The 1970's Infinity QLS 1...How would it compare?

I realize I'm digging up an old thread here, but I just wanted to state for the record that after a few days of work and a few hundred dollars worth of crossover rebuilding and new internal wiring, AND with these speakers being properly driven (which was clearly important to the OP and not addressed above) by a single 500Wpc Yamaha PC5002M amplifier (the pro version of the 101M), I believe you'd all find that the QLS1s are a truly fantastic speaker, certainly much better than what's been described above.

The only criticism I can still agree with is that there IS a little extra midbass, though it's not much. I haven't done a frequency response sweep to make sure my potentiometer settings are dialed in properly, so this may be the answer to that. If not, I'd bet that a judicious re-stuffing of the midbass coupler's transmission line should get rid of most of the issue. Oh, and the cabinet, though already braced, can indeed get a bit resonant with some loud bass hits below 35Hz or so. However, this is fairly simple to fix with a dowel rod and some DIY instructions, and I actually intend to do this in the next few weeks.

I guess that ultimately it depends on what exactly what you want out of a speaker, and how you rank these different wants. I would say that a rebuilt QLS1 does almost everything quite well, and some things even better than that. I have no experience with new >$2k speakers, so I can't speak to that part of the OP. Just don't expect the world out of a completely stock model, and be prepared to spend some dough on a serious amp.

I happen to own two pair, and have a large mound of serious ampolification (also old) to light them up. They are phenomenally inefficient, but worse than that, a extremely reactive. Take what you consider a decent amp (and skip the receivers) and the QLS will leave it straining both nuts to keep up. I have some rebuilt SAE amps which are good, and a Nakamichi PA-7 (the STASIS design) which is great. I biamp them using the built in biamp capability. The bass is powerful and solid (the PA-7) and the highs are fast and transparent. Also, the 48" column of tweeters has an extraordinary imaging trait. The soundstage does not move as you move up and down. It is like a "wall of sound", not a point of sound. The imaging is very good, but not so good as some more modern MTM designs.

With the QLSes, expect to spend some serious time auditioning amplifiers in your house with your speakers. Once dialed in, however, they are amazing speakers.

And you need a decent room to make them sing, also.

QLS-1s were not bad when they were new, but I had nothing but problems with them. I blew out a mid-bass coupler, then had CONSTANT problems with the EMITs, often spending more time fixing them, than listening.

Neat concept and imposing, but an overall disappointment

I have owned a pair of QLS1's for 30 years and I have never auditioned another system in any high end audio shop or in anyone's home that was even in the same league.Visitors to my home have initially commented the system didn't sound right to them until they listened to their own system later,then they cursed at me.The only problem with ever owning the QLS1's is that you will never be able to go back to the days when you enjoyed music from a typical stereo system.BTW, when i purchased these speakers i understood they required massive power amps, people that can't afford the amps will never truly hear what these speakers are capable of. Sincerely,Tony Barr

The reason drivers including the EMITs are blowen is due to under powered amplifiers. I have 8 pair of other speakers, but these sound more alive than others I tried. In the past I switched to other speakers such Magnapan Tympomies, Acoustats, AR 9As, but always returned to them. For components, I purchaced thre pairs and removed all usable components. I also am using a 600 watt per channel amp.
Ive owened them since 1982 I will likely sell them in the near future because I must down size.

Henry