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Thread: HiFi connundrum. Boffins welcome.

  1. #1
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    Default HiFi connundrum. Boffins welcome.

    A friend has a seperates system with some very high end self made speakers he inherited. The amp is an 80's Technics stand alone lump, can't remember the model.

    Only one speaker was working.. so in order to diagnose the problem, I swapped the speaker cables around in the back of the amp to see if one speaker was defective or it was an amp problem.

    When I swapped the speaker wires, the previously working one stopped working, and the previously silent speaker started working.

    I swapped the amp for another one, known to be working flawlessly. Same thing. Speaker cables swapped, same result.

    Therefore we can conclude..

    1. It is not the amp..it must be the speakers.
    2. Both speakers work but not at the same time. No matter which way you wire them.
    3. One, (or both) of the speakers is stopping both of them working at the same time.

    I have yet to get into them.. I'm actually a week / ten days away from getting into this, but seriously.. this foxed me!

    I don't know too much about speakers, but could it be a wrongly wired or wrongly spec'd crossover in there? Something else?

    I'd really like to get to the bottom of this!

    Thanks for any help or advice you may be able to give me!

    Martin.

  2. #2
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    Default Re: HiFi connundrum. Boffins welcome.

    Thatís a curly one but I would replace the speaker cables first. There may be a break in the cable you canít see.
    Last edited by Hallam; 11-14-2022 at 01:55 PM.
    Simplicity is the ultimate sophistication. Leonardo da Vinci.

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  3. #3
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    Default Re: HiFi connundrum. Boffins welcome.

    Did you try different music sources or always only the same one? If for example the CD player only has one working channel and the other one in the CD player is dead - you can swap amps and speakers as long as you want, you won't get to hear both when only using the CD player as a source ...

    The same for the cable connecting the music source to the amp.

    Just an idea.

  4. #4
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    Default Re: HiFi connundrum. Boffins welcome.

    Both cables are working.. both speakers are working, just not together

    It does not matter which source is selected, phono, tuner, CD, tape or bluethooth, same result.

    The logic says it is the speakers, but how, I do not know.

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    Default Re: HiFi connundrum. Boffins welcome.

    Some thoughts; Is there consistency with respect to what side of the amp does not work ie L or R even with the 2nd amp? It might be some sort of impedance issue. Most amps will not work well with a 2 Ohm load. The amp may have a protection circuit breaker switch that cuts out one side when both speakers are connected because of an impedance issue.

    Can Speakers Damage an Amplifier? Here are the Facts! - Geek Musician
    Last edited by Hallam; 11-14-2022 at 04:43 PM.
    Simplicity is the ultimate sophistication. Leonardo da Vinci.

    If war is the answer........... it must be a profoundly stupid question.

    "Freighters on the nod on the surface of the bay, One of these days we're going to sail away"
    Bruce Cockburn

  6. #6
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    Default Re: HiFi connundrum. Boffins welcome.

    Does the receiver or amp have a stereo/mono switch? Does it make any difference in whether the speakers work?

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    Default Re: HiFi connundrum. Boffins welcome.

    Did you swap the cables at both ends, or just at one end?
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

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    Default

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    Did you swap the cables at both ends, or just at one end?

    I was going to say, first thing to do is swap out the interconnects, one at a time, for new, known-good ones. Then try a different amp. You want to isolate the failing component(s).
    You would not enjoy Nietzsche, sir. He is fundamentally unsound. ó P.G. Wodehouse (Carry On, Jeeves)

  9. #9
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    Default Re: HiFi connundrum. Boffins welcome.

    Quote Originally Posted by P.I. Stazzer-Newt View Post
    Did you swap the cables at both ends, or just at one end?
    I swapped them at the amp, but checked the connections to the speakers, which are not bi-wirable. I have not been inside them yet.

    The amp when connected to even a simple BT reciever (as well as all the other peripheries) when plugged into as many RCA inputs as possible they all behaved the same way.

    I swapped the amps.. it is not the amps.

    Again, logical conclusions..

    1. It is not the amp..it must be the speakers.
    2. Both speakers work but not at the same time. No matter which way you wire them.
    3. One, (or both) of the speakers is stopping both of them working at the same time.

    Hmm, maybe Hallam has a clue there with the ohmage protection.. I'll have to check that.

    Who is the guy here that made really nice homemade speakers?

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    Default Re: HiFi connundrum. Boffins welcome.

    ^^
    Pipefitter,pretty sure.
    I would put an ohmmeter on the speakers and the cables,seperately.
    R
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  11. #11
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    Default Re: HiFi connundrum. Boffins welcome.

    Has the amp got a headphones socket, might be worth trying so as to find the source of the problem.
    Last edited by oldcodger; 11-15-2022 at 10:37 AM. Reason: clarification

  12. #12
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    Default Re: HiFi connundrum. Boffins welcome.

    Also check Pipefitter's thread 'Why I HiFi still' from back in 2020



    Rick
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  13. #13
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    Default Re: HiFi connundrum. Boffins welcome.

    Back in the days ... we had some weird effects because speaker cables were (they were isolated) touching each other / crossing each other behind the amp. Must have been induction. The sound coming out of the speakers was - complete crap. Some tidying of the cables, ensuring proper distances, behind the amp sorted the issue. Now - something like that with a protection circuit just might do something strange. Might. But it sounds a bit farfetched.

    Any chance of attaching a different pair of speakers with different cables to the amp?

  14. #14
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    Default Re: HiFi connundrum. Boffins welcome.

    are the speakers passive or active (internal circuitry)? what's their make/model?

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    Default Re: HiFi connundrum. Boffins welcome.

    As you have a spare amp.

    Have you got.

    1 - an alternate pair of speakers?
    2 - an alternate set of cables (Three amp lighting flex does for that)?
    I'd much rather lay in my bunk all freakin day lookin at Youtube videos .

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    Default Re: HiFi connundrum. Boffins welcome.

    I’m also wondering about the design of the crossover in each speaker. It’s normally passive two way; low pass / high pass filter. Unless there are mid range drivers then it’s three way. Also some have attenuation that can be set by the user
    Simplicity is the ultimate sophistication. Leonardo da Vinci.

    If war is the answer........... it must be a profoundly stupid question.

    "Freighters on the nod on the surface of the bay, One of these days we're going to sail away"
    Bruce Cockburn

  17. #17
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    Default

    If you swapped the wires at the amp, then I would think its a bad channel on the amp not the speaker.

    Did you swap cables at the amp or at the Speakers?


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  18. #18
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    Default Re: HiFi connundrum. Boffins welcome.

    Update?
    Simplicity is the ultimate sophistication. Leonardo da Vinci.

    If war is the answer........... it must be a profoundly stupid question.

    "Freighters on the nod on the surface of the bay, One of these days we're going to sail away"
    Bruce Cockburn

  19. #19
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    Default Re: HiFi connundrum. Boffins welcome.

    Where’s Norman? He’s the expert in this field.

  20. #20
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    Default Re: HiFi connundrum. Boffins welcome.

    Quote Originally Posted by lupussonic View Post
    A friend has a seperates system with some very high end self made speakers he inherited. The amp is an 80's Technics stand alone lump, can't remember the model.

    Only one speaker was working.. so in order to diagnose the problem, I swapped the speaker cables around in the back of the amp to see if one speaker was defective or it was an amp problem.

    When I swapped the speaker wires, the previously working one stopped working, and the previously silent speaker started working.

    I swapped the amp for another one, known to be working flawlessly. Same thing. Speaker cables swapped, same result.

    Therefore we can conclude..

    1. It is not the amp..it must be the speakers.
    2. Both speakers work but not at the same time. No matter which way you wire them.
    3. One, (or both) of the speakers is stopping both of them working at the same time.

    I have yet to get into them.. I'm actually a week / ten days away from getting into this, but seriously.. this foxed me!

    I don't know too much about speakers, but could it be a wrongly wired or wrongly spec'd crossover in there? Something else?

    I'd really like to get to the bottom of this!

    Thanks for any help or advice you may be able to give me!

    Martin.
    '80s amps. . . will have analog potentiometers for all the controls (they're mostly digital now) and they almost always fail. Every old amp I have worked on has needed a Deoxit treatment of the pots before anything else. Usually, the channels will cut in or out just touching the controls, or you will hear static while adjusting them if this is an issue.

    I can't imagine anything else in a speaker that would drop a channel without blowing a fuse. Still, I would ohm out the speakers before hooking them up to anything else.

    Most common consumer brand speakers of the '80s were 8-ohm. Now they are all-over the range from around 2 ohms up and homemade speakers did not always follow these ratings and many homemade designs didn't follow these rules at all. This is why we can't just combine any old drivers and all of this load stuff needs to be worked out rather carefully. Many amps cannot drive less than an 8-ohm speaker and you have to look even now to make sure an amp is capable for these different loads. My homemade speakers are around 6 ohm and my amp will handle even 2 ohm loads. My older Pioneer amp struggles with my homemade speakers if I push them and it gets warmer than usual so I don't use it for those.

    Most people who are into building speakers now will have equal interest in custom, or high performance specialty amps as well. I have amps from Adcom, Denon, Carver, Rotel, Icepower, Pass DIY, along with a few of the more common household name brands.
    Last edited by pipefitter; 11-29-2022 at 04:21 AM.

  21. #21
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    Default Re: HiFi connundrum. Boffins welcome.

    Quote Originally Posted by Ralphie Boy View Post
    Where’s Norman? He’s the expert in this field.
    I would start with a logical plan, where each element in the system is independently tested. If this can be proven not to be a cable or speaker problem, then it could be a circuit problem inside the amp, and that takes skills that are out of the range of most folks who own systems like this. It’s not something that I could guide someone through, via posting.
    "Reason and facts are sacrificed to opinion and myth. Demonstrable falsehoods are circulated and recycled as fact. Narrow minded opinion refuses to be subjected to thought and analysis. Too many now subject events to a prefabricated set of interpretations, usually provided by a biased media source. The myth is more comfortable than the often difficult search for truth."







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