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-   -   Using latching signal relay in SE guitar amp. (http://www.diyaudio.com/forums/tubes-valves/53908-using-latching-signal-relay-se-guitar-amp.html)

G 20th March 2005 08:49 PM

Using latching signal relay in SE guitar amp.
 
Hi all,

I am planning on building a small guitar amp and I would like to build a McTubeII tube overdrive unit right into the amp and use a SPDT relay to switch between overdrive and clean modes. I think that I want to use a SPDT latching relay. Does that sound right? I would like to be able to use a patch cord to plug in a footswitch with a momentary contact switch to actuate the relay to either run the signal through the overdrive unit or bypass the unit and run the signal directly into the amp. I hope I am describing this right. Does anyone know what I'm talking about and do you have any advice? Thanks.

G

PRR 21st March 2005 02:35 AM

> I think that I want to use a SPDT latching relay. Does that sound right?

Latching relays are rare beasts.

And their main point, zero static power consumption, is kinda pointless in context of a guitar amp.

And the vibration in a guitar amp may unlatch a latching relay.

And they don't work as you describe. You put in a positive pulse to latch one way, a negative pulse to latch the other way.

It would be possible to re-wire a many-contact latching relay for alternate action, or rig a CMOS chip to do something, but.....

Isn't the standard guitar stomp-pedal alternate-action? It shorts the reverb channel. Stomp once, it shorts, reverb is off, stomp again, it un-shorts, reverb is on.

In that case, just use a plain double-pole relay from an appropriate DC supply to the pedal jack. When pedal shorts, relay one way, pedal un-short, relay the other way. This means the relay coil may be on for long periods of time, but power consumption is maybe 1 Watt, irrelevant next to tubes.

G 21st March 2005 09:21 PM

Quote:

Originally posted by PRR
> I think that I want to use a SPDT latching relay. Does that sound right?

Latching relays are rare beasts.

And their main point, zero static power consumption, is kinda pointless in context of a guitar amp.

And the vibration in a guitar amp may unlatch a latching relay.

And they don't work as you describe. You put in a positive pulse to latch one way, a negative pulse to latch the other way.

It would be possible to re-wire a many-contact latching relay for alternate action, or rig a CMOS chip to do something, but.....

Isn't the standard guitar stomp-pedal alternate-action? It shorts the reverb channel. Stomp once, it shorts, reverb is off, stomp again, it un-shorts, reverb is on.

In that case, just use a plain double-pole relay from an appropriate DC supply to the pedal jack. When pedal shorts, relay one way, pedal un-short, relay the other way. This means the relay coil may be on for long periods of time, but power consumption is maybe 1 Watt, irrelevant next to tubes.

Thanks PRR. I came to the same conclusion after further research.

Cassiel 22nd March 2005 12:08 PM

Quote:

I would like to build a McTubeII tube overdrive
I did and was not totally happy with its sound. 12ax7s prefer higher voltages. What i did was to clone the pre section of the Fender princenton amp 5f2- A....much better sound.
But if your after death metal distortion forget it...you'll just get the best crunchy tone i've ever heard. ;)

Cheers,


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