Prism Sound makes some of the most expensive digital converter systems found anywhere. Some of their converters have the Over-Killer technology builtin or included (I have not examined every unit). On the surface, this seems to be very similar to a Waves L2 limiter in function, but looking deeper you see and hear it’s not at all similar.
OVER-KILLER - Retail Description
The Over-Killer barrels are described as “a unique, super soft clip circuit, which stays soft even when large overloads are present”. It is said to “not become HARD like less sophisticated systems. The clip level of the Over-Killer is carefully set so that peak modulation is very close to the nominal maximum level”. Over-Killers are supplied as a set of two passive Switchcraft barrels suitable for use with balanced, stereo analogue, line-level signals.
WHAT’S INSIDE?
All I can do is guess since opening up and going inside the barrel would void the warranty. Other users — as reported on some forums — have looked inside and said the guts are covered in epoxy to prevent easily seeing what is going on. I suspect special matched zener diodes in anti-parallel configurations, possibly joined by a resister or two. It’s not much circuitry, protected with a clever implementation.
THE DREAM
I call the idea behind these “the Dream” because in my testing they just don’t do what I think they should be doing (if you value sonic truth), namely, cutting off increasing loudness above +18 dBu (that’s the level stated on the label). The reality is, peaks above +18 dBu can still get through and be recorded. The marketing department says “turn up the heat on your new cuts” On the way to these peaks, your signals will get more blurred and murky sounding — that’s not the kind of heat I want on my mixes — if you’re looking for friendly peak level distortion, here it is.
TESTING
There are no switches, controls or knobs on the Over-Killers which makes them difficult to compare, with and without them in the circuit. I connected them to Loop-#4 on my Coleman TC-4, this piece of gear let me instantly switch the limiters in and out of the circuit to hear their effect in a very precise and predictable way.
I measured signal level from the Over-Killers using several methods. A JLM Peak and RMS meter was used for one round of testing. In another test I fed my Tascam DA3000 stereo recorder with the Over-Killers in the input signal path, this allowed me to SEE peaks on the meters and RECORD peaks, which could then be played back and demonstrated. In further testing I played signals into the Over-Killers and then monitored the output with a Neutrik Minalyzer to see the level.
A complex original recorded song featuring wide swings in dynamic range was the source material for testing. The recording was fed through one of the studios Neve 8816 mixers, this was chosen for its ability to cleanly operate well above the +18dBu clip level of the Over-Killers. With this setup it was easy to see and hear the performance of the Over-Killers while monitoring on Sennheiser HD600 high resolution headphones using a precision headphone amplifier.
Peak Reduction: I could stage the mix with the Neve output knob and listen to the effect of the Over-Killers as the level pushed up towards +18dBu. I could easily take the mix down to +12dBu peaks and it cleaned up though it was possible to hear detrimental effects from the Over-Killers happening when peaks were well below their preset level. As I pushed louder towards +18dBu, the signal level was clipped off but not smashed flat. More importantly, a few peaks above +18dBu were still able to get through. With the Coleman TC-4 it is possible to bypass the stereo Over-Killers with the press of a button. This made it easy to hear how much the limiters were reducing the overall signal level and how much of their clipped, distorted, garbage was potentially being smeared on my mix.
HOW THEY SOUND
With the Over-Killers in the signal path the mix sounded slightly congested, less clear and less distinct. The output from these limiters is destructive and always degrades the sound quality if they are in the signal path. Listening with the Sennheiser HD600 headphones powered by the Little Labs Monotor amp made it quite easy to hear just how much the sound was changed and degraded by having the Over-Killer barrels in the signal path. Once I understood how bad they made my audio sound, I removed them from use and put them on the table to sell.
LIKES
- Simple to use
- Very heavy duty packaging
- Switchcraft connectors
- No power supply required
DISLIKES
- Degrades sound - blurry, less distinct, distorted
- Does not stop peak “overs” greater than +18dBu
- No bypass switch
EPILOGUE
I am surprised that the company which produces some of the most expensive digital converter packages in the World, also markets something which degrades your mix so badly. I see that Over-Killer technology is included in some of their converter packages, I wonder if it is easy to turn on and off while monitoring? With regards to these standalone Over-Killer limiters, To hear it is to hate it. I’d rather have a pot than an Over-Killer - just turn the signal level down — do you really need this fixed limiter to clip off dynamic peaks? It won’t leave your beautiful mix sounding as beautiful, the Over-Killer always leaves its mark like an ugly stain that can't be washed out -- it’s not pretty.
I did not buy mine used, damaged or preowned, I purchased my Over-Killer limiters brand new from Alto Music. I experimented with them about 10 times trying to hear exactly what they’re doing and determine if I wanted them in my mix. Before I got the Coleman TC-4 it was really hard to pin the Over-Killer effect down. Now that I’ve really heard the difference — with and without — I don’t want Over-Killer limiters on my mixes, I don’t need their “soft clipped sound” blurring my recordings.
Thanks for reading High on Technology, Good Music To You!
©October 2025 by Mark King, it is NOT ok to copy or quote without written permission from the author.
Have you done any critical listening or experimenting today, or just read some stuff on the Internet? Maybe it’s time to go create something beautiful or listen to some Mark King Radio for a bit of inspiration. Check out “War of the Worlds”, the song.
