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New Infinity Qb from scratch

Thanks !

They will sound like any Infinity Qb I think. ..

I'm thinking to wind the coils by myself. 1mH and 1.4 mH. Probably air core for the woofer too (original is iron core)

If somebody is fixing a pair of Qb or has a crossover at hand, I'd like to know the wire AWG used in the inductors, so I don't open my own Qb cabinets just to measure that.
 
This project is a bit delayed, but keeps going. I had the time to open my Qbs and measure the original inductors. (posted this same info at the Speakers sub forum)

Infinity Qb, serial number 815480, no tweeter attenuator (just mid-range attenuator)

WOOFER inductor, iron core, measures 0.85mH 1.4 Ohm, AWG16 (1.5mH iron core on the datasheet)

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The mid-range air core inductor is clearly labeled 1mH, and measured 0.96mH, 2 ohm. AWG is approx 18 or 19 (I'm measuring almost 1mm wire diameter including enamel)
20210104_112432.jpg

My 1st iron core inductor (I'm tempted to try an air core for this application):

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Slowly, the project keeps going. Today I did the 1mH air core inductors (and added a layer of liquid epoxi)

The originals are 1mH 2 ohm, and my version is 1mH 0.7 ohm. I need to take into account that difference.

Also, checked the Philips AD5060 that were in a box for MANY years.

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elnaldo said:
I received the boxes a couple of weeks ago, and honestly I think they are too reddish, If I knew the color in advance, I'd choose another finish. I'm really tempted to redo the finish, but the speakers are for a friend, not for me, I asked him and he told me he doesn't care of that detail, that I can leave them alone.
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After redoing my RSa's I'm about 95% positive that they used a thinned shellack originally and then a hand paste wax. I found a good way to get raw boxes real close is Minwax Golden Oak #210B and then a hand paste wax.
This is how they turned out.

 
These boxes were made from scratch and don't have anything in common to the Kappa line. They are now painted with some polyurethane finish. I could make them darker using the same product, but I'm not 100% sure what product was used, so I'll leave them alone by now.
 
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That iron core looks pretty nice, most of the time they are quite cheap...I usually swap those for laminated steel...
 
I don't know the exact alloy used in this core. Just bought them by size at a local store. Measured the original ones and matched the inductance.

I'll assemble everything next week. Fingers crossed.
 
Almost finished...

I see the drivers are from the earlier versions. A bit different from my own Qb.

I'll post details of the crossover later. This is a Qa plate, I've added a fuse holder (not present in the Qa plate) and replaced the mid range attenuator with 2 resistors, simulating the attenuator at 1 or 2 o'clock, what sounds good to my ears after playing my Qb for 20 years.

Tweeter capacitor are 2 motor run caps in parallel (3 and 3.5uF x 450V AC), polypropylene film, measured 6.6uF total, to me close enough to the 6.8uF original cap.
Mid range capacitor, Epcos motor run capacitor, polyp. film, 12.5uF 450V AC

Still not sure about the poly fill inside the cabinet, I think I've used too much, my original cabinets were not so full of filling.

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I actually bought years ago some binding posts, but never used them. This project took too long, I don't think I'll open them again to modify those connectors. My original connectors are fine after 40 years.
 
I've made reproductions of the badges. Scanned and printed on Photo Paper, covered with clear epoxy. Not installed yet.

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elnaldo said:
I live in the 3rd world... Not so easy as going to ebay and buying something...
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I think they look awesome. When they're mounted on the grills you'll have to look hard to see they aren't the real deal. BTW I have two Bogen DB20 amps and one is missing the front escutcheon plate. I'm thinking of taking of the good one off, and making a color photocopy of it, then dry mounting the copy to a piece of aluminum (pre-cut to the right size with all the holes punched) and using epoxy to seal it. Similar idea to what you did.
 
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