A client of mine – Ed Tullett, a songwriter and producer from the UK – is using the N-audio 8X7 amp switcher and recently bought the new Reload II from Two Notes, which is a company I really like. Their power attenuators are solid, I always recommend them to anyone who needs one. But in this case, there was a problem, and I thought it’d be a good idea to share it here – just in case someone else runs into the same thing.
Basically, the Reload II doesn’t work when used with the N-audio 8X7 or 4X4 amp cabinet switchers. At least not for now.
So, the Reload II is an active power attenuator – same idea as the Fryette Power Station or the Boss TAE – meaning it has a built-in power amp. That’s actually cool, because it gives you line-level signal after the attenuation circuit going to the internal amp, so you can add effects in between without needing a send/return loop on every amp. Also, unlike passive attenuators that have fixed or semi-fixed output levels, active ones give you full control over the volume – from zero to full blast. And the Reload II has a 200W built-in amplifier.
What makes the Reload II different from the Fryette or the BOSS TAE?
The answer’s in the power amp. The Reload II uses a bridged mono amplifier. That means both the tip and the sleeve of the speaker output are hot – there’s no ground.
I messaged Guillaume Pille the owner of Two Notes. Big thanks to him for the quick reply and the friendly chat. He basically confirmed what I was suspecting, and I was right when I checked Ed’s setup!
Hi Niki,
Reload II is using a stereo class D amp, and as in most Class D amps the output is bridged yes. I would certainly not recommend grounding the output!
This image shows the basic block diagrams of all types of power attenuators. More detail about bridged mono amps here.
And here’s the main point: I believe all amp cabinet switchers on the market that offer an attenuator insert – including N-audio 8X7 and 4X4 are designed to work with attenuators where the ground is shared between input and output. But with the Reload II, both output wires are active, so if you connect it to the amp switcher, it actually shorts the power amp. There’s an error LED on the back of the Reload that lights up when that happens – a good warning sign that the output is being shorted by grounding one of the hot lines!
in conclusion
The Reload II is a new kind of device, and honestly, I haven’t prepared for something like this. It’s the first power attenuator I’ve seen with a bridged mono amp inside. All N-audio amp cabinet switchers already support bridged amplifiers just fine, but having an attenuator with a bridged amp is something completely new, and that’s where the problem comes in. I’ll need to redesign part of the circuitry to make it work properly. It’s clear things are moving in that direction, so I’ve already started working on a solution. The plan is to update the N-audio 8X7 and 4X4 soon!
Niki Hristov
