Amplifier Output Relays

Stop playing around and just replace those relays.

I had a 1980's era pro amplifier with output relays.  Replaced them and noticed the contacts on modern relays were much better.  Instead of being a ball on a flat surface they were hemi-spherical matching surfaces so the contact area was much larger with the replacements.

Erik, these aren’t that old, there still being used today. Anyway, no kidding but I’ve got to convince my tech to do this at my home. The task should take ten minutes to get to but he’s saying the PCB needs to removed (it doesn’t) and this behemoth needs to go to his shop (it shouldn’t). 

Replace with Amplimo loudspeaker relay if possible.

https://shop.dadaelectronics.eu/loudspeaker-relay-24v-lr-24-amplimo-108462111.html

As far as the Amplimo, I know this isn’t the relay that needs replacing. I can make mention of it to the manufacturer. Maybe someone could explain the Amplino loudspeaker relays? The parts are ALE2X302 output relays.

The purpose of the amplifier output relay is to avoid annoying turn on and turn off "thump" sound from the speakers. Another function is to disconnects the speaker immediately if there is short circuit, over current or DC detected on amplifier output.

However, almost all relays have a minimum load requirement is that the mechanical action of closing coupled with an actual current flow are required to ’whet’ the contact and break through a layer of oxidation that invariably builds up. That is one reason that small signal relays generally use gold plated silver contact to resist oxidation, but gold is expensive and would simply be burnt off under power switching conditions.

The Amplimo LRZ loudspeaker relay is a special relay designed specifically for amplifier output connect to speaker. It has two contact areas, one tungsten contact which can switch 100A (at 50V) to take the arc upon making and breaking contact for loudspeaker current. And a gold plated silver contact, giving negligible contact resistance even at small currents to bypass the tungsten contact.

IMHO, Amplimo LRZ relay is one of the best amplifier output relay other than MOSFET solid state relay.

imhififan, thank you for sharing your knowledgeable insight tower I'm not sure a different relay would be applicable. AS I said, I will make mention of it but ultimately I need to follow the advise of the manufacturer.

I also com to realize that a direct modified relay has nothing to do with using Direct RCA inputs so please disregard my previous statement as such. As for what direct modified relays are, I'm still not sure.

Amplifier output relays are a common failure component and will seriously degrade the sound of an amplifier. +1 for imhififan, his explanation and LRZ loudspeaker relays. I now replace output relays when servicing amplifiers after years of learning.

I'm assuming that once the relays are exchanged that operations will go back to normal.

Intermittent channels dropout is the most difficult to diagnosis, it can be caused by bad relay contacts, cold solder joints, cracks on pcb trace or bad contacts between male/female connection on ribbon cables. Simply replacing relays may or may not  fixed the problem. 

I also com to realize that a direct modified relay has nothing to do with using Direct RCA inputs so please disregard my previous statement as such. As for what direct modified relays are, I'm still not sure.

Seems like you're going to replacing input relays and not the amplifier output relays, have you tried using a different input instead of the "direct" input to confirm the culprit is the relay from that"direct" input?

Depends on how the amp was made.  If the relays are soldered in directly then yeah.  If they are socketed then no, they should pop put in seconds.

I've been In contact with the manufacturer who's been nothing short of amazing since the issue started with the right channel. His comment is that the right channel issue was with the output relay. The issue with the left channel started shortly after the tech cleaned the right relay and got it working again. I will check the headphones since that is a separate relay altogether. I then will try other inputs. Once I check these, then I'll post my findings.

Cleaning of relays do not last and if only the right channel was cleaned, the relays are most likely the same age. Correct? Good idea to check the headphone output, but are they really a different relay? For sure check other inputs!

Yeah, according to the manufacturer, the headphones use a separate relay. His instructions are the same; tap the relay to see if the tone changes, try the headphones and try different inputs.

Also, my tech found two bad solder joints and a loose wire and fixed those many months ago when I initially started having problems. When he found the relay was reacting to his tapping on it, he checked those solder joints and they were good. When the cutting out in the left channel started a couple of days ago, I couldn’t understand why he didn’t do the same to the left relay as he did to the right but that really doesn’t matter at this point. Yes, the relays are the same age. They are the original parts.

imhififan,

I played the amp today while listening through headphones and it played flawlessly. Pretty much what I was hoping for.

Great, look like you've found the culprit! Hope  you get it fix and enjoy music again.

Happy Holidays!