Direct Box Question - Speaker out

Speaker out is powered amplified signal...
This would destroy any pedal i know about.
DIs run on instrument or line level, not amp powered (afaik)

 

If your amp has an output transformer, like almost every all-tube amp, or like almost any amp with a tube power section, or a rare few older solid state amps, then it absolutely must have a speaker load. The DI boxes that can take a speaker level signal attenuate that signal so it can be fed into a mixer, but they DO NOT provide the necessary load. You still have to use a speaker. There are dummy loads that aren't actual speakers, but they are mostly available only for low wattage (like 100 W or less), and they are not generally a great solution.

If your amp does not have an output transformer, like the majority of modern solid state amps, then you do not need to DI the speaker output. They all have a line out jack, which either is a DI already, or which can be hooked up to any ordinary DI. There is zero benefit to using the speaker output in that case.

 

The Radial JDX is specifically designed to go between amp and speaker, and uses what they call a "reactive circuit" to include the electrical push-back from the speakers into the sound delivered to the DI. I haven't tried one myself, but they're only $200.00 You can check out youtube for some examples.

 

I believe the Avalon U5 does this, but I've never tried it with mine. Also unsure as to whether you need a speaker load with it too... I do remember that it can only handle about 300 watts at the most.

 

It does not include a load, a speaker still has to be used (with tube amps etc.).

 

That goes for the Radial JDX, too. Must still use speaker. Sorry, I overlooked that in the OP.

 

There are certain types of amps that will fail if you try this. I forget which ones agedhorse from Mesa/Genz Benz said they were, but really, speaker level DI is only effective for tube amps IMHO since SS and hybrid amps don't rely on the power amp to add tonal flavor. And you can't use a DI in place of a speaker load on a tube amp.

 

You can use almost every DI with a speaker signal. A -20dB pad might be handy.

HOWEVER:
Most DI's are not made to let much current through. Meaning, when you hook up your DI box and your cab, make sure that you either go from the head into both (DI box and cab) or from the head into the cab and then use the parallel out into the DI.
Not: Head - DI-Box - cab. That would be too much power through the DI.

Why is this the case? The DI has a very high resistance, often 500kOhm or even higher. When you have an 8 Ohm cab, your amp "puts out" less Watt than with a 4 Ohm cab. Imagine now a 500'000 Ohm cab. Not much energy flowing there.

The Radial JDX is a different approach, since it has a speaker simulation built in. Tonally completely different.

 

Huh? You're saying that adding the DI would cut the effective wattage of a 500w amp to .0001 watts? First I heard of that

 

What do you mean with cutting wattage? For the overall output, it does not make any noticeable difference whether the DI is hooked up to the second speaker output or not. The other cab is still as loud as it was without the DI.