speaker load/load box

[EDWARDEFFECT1]

whats the scoop on speaker loads? you need a speaker load for all tube amps and for some solid state amps,but not all! how do you determine what solid state amps need a load before powering up for testing and what solid state amps don't....thanks!!

[Roly]

Strictly; an amp with an output transformer should not be operated without a load.  An OTL or Output TransformerLess amp may be operated without a load.

Almost all valve/tube amps fall into the first class, they have output transformers.  Most solid state amps fall into the second class, but it's not quite so clear cut because there are s.s. amps that are made to drive voltage PA lines using an output transformer.  It's rare that you will encounter such a beast, and rarer that you will damage it by unloaded operation, but it is just possible.

So, all output transformers need a load.

HTH

[DrGonz78]

I am sure greater minds will sound off... My thought here is that almost no solid state amp should have a load until it has been tested. Now I say this in the case of an unknown or possibly broken solid state amp. However there are amps that I have read about that used output transformers. Macintosh and Sansui types from long ago... My guess here is that those types of amps require a load present at all times much like tube amps. 

Edit: Simulpost!!! lol. Looks like a great mind sounded off while I was still typing ;-)

[Enzo]

I can't think of a solid state amp that NEEDS a load.   Tube amps do, but remember the impedance ratio of a tube output transformer is something on the order of 5000 ohms to 8 ohms or 4 ohms.   SO when an unterminated secondary wants to bounce a spike back at the primary, it can be a thousand volts or more.   The matching transformers they stick on 70v output transformers on solid state gear have nowhere near such steep turns ratios.


And as a practical matter, if one is concerned, one can disconect the OT from a SS amp and connect a suitable load directly to it... or not.