Infinity Qb vs Quantum Jr

[WattWarrior]

Hey guys, I’m looking to try another pair of Infinity speakers in my system. I currently have the Qb’s and they sound fantastic, but I saw a pair of Quantum Jr’s come up for sale. Is there a noticeable difference in sound between the two? Would this be a noticeable upgrade or not? Both have the emit tweeters and similar driver layout. (The Quantum Jr has the Watkins woofer I believe.) They’re both from around the same time period(1977-78) The Quantum was higher up in the range when new but that doesn’t always mean they sound better...right? Any feedback is appreciated. Thanks!

- WattWarrior

(here are two images from Google of both speakers) not my images.

 

[Erik Tracy]

I used to own the Quantum Jr.

Never had the chance to hear the Qb, so can't give you a direct comparison.

The Jr was a very good sounding speaker, but beware, it's a 4-ohm speaker and would benefit from a good amp with clean power. The Emit can fry if you ask too much of the amp.

 

[WattWarrior]

I used to own the Quantum Jr.

Never had the chance to hear the Qb, so can't give you a direct comparison.

The Jr was a very good sounding speaker, but beware, it's a 4-ohm speaker and would benefit from a good amp with clean power. The Emit can fry if you ask too much of the amp.

Thanks for the reply. How many watts per channel do you think would be suitable for the Jr’s? I have a McIntosh 2505 amp that I’m using now. Would that be ok?

 

[jazzmans]

My Qe's are currently powered by a carver outputing 350 wpc @ 8ohm.

power alone isn't the problem, it's extended listening above (relatively speaking) 90db that melts the diaphram.

That being said, I've never blown an Emit, Emim, or any other infinity driver, and I currently have 8 pairs of Infinity speakers.

as always, YMMV.

 

[Erik Tracy]

Thanks for the reply. How many watts per channel do you think would be suitable for the Jr’s? I have a McIntosh 2505 amp that I’m using now. Would that be ok?

Depends.

I had my Jrs paired to a Sansui 6060 with only 40 watts per channel. But, to be completely honest - this was back when I was a teenager who liked to turn it up in a medium sized room.

So, it'll depend on your listening habits, size of the room, and distance of the speakers to your listening spot. Just saying....

 

[WattWarrior]

I don’t like to turn it up too loud as I have a somewhat small room. Maybe a little less than 1/4 of volume. I recall many people saying Infinities are very “power hungry” so this is what confused me.

 

[Erik Tracy]

I don’t like to turn it up too loud as I have a somewhat small room. Maybe a little less than 1/4 of volume. I recall many people saying Infinities are very “power hungry” so this is what confused me.

You should be fine.

 

[swechsler]

The Quantum Jr. and the Qb are both 4Ω. Major differences are 12" vs. 10" woofer (for the Qb), dome vs cone midrange, and real wood veneer vs. a nasty vinyl. The Quantum Jr does not have a Watkins woofer; however, I'd still expect a bit better bass from the Jr.

That said, the Qb is already pretty damn good, and I'm not sure that the differences would be that dramatic.

 

[stinz]

I have 2 pairs of Quantum Jrs and love them, you should have plenty of power with your 2505, make sure the soft dome mids are working if you decide to get them.

 

[Swann36]

I have a pair of Quantum Jrs ...i can say they sound fantastic and also that they do need some power to work well ...

 

[Pyrrho]

You might want to compare at these links:

http://infinity-classics.de/models/Quantum-series-1976/Qb/body_qb.html

http://infinity-classics.de/models/Quantum-series-1976/Quantum-Jr/body_quantum_jr.html

Looking at the technical sheets (there are links to the technical sheets at the links above), if they are accurate, the tweeters are the same, so the treble should be pretty close to the same. But I expect that the Quantum Jr., being a step up the Quantum line, should sound like it is a step up. I would expect the midrange and bass to be noticeably better. And real wood veneer, as mentioned by swechsler above, would be a very welcome improvement to me.

But the depth of bass difference claimed is not dramatic (see info at links above).

So, you may or may not find the step up to be enough to justify getting them.

 

[tubed]

The Qb is nice, however I think the Qjr has better overall sound with a much better woofer with extended bass which really improves the midrange presentation.
It's a step up.
It just depends on how high you want to step.

 

[muziekfreak]

I got a Qe somewhere hanging out, I like the quantum line speakers. Haven’t heard the higher up quantum speakers as of yet.

 

[WattWarrior]

Thanks for all the replies! I ended up getting a pair listed online yesterday. Should be here by tomorrow!

 

[Audiokingman]

Thanks for all the replies! I ended up getting a pair listed online yesterday. Should be here by tomorrow!

Well?.....how do you like them?

 

[Swann36]

Thanks for all the replies! I ended up getting a pair listed online yesterday. Should be here by tomorrow!

Yes do tell us how you are getting on with them

 

[jaye50]

found these in my storage shed... bought them about 3 years ago at an auction for $10 without really knowing what they were...