Any Infinity QLS owners here?

...Or, have any members at least heard the Quantum Line Source?
I remember reading about these big expensive Infinity speakers back in the late 70's. I remember reading the ads: "Watkins dual-drive woofer" comes to mind. I believe these speakers required tremendous amp power....if I remember correctly....each woofer needing(having?) its own amp.

Anyone remember these beast well? First time I saw them on the back cover of Stereo Review magazine I just stared & said: Wow.
Wonder if they live up to the "hype-of-the-day", back then. Now these are speakers I'd love to hear someday. I'm not looking for these....just thinkin 'bout the old days is all and I don't hear much talk about the QLS anymore.

Certainly someone here has heard them before. If anyone has a review that they could post, that'd be cool to read!!



Cheers,
Russ

Searched Google

Here is what I found...
http://www.bobbyshred.com/infinity/QLS.html

Yep, I’ve heard of them, but sadly have not heard them. As near as I can figure, those who have these speakers have nothing but praise for them, but as information is scattered, there must not be many out there.

Now, if the little brother of the QLS-1 counts, the Quantum 2 (now listed on the Infinity company website as the QLS-2), then yes and no. The Quantum 2 is essentially the same design; only the cabinet is a little shorter and there are only 4 EMIT tweeters and 2 dome midranges per speaker, versus the 9 and 6 respectively for the QLS-1. I have a pair of Quantum 2 speakers that I picked up over a year ago, but have yet to hear what they sound like do the midrange tinsels being broken (and beyond my abilities to solder thanks to some sort of coating on the wires [I’d appreciate any help in regards to this]). All I can vouch for with them is that the EMITs alone sound mighty nice and that the Watkins woofer in its sealed design is very tight and fast for what it is. In fact, I’m using these speakers as stereo subwoofers for my Magnepan MG-Is and feel that they can keep up with the planar sound fairly well. (Yes, my apartment is very, very full of speakers and audio goodies; I blame Goodwill for it.)

The Infinity Company that made these speakers is still around, though producing, imho, inferior products. Fortunately, they do have some very limited information regarding their previous offerings including the Quantum line. Their page concerning the QLS-1 states the power requirements of at least 100 watts per channel up to 500.

Now, just running the Watkins drivers on mine, I can vouch for how power hungry these are. When I first ran them to test my refoaming skills, they killed a Pioneer VSX-3300 I had scrounged up at low levels, as well as some supposedly 120 wpc ‘80s Technics receiver. I’m now running around 200 wpc and still having troubles driving those Watkins, but it is worth it. (I did briefly try these on a Pioneer SX-838 at low volumes and the bass was incredible.)

For further information, there are at least a couple of QLS-1 owners over on the fairly active Infinity Classics Yahoo Group that seem moderately talkative and most likely would be willing to share their opinions upon their speaker. You can find this group here:

If you’re curious, you can find the brochure for these speakers at Bobby Shred’s page.

Now, as to your request for reviews, there’s the Infinity-Classics page that used to have the manual for and reviews of the QLS-1. However, those seem to have gone missing, as near as I can tell not being able to read German and all. I did save the 2 page Stereo Magazine review from an earlier visit and will post it for your viewing pleasure.

My writing skills seem to be severely lacking this evening, so my apologies if I’m not too clear in what I’m trying to say.

- JP

Edit: Drat, clifselina posted Bobby Shred's link while I was typing up my overly long response. I better be quicker next time.

I have a set of QLSs that I bought about six months ago. I think the amp problem is that the Watkins woofer dips down to about 2 ohms, which sucks power. I'm not using them day-to-day, but when I first got them I hooked them up to an MC-2105, which seemed to struggle a little, then an MC-602, using the 4-ohm taps, and it worked well. To me, they sounded good, with a wide soundstage and great detail in the mid and treble. Bass was a little off, but I think the woofers are almost shot. I have a pet peeve about vertical dispersion: I hate it when the sound changes drastically between standing and sitting, so I'm drawn to line sources, which is why I bought these.

I'm trying to find someplace to restore them, and they need a lot of work. Anyone have recommendations (preferably near Lake Tahoe as they weigh a ton)?

Alright, I've had to mutilate these scans to fit in under the attachment size and orientation limitations, but hopefully they're still legible.

Review taken from Infinity Classics

- JP

Negotiableterms,

they weigh a ton

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Haha, while they don't technically weight a ton, they sure feel like it. I remember carrying my Q2s (lighter at ~140 lbs each) out of Goodwill and to my truck. I couldn't figure out why I was tired and was surprised at my seemingly being out of shape. I was thinking, "They can't be that heavy." I probably would not have carried them had I known their weight before buying them.

- JP

Qls

I have 2 sets Of the Quantum 3s .I do not know how they compare to the QLS but these speakers are the only ones I have ever heard that will be with me till one of us is beyond repair ,shoot I might be buried in one.I really love the sound of them.1 set is driven by a 350 watts @4 ohm Soundcraftsmen Ma5002 amp and the other set I modified for biamping with 1 Ma5002 amp driving the woofers and anything from a Yamaha ca-2010 amp to a pioneer sx-1250 driving the rest.Its all sweet to my ears.

Restoration

Does anyone have any suggestions for a restoration shop for a pair of QLSs? Thnaks!

Charivari said:

I have a pair of Quantum 2 speakers that I picked up over a year ago, but have yet to hear what they sound like do the midrange tinsels being broken (and beyond my abilities to solder thanks to some sort of coating on the wires [I’d appreciate any help in regards to this]).

Click to expand...

I resoldered the broken tweeter leads on a cheap pair of Technics 3 ways by removing the insulating layer on the wire. Either sandpaper or a couple passes with a razor blade over the wire. Support the lead with your finger while doing this or you'll risk snapping the wire.

Once there is good copper to solder to, you'll probably be set unless the break shortened the lead significantly. I had to splice a short length on my cheap tweeter. Hopefully you won't.

It took me six tries to get it right so you probably want to practice on something expendable before tackling the Qs.

I'm actually hunting for a speaker restoration shop to work on three pairs of speakers: the QLSs, a pair of Kappa 9s that badly need refoaming, and a pair of ESS AMT-3s that need all kinds of work. Anyone have any experience with professional restorers?

Negotiableterms - what do you mean by restoring? If its just driver work (reconing or refoaming) then try either of these places. You might want to send the drivers out to have repaired and then have any cabinet work done locally.

http://www.speakerrepair.com/
http://www.simplyspeakers.com/

Of course our resident speaker guru GordonW does great work too (including my SB7070 woofers that somebody had kicked in) but Orange County (www.speakerrepair.com) is closer to you. I believe they are an authorized Infinity repair center too. For the ESS you might want to directly contact the company if you need new diaphragms.

Gonzo- Thanks, I'll look into all three of those. By "restoring" I'm hoping to find a place that can re-foam/re-cone along with testing the internal wiring and crossover. After this many years, all of the crossover caps and some other components probably need replacing. At this age, the grilles need work to fit correctly, the grille cloths need replacing and the cabinets need re-finishing. If you send them to a furniture refinisher, the cabinets look great but the drivers have random drops of stain applied and the new grill cloth is acoustically opaque (painful experience). I've tried re-foaming on my own, and while it wasn't awful, the sound wasn't quite what I remembered, and I wound up buying replacement woofers, which sounded correct. I guess this has something to do with being a newbie at re-foaming, just like I am at AK.

I've heard them, every Sunday morning at 7:30am my dad would wake me up as he read the paper listening to his QLS's. I feel guilty, because I boxed these up and stored them under my moms house about 10 years ago (my dad passed away in 86, he's probably rolling over in his grave thinking about his speakers.) Researching the net, now I'm starting to realize the sin I committed burying these fine speakers for so many years. I'm going to unpack them and take a look, hopefully they are still in decent condition.
My dad powered them with a single Dynaco 416. I remember in High School (when my dad was a work...) I used to suck the amp dry powering the Watkins subwoofer. I played around with hooking up a Phase Linear 400 amp and the Dynaco, one powering the woofers and the other the mid and highend, sounded pretty good but I'm no audiophile (especially back then.)

Anyone have any ideas what would be good current day amps to power these speakers?

jim_arndt said:

Anyone have any ideas what would be good current day amps to power these speakers?

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IIRC (and someone correct me if I'm wrong) your major job is to find an amp that tolerates really low impedence loads, as that Watkins woofer takes them down to less than 2 ohms at some frequencies.

Obviously, any of the current crop of "true voltage source" amps will do the trick, but cost a fortune. On the used front, try a PS Audio 200CX. Make sure it's a CX, though, the C wasn't as stable. Even better (and much more expensive), current new or used, try any of the McIntosh big-watt autoformer amps with 2 ohm taps. Ummm... I think MC-2255 on up, but I'm not sure, so check Roger Russel's site to be certain. I think you need at least 200 watts @ 8 ohms, with 2 ohm taps. Current models, an MC-252 is minimum, but an MC-402 should make them sing. Recent past, an MC-352 would be almost as good.

The other guys here may have better ideas, but if they're in good shape, you've got a pair of classic, collectable speakers that sound great!

Jim Arndt, Welcome to AudioKarma!

I'm an owner of a pair of Quantum 2s, the little brother to your QLSs and would love to have the bigguns some day. They're definitely great speakers and will require a rare amplifier considering, as Negotiable Terms mentioned, that they dip down into the sub-2 ohm regions and are only 81 dB/1 watt/1 meter efficient.

I've been recently looking for information concerning a pair of Infinity electrostatic headphones and encountered a former Infinity salesman over at AA. He mentioned the QLS and made some mention of amplifiers to drive them; I've reproduced it for you below.

Vinyl Rules! said:

Our best Infinitys were the Servo Statiks (when they were working and we weren't replacing the electrostatic drivers). Another good Infinity we sold were the original QLS (Quantum Line Source) speakers with the Watkins woofers, but few amps would drive them well. The original QLSs were big, requied a very large room, and used a line array of tweeters. They later morphed this speaker down to several smaller sizes and changed the tweeters from domes to their EMIT tweeter they developed.

We found that Mark Levinsons and Ampzillas worked well. Interestingly, we took in a mint McIntosh MC2505 on trade (we weren't the McIntosh dealer iin town) that would barely drive them no matter which output taps we used, and it was one of the few times I heard a McIntosh amp sound terrible - It was not a good match for the QLS, but then it was only a 50 wpc amp and Infinity recommended at least 100 wpc for the QLSs. The Infinity Class D switching amp also would do a great job on the QLSs before the amp imploded.

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As to fixing them up, you've come to the right place. The Watkins woofers should be an easy fix for you, its a given the foam surrounds will be shot by now, and most around here can help you out on that or you can have the original designer do the repairs. The midrange domes, if they've broken those all to fragile tinsels while in storage, can be repaired. If the EMITs may have gone bad, AK mod Army knows someone who can fix those for you.

Oh yeah, if at all possible, pictures would be nice.
- JP

Charivari-

Thanks for the Watkins site!!! I had no idea.

Now, the bad news is what it's going to cost to ship those two behemoths across the whole country. Yeech.

Thanks again!

Negotiableterms said:

Charivari-

Thanks for the Watkins site!!! I had no idea.

Now, the bad news is what it's going to cost to ship those two behemoths across the whole country. Yeech.

Thanks again!

Click to expand...

No prob. You've still a pair, right? What needs to be done with them? If you just need the Watkins woofers fixed up, you can send just them. For the rest, Orange County Speaker Repair is commonly recommended for fixing up the older Infinities. Or ... you could always send them up my way. :thmbsp:

Oh yeah, QLS.


Just general info for any vintage Infinity fans, keep these websites in mind.

Infinity Classics

Bobby Shred's Vintage Infinity Speaker Page

Infinity Classics Yahoo! Group

- JP

I still have them, but they're sitting in storage, inappreciated. I also have a pair of almost-mint IRS Betas, and those are all the Infinity fix I need, so the QLS's stopped being a priority to restore.

I'd still like to get it done though, so Orange County seems like the place. Cheaper shipping, too. The main problem with large full-scale speakers: they're impossible to service and transport.

You'd think I'd have better things to gripe about, no?

You mean these Betas? Ok, I hate you now. Those are the little sibs of my dream speakers, the IRS V, and I'd probably stand a good chance of being happy with just those. And to have a pair of QLS-1s to boot. Yep, I'd love to have your problems. Say, I know someone who'd fix up those QLS and appreciate them. (Having brought back a pair of Q2s from the dead -- hacked crossovers, damaged Watkins sans foam, and 3 out of 4 midrange domes with broken tinsels.)

- JP

I think my QLS's need a lot of work. They need cabinet work, wiring, crossovers, drivers, etc., etc... At the price today of EMIT drivers, it wouldn't be cheap, and I think the dome midranges are unobtanium, as is the mid-bass coupler.

I usually get this stuff wrong, but... you're a student, right? EE or something similar? Either way, you're way too young to have insomnia!