Quantum 3 CPR

willie-aspen

AK Subscriber
Subscriber
Picked up a pair of Infinity Quantum 3s off Craigslist this weekend and was hoping for an inexpensive sonic adventure...they were described as just needing the woofers refoamed.

The good...
The woofers have continuity on both voice coils.
The EMITs all have continuity.
The midbass couplers are good.
The cabinets are in pretty nice shape considering they are getting ready to turn 40!

The bad...
The midrange drivers are both out (no continuity).
One EMIT is not passing signal (need to check the wiring).

The woofers confused me for a bit since they are numbered 5514447. They look correct and they are dual voice coil, but not 902-1180 woofers per the Infinity tech notes. Which shouldn't surprise anyone too much. See pics.

IMG_1244.JPG
IMG_1245.JPG

I noticed a guy on ebay who rebuilds the midranges, but he wants $83.44 plus $25 shipping for each one. If I ship him 2, I get a break on shipping ($12.50). So, for the pair, it would be $204.38. Oh, and I have to ship them to him too. Doesn't seem like the most economical option. I just bought 2 midranges from someone parting out a QLS-1 each for $60 plus $10 shipping. So, I just saved at least $65. But I feel guilty about not getting the originals repaired.

The crossovers have the big 600uf can caps (that I will replace with bipolar) and the 40uf electrolytic (that I'm going to upgrade to polypropylene), but the rest are film caps.

The other weird thing is that the top tweeter on both speakers has little plastic shims on the bottom screws to make it tilt upwards. Why did they do that?

Jeff
 
Congratulations!
There's also good news they are an easy repair if the reason for them not working is a visible break in the tinsel wire by the dome.
I suppose the tweeter shims were for vertical dispersion.
 
Great speakers, the woofers are correct. Make sure you wire them correctly when you put them back in. Solid red wire 4 ohm positive, solid black is 2 ohm positive.
 
The shims are factory. I have them on a set of my Q3's

After I saw them on the 3s, I went back and noticed the angling of the tweets on the Quantum brochures. I guess my questions is does this help vertical dispersion enough to be worth the early reflection? Has anyone compared the sound without the shims?
 
Great speakers, the woofers are correct. Make sure you wire them correctly when you put them back in. Solid red wire 4 ohm positive, solid black is 2 ohm positive.

Thanks Slim! I took a picture before I disconnected and the tech notes also specifies which wires connect to which VC.
 
And I'm going to have these on carpet and find the cabinets fairly unstable, i.e., they like to tip over...which would be bad. Has anyone had any experience with carpet spikes that they could share?
 
And...the midranges arrived today...one had continuity, but one of the wire clips was broken and the plastic flange was cracked near one of the screws. The other one looked great but had a break in the wire near where it enters the channel in the flange. Now I have 3 mids that I need to get rebuilt...
 
Have you contacted the seller about the issues with the midranges you just bought?
I'm guessing the repair person you mentioned before is in the mid south and possibly a doctor.
Have you considered contacting MillerSound about repair costs.
 
Millersound fixes those for sure. They can be repaired diy though. Couple ways to do it depending on where the wire is broken. The clips are an easy fix as well just take it apart and solder a small piece of wire to it.
 
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