Quantum vs RS line

I am the owner of RSM and RS 1.5 speakers. I seem to prefer the look of the Quantum line - walnut vs oak is probably why, but also the cleaner lines on the quantum and the veneer on the front also help.
As far as the design and history go, I am a little lost as to the difference between these lines.
So, my question is other than the looks what separates the Quantum line (2, 3 and QLS for e.g) and say the RS 1.5, 2.5 and 4.5 line that have the Watkins woofers.
One noticeable design difference is the mid bass coupler (maybe one of the mids on the 2.5 and 4.5 do the same thing?). Are they very similar with just historical difference, the Quantum preceding the RS Watkins line?

I think the RS was just a newer line.....On Bobby Shred's website the ads for the QLS says 1973 or 77 at the bottom (not sure using laptop) and the ad for the 2.5 reads 1979...

Yes, that would be my guess, although it seems like there was some overlap in production years. Maybe they were trying out the design with and without the transmission-line mid bass coupler (whatever that is)?

apples and oranges.

the reference standard (RS) series went in a lot of directions, driver-wise. some got high zoot drivers, others, not so. though there were variations, quantums were a little more consistent within their line.

with the exception of the RS 1.5, 2.5, 4.5 most of the RS series did not have watkins woofers. the numbered quantums did. a few of the RS dual woofer variants (but not all) used woofers in a staggered resonance configuration.

none of the RS have mid-bass couplers. of the quantum line, only the QLS 1, Q2, and Q3 do, and they use the philips.

the RS line used a lot of different mids. polydomes, emims, poly cones, etc. the Q series used a braun sourced dome mid.

as for tweeters, all quantums got emits. some RS got emits, some got polycells.





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It is a bit ironic that the QLS series was prior to most digital recordings where as the RS series came out as digital recordings started to emerge. It might just be a figment of my imagination but the speakers seem to mimic the attributes of the differences between analog and digital.

The QLS seem very much like a warm vinyl recording, while the tonal signature of say my RS-1b's or the RSIIb's seems much more quick and digital in their signature.

Or I could just be a bit nuts.

Bkphoto said:

I think the RS was just a newer line.....On Bobby Shred's website the ads for the QLS says 1973 or 77 at the bottom (not sure using laptop) and the ad for the 2.5 reads 1979...

Click to expand...

QLS-1 was introduced in '77.

Ken Boyd said:

It is a bit ironic that the QLS series was prior to most digital recordings where as the RS series came out as digital recordings started to emerge. It might just be a figment of my imagination but the speakers seem to mimic the attributes of the differences between analog and digital.

The QLS seem very much like a warm vinyl recording, while the tonal signature of say my RS-1b's or the RSIIb's seems much more quick and digital in their signature.

Or I could just be a bit nuts.

Click to expand...

Interesting point, Ken.
The tonal signatures of earlier and later designs, that is

Thanks loquatious for clarifying the technical difference. I'm guessing they did have their own particular sonic differences for Infinity to have produced both lines at the same time, the quantum line being pulled before the RS line.
And thanks Ken for your feedback on the sonic characteristics. I am curious as to how the quantum range sounds since I've only listened to some of the RS line and the Kappa line, which in my opinion do not sound dramatically different from each other.