There have been many before, but here is MY QLS-1 thread!!!

[Mehta Youngs]

Longtime reader of this forum. Haven't had occasion to post before. I've bought and sold a heckuvalotta speakers and amps. This score is worth gloating over a bit.

Generally when a set of QLS-1 come up, they are going to be a project that takes many years to get working properly. The set I found was just re-done by a former Infinity tech and they are working 100%. Cabinets are good.

When I saw the listing after releasing my album today (doing a little celebratory browsing), my heart fluttered. Of course, the guy responded "not a chance" when I asked him to ship these 200lb beasts. I told him that I already owned a set of Quantum 2 and that I knew what I was looking at. I said that I would get a local outfit to package them and take them to the shipper.

He gave me his phone number as he was clearly not much of a text guy. We had a long, long discussion about audio fundamentals, the crazy amplification requirements of these speakers, the incredible cost and effort of shipping these mammoths. I explained to him that I'm an audio professional who views this as an endgame system for pleasure listening, that they would be well powered and correctly placed in a room which is dedicated entirely to listening. He warmed up to me.

I'm pretty sure this seller was just afraid of shipping these inefficient beasts to someone who would play Youtube or other badly compressed audio with a 30-watt Pioneer receiver and then complain that their Bose sounded better.

Because as we know, without the amplification, QLS-1 are not worth it.

I do have some questions. I'm familiar with amp-per-driver active systems that are common nowadays, and I understand how to biamp a passive speaker, but in the latter case, I can only see it being beneficial if the amplifier models you have are lacking juice.

Since you are still using the passive crossover, you don't gain any efficiency with biamping. If you only had access to 100 watt amps, which is the case for most home users, you would need to biamp the QLS-1. The amp that my store carries semi-exclusively reaches 1200 watts per channel at 10% distortion. With that kind of headroom, it seems completely unnecessary to biamp. Happy to hear any criticism about my thinking here.

The pic is from the seller. The will be properly set up in my room. My room isn't huge, but my house was built in 1930, and I use lots of big woofers and high power amplification. I'm selling a powered portable PA system with 18" woofers to buy the QLS-1. My life as an event promoter ended Dec 2019 (in the nick of time, apparently) and my listening room will be much better served by this incredible gift of vintage hi-fi.

Here's my album, released today, if anyone is interested: https://mehtayoungs.bandcamp.com/album/gel-raft-today

 

[jazzmans]

Congratulations!

what is the amp you plan on using?
Any particular reason you didn't put this thread in the infinity subforum?

 

[Mehta Youngs]

Ahh I didn't realize that there was an infinity subforum. I don't often browse, I'm usually googling speakers and looking at old threads. Not exactly a regular!

My retail store SynPar carries a PWM Class-D amp that performs very well, the DARE A3. It is stable to 2 ohms, or I guess technically 2.5 ohms nominal. QLS-1 are listed as 4 ohm nominal, but the guy who is selling them to me said that they can drop down to 1 ohm on some transients. He says he has destroyed half a dozen amps with these speakers. Pretty much any serious full range will annihilate any cheap receiver though.

My amp specs:

• Material: Alum, Iron, integrated PCB
• Power: 2*1100W/4Ω; 2*625W/8Ω
• Stable to 2.5Ω
• THD: <0.005%
• N/S Ratio: >112 dB
• Frequency Response: 20Hz-20KHz +/-0.25 dB
• Damping Factor: >1000
• Controlled Slew Rate: >50V/us
• PDM Frequency: 400KHz
• Input Resistance: 30K Ohm Balanced
• Input Sensitivity: 0.775V
• Max Output Voltage: 100Vpeak/50Apeak
• Power Factor: >0.95@>500W
• DC Remain: <5mV
• Size: 1U, 48.2*4.4*16.5 cm
• Weight: 4 kg
• Power Requirement: AC 90-250V full range voltage

 

[Mehta Youngs]

Another thing I'd like to hear about is whether anyone has used these in a normal-sized room. Positioning matters. I find that if you dedicate a whole room to the sound and do it right, it tends to work out. Obviously you can't cram these into the corner of your bedroom. I have personally never felt that any system I used was too large for the room, even 4x 18inch subwoofers + 2x 12inch midbass/midrange with 5000 watts RMS in a studio space about the size of a large bedroom, hahah. You just have to know what you are are doing. I am kinda infamous for putting huge PA systems into small rooms in my city.

 

[LoStrings]

I have been using a pair for about a year. Truly amazing speakers, but yes what amplifier you use will make a big difference. I use two NAD 2200PE's in mono, which gives me the power, and current to run these beasts. Another thing to mention..make sure you put the tweeters to the inside right and left. Have fun with your new speakers, enjoy this hobby.

 

[tubed]

More than likely those are an older version.
They'll probably benefit from new capacitors, at least the smaller electrolytics.
The two larger value caps could be tested to see if they are still within range.
Also it wouldn't hurt to make sure all the wiring is correct, inside and out.
Enjoy.

 

[Mehta Youngs]

More than likely those are an older version.
They'll probably benefit from new capacitors, at least the smaller electrolytics.
The two larger value caps could be tested to see if they are still within range.
Also it wouldn't hurt to make sure all the wiring is correct, inside and out.
Enjoy.

These have been totally looked over by a former Infinity tech.

I tried to touch base with the guy today and I couldn't get ahold of him .. sent an email. Hmm.

 

[Lavane]

Better move that violin. At higher volumes the strings are gonna start singing.

 

[Mehta Youngs]

Better move that violin. At higher volumes the strings are gonna start singing.

Haha!!! That's not my pic, that's the seller. I have a cello in my test room right now though! I have two rooms dedicated to audio in my house, a professional recording/mixing/mastering studio, and a "test" room, meant more for pure listening.

Anyway, this ended up being a dead end. Guy got cold feet about shipping, at least that's what I figure. The Quantum 2 are just over at my dealer's place, held with a deposit. -3dB at 24hz is a whole different ballpark than -2dB at 18hz. I just realized what I actually need is an infrawoofer that plays the very lowest octave, from 30hz down to 15hz. Rhythmik would be a good bet. Trying to have infra response in a single column is an impossible challenge. I'm considering it a near-miss.

 

[onwardjames]

. I just realized what I actually need is an infrawoofer that plays the very lowest octave, from 30hz down to 15hz. Rhythmik would be a good bet. Trying to have infra response in a single column is an impossible challenge. I'm considering it a near-miss.

Opinions vary on this, as with many things, but there just isn't much musical information at that depth.
Unless you're listening to pipe organs much, or maybe electronica, don't sweat it. That's my advice.

Very desirable speakers you have, best of luck.

 

[tubed]

The Q2's, although not quite as deep and loud, are perhaps the better sounding speaker.
Of course live and in person tells a better tale