Hi, I am new to this forum and serious hi fi equipment. I've recently bought a second hand Quad 306 amp, and am running B&W DM601 S2 speakers with it. At high volume the amp overheats after about 2 mins and shuts down. But when I run them with my Quad 303 it's fine, but doesn't have quite the grunt. Why is this, is the 306 faulty? the 303 is 45W per channel, 8 ohms the 306 is 50w per channel, 8 ohms the speakers are 100w max, 8 ohms If I can't get the 306 working properly, i may get another 303 and try bi-amping the B&Ws, would this setup work well? Thanks Harry
harry - It's difficult to tell what is happening with the 306 based on your description. The first thing to do is connect a different pair of speakers to the amp. If the amplifier responds in a similar fashion, you should decide whether you want to repair it or not. If you decide to fix the amp, take it to a Quad specialist as the circuitry Quad uses is not a typical situation for your average technician.
Bi-amping the B&W's? With a passive connection? Or, do you use an outboard electronic crossover in front of the amplifiers?
Hi Jan, I've connected the 306 to a couple of old Tannoy 15" monitor golds and it's fine, doesn't cut out. The B&Ws have 4 inputs, is this passive. If I've undserstood right I'd connect one amp to half the speaker and one amp to the other 2 connections, repating for the other speaker. But I also have a pair of Kefs (not sure the model as they're in the ceiling) with only 2 inputs, will I be able to include these in the system? Thanks
actually I take that back, the 306 still overheats with the tannoys. The volume was pretty high but I would have thought an amp like the 306 could drive low rated speakers indefinitely? Maybe it's time for a service...
Possibly a few components have drifted from spec'd value just enough to cause the problem. A decent tech should be able to give you an estimate of repair costs before performing any work.
Passive bi-amping is not as effective as active bi-amping where the frequencies are selectively assigned to the amplifier and the high frequency amp doesn't see any of the large voltage/current draws which drive the low frequencies. However, since the high frequency amp is isolated from the back EMF of the low frequency driver, there are benefits to be had. My opinion of passive bi-amping is try it and listen for the benefits. They will not be as great as employing active crossovers before the amps but might be enough to warrant the effort.
Since the amplifiers will be seeing the full frequency range in a passive bi-amp set up, you can connect another pair of full range speakers to the amplifier's outputs. I'd use the amp driving the low frequencies for the second pair of speakers. If you intend to run all the speakers at the same time, however, you've pretty much negated many of the benefits of the passive bi-amping. Once again try it and give a listen.