Dummy loads across speaker terminals

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shedshrine
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Dummy loads across speaker terminals

Post by shedshrine » Fri Apr 15, 2016 3:37 pm

Would like to see if it is possible to use an old 12 watt integrated stereo tube amp
as a stand alone stereo preamp via its tape outs.

With no speakers attached, I've read you need to provide a "dummy load across the speaker terminals".
What exactly does that entail, as far as actual components and configuration?
..And will it harm the amplifier if this load is in place long term.

Thank you and have a nice day.

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Drone
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Post by Drone » Fri Apr 15, 2016 4:31 pm

Two ways to do it.

1. Buy two power resistors, probably 8 ohm, and connect one across each set of speaker terminals.

https://www.radioshack.com/products/rad ... 5717262405

2. It's likely the preamp feed is taken before the power amp section. Remove the output tubes. Run the amp like that.
The previous statement is from a guy who records his own, and other projects for fun. No money is made.

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Scodiddly
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Post by Scodiddly » Sat Apr 16, 2016 7:12 am

http://www.mouser.com/ProductDetail/Vis ... NhrW04c%3d

Assuming 8-ohm load, that is. Probably totally fine. No problems with long-term use. If you tap off the speaker outputs, say into one of those DIs that have a big pad switch for speaker-level outputs you'll likely see a bit different sound than with a real live speaker connected.

For under $15 including shipping it doesn't seem like a big risk.

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shedshrine
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Post by shedshrine » Sat Apr 16, 2016 2:09 pm

Going to order a couple of those Vishays and see how it goes.

Thanks guys for the input.

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Drone
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Post by Drone » Sat Apr 16, 2016 2:53 pm

Be careful with them, as they are inductive being wirewound.

I always try and get non-inductive for dummy loads, yes a loudspeaker is inductive too, but you can predict what happens with a purely resistive load.

If you're not near a Radioshack, which is the easy option, parts express do non inductive dummy load resistors, bigger than you need, but chassis mountable and non inductive.

http://www.parts-express.com/cat/dummy- ... stors/1535
The previous statement is from a guy who records his own, and other projects for fun. No money is made.

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supafuzz
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ceramic resistors

Post by supafuzz » Fri Jul 22, 2016 8:28 am

I used to have these hug he ceramic resistors that looked like a pair of claves and were about 8 inches long and 1-1/2" diameter and they worked great as a dummy load on a fender tube amp. Not sure why I needed a dummy load at the time but I did and it worked.Image

like the one on the left
Super 70 Studio.. Never tell a perfectionist that the mix is perfect!

http://www.super70studio.com
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supafuzz
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ceramic resistors

Post by supafuzz » Fri Jul 22, 2016 8:29 am

I used to have these huge ceramic resistors that looked like a pair of claves and were about 8 inches long and 1-1/2" diameter and they worked great as a dummy load on a fender tube amp. Not sure why I needed a dummy load at the time but I did and it worked.Image

like the one on the left
Super 70 Studio.. Never tell a perfectionist that the mix is perfect!

http://www.super70studio.com
http://www.facebook.com/Super70Studio


now in glorious HD3

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