Phil Jones Head DI without speaker load?

[andyhaines]

Hi All,

 

Got my eye on a PJB D400 which I also want to use as a preamp/DI for teaching online lessons. Anyone know if PJB heads can be run safely without having a speaker load attached? Conventional wisdom seems to indicate that class D power amps don't need a load, but wanted to check!

 

Thanks!

 

Andy

[Bill Fitzmaurice]

SS amps don't need a load, valves do. 

[andyhaines]

Thanks Bill, good to know.

[Hodge]

On 06/08/2025 at 11:40, Bill Fitzmaurice said:

SS amps don't need a load, valves do. 

Out of interest, how does this apply to SS amps with a valve pre-amp?

Is it only valves in the power stage and that need a load?

[Bill Fitzmaurice]

Only with valve power stage. SS outputs have a minimum load, but no maximum. Valves have a maximum load, but no minimum. Many valve amps incorporate a switched output jack that will short circuit the output when nothing is plugged in, to prevent damage in that event. 

[Hodge]

I see, thanks for that.