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Assorted Helix mic/cab trivia


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I've been piping pink noise through the Helix Native mic+cab sims to learn more about them. I don't care at all about what the real units sound like, just about how they shape the sound. This is what I've seen so far:


For pretty much any mic, increasing the Distance parameter causes some boosts and cuts in the mids, the frequencies of which which seem to depend on the cab. For instance, on the 4x12 WhoWatt 100, increasing distance significantly cuts 1.2KHz, whatever mic you use. In fact almost all cabs see cuts around the 1-1.5KHz range, with the 4-speaker cabs showing the biggest effects.


On top of that, for pretty much any mic+cab, increasing the Distance parameter causes a low roll-off typically of between 6 and 12dB, and a small high-end cut, and a more gentle output decrease across the board. A couple of cabs also see small boosts in the mids, like the 1x12 Celest 12H. I don't think the proximity effect is being modelled because the low end reduction doesn't seem significantly different across the mics.


Increasing the Early Reflections parameter causes a broad but small boost in the 300-500Hz range. I didn't measure to see if there was any actual reverberation/delay effect included.


By averaging the response across all the mics for a given cab you can get a good feel for its 'signature'.

For example, the 4x12 Greenback has a slight boost in the low mids, then a pretty smooth roll-off as the frequency goes up, except for a big boost between 2K and 6K. Good for taming the treble of high-gain, while letting it cut through at the same time.

By comparison the 1x12 US Deluxe is almost flat right up to that 2K mark, falls off at 5K, but with a characteristic spike around 12.6K (probably now inaudible to anyone who played through the speaker when it first came out!)

And the 2x12 Jazz Rivet is also pretty flat, with a smooth but steep rolloff after 5K, punctuated by a sharp notch at 6.6K.

...and so on. If, like me, you know nothing about the cabs and don't have a specific sound you're going for, it's definitely worth trying some different ones to make sure their particular brand of cuts and boosts fit your material.


Arguably the flattest response, with otherwise 'default' settings, is the 2x12 Double C12N, with Distance at 1", and using the 67 Condenser mic. If you want a fairly neutral starting point, I recommend this.


For the most low-end, the 4038 Ribbon mic is the one to consider, followed by the other ribbons. For the most high-end, the 421 Dynamic, closely followed by the 112 Dynamic, seem to be the best choices of mic, which seems to tally with the real-life frequency response charts.


The 12 Dynamic mic has a significant boost around 700Hz, and which strangely isn't present in the frequency response diagram for the real life equivalent. Might be good for helping leads cut through the mix though.

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I would be really interested to see a chart of all of this for each model. Not necessarily saying you have to do it all, but it would be interesting and might help when trying to nail something down. Mostly just the info you've presented here: each cab's signature, each mic's signature, and what the different parameters do with each cab (generally, not for each mic). Perhaps just an averaged frequency response chart for each cab (graphical version of the signature), same thing for the mics, and then just a description of what the parameters do. I suppose each cab chart could actually overlay a few different charts, one for average with minimum distance and one for average at maximum distance, etc.


As a side note, from my own experience I am fairly certain the early reflections does add reverb. Like a small, short room reverb. It's more noticeable when you crank it way up. Not sure if that has anything to do with the boost.

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Thanks. Good info to have. I have always found that there is no substitute for using my ears to determine what sounds best. YMMV, as it is all based on what you feel best suits your taste and style, for a particular genre, and monitoring/playback system.

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