Amplifier Output Relays
Hi Goner’s,
Well after way too much time and money in parts and labor, my tech tapped on the right channel relay and discovered the reason for why the right speaker kept cutting out. So he cleaned off the corrosion and sprayed it with Deoxit and it came back. I was gratefully playing the stereo for a few hours when I decided to play the Ayre test CD ‘Irrational but Efficacious’ full glide tone and heard the two speakers drop out for a second and then experienced cutting in and out of the left channel. It’s strange to me that this full glide tone could trigger an issue but that seems to be the case. Anyway, the relays that I need to order are modified for direct inputs. I play strictly through the direct rca’s rather than CD 1, Phono, etc…The technician wants to exhaust all possibilities that the relays can be salvaged but he is overestimating the amount of work involved in changing them. The parts for both sides is a total of 60 euros so I plan on ordering them soon. Any advice from people who are familiar with this headache?
Thanks!
Happy Holidays!
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. |
Replace with Amplimo loudspeaker relay if possible. https://shop.dadaelectronics.eu/loudspeaker-relay-24v-lr-24-amplimo-108462111.html
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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. |
