Pioneer SX-950 cutting out

[chetektech]

Hello all! New to the forum and would like a little help with my setup.

I have a Pioneer SX-950 driving 4 DLK 1.5 Speakers. Once I get over about 4 on the volume, the receiver cuts out. Back it down and its’ fine. This will happen when the receiver is cold as well, no difference. I checked the resistance of each speaker and measured all around 6 ohms? but the speaker backs say they should be 8 ohms? My receiver wants 8 ohm connections if 4 speakers are being used. What can I do to load balance these speakers so the receiver safely can handle the load? I love my setup but would like to apply a little more power once in a while.

Thanks, Joe

 

[j_garcia]

Impedance isn't the only factor, since that doesn't really tell you how much real current the speakers require. Four 6 Ohm speakers that draw a lot of current could easily overwhelm the amp. I have an SX-990, and the power output of these guys isn't that spectacular, though they do sound good. Does it still cut out with just 2 speakers? If you haven't looked inside, make sure you clean it out pretty well as dust can accumulate over time and cause issues.

cleaned:

 

[chetektech]

Impedance isn't the only factor, since that doesn't really tell you how much real current the speakers require. Four 6 Ohm speakers that draw a lot of current could easily overwhelm the amp. I have an SX-990, and the power output of these guys isn't that spectacular, though they do sound good. Does it still cut out with just 2 speakers? If you haven't looked inside, make sure you clean it out pretty well as dust can accumulate over time and cause issues.

No, it does not cut out with two. Unit has been cleaned regularly.

 

[Midcow2]

My Ideas

Hello all! New to the forum and would like a little help with my setup.

I have a Pioneer SX-950 driving 4 DLK 1.5 Speakers. Once I get over about 4 on the volume, the receiver cuts out. Back it down and its’ fine. This will happen when the receiver is cold as well, no difference. I checked the resistance of each speaker and measured all around 6 ohms? but the speaker backs say they should be 8 ohms? My receiver wants 8 ohm connections if 4 speakers are being used. What can I do to load balance these speakers so the receiver safely can handle the load? I love my setup but would like to apply a little more power once in a while.

Thanks, Joe

You have 30+ year old speakers and receiver; they might jst be tired and need to be replaced.

The Pioneer SX-950 was made in 1976-1977 and was rated at 85 watts RMS into 8ohms and 110 watts RMS into 4 ohms. All things being equal the power should double if you go from 8 ohms to 4ohms, but in your case it is 64%. That is okay you just can't turn the power all the way up.

It is hard to find much information on the DLK 1.5 speakers. They were very good speakers in their day with two 8" speakers and one 1" tweeter, around $875 a pair in the late 70s. They were rated at 4 ohms. Impedance varies with frequency an the rating given is a nominal rating and the could really have a range like 2-10 ohms.

I would consider replacing both speakers and receiver.

Now, let's think about your current problem. I think it could be cuase by one of the following four items : (1) short or whisker short in one of the speaker or receiver connections, (2) short in the speaker wiring, (3) short internal in the speaker, (4) a bad capacitor or other component in the reciver ( if you decide not to replace, you might consider getting it serviced).

A good way to diagnose is to unhook everything and then hook up on speaker at a time and try the volume test. if you do find a bad speaker, wire combination, then change-out the wire or speaker or receiver port to further isolate whethe it is a wire short, receiver channel or speaker.

Good Luck,

MidCow2

P.S.- I still have a Marantz 1060 amp and a Fisher Studio standard AM/FM digital tuner that still work and both are 30+ years old also All my speakers that were that old have failed and have been replaced.

 

[j_garcia]

Sounds like the load of all 4 is just too much for this guy, especially if you are looking to crank it. Like Midcow said, impedance varies with frequency, and if you are trying to play something with a lot of bass with it turned up, the receiver could just run out of steam. Mine still works fine, just a button or two that need some cleaning inside because they get stuck.

 

[TLS Guy]

Hello all! New to the forum and would like a little help with my setup.

I have a Pioneer SX-950 driving 4 DLK 1.5 Speakers. Once I get over about 4 on the volume, the receiver cuts out. Back it down and its’ fine. This will happen when the receiver is cold as well, no difference. I checked the resistance of each speaker and measured all around 6 ohms? but the speaker backs say they should be 8 ohms? My receiver wants 8 ohm connections if 4 speakers are being used. What can I do to load balance these speakers so the receiver safely can handle the load? I love my setup but would like to apply a little more power once in a while.

Thanks, Joe

You measured the DC resistance of the speakers. That is not the same thing as the impedance at all!.

Obviously you can only drive one pair of those speakers.

 

[duckpond49]

Pioneer SX 950 solution

Hey, I think I've got an answer for your volume problem. I was checking out an SX 950 on my test bench the other day and it was doing exactly what you describe. At first I thought I had a unit with a faulty protection circuit or a bad power amp section putting a lot of DC on the speaker outputs.

When I rechecked everything I saw that I had my scope ground on the speaker positive and probe on the ground. I switched it around and voila! it cranked out 92 watts into 8 ohms at 1kHz. It apparently had a problem with a ground fault between the Sig Generator and the Scope.

Try unplugging everthing that is jacked into your receiver--tape, phono, etc. and see if it still does it. If it still does, leave just one speaker hooked up on one channel. If it stops misbehaving, start plugging everything back in, one at a time until it acts up. When you find what's doing it, reverse the AC plug or use a ground lifter adapter to see if it straightens it out.

That's got to be it. It's exactly what I was seeing.

 

[Adam]

Thanks, duckpond49, and welcome to the forum! Great first post.

Unfortunately, chetektech will probably never see your solution. He or she came, posted, left...and hasn't returned since August. Oh, well. Your solution might help out someone else who comes upon it during an internet search. Thanks!

 

[highfigh]

Hello all! New to the forum and would like a little help with my setup.

I have a Pioneer SX-950 driving 4 DLK 1.5 Speakers. Once I get over about 4 on the volume, the receiver cuts out. Back it down and its’ fine. This will happen when the receiver is cold as well, no difference. I checked the resistance of each speaker and measured all around 6 ohms? but the speaker backs say they should be 8 ohms? My receiver wants 8 ohm connections if 4 speakers are being used. What can I do to load balance these speakers so the receiver safely can handle the load? I love my setup but would like to apply a little more power once in a while.

Thanks, Joe

Since you aren't paying attention to the recommended impedance rating, think about why it could be happening. If it's rated for 110W @ 4 Ohms but indicates that if speakers A & B are used, they should all be 8 Ohms or higher, does it seem likely that the speakers are connected in parallel, through the selector? The DLKs are 4 Ohm and this would present a nominal 2 Ohm load. If you want to test this, disconnect one pair and select A+B. If the sound goes out, they're in series and if it doesn't, they're parallel. Since you don't have a surround or Quad system, if you want to use all four and turn it up louder, wire the speakers for each side in series. The receiver will be much happier and it'll sound fine.

 

[chetektech]

Hey, I think I've got an answer for your volume problem. I was checking out an SX 950 on my test bench the other day and it was doing exactly what you describe. At first I thought I had a unit with a faulty protection circuit or a bad power amp section putting a lot of DC on the speaker outputs.

When I rechecked everything I saw that I had my scope ground on the speaker positive and probe on the ground. I switched it around and voila! it cranked out 92 watts into 8 ohms at 1kHz. It apparently had a problem with a ground fault between the Sig Generator and the Scope.

Try unplugging everthing that is jacked into your receiver--tape, phono, etc. and see if it still does it. If it still does, leave just one speaker hooked up on one channel. If it stops misbehaving, start plugging everything back in, one at a time until it acts up. When you find what's doing it, reverse the AC plug or use a ground lifter adapter to see if it straightens it out.

That's got to be it. It's exactly what I was seeing.

Thanks Duckpond, That did it! It was the CD connections. Disconnected and all was fine, replaced and good to go. I didn't suspect because it occurred across all inputs.

Thanks again for all the help and apologize for the delay in my response, I just don't get on here much. The receiver is my garage and due to our climate, my man cave has only become livable in the last few weeks.

I have another problem that has popped up with the FM on the same receiver but will create a new post for that.

Joe

 

[highfigh]

Hello all! New to the forum and would like a little help with my setup.

I have a Pioneer SX-950 driving 4 DLK 1.5 Speakers. Once I get over about 4 on the volume, the receiver cuts out. Back it down and its’ fine. This will happen when the receiver is cold as well, no difference. I checked the resistance of each speaker and measured all around 6 ohms? but the speaker backs say they should be 8 ohms? My receiver wants 8 ohm connections if 4 speakers are being used. What can I do to load balance these speakers so the receiver safely can handle the load? I love my setup but would like to apply a little more power once in a while.

Thanks, Joe

You don't want to use low impedance speakers on that receiver.