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Quantum 3's

micrometer

micrometer

chameleon
I'm quite new to the vintage audio arena. I just picked up some Infinity Quantum 3's.

I need some recommendations for a preamp to run these speakers. I'd like to keep to a single preamp instead of some arrangements I've read about like tubes on top and SS for the Watkin's woofers (this scenario looks to be out of range of my budget).

Will I need an amplifier running at 4 ohms instead of 8 ohms to prevent damage to the Watkin's woofer?

Any assistance would be greatly appreciated.

Thanks
 
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Very nice score, Micrometer! I cant believe how many Quantum series are found everywhere except in Los Angeles where they were built(envy)........as far as amplification get as much power as you can afford. The amp's specs should be rated at 8/4/and 2 ohms. Running too low a current can damage drivers(more likely the mids and emits) and be hard on an insufficient amplifier. For the Q3's I'd try for at least 150 watts per channel.JMHO
 
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micrometer said:
I need some recommendations for a preamp to run these speakers. I'd like to keep to a single preamp instead of some arrangements I've read about like tubes on top and SS for the Watkin's woofers (this scenario looks to be out of range of my budget).

Will I need an amplifier running at 4 ohms instead of 8 ohms to prevent damage to the Watkin's woofer?
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I think what you are referring to is above is an amp. A preamp is the component that usually has volume and balance controls, sometimes has tone controls, and provides the means to switch between sources (turntable, tuner, CD, tape, etc.) The preamp outputs its signal to the amp. The amp's job is to amplify the signal and drive the speakers.

What you are talking about above is bi-amping, using two separate amplifiers, fed by a single preamp, to power the speakers. There is no reason you have to bi-amp your speakers, as one good-quality high-current amplifier will drive these speakers just fine. But bi-amping may be something you might want to try some time down the road when funds allow, and the RS-2.5's will respond very well to biamping.

Regarding amps, you will want an amp that is happy driving a 2-ohm load, and is capable of producing current, not just watts. I recommend something of around 200 wpc @ 8 ohms, doubling down to close to 400 wpc @ 4 ohms. If you are on a budget, you might want to consider an Adcom GFA-555, Forte Model 3, Forte Model 6, some of the Yamaha M-series amps, and some of the Soundcraftman models. I've used both Forte amps and the Adcom with vintage Infinity's (the ones in my avatar) with great success.
 
I've got a pair of Quantum 3's and they aren't capable of being biamped. But, with a 250wpc Soundcraftsmen amp on them, they don't need it. ;) Great sounding office rig although I might have to bring them in the living room and see what they do in here. You will definitely need an amp rated for a 4-ohm load, too. Here is a link to some information on them if you haven't already seen it.
 
The seller is correct. I'm running my pair with a Crown PSA-2 (under $300) - lots of high current output and built like tanks, 340 watts stereo into 8 Ohms and can go down to 1 Ohm or less and they sound fantastic. Of course you will need a preamp as well.

Cheers,
Bob

micrometer said:
Thank you for the replies. This will help me in my search. The previous owner of the Quantum 3's mentioned Crown amps.

This Crown says it will, "Load Impedance: Rated for 2 to 8 ohms per channel in Stereo".

http://pro-audio.musiciansfriend.com/product/Crown-XLS-402D-Power-Amplifier?sku=481585

Any comments on this one?

Thanks
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I had good luck running my quantum 3's with a sansui g8000. The q3's are notoriously tough on amps but the g8 never broke a sweat even when driving the quantums pretty hard. The quantums do sound their best when being driven by tubes though. 85 watts of tube power really makes mine come alive much more so than the g8000. I'll have to try my 250 watt soundcraftsman on them someday like avguytx suggested. I'll just bet that's a great sounding pairing as well.
 
Crown with Preamp

I'm leaning toward the Crown amp. I have two preamps. An early 80's Sony STR-V55 (55 wpc) and a Technics ('97) SU-G86 (120 RMS @ 8 ohms).

Any thoughts on using these as my preamp? :scratch2:

This will show my naiveté, but when the crown amp is connected to the preamp via EQ/EXT terminals and the front Q 3's connected to the Crown amp are the existing A/B speaker terminals on the preamp available for use such as driving a rear set of speakers?:scratch2:

Regards
 
I would STRONGLY recommend a professional Crown amp or something like that (QSC amps are also good, Hafler's professional TransNova series are also good, the JBL/UREI amps of the 80's are also good). You need AT LEAST 200 watts a channnel. You can not have too much power for these things. I have a pair of Quantum 3's and a pair of Quantum 5's and both are power hogs. The most dangerous thing to do with these speakers is to UNDERPOWER them. Too small a power amp is a sure fire way to blow the EMIT tweeters (trust me, I have blown several of them).

A professional amp, like a big Crown, is made to handle the difficult loads of running multiple speakers in a big P.A. system, club, or concert hall. This is IDEAL for powering something like a Quantum 3. Even though these amps are not sold specifically for home use, and you can't find them at the Best Buy, do NOT let that throw you. All modern Crown amps will work just fine in a home system, have excellent full range frequency response, low noise, and sound great. Having large amounts of solid power from something like a big Crown amp really helps the Watkins Woofers come to life. Most of these amps do have a small internal fan which will run when the power is on, kind of like a computer, but the noise is usually not an issue. These amps are fairly cheap on the used market and are usually built like tanks.

J. Mike Perkins
 
+1 - what he said... bought mine - blew the amp in like 3 minutes, al I wanted to do was "test" the sound. Don't do it. I blew a 70 wpc Technics SE-9060 "pro" amp. Moved QUICKLY to Crown and haven't the need to look any further. Smooooth sounds now even with radio and when I listen to LPs mmmm just right, CDs can become a problem as you will hear the crappy crap if its there, same on LPs but I'm particular with LP quality. Also these speakers will reveal the chain of command. If you have a weak link - it's NOT the speakers (if they are fully operational). Nice pic but expect to upgrade the rest of your gear. Ask for help if you are not sure. Patience is a virtue.... its really true. Ask your Mother.

Cheers,

Bob

jmikeperkins said:
I would STRONGLY recommend a professional Crown amp or something like that (QSC amps are also good, Hafler's professional TransNova series are also good, the JBL/UREI amps of the 80's are also good). You need AT LEAST 200 watts a channnel. You can not have too much power for these things. I have a pair of Quantum 3's and a pair of Quantum 5's and both are power hogs. The most dangerous thing to do with these speakers is to UNDERPOWER them. Too small a power amp is a sure fire way to blow the EMIT tweeters (trust me, I have blown several of them).

A professional amp, like a big Crown, is made to handle the difficult loads of running multiple speakers in a big P.A. system, club, or concert hall. This is IDEAL for powering something like a Quantum 3. Even though these amps are not sold specifically for home use, and you can't find them at the Best Buy, do NOT let that throw you. All modern Crown amps will work just fine in a home system, have excellent full range frequency response, low noise, and sound great. Having large amounts of solid power from something like a big Crown amp really helps the Watkins Woofers come to life. Most of these amps do have a small internal fan which will run when the power is on, kind of like a computer, but the noise is usually not an issue. These amps are fairly cheap on the used market and are usually built like tanks.

J. Mike Perkins
Click to expand...
 
Crown Com Tech 400 it is

I picked up a Crown Com Tech 400 on ebay. It'll produce some 200 watts per channel. I'm waiting for some y cables for my preouts so I can use my receiver to drive rear speakers and the Crown for the front Q 3's.

Thanks for all the good advice!!
 
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