fry run ning some oldies but goodies.

And we used to stack them. Like a pair of Boston A-150s wired in parellel w ith a pair of EPI 100s or something, regardless of whether the speaker swit ch wired them in series or not. (wiring A + B speakers in series should be an indictable offense, IT IS CHEATING and it FUBARS the respnse of both pai rs)

So actually, to the OP I must offer this disclaimer - Whatever you do, when you go to listen to these speakers and enjoy them, get an amp that is abou t 30 years old.

I owned four RS-4.5s. It was in the Infinity literature.

That seems consistent with my understanding of how they worked.

I don't know enough to have intelligent answers for your other questions. Have you considered calling Watkins?

By the way, I doubt the OP's speakers use a Watkins woofer.

Have you considered calling Watkins? "

Well you know more than I about it. Calling them ? Well I guess it wouldn't be the worst idea in the world but my interest in this currently is only a bout the OP, the fact that I am no dummy on speakers, and I am curious abou t this Watkins deal, especially if it presented such a wierd load that is n eeded a fix for the Phase Linear, which is a pretty basic design. It's not loike I want to buy one or anything right now.

Logical I say. It doesn't seem logical to use two of those woofers, and in

es as a mid. If they used bot woofers for midrange it produces some undesir

s avoid this by simply cutting the midrange out of the bottom woofer. Actua lly they have quite good results. I had a pair and I can't even remember th e damn brand name. They sounded GOOD and were pretty loud, but not loud eno ugh.

I returned them because they said they could handle 250 watts RMS (I know, no such a thing but) and they couldn't even handle 150. The protectors buil t in kept going off. Sure, they can handle 150, if you want sound half the damn time. when you ge to 250 ?

Well that is another thing that changed. When they say can handle 100 watts now, that means that they can handle a 100 watt amp. Try putting 100 watts into one of those surround speakers. The new wattage rating are IINH. That means : "If It Never Happens".

Well, I guess it is better tha PIPILS. (Peak Instantaneous Power If lightni ng Strikes) which was used on those 200 watt car amps that had a four amp f use and ran on 14.4 volts. Georg Ohm would be rolling over in his grave if he saw the formula for that, what.

There is no standard for rating power-handling capacity. The most-reasonable standard is to specify the biggest amplifier the speaker can handle, without audible distortion. This should be higher for music with a wide dynamic range (classical orchestra) and lower for highly compressed music.