HiFi connundrum. Boffins welcome.

[lupussonic]

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.

[Hallam]

That’s a curly one but I would replace the speaker cables first. There may be a break in the cable you can’t see.

[Henning 4148]

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.

[lupussonic]

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.

[Hallam]

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

[Jimmy W]

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

[P.I. Stazzer-Newt]

Did you swap the cables at both ends, or just at one end?

[Nicholas Carey]

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).

[lupussonic]

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?

[Ron Williamson]

^^
Pipefitter,pretty sure.
I would put an ohmmeter on the speakers and the cables,seperately.
R

[oldcodger]

Has the amp got a headphones socket, might be worth trying so as to find the source of the problem.

[hawkeye54]

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



Rick

[Henning 4148]

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?

[Durnik]

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

[P.I. Stazzer-Newt]

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)?

[Hallam]

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

[Breakaway]

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?


Sent from my iPhone using Tapatalk Pro

[Hallam]

Update?

[Ralphie Boy]

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

[pipefitter]

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.

[Norman Bernstein]

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.