To dummy load or not to dummy load... SS amp

[NaBo]

While I'm flattered that my questions are now at a level that no one can give me an answer, I still need to know, so I'll make a nice specific thread about this issue (see if that doesnt provoke someone )...

I've read a lot of conflicting info on the net about whether its safe to switch on an SS amp without a load, or switch speaker cabs while its running.

As you can see in this thread, I'm making a ex-combo practice amp into a head/talkbox stomper, and am unsure whether i should bother putting a wirewound resistor where the original speaker was...  please reply in that thread if you can.

Thanks guys

[dosmun]

If you are using it as a Talkbox amp then it shouldn't matter because the Driver for the Talkbox is the speaker load.

[NaBo]

Ah... shoulda specified, the driver will be in its own little cabinet.  Quite a modular little setup.  The amp is a head, as well as a talkbox stomper, though the latter will be its main use.  But is your post implying I should indeed wire that resistor as the if-nothing-else-is-plugged-in load?  I just dont wanna waste the resistor (almost 5 bucks :roll:), or space, if its not really necessary.

[petemoore]

when connecting speakers to an amp remember lower resistance = more current = more load
 The amp should have a Min load [ie 4ohm or 8ohm] printed by the speaker outputs, dont exceed the load the amp was designed for.

[NaBo]

Yeah, I got the minimum load covered... it was a 4 ohm speaker originally and this is a 10 ohm resistor.  To clarify for anyone else reading, by "exceeding" the load it was designed for, he means undershooting the resistance, like using a 4 ohm speaker with a min 8 ohm amp.  No good can ever come of that.

I'll elaborate again on what exactly I'm looking for:  I've read from some sources that you dont have to worry about a powered up SS amp without a load at all, only tube amps.  I've read from others that MOST SS amps have open circuit protection, some would die just as surely as a tube amp.

So which is it?  Do I have to worry in my case?

[lovekraft0]

I wouldn't worry about it - R38 and R39 should be enough load to eliminate any problems with an open output, and the TDA2030H is short-circuit protected, according to the data sheet:

http://www.ortodoxism.ro/datasheets/SGSThomsonMicroelectronics/mXurvyq.pdf

[NaBo]

Ahhh, a datasheet... duhhh me...  

Thanks a bunch lovekraft.  

I may still use the resistor just to be cool... I can use the original speaker clip to hook it to the board and then if i ever need it down the road i can just unhook it.  But it's nice to finally put this worry to bed.  Back to painting...  

[Ardric]

Tube amp guys sometimes use a larger value resistor switched on the speaker jack, like 180 ohms.  It's far from an ideal load, but it's enough to save the output transformer if it comes to that.  A larger value allows you to use a smaller wattage.

[Duff]

If I have a 25w amp with a 4ohm speaker, and the resistor is 4ohms, it should be over 25w?