Weird problem with 8 ohm speakers on 6 ohm amp

Ssmusic New member Username: Ssmusic Post Number: 1 Registered: May-10	Posted on Thursday, May 13, 2010 - 00:21 GMT I'm using an old Aiwa component which has an output for 6 ohm speakers. I have big, 8 ohm speakers I want to connect to it. When I do it, a strange low frequency sound starts to come out of the speaker, and the digital EQ from the component shows this. When I first connected both speakers to L and R outputs, the thing turned off so I freaked out and tested it one by one, connecting both to each channel and having the same results. If I connect 6 ohm speakers, nothing happens and it works great. What could be happening here?
David Mitchell Gold Member Username: Dmitchell Ottawa, Ontario Canada Post Number: 3871 Registered: Feb-07	Posted on Thursday, May 13, 2010 - 00:28 GMT This is the opposite of what I would expect. Normally a lower impedance speaker would cause problems, not a higher one. What kinda Aiwa component is this?
Ssmusic New member Username: Ssmusic Post Number: 2 Registered: May-10	Posted on Thursday, May 13, 2010 - 02:26 GMT Hi David, I thought as well. The Aiwa component is hard to describe since it has several modules, the main one says "NSX-D7" and "Stereo Integrated Amplifier MX-N7". I disconnected the Cassette module since I don't use it, and the voltage comes from the CD player, "DX-N7". This connects to the wall outlet and has a cable that also powers the NSX-D7. I have also connected the Tuner "TX-N9". The weirdest thing among the weird is that this sound is shown on the graphic EQ, it's like there's a feedback or something but I'm only connecting speakers! Also, I tested the speakers before buying them and they work fine. I'm sending a pic of the back of the main module and the front of everything. Sorry for the poor quality of the images but thought it may help. I haven't got the manual and searched for it online but when I found a "NSX-D7" manual it was a completely different device. It doesn't shows well but on the lower right of the first pic is where I connect the speakers, it says SPEAKER IMP: 6 Ohm
Jan Vigne Platinum Member Username: Jan_b_vigne Dallas, TX Post Number: 14854 Registered: May-04	Posted on Thursday, May 13, 2010 - 14:09 GMT . I remember that unit and the "Super-T Bass" system. Even for compact systems from the early 1990's it was funkyshit. At the time Aiwa was the "we know nuthink" arm of Sony that was allowed to come up with the really weird stuff that was always loaded with BS circuits, always had way too much crap for the price, always sold as blow out reconditioned "B" stock and always broke - again. Just read the front panel of that thing. I had been hoping never to see one of those conglomerations again! As with most rack and compact systems of the day - and I assume still today - the power supply is fed from one "master" unit to the next and to the next and to the next through umbilicals. This makes the entire unit one large ground loop as the units are typically eq'd through the feedback circuit of the amplifier (which draws its power from some other unit) to goose the sound of some pretty low rent O.E.M. speakers. The stated impedance of the speakers has nothing to do with your problem. The issue is in the ridiculous design and construction of a cheap system meant to be wholly self contained - read as; if you wanted better sound, why'd you buy this? Without the intended speakers hanging off the outputs of the amplifier to keep everything under the radar of thermal fusion the amp has an open ground loop system - 60Hz ground noise. That's what you're hearing and there's nothing I know that will fix it other than putting this system in another room or a closet and buying a cheap receiver to use with your new speakers. Upgrading this system is not going to happen. .
Ssmusic New member Username: Ssmusic Post Number: 3 Registered: May-10	Posted on Thursday, May 13, 2010 - 14:36 GMT Hi Jan, thanks for the reply. This unit was a gift from the 90's and I thought to make a better use of it. Of course I wouldn't buy this for better sound, although I have to say I've been using it for some studio monitoring with good results. All I want is, as you say, a cheap receiver to do the work, but I'm afraid to get the same problem. Is there a "consumer" solution for this? Any recommendations? I don't want to spend a lot right now, just to plug this great speakers I have for live sound even if I don't get too much power out of the unit in question. The speakers in question are big, 150W RMS/300 W Peak. I want something that can handle them but I'll use it at home with much less power than that.
Jan Vigne Platinum Member Username: Jan_b_vigne Dallas, TX Post Number: 14855 Registered: May-04	Posted on Thursday, May 13, 2010 - 17:41 GMT . I don't know what you're asking. Are you intending to use the speakers and amplifier for sound reinforcement of live performances? If so, you should be looking at sound reinforcement equipment. For the most part such amplifiers operate somewhat differently than home audio gear while the intent of home audio is to sit quietly on a shelf and reproduce recorded music. Using home audio for live music is sort of like using a skillet for braising a roast. Two different purposes and two different tools. " The speakers in question are big, 150W RMS/300 W Peak. I want something that can handle them ... " Ignore any "watts" numbers on speakers, they are virtually meaningless. The amp doesn't care about handling the minimum or maximum watts of the speaker and neither should you. You are concerned with the "sensitivity" spec of the speakers and the impedance of the load they present. The higher the sensitivity, the better. The higher the impedance, the better. Other than those two numbers not much else matters as far as the amp is concerned. What are these speakers and can you provide a link to their manufacturer? What is the sensitivity spec for these speakers? .
Ssmusic New member Username: Ssmusic Post Number: 4 Registered: May-10	Posted on Friday, May 14, 2010 - 00:09 GMT It's both. I'm using them on live performances with a 150W power amp. This amp is not always in my posession so I got nothing to power these speakers. I bought them second hand very cheap, so didn't care too much about sensitivity, directivity, etc. It was just a bargain and I took it. The guy told me they were 300W peak, I know for a fact they handle 150W because I use them with a 150W per channel power amp and sometimes all the way up and work fine. They don't have any marks or inscriptions, I believe they're manufactured by a small company or something, but they work fine for sound reinforcement. I tested their impedance offline by connecting a multimeter to their terminals and it's around 8 ohms. I want to stress the fact that there is nothing wrong with the speakers if used with a power amp (the only way I used them). When I go home, sometimes I want to listen something somewhat loud, and if I play low frequency sounds on the OEM's aiwa speakers, the woofer is destroyed (literally) at about 1/3 (more like 4/10) of the volume knob. That's why I wanted to try this. Of course it's stupid since the speakers in question are 2 feet tall, 1 1/4 feet wide and 1 feet depth with 12'' woofers, but what the hell, had to try. I wondered if I could ever plug this kind of thing into a consumer artifact for home use.
Jan Vigne Platinum Member Username: Jan_b_vigne Dallas, TX Post Number: 14856 Registered: May-04	Posted on Friday, May 14, 2010 - 01:22 GMT . A consumer artifact?!!!
Ssmusic New member Username: Ssmusic Post Number: 5 Registered: May-10	Posted on Friday, May 14, 2010 - 02:37 GMT Yes, a consumer component. A cheap one.
leo stierer Gold Member Username: Magfan USA Post Number: 1158 Registered: Oct-07	Posted on Friday, May 14, 2010 - 23:05 GMT Sounds like 8 ohm or NOT, the amp simply doesn't like these speakers. Some kind of LF oscillation? Too reactive a load coupled with a low impedance dip may do it. If you turn it up, I suspect you'll damage the amp....permanently, since it won't be worth the fix.
Nuck Platinum Member Username: Nuck Post Number: 14975 Registered: Dec-04	Posted on Saturday, May 15, 2010 - 00:35 GMT Buy a 150W amp of your very own?
Ssmusic New member Username: Ssmusic Post Number: 6 Registered: May-10	Posted on Saturday, May 15, 2010 - 01:49 GMT Leo: Yes, it seems so. I tested it with other consumer speakers and they worked. This only happened with these sound reinforcement speakers. I want (need eventually) to buy a 150W amp for sound reinforcement. I just wanted a, let's say 20W receiver to connect these to and use them at home. Besides it's more "family friendly" than a power amp used in pro sound (which I wouldn't allow anyone to touch at home). But it seems it'll finally have to be a 150W amp.
Jan Vigne Platinum Member Username: Jan_b_vigne Dallas, TX Post Number: 14858 Registered: May-04	Posted on Saturday, May 15, 2010 - 14:46 GMT . http://www.jr.com/sherwood/pe/SHE_RX4105/ http://www.bestbuy.com/site/Insignia%26%23174%3B+-+200W+2.0+Channel+Stereo+Recei ver/9693507.p?id=1218151628383&skuId=9693507&st=receiver&cp=1&lp=2 .

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