Question for R.G. Keen - Head amp switching

[bent]

Hello everybody,
My question is mostly for R.G. and here's why:
- I want to build a unit that i can switch between 2 head amp for the same cab speaker....
-R.G., in another topic, you strongly suggest the use of the Nec EA2 in relay switching, but can they be use for this type of switching or the load is too high for them ?
- And what kind of "dummy load" or something like that can i use to put a load on the head amp that is not used?

something like that https://taweber.powweb.com/store/2head.htm

Thank you very much....

Bent

[geertjacobs]

(search for "headswitch" : reply #8)
http://www.diystompboxes.com/smfforum/index.php?topic=77920.0

[R.G.]

Switching power to cabs is a different animal to switching low power audio voltages.

In some ways it's harder, because you have to use relays specified for the higher currents. But in some ways it's easier, because the higher voltages and currents mean you need a less "precision" relay.

The tricks are to
- switch both hot and ground, not just hot
- put a dummy load of some kind on the "off" head. This should be sized to keep the "off" head happy, and may or may not have to be the same as the cab impedance.

Read the preceeding stuff and yell with questions.

[bent]

Thank's R.G.,
so i cannot use the nec  ea2.....

do you have a suggestion for a type of relay to use....

just found on the schematic a type to use.....Omron G5LE-14-DC5

thank's
Bent

[bent]

JUST HAVE A QUESTION ON THE SCHEMATIC....   

ON THE RIGHT SIDE, THERE'S A RESISTANCE FROM AMP 1 (AND 2) OUPUT TO GROUND....DOES THE VALUE IS 470k OR 470ohm / 5W

THANK'S

BENT

[G. Hoffman]

JUST HAVE A QUESTION ON THE SCHEMATIC....   

ON THE RIGHT SIDE, THERE'S A RESISTANCE FROM AMP 1 (AND 2) OUPUT TO GROUND....DOES THE VALUE IS 470k OR 470ohm / 5W

THANK'S

BENT

I'm pretty sure it is supposed to match the impedance of your speakers, or nearly so.


Gabriel

[bent]

I dont think...cause there's already all the set up of resistance that match the impedence for the load, i think it's for always having some sort of resistance to ground between the transition of load/speakers...

[G. Hoffman]

Well, I haven't looked at that schematic, so I could well be wrong. 

That being said, I've been meaning but forgetting to post a link to THIS since you first asked.  I use a couple of these for switching between the internal speaker in my amp and my Leslie.  Now, this is only an 18W amp, so you may need a larger relay, but they have worked perfectly for me.


Gabriel