Safe to use Radial direct box between Head and Cab?

[Charlie E.]

Hey guys a mixing engineer has asked me to capture the output of my head for our upcoming album.
I felt a little iffy about it but he just told me to switch the direct box to "speaker" mode and that it'd be fine. My J48 doesn't have a speaker switch but my JDI does.
Should I hit the Pad button as well as the speaker switch for safety? I'm a little concerned.

 

[colonel_claypoo]

did it with my JDI and worked fine. just had to engage the pad but didn't even need the speaker emulation which is a filter plus another pad.

 

[Charlie E.]

You used the pad but didn't engage the speaker button? Is there a reason you did it this way? I suppose trying to avoid the filter?

 

[JakeAC5253]

Have the mix engineer sign a document saying that WHEN your tube amp fails he will assume responsibility for all accrued damages. Get his signature, a clear description of the situation, and a date.

That is all.

 

[colonel_claypoo]

You used the pad but didn't engage the speaker button? Is there a reason you did it this way? I suppose trying to avoid the filter?

exactly.
but try it with the speaker emulation on first just to be on the safe side in case your signal is too hot.

 

[Trevoire520]

Look at the manual for your DI and see if it can handle that much power. I know some of the Behringer DI's can. And I think my BSS can too. But not all DI boxes will be happy taking a power amp signal.

I wouldn't switch on any speaker simulation either, leave it raw so he can put his own impulses on it.

 

[Charlie E.]

Thanks for the replies guys. I went and dug up an old email and he swears everything will be fine as long as I engage the speaker button so I'm gonna give that whirl instead of the pad just to be on the safe side.

I did look at the manual but they expect you to use the parallel out of my cabinet, not put the JDI between the head and the cab like he wants. I wouldn't be able to do that anyway as my cab doesn't even have a parallel out.

It's a respectable engineer so a contract is not needed :Smokedev: hopefully lol

 

[deLuther]

JDI must be routed to cab from THRU output, that will be parallel to cabinet, because THRU output wired parallel to transformer with some sort of voltage divider with PAD engaged. -15 db (with PAD) equals to 0.18 ratio. 100 Watts into 8 Ohm means sqrt(100*8)=28.3 V, so with -15 db reduction it will be 5 V...

 

[colonel_claypoo]

I did look at the manual but they expect you to use the parallel[...]

that's what I did. sorry, misread your initial post. you're planning on putting the JDI between head and cab? sorry, can't confirm that this is safe, I only ever hooked it up in parallel.

 

[Charlie E.]

JDI must be routed to cab from THRU output, that will be parallel to cabinet, because THRU output wired parallel to transformer with some sort of voltage divider with PAD engaged. -15 db (with PAD) equals to 0.18 ratio. 100 Watts into 8 Ohm means sqrt(100*8)=28.3 V, so with -15 db reduction it will be 5 V...

I follow your math but I guess I'm just dumb cuz I don't understand how -15db = 0.18 ratio or what the end result of 5V even means....

For the record my cab only accepts 16ohm so I'm gonna have to run the head at 16. The only alternative would be to use half of the speakers as it accepts a stereo input at 8ohms.
Going to do this today so any last tip recommendations would be helpful.
For now I plan on engaging both the speaker button and the -15 pad because that's what the manual suggests.

 

[Brett - K A L I S I A]

Do what the JDI manual suggests and start at a very low amp volume then work your way up.

 

[Charlie E.]

Thanks I'll definitely start low. Good tip.