Blown out Audio Research SD135 again !

[jcarlson9]

I purchased an old Audio Research SD135 amp around christmas. At the same time i picked up some rebuilt KEF107's. the amp is 10 years old, the speakers 20. When I connected it the sound was very staticky. I returned the amp and they replaced (12) tubes ? I don't recall exactly.. They were good for about (3) months, then the power to the amp went out. So now I just got it back. The owner at the repair shop told me to check the amps from the KEF'S. Could the speakers be damaging the amp ? Thanks !

 

[joeinid]

Welcome to the forum.

 

[audio.bill]

I purchased an old Audio Research SD135 amp around christmas. At the same time i picked up some rebuilt KEF107's. the amp is 10 years old, the speakers 20. When I connected it the sound was very staticky. I returned the amp and they replaced (12) tubes ? I don't recall exactly.. They were good for about (3) months, then the power to the amp went out. So now I just got it back. The owner at the repair shop told me to check the amps from the KEF'S. Could the speakers be damaging the amp ? Thanks !

There's definitely a problem here... I hadn't heard of that model AR amp so I did a quick search and found it detailed here, and it's a solid state amp! So if you had it serviced and they said they replaced tubes there is an issue! Maybe it was other parts they replaced, possibly transistors, capacitors, resistors, etc, but since it blew again it is correct to question the 20 year old speakers as being the possible cause. They should be checked out preferably by whoever claimed to have rebuilt them, but I'd suspect a likely short due to the age of its crossover components. If the speakers are presenting a short (low impedance approaching zero ohms) or a highly reactive load to the amp it can cause the amp to fail. Hope this helps... also check your speaker cables to ensure they're not shorted and that you have them connected correctly as that could also cause a problem.

 

[jcarlson9]

There's definitely a problem here... I hadn't heard of that model AR amp so I did a quick search and found it detailed and it's a solid state amp! So if you had it serviced and they said they replaced tubes there is an issue! Maybe it was other parts they replaced, possibly transistors, capacitors, resistors, etc, but since it blew again it is correct to question the 20 year old speakers as being the possible cause. They should be checked out preferably by whoever claimed to have rebuilt them, but I'd suspect a likely short due to the age of its crossover components. If the speakers are presenting a short (low impedance approaching zero ohms) or a highly reactive load to the amp it can cause the amp to fail. Hope this helps... also check your speaker cables to ensure they're not shorted and that you have them connected correctly as that could also cause a problem.

Thanks for your help. So, no they didn't say tubes, I believe it was transistors, and this time it was the same thing. It happened when I had the volume up very hi. I'm not sure if I need to sell the KEF'S or the audio research amp ? I don't want to ruin the amp again !