Using Isolation Box or a Rivera Silent sister for direct amp profiling

In my experience, this works well.

My setup for doing this is using a Suhr Reactive Load box to replace the speaker on the amp, feed the line-out of the Suhr RL into my Helix using a return block, after the return block use an IR for cabinet modeling, and feed the output of that back into the Kemper reference input. Then profile away.

Works really well, and is very easy to make direct, studio, and merged profiles. For the direct, just disable the IR block in the Helix and redo the profile.

I've gotten really nice profiles this way - all silent and can do them anytime without bothering neighbors or family in the house at all hours of the day or night.

Edit: I've done little amps as well as big amps this way (up to 100W heads). Both work well.

Direct profiles don't use a cabinet so you have to use some type of device that sits between the amp and the cabinet that sends the raw amp signal back into the Kemper, instead of the chain that includes the cabinet.

The Suhr Reactive Load box is not just a resistive load, it's an inductive load like a real speaker, so it doesn't color the raw amp signal like cheaper resistive load boxes. You can think of it as a very inefficient speaker. You can actually hear it, if you put your ear down to it as the power flowing through it slightly vibrates the coils within it. It can handle up to a 100W amp at full master volume.

If you mean do I get better profiles than actually mic'ing a cabinet, for *me* - I'd have to say yes. IRs are usually expertly mic'd and sometimes with multiple mics. I get great results making studio profiles this way. And to make the Direct profile, all I have to do is disable the IR and I get the direct raw amp signal that is what you need for making a Direct profile.

When I profile, I usually do both studio and direct profiles, and then merge them, so that when I turn off the cabinet in the Kemper when I want to drive a real cabinet instead of FRFR, I get better authenticity than if you turn off the cabinet from a studio profile. So if you have a powered Kemper you can power a speaker cabinet directly, and if you don't have a powered Kemper, you can still send the Kemper line-out into a power amp connected to a real cabinet. Sounds really great doing either of these.

Does that answer your question?

You would disable the speaker emulation for doing raw direct profiles.

I actually tested one of those before I settled on the Suhr RL. It worked very well when I was testing it.

The Two Notes Captor and the Suhr RL were actually very close. I did compare side by side, and they were very close.

IME iso boxes are bad, boxy sound in a really bad way.

I picked up a SPL Reducer that is just great. May be work checking into.

Quote from benmars800

Interesting! How do you use it ?

I have been having great success with pretty heavy attenuation when needed. I am using Neve RNDI with it for the direct out part. Not all amps need a lot of attenuation. Really depends on the master volume.

Quote from benmars800

@bsd512
Speaking of your successful direct profiles, do you experience loss of low and mids after making a final profile ?
I have open up a thread and not sure if you have seen it

Fix the Low and Mids lost Frequncies for Direct Amp Profiling

No, I can't say that I have. Kemper profiles the feedback it receives when it injects a signal into the amp. Anything that doesn't sound accurate is usually taken care of by Refining in my experience.

The only issue I've had with profiling has been for very light crunch. I can't tell any difference between the profile and the real amp when doing chords and more heavier picking. But light picking on those lighter crunch or push profiles seem to be a challenge for the Kemper to get accurately. I can always tell a difference. The Kemper profile sounds almost clean instead, missing some grit.

For high gain tones, Kemper is usually spot on.

How you refine definitely makes a difference. I had suggested in the Suggestions section of this forum that I think it would be great if Kemper had a built-in refining sequence it could inject instead of having us do it. That way refining would be done "by the book". Kemper's instructions on this are pretty open ended - just play some chords or something to that effect. Not very specific when how you refine makes a pretty big impact on how the profile turns out.

During profiling.

Are you finding that after you save the profile, the sound is different? It's a lot easier to A/B directly on the profiling screen using the "Kemper" and "reference amp" buttons. I listen and sometimes adjust a parameter or two to make them sound the same.

Is that what you're asking? Sorry, I'm not trying to be dense.

Nope, I haven't used a head switcher to A/B.

And if there is any difference in lows and mids, it's not enough for me to notice without a/b'ing.

Doesn't the Kemper turn off some things during profiling that are not off when not profiling? I'm thinking of something like "real cab" (defaults to 3 unless you turn it off in globals) - granted, I know that is not it because you're running without cabinet emulation. But could there be something else that is off during profiling but on when in browse or performance mode? I'd be real surprised if there's a difference between the profile while you're in the profile section, and the profile after it's saved. Why would Kemper do that? There's probably another explanation for what you're experiencing.

A better A/B test might be: instead of using the Kemper's built in amp to your cabinet, to instead use its line out and feed it into the Return of your tube amp if it has an fx loop. The way you're A/B'ing now is using two different power amps - the Kemper's built-in amp, and your guitar amp's power amp. Feeding your Kemper's line-out into your amp's fx return would feed your Kemper through your tube amp's power amp. So you'd eliminate one variable from your A/B test and maybe get a closer comparison.