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SurfGuitar101 Forums » Gear »

Permalink Alamo 2570 external speaker question

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Asking for someone else

I just wanted to ask a question about my Alamo 2570,,,,it has two 10 inch speakers and an extra speaker jack in front ,,,,what omm speaker should I use for the extra speaker help with this would appreciated

Site dude - S3 Agent #202
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"It starts... when it begins" -- Ralf Kilauea

You might want to ask Bill aka remora1. He said he had one in this old thread and he still is active on the site.

I'm guessing he has the early 1960's tube model. From looking at some pics on the internet and doing a little research the amp should have two 10 inch speakers, 16 ohms each wired parallel. The output transformer would see a 8 ohm load. The wires from the OT to the ext speaker jack look to be a parallel circuit to the speakers. If your friend plugs a 8 ohm speaker cab into the jack the OT would see a 4 ohm load. Looking at some pics on the internet the output tubes have 20 uf caps above the tube sockets indicating cathode bias. This should allow for an 8 or 4 ohm load to self adjust with out stressing the output circuit. Fender amps have the same circuit where there is a speaker and ext speaker out although not using cathode bias. Fender amps OT can handle + - 100%. I suspect they were not the only ones using well built OT's. Plug a 8 ohm speaker in and see what happens. If the volume is the same or a little louder you should be ok.
Here is a link to the pics I'm referencing to
Also he could submit a question to Skip Simmons TAVA pod cast
Or he could call or email Skip from his web sight

Last edited: Jan 22, 2020 19:37:22

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