Infinity QLS 1 Potentiometers

IndyAudio said:
LOL - what an unnecessary scare! But glad it's all OK.

Interesting to know the old caps were close to spec…..I didn't test mine, but have them and may just do that some time for grins.

Curious why you changed all the inductors? Hope this doesn't change the voicing of the speakers - did you get exact duplicate specs? I don't see folks changing those often unless they are damaged or are attempting to "upgrade" and revoice the originals. Just curious, thanks and great progress!
Click to expand...

I guess I replaced the inductors because there's a part of me that's a bit anal. :) I didn't want to go thru all the effort and put old parts back in...though I'm pretty sure the old ones were OK. ERSE has inductors that match the Infinity values and I've come to conclusion, after reading many posts here, that given Infinity's propensity (likely based on supply) to change parts during the production run, that there's a fairly ample margin of error. That and given the fact that I haven't heard these speakers since 1993, I don't really remember their "voice." Plus, the new ones "look nicer." :)

Regard the caps, I purchased a meter.

One thing I should correct is that my original woofer caps were 1400uF and 1600uF. It was recommended that I recap at the Infinity schematic values of 1100uF and 1400uF with the new Watkin's woofers which is what I did.

Also, I have been a bit surprised at the shoddy, to me, level of the crossover construction. The soldering points were not well done, and using plumbers putty to adhere parts to the crossover was low rent. I suppose they never thought an owner would be inside to see it. LOL

Regards...
 
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Mid range wiring

I finished building both crossovers from scratch and tested each one. All drivers work except two midrange domes (3&4 from the top on the right speaker) which have no output. When I pulled them both wires on #4 had broken. I rewired them and now have output from all the mid range domes, But I'm unsure if they are wired correctly, the odds being 50/50. :)

Does anyone have a schematic for how the midranges should be wired? I get sound with both hookup options, but there must be a correct hookup.

Also how does one tell the positive/negative inputs on the domes.

Now that I'm this far along, I want to hook them up and listen to them for the first time since 1993. :)

TIA
 
Great progress, you are getting close!

This should help if I've attached the right document.
 

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  • Infinity Quantum_Line_Source_1_technical_sheet.pdf
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Thanks, my face is very red and not from dinner's wine and cognac. LOL

I've used that very document as a check against the schematic before soldering anything to insure against errors. Thanks for pointing me to the blindingly obvious. :)

I did find a red dot stickum next to one terminal and I'm taking that as the positive connector.

As this has been my first foray into this type endeavor, it's been quite a learning experience and surprisingly enjoyable. The fact that my better half is in Ireland enjoying herself has allowed me to proceed at my own pace and without having to answer for all the UPS and FedEx deliveries. LOL

In a funny twist, the pacing item to seeing how they sound is a new inner tube for one of the tires on my hand truck used to get the speakers up to the first floor from the cellar.

One area of interest to some maybe my re-veneer of the lower front panel of the left speaker. I used Tightbond III in my first attempt which didn't take well. I pulled it, cut another, and used contact cement, which worked perfectly. Some walnut filler along the seams, and staining and oiling has resulted in a literally perfect match. If anyone is interested I can provide info on the veneer and stain.

Thanks to all who posted their help and ideas. I'll post my impressions after I fire them up.

Ciao...
 
Glad Indyaudio found you the wiring info you needed, I thought you were reffering to the series-parallel wiring of the drivers.

You know that Home Depot and Lowes have innertubes for handtrucks right?

My Q bases were completely shot from water damage when I got them. I built new ones from birch ply and yes, the contact cement method is the way to go.

Please post pics and impressions once you have them set up!
 
jimreeves said:
Glad Indyaudio found you the wiring info you needed, I thought you were reffering to the series-parallel wiring of the drivers.

You know that Home Depot and Lowes have innertubes for handtrucks right?

My Q bases were completely shot from water damage when I got them. I built new ones from birch ply and yes, the contact cement method is the way to go.

Please post pics and impressions once you have them set up!
Click to expand...

Thanks for the store tip - I ordered one from Amazon as its 30 miles to the nearest store and Amazon will have it here in two days, barring a blizzard delay.

If I remember correctly, it was your post on the bases that gave me the idea for replacing the chipped veneer on my left speaker. While my issue was not nearly as extensive as yours and my carpentry skills near nil, I was pleasantly surprised at how easy it was and how good were the results. I daresay one cannot tell it's been redone.

The inner tube delay will give me time to layout my cabling, as I'm going to make runs of 10 and 12 AWG cased in Techflex, under the floor in the cellar, to the sides of a fireplace in the room I'm putting the speakers.

Regards...
 
No, I stopped looking after I pulled mine and realized they were like new... inside and out. However, as I commented in another post, they were very different than pics of others posted here on AK. Since I'm the original owner, they came from Infinity that way...different parts in the middle of the production run... strange as mine are early black baffle models.

I simply pulled them apart, cleaned them with DeOxit, treated them with FaderLube, put them back together, and remounted them.

Interestingly, they all measured as expected before cleaning, but inasmuch as I had them out, might as well clean and lube them.

Regards...
 
IMHO, the original ceramic pots are, ahem..., junk. I wouldn't hesitate to replace them with new 4 ohm pots if I needed to. Buddha6's pots look to be much better made examples than what's typical.
 
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8 ohm is all I've found too. Using the stereo l pads and paralleling them for 4 ohm sounds like an alternative but drives the cost up even further. Sure would like to have some that worked smoother.
 
jimreeves said:
IMHO, the original ceramic pots are, ahem..., junk. I wouldn't hesitate to replace them with new 4 ohm pots if I needed to. Buddha6's pots look to be much better made examples than what's typical.
Click to expand...

I fully expected to see those ugly ceramic pots when I pulled the crossover as they were all I had seen everywhere. I am fortunate to have been surprised by the relative quality and condition of the pots in mine.

I am looking forward to getting back to the US next month to actually listen to them. :)

Regards...
 
I guess it's worth noting again that Infinity used Potentiometers in the Quantums, not Lpads, even though it seems like a Lpad would make more sense. That may be why it was reported that the Pots used had minimal effect attenuating, something like +-2dB. What they did to the impedance in the circuit and the resulting crossover frequency changes I can't say.
There are vintage mil-spec 5 ohm 25 watt pots available on ebay but they look huge.
 
jimreeves said:
I guess it's worth noting again that Infinity used Potentiometers in the Quantums, not Lpads, even though it seems like a Lpad would make more sense. That may be why it was reported that the Pots used had minimal effect attenuating, something like +-2dB. What they did to the impedance in the circuit and the resulting crossover frequency changes I can't say.
There are vintage mil-spec 5 ohm 25 watt pots available on ebay but they look huge.
Click to expand...

Thanks Jim. It was indeed worth noting again for my sake if no one else. I thought I had read these actually were L pads. Understanding somewhat the difference, but not the inner designs, I assumed that they were L pads. It does look like 5 ohm 25 watt pots are found a bit easier. I think the mid is really the only one that uses all 3 tabs with the resistor in parallel with the driver. I guess this makes it operate slightly more like an L pad but not.:D

Appreciate the clarification!!!
 
I have been looking for some 5 ohm 25 watt pots for my Quantum Jrs but been unable to locate them and I'm not finding anything on ebay.
 
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