I have Infinity speaker boxes that need new or repaired 8 inch
speakers. Total of four needed. The mid and tweeters are still OK.
The manufacturer says they no longer have replacements.
These are admittedly very old and I did do a replacement about 15 years
ago using the manufacturer's speakers. I am pretty sure they are 8
ohms but ...

What should I do? Where do I get best parts?
Suggestions please.



--- news://freenews.netfront.net/ - complaints: ---

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

On 06/19/2014 08:47 AM, OldGuy wrote:
I have Infinity speaker boxes that need new or repaired 8 inch
speakers. Total of four needed. The mid and tweeters are still OK.
The manufacturer says they no longer have replacements.
These are admittedly very old and I did do a replacement about 15 years
ago using the manufacturer's speakers. I am pretty sure they are 8 ohms
but ...

What should I do? Where do I get best parts?
Suggestions please.



--- news://freenews.netfront.net/ - complaints: ---

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

RS4

http://www.bobbyshred.com/infinity/Infinity_RS-4B.html

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

on 6/19/2014, dave supposed :
On 06/19/2014 08:47 AM, OldGuy wrote:

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.

Come on over and give me a hand.

I have Infinity speaker boxes that need new or repaired 8 inch
speakers. Total of four needed. The mid and tweeters are still OK.
The manufacturer says they no longer have replacements.
These are admittedly very old and I did do a replacement about 15 years
ago using the manufacturer's speakers. I am pretty sure they are 8
ohms but ...

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.

RS4

http://www.bobbyshred.com/infinity/Infinity_RS-4B.html

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

http://www.infinity-classics.de/tech...ical_sheet.pdf

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.

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

RS4
http://www.bobbyshred.com/infinity/Infinity_RS-4B.html

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.

In article ,
David Platt wrote:

Really, this latter feels like your best bet... it claims to be
exactly what you need. If it works, you've got your original speaker
system restored to life and original quality in an afternoon. If it
fails, you aren't out a lot of $$ and can still pursue the idea of
replacing the drivers.

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.

http://www.simplyspeakers.com/infini...er-repair.html

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 someone said they thought no. I am not sure exactly how to tell, but if there is a capacitor in the crossover like 1,000 uF or more, they probably are. What this means is by not using the exact replacements, they will not sound the same. Probably will lack that bottom octave.

I would suggest a phopen call to these folks :

http://www.watkinsstereo.com/

If they ARE Watkins woofers, refoaming is the very best option as long as the 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 woofers. If you look at the procedure on youtube, the one with the complete job of aligning the voicecoil and not hoping for the best, and the cost of the new surrounds, the price really isn't all that bad.

If they aren't Watkins wookers and they are otherwise damaged or blown, relacemetn 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 passive radiators. If it is a sealed box it takes one kind of woofer, if ported or usin a passive radiator it takes a different kind of woofer.

An explanation of this is available at :

http://www.eminence.com/support/unde...dspeaker-data/

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 them out there.

Another parameter is Re, which is the DC resistance of the voice coil. Whilie it is related to impedance, it is not the last word. Some have more turnss of heavier wire and others have fewer turns of thinner wire. In my opinion, 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 don't take too kindly to four ohms. We just sold one of those old big ass Kenwoods to someone who said they were buying it because they have four ohm speakers. 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 series.

OR, it might be a 3½ way system using the top woofer as a mid/woofer and the bottom one just as a woofer. AM examination of the crossover should reveal that.

If you cannot tell for whatever reason we will go from there by getting more detailed info on the net somewhere, or you could most likely find out from the Watkins people. their phone number is on the website at the watkinsstereo 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 this for years now. Thanks.

I do believe I saw one a long time ago. It was kinda wierd, disconnecting one 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 for the fact that the radiating surface is so much smaller than the wave to be radiated.

Actually in selecting woofers, this is why I tend to prefer the ones with a lower Re which is DC resistance. Without a ****load 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 more money because of the lack of a solid low octave and underbuilding (IMO) the output stages of these amplifiers.

I've been doing a little vintage audio lately, and my pardner has this Sansui AU-9500. I think the thing is great. Really. Iopens it up and looks at the transformer and heat sinks and think "Hmm, what is this about 200 a channel ?". Nope SIXTY FIVE ! (or something like that).

Older, quality amps, were built to work into the lower impedances. They expected 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 same "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 clones 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 extremely 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 was 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 voice 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 efficiency 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 inductive. Amps that can claim 100 watts, into a resistor, but into a REAL speaker would choke. Either the protection would kick in or it would fry running some oldies but goodies.

And we used to stack them. Like a pair of Boston A-150s wired in parellel with a pair of EPI 100s or something, regardless of whether the speaker switch 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 pairs)

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 about 30 years old.

wrote in message ...

How did you come by this knowledge [about the Watkins woofer]?

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


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

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.

On 20/06/2014 1:47 AM, OldGuy wrote:
I have Infinity speaker boxes that need new or repaired 8 inch
speakers. Total of four needed. The mid and tweeters are still OK.
The manufacturer says they no longer have replacements.
These are admittedly very old and I did do a replacement about 15 years
ago using the manufacturer's speakers. I am pretty sure they are 8 ohms
but ...

What should I do? Where do I get best parts?
Suggestions please.


**If it is just the roll surrounds, then the job is easy enough for any
competent tech to manage.

BTW: The Infinity RS4B was an excellent speaker system.


--
Trevor Wilson www.rageaudio.com.au

"I don't know enough to have intelligent answers for your other questions. 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 about the OP, the fact that I am no dummy on speakers, and I am curious about this Watkins deal, especially if it presented such a wierd load that is needed 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.

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

Logical I say. It doesn't seem logical to use two of those woofers, and in a 3½ way system, I think sharing cabinet space might be a bad thing. I've seen some pretty good 2½ wat systems. this is where the top woofer doubles as a mid. If they used bot woofers for midrange it produces some undesirable directional effects in the vertical plane. The anything and ½ systems avoid this by simply cutting the midrange out of the bottom woofer. Actually they have quite good results. I had a pair and I can't even remember the damn brand name. They sounded GOOD and were pretty loud, but not loud enough.

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 built 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 lightning Strikes) which was used on those 200 watt car amps that had a four amp fuse and ran on 14.4 volts. Georg Ohm would be rolling over in his grave if he saw the formula for that, what.

wrote in message ...

I returned them because they said they could handle 250 watts ...
and they couldn't even handle 150. The protectors built in kept
going off. Sure, they can handle 150, if you want sound half the
damn time. when you ge to 250?

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.