Dynamo 500 subwoofer: How to modify/bypass auto on switch

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Dynamo500

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Hi,
Can anyone assist in advice on how to modify/bypass the auto on switch on a Martin Logan Dynamo 500 subwoofer. It only has an auto on switch and I want it to stay on all the time.
I am using Marantz SR5006 amplifier and listen to mostly 2 channel audio at lower volumes.
Thanks much
 

JonFo

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It likely has a 'music-sense' circuit linked to the RCA input jacks.

You could replace the two wires feeding that with wires leading to an externally mounted AA battery holder with a 1.5v battery.
I'm assuming that DC will be ok (music is much more variable (well, certain styles excluded ;) ) as the 'sense' is just looking at voltage.
As long as the battery is good, and plugged into AC, it should work.

Alternatively, is some other part of the board generates a voltage below 2v. you could pull from that.

Disclaimer: Just an educated guess, it might not work, or worse.
 

Dynamo500

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Thanks for your suggestion...will look into this. Yes...it would be nice to have a dedicated "on" switch instead of this intermittent "auto-on".
 

roberto

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Hola Chicos,
Yes, that must be annoying. Instead of DC, why don't you change the sensing voltage circuit for a lower trigger reading? Changing some resistors will do that where the sensing posts are. Ask ML about this. They might have an answer for this. I do not have an schematic for this, but this might be the way to go.

Happy listening!
 

roberto

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Dynamo500,

Did you change the sub RCA cable? Sometimes a bad high resistive cable can do that. Changing the cable solves the problem.
 

Dynamo500

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Hola Chicos,
Yes, that must be annoying. Instead of DC, why don't you change the sensing voltage circuit for a lower trigger reading? Changing some resistors will do that where the sensing posts are. Ask ML about this. They might have an answer for this. I do not have an schematic for this, but this might be the way to go.

Happy listening!
Thanks... Perhaps this would work...I will see if ML has a schematic. Does anyone have a schematic for a Dynamo 500 sub?
Also...I don't have the electronic background to tackle this myself... But I could get assistance.
 

roberto

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Just thinking loud, to make the subwoofer to stay on all the time, it does not seems to me a difficult task. Ask to any high electronic tech near you about this. He might have a simple solution for it.
Happy listening!
 

roberto

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I have a potential solution. Increase the bass output volume from your receiver to the sub input, and decrease it with it´s volume level control knob. This solution might work for you.

Happy listening!
 

Dynamo500

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Just thinking loud, to make the subwoofer to stay on all the time, it does not seems to me a difficult task. Ask to any high electronic tech near you about this. He might have a simple solution for it.
Happy listening!
I have a potential solution. Increase the bass output volume from your receiver to the sub input, and decrease it with it´s volume level control knob. This solution might work for you.

Happy listening!
Good point.... Thanks for your input!
 

roberto

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If there is voltage at the input of the sub, it will stay on. This is how the circuit works. Increase it at the maximum, that will not harm the receiver or the sub.

Happy listening.
 

spkrdctr

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Roberto nailed it. His suggestion is exactly what I do with mine. I have the "extra bass" turned on in my receiver and use it to turn on the sub. I just hit a button and it turns off the extra bass, but the sub stays on. Now if the sub turns off after you get it on, then you will have to go in and adjust the sensing circuit as Roberto mentioned. ML should be able to tell you exactly what to do to make it work. Good Luck!
 

Dynamo500

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Hi all,
My Martin Logan Dynamo 500 subwoofer only has an "auto on" switch.
I would like to add a dedicated on switch. schematic attched
Thanks much
 

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Dynamo500

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ML informed me that they do not have the schematic for the power supply for this sub.
Any suggestions given the schematic supplied?
 
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