QLS-1 Finally found a pair!

chef free

Super Member
I bought a pair of QLS-1 speakers at an "antique" store, here in Oakland today. The right speaker is completely working but the domes cut out if I turn the mid range pot on the crossover. The left speaker domes are all out, I'm hoping that is a pot/crossover problem, the crossovers are original with those crummy black and red caps.

I'll pick them up tomorrow when I can use our van and my brother-in-law to move them. After a quick inspection I'll report back. I expect that this thread will become another QLS crossover rebuild thread.

These speakers are rosewood, was that an original finish option or has someone veneered these speakers?
 
1 set of my QLS-1's are rosewood , the other set are oak. good luck on your endeavor :)
Al
 
Another QLS-I into the fold.
I can remember when only cdfac had the only pair to parade.
Getting up to a dozen or so:)
 
First impressions:
Wow! These are beautiful speakers! The finish is in excellent condition with only a few scratches under the covers. I couldn't find any evidence that this rosewood is over another layer of veneer, this looks factory. (#'s 7000269 and 7000271) The seller said he had seen other QLS in rosewood. The covers are in great shape too.

Yes the right speaker works perfectly. It's mid range control is very scratchy and feels rough to turn. It looks like it took a good shot once, the plastic panel that it's mounted to is cracked and the shaft seems bent.

Yes, all six domes are are silent on the left speaker. Plus the mid range control has had is shaft broken off, turning it with a screw driver does not make the domes work. The midbass coupler will not work unless I push the cone in about 1/8 inch. Broken wire?

I can't really comment on sound quality just yet except to say that they have ridiculous bass response, and I use a depth i sub! Typical Infinity generous high end.

I guess the next step is to remove the woofers and start diagnosing.
 
My rosewoods are 7000290 and 7000291, check the fuse for good contact on the one that the dome's don't work, maybe bad contact or blown :)
Al
 
My rosewoods are 7000290 and 7000291, check the fuse for good contact on the one that the dome's don't work, maybe bad contact or blown :)
Al
 
Another QLS-I into the fold.
I can remember when only cdfac had the only pair to parade.
Getting up to a dozen or so:)

Yeah I remember his thread when he was recapping his, and he had that Yamaha pro amp with the meters. Now we have them growing out of the wood work with all kinds of wood veneers, Rosewood, and now Oak.:smoke:
 
Today I found that a wire from the mid dome pot was disconnected. I soldered it back on and ALL the domes work! Next I removed the "mid bass coupler" and found the wire from one side of the voice coil was kinked so badly that it was broken. I desoldered the broken end and the end from the VC was long enough to resolder to the terminal. 34 working drivers!
 
Today I found that a wire from the mid dome pot was disconnected. I soldered it back on and ALL the domes work! Next I removed the "mid bass coupler" and found the wire from one side of the voice coil was kinked so badly that it was broken. I desoldered the broken end and the end from the VC was long enough to resolder to the terminal. 34 working drivers!

"Knock on Rosewood"!
Pics or it didn't happen.
 
Today I found that a wire from the mid dome pot was disconnected. I soldered it back on and ALL the domes work! Next I removed the "mid bass coupler" and found the wire from one side of the voice coil was kinked so badly that it was broken. I desoldered the broken end and the end from the VC was long enough to resolder to the terminal. 34 working drivers!

That's great to read.gotta love it when something this good happens.
 
Once I managed to get all the drivers working, I started in on those pots on the crossover. These speakers spent their lives on the coast so there was LOTS of corrosion inside the pots. Turning them felt like sandpaper! I dosed them with D5 and turned each knob about 50 times as I learned from the DeOxit sticky. I did this three times and the pots smoothed out. I sprayed them with Fader Lube them reinstalled the woofers for a little listening.

These speakers are very low sensitivity, according to internet legend they're 82db. Does anyone have a source for this data? I'd love to see a comparison of the Quantum 2, 3, 4, and 5 sensitivities, I suppose more drivers may increase the need for power. My Terry fresh MC2200 just couldn't get them very loud.

These speakers have a nice center image and good detail. A two mic recording of the Berlin Philharmonic sounded great doing some Dvorak. I could point to the placement of the instruments. I see why line source speakers are popular!

Not a big soundstage however (I'm used to ESS Heils) and the rear tweeters did not do much, there should be a volume control for them. Is a speaker with tweets on the rear a dipole? I used the Cardas method for dipole to choose speaker position.

There seems to be some trouble with one woofer. It makes a cricket-like shuddering noise when the bass gets really low and loud, like the heartbeat intro to DSotM or a Grateful Dead drum duo. They were refoamed before I bought them so that may be it. I will diagnose them after I replace the old electrolytic caps.

I ordered some Parts Express 5% NP poly caps, 7 200uF for the 1400uF circuit and 5 200uF and 2 50uF for the 1100uF circuit. I will report back when they are installed.
 
Last edited:
Not a big soundstage

It's there...they just haven't given it up for you yet. Could be the room, gear, or simply the fact that they're not operating at 100%. A tube preamp helped open up the sound stage with mine. The QLS-1's offer impressive sound stage depth and the overall scale is some of the biggest I've ever experienced. Imaging and sound stage population is up there with some of the best I've experienced as well. The rear firing EMIT doesn't do a whole lot for the overall presentation, IME. I actually prefer to turn it off since it attenuates the front EMITs a bit when it's on and I think the overall sonic presentation benefits from the added energy of the line source of EMITs running full steam. But then again, a I've found a few of mine are playing with a weaker output than others, so perhaps my observation isn't valid. I think tubed said he likes his rear EMITs turned off as well.

I think you'll find these speakers will reward you handsomely as you put more effort into giving them what they like. Mine liked high current, class A SS power with a tube pre. I never tried tube power with them, but I finally have a tube amp powerful enough to power the mids and EMITs and look forward to hearing them with it once I get around to getting them out again. Since the dome mids have such a wide dispersion pattern room reflections can mask the magic...so unless your side walls are a good distance away from the speakers some absorption there is strongly recommended. How big did you say your room is again?

Of the several dozen speakers I've had the pleasure of owning and auditioning I have to say I think the QLS-1's are some of the most versatile, easy to listen to, and sonically capable of them all. Perfect? No. Of course not. But you can't hardly find a damn thing they're even half way bad at doing. Except sound small and move easily. They suck at both of those.

- Michael
 
My QLS-1's put a fresh Emotiva XPA-2 into protect mode twice. And I wasn't really even cranking it. Soundcraftsmen MA5002, Aragon 8008 and Threshold s/300 power them without a whimper.
 
Back
Top Bottom