I have a pair of Quasar QS1 speakers. A bit of background on them! They were high-end top of their range Rosewood monitors made in 1974 by Eagle International for export from England to the USA, the deal fell through when the American dealership wanted to assemble them in the USA but Eagle International didn't trust them to do it properly. Anyway, I am driving them with a Sansui AU-11000 but I have the volume at 1 o'clock to drive them at my usual level when other speakers go to only 9 o'clock? They are supposed to be driven with an amplifier with a maximum of 50 WPC? They still had the old electrolytics in the crossovers when I first got them so I changed them out thinking that was the problem but no, it wasn't? They are still hard to drive, they sound great but I'm wondering why they are rated at 50 watts when I have to give them at least 50 watts to get them going? I thought it might have been the HF switch on the back of them getting oxidized but they are both of exactly the same volume! Any ideas anyone?😀
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Are you getting decent bass out of them? sometimes the surround on the woofer can harden up and prevent the cone from moving as it should.
And its possible that other components on the crossover have issues, and even the other drivers (midrange, tweeter and super tweeter) have problems as well.
Have you taken any of the drivers out to test?
And its possible that other components on the crossover have issues, and even the other drivers (midrange, tweeter and super tweeter) have problems as well.
Have you taken any of the drivers out to test?
If the sound is balanced (all drivers functioning at the appropriate level), then the speakers could be of low sensitivity e.g. 82dB/W/m or less.
Even then, at 6 feet from the speaker, a mere 4 Watts would give the average reference volume of 85dB and 40 Watts would produce a very loud 95dB.
It may be worth checking whether a loudspeaker protection device such as a polyswitch is in circuit. These can go go faulty, assuming a high resistance and reducing the output from the speaker.
Even then, at 6 feet from the speaker, a mere 4 Watts would give the average reference volume of 85dB and 40 Watts would produce a very loud 95dB.
It may be worth checking whether a loudspeaker protection device such as a polyswitch is in circuit. These can go go faulty, assuming a high resistance and reducing the output from the speaker.
Can you do a thorough check of the crossover and the wiring path to the speakers ?. Maybe a shunt component in the crossover has gone low, or a series one gone high.
You mention the tweeter switch, maybe both cabinets have an issue.
Critters inside the box?
As other have suggested bass driver suspension hardening up. You would normally definitely expect a vintage 12 inch driver to give you some sensible volume, yet do they seem balanced when they have the volume control at 11 o'clock?
You mention the tweeter switch, maybe both cabinets have an issue.
Critters inside the box?
As other have suggested bass driver suspension hardening up. You would normally definitely expect a vintage 12 inch driver to give you some sensible volume, yet do they seem balanced when they have the volume control at 11 o'clock?
Thanks for the suggestions fellas, I will check the crossover circuits and those HF attenuator switches, Ill give them a clean with some DeOxit and see how things go? I will check the skirt I think its called on the woofer (it connects the cone to the voice coil) to see if it's gone hard? The thing is the speakers sound great as they are it just takes a lot to drive them?
I think the skirt is more commonly called a spider, it's the wavy orange bit in the back, under the magnet, that centers and supports the voice coil.
If they sound great, it seems less likely IMO that e.g. the bass driver has a significantly stiffened up in the surround or spider; they would probably sound shrill instead. Cleaning and checking the electrical components seems like a good step. A cheap multimeter would come in handy, and possibly a spl meter.
If they sound great, it seems less likely IMO that e.g. the bass driver has a significantly stiffened up in the surround or spider; they would probably sound shrill instead. Cleaning and checking the electrical components seems like a good step. A cheap multimeter would come in handy, and possibly a spl meter.
I see that the Quasars have been discussed on this forum before: Quasar QS1 Studio Speakers.
P.S. Glad you changed out those ELCAPs!
P.S. Glad you changed out those ELCAPs!
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I have a Fluke 87v DMM and all the gear, I have been into repairing audio for years now? My memory isn't as good as it once was! 😀
Yes, both woofers are balanced and working well, I cranked these speakers right up with Status Quos Caroline it's like being at a live concert. I forgot that they were only rated to 50 watts. I'm lucky it didn't burn the voice coils? I'm taking the drivers out today to have another look at them?
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If you could disconnect the speaker drivers, maybe just try driving the woofer (but not the tweeter) directly from the amp and see how loud it goes. Will be able to pinpoint whether it is from the drivers or the crossover.
Oon
These speakers have two tweeters a normal tweeter and a super tweeter, should I disconnect the mid-range driver as well leaving just the woofers?
The woofers are working Ok I disconnected everything leaving just the woofers. I think I may have found the problem! I hope so anyway? While I was disconnecting the Tweeters etc... I noticed I had forgotten to change out an original capacitor on the cross-over. It's that drab green one at the left-hand bottom of the 3 yellow polypropylene caps. It reads 470n 160v -+ 10% I will find some suitable polypropylene caps and see how it goes then?
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Remount some of the coils on the PCB so that they aren't all parallel to each other. That will massively reduce the crosstalk from the air core coils.
Just to be sure that there is no confusion. What I meant was to remove the connection from the woofer to the crossover and connect the woofer directly to your amplifier (without the crossover). Should be able to give you a rough idea how loud it was meant to sound...
Oon
I'm not going to mess with that for the time being, these speakers were the top of the range for Eagle International at the time, I'm pretty sure they knew what they were doing when they designed the cross-overs especially in 1974 in the middle of the Golden age of Hi-Fi. If the cross-overs can be improved upon with modern techniques though, I'm all for it. What about just shielding the coils?
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From the orientation that they mounted the coils in, I can guarantee you that they did not know what they were doing.
Ok I will shield them from each other, that should fix it. Thanks for the advice mate!
If you use anything with iron in it to shield the coils, that will change their inductance, which will completely change the crossover characteristics.
Just rotate every other coil 90 degrees, then their magnetic fields won't couple to each other and they won't behave as transformers.
Just rotate every other coil 90 degrees, then their magnetic fields won't couple to each other and they won't behave as transformers.
I've had a look at the coils, they are already at 90 degrees from each other? There are two facing the same way but they are offset and not in line with each other. I was thinking of using aliminum foil and cling wrap to shield them.
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