Relay circuit

[bluemike]

Hi
I have an LM 3886 amp that comes with speaker disconnect switch
is it better to put in in a timer circuit instead of using the switch

If I forget to trip the speaker switch on shut down, I risk damaging my speakers
does the timer circuit i'm thinking of degrade the sonics in any way

 

[Mooly]

Yes, having a switch on delay and a rapid disconnect is always a good feature. There are many designs around of varying complexity. Here is a simple one I designed that would fit the bill,

http://www.diyaudio.com/forums/solid-state/224957-simple-universal-speaker-delay-using-triac.html

 

[bluemike]

Thanks
Does adding this speaker delay effect overall sonics in any way ?

 

[Mooly]

It shouldn't do. The only degradation comes from the relay contacts (similar to a switch really). The circuitry adds nothing and the power requirements so small that it has no overall impact.

 

[AndrewT]

I would rather have the choice between a damaged speaker, or perfect sound quality.
Once that choice is available, I would choose the "NO DAMAGE" option.

Is your thinking along the same lines?

Or, are you prepared to accept the risk of damage in the search for that "perfect sound"?

 

[bluemike]

Agreed
Any more opinions
Does the relay effect sonics or is it the same as a switch inserted

 

[Mooly]

It can be considered the same as a similar rated switch.

 

[bluemike]

I actually kept the disconnect switch and added a relay will I hear an audible difference

 

[Mooly]

No difference, it will be fine. Once you have it all up and running there is no reason to keep the switch, you could remove it. But as to it affecting the sound... no.

 

[Michael Chua]

If I forget to trip the speaker switch on shut down, I risk damaging my speakers

If you forget to trip the speaker switch, why would your speakers be damaged on shut down?

 

[AndrewT]

Big DC or AC pulse as the amplifier drains the supply rails.

Some amplifiers become unstable and oscillate badly during this shutdown. This can burn out Treble drivers.

Delayed ON ans instant OFF is very useful. Even when the tiny bit of added distortion is included in the overall protection system.

 

[bluemike]

Thanks Andrew I didn't really know how to respond

Do you think I did damage to my speakers when I turned them on before the amp stabilized I heard a hum coming from the speaker and immediately unplugged the amp from the wall

 

[Michael Chua]

Andrew
This is a LM3886. It is completely silent on power up and power down.

bluemike
If you're getting a hum, buzz or anything else, there's either a problem with the LM3886, the circuit or your system. For a start, I suggest you check the output of your LM3886 for DC.

 

[bluemike]

There is no dc when I tested it
The amp also has a tubed pre it's an integrated with phono stage

 

[AndrewT]

....................This is a LM3886..............
..........

................The amp also has a tubed pre it's an integrated with phono stage

is it just a 3886?

 

[Michael Chua]

That's what I mean when I said "system". The LM3886 is a very "polite" amp. No funny noises when power up/down.
Since there's no DC, look upstream. Identify the source of the problem and try to correct it first instead of applying a band-aid.

 

[bluemike]

is it just a 3886?

It's an integrated amp that has 12b4a tube pre and lm 3886 chip
with a separate power supply