S2400 Analog Filtered Outputs sound very different from SP1200

I dont think the manual says anything about the analog filters except that they are fixed low pass filters with an increasing cutoff frequency going from output 3 to 6.

Personally I dont care if they sound like the sp1200 or not, I’m just trying to fing out if they are supposed to be cutting as much high end as they are on mine, as I have nothing to compare to. Are the analog filters on your unit suitable for just filtering out the aliasing? On mine they sound like a hard low pass filter cutting off most frequencies above 1000 hz or so, even the one on channel 6. This makes em suitable for doing filtered basslines and stuff, but not for smoothing out the high end.

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What I hear - and see by frequency metering - is Output 3 having a maximum cutoff frequency of just under 8K and Output 6 having a maximum cutoff of 12-13K. The Mix output (unflitered) is just slightly above 13K. If your S2400 is genuinely cutting off around 1000Hz on Output 6, something is definitely not right.
There are marked level differences in each output, so your ears might be telling you that lower amplitude sounds are less bright than they actually are. At similar amplitudes there’s noticeable differences between outputs, but nowhere near as dramatic as some people are claiming here - unless their units are way out of spec.

Edited just to clarify - obviously the slopes after the cutoff points are crucial - so here’s some screengrabs that show what I mean.

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Working as intended for me

Having listened to OPs comparisons, none of the samples contained any aliasing so hard to make a judgement. That said, the 2400 filters are clearly more rolled off, and the SP dynamic filters have a different release envelope on that example, not quite sure why.


The 2400 filters are definitely more rolled off. Can’t wait for the filter card as I really want to keep using this machine.

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Thanks for the detailed response! I might be exaggerating with the 1000hrz, I’ll do some tests later tonight as output 6 def doesnt sound like 12-13k to me… hope my unit isnt faulty!


I did some more testing this morning, here’s an example of the same sounds (first a sample, then some snares) played through output 1 (no analog filter) and then output 6 (analog filter enabled). The tracks are both set up identically, and are both set to mono, both in the sample page and the panning page.

Are the filters supposed to cut out this much high end?


I sent the same file to support by the way, but maybe you guys can compare to your units…

Yeah - that seems way too much roll off compared to what I’d expect from O/P 6. I don’t know whether the gain level before the output filter changes the behaviour of the filter cut off (even though it’s ‘fixed’) – And not sure whether there are trimpots on the PCB to change it. I wonder what support will say.

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Thanks for the reply man! Thats what I thought… hope to hear something from support soon, will share what they say.

Any others with this same amount of filter cutoff?

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I checked some photos I took when I had a peek inside my machine a while back, and the only trim pots I could see are for channel 1&2. So I don’t think you can adjust the rest unfortunately.


Yep that’s right, only channel 1 & 2 filters are dynamic and the rest have fixed cutoff frequencies as per the machine specs. Makes sense that there would only be adjustment pots for channels 1&2.


I’ve also always thought the S2400 fixed filters are far too rolled off to be much use for anything you want any high end content in. But not having a 1200 I don’t know what they’re ‘supposed’ to sound like. I know that whenever I 45rpm sample something like piano and find it to be far too harsh, I always find any of the filters too be far too aggressive in what they roll off. I also find there to be barely any difference between filter 6 (most open) and 3 (most rolled off). Most of the difference between the two is above 13k which is already heavily reduced by Filter 6 compared to unfiltered.

I sampled some piano/bass/ride at 45 and pitched down, and then a further 3 semitones which is typical for me and where the aliasing starts to become overbearing.

Filter 6 dropped the 9k peak by about 20db. Is it meant to do that? Even if it is, I find it to be too much to be usable on most samples.

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Mine does the same. I sent the audio examples I posted above to support.

They responded saying they are aware the filters sound darker than the original sp1200 filters, and they can’t change that. They pointed to the analog filter card coming.

This takes away my worry that something is wrong with my machine. The s2400 just has way darker analog filters. Because of this they might not be suitable for just taking out some aliasing, I’ll experiment the coming days to look for other logical use cases for these filters.


i mainly using it for bass lines and getting some of the hiss out of records. feel that they’ve worked like a real charm in that way. in fairness that’s the only way i’ve been using filters for most of my 20 years making beats, be it my 3000, s950 or this. i’ve got three S2400 beats being released this year on a major label and the filters didn’t seem to be a hindrance to them being selected. just my two cents, but it works fine for me. also really looking forward to the filter board too!


Hi bro, the actual E-MU SP1200 does have filtered outs just like the S2400. The ones that are sounding too rolled off were originally inted to only output bassline and kick drums. I’ve owned 3 EMU SP1200’s. They all do this rolloff that sounds drastic. I thought it was way too much when I owned the EMU SP1200 myself. I did a bunch of research reading about the intended use. It was intended to output bass and kick. The company rolled off so low because most times if your sampling from vinyl records you may like a songs drums. If you need to chop up drums from a sample and seperate the kick, snare Hi Hats etc. The kick will usually contain a hi hat as well. This is why you need to have that very low rolloff of high frequency. It will cut the hi hat out of being on that kick. So smile mate. NO DAMAGE! :+1:


I think he knows. He’s comparing the filters to the actual sp1200 in his post and saying they don’t sound similar to him.

Oh, ok my bad.

Thanks man! I’ve never owned the original sp1200 so I cabt compare the sounds. A lot of people always say those filters are a big part of the ‘sp1200 sound’ and this made me wonder if the filters on my s2400 are working correctly. I can indeed see the use for filtering basslines and kicks, but the filters cut too much high end to be used on every track.

Your reply and the reply I got from support before put my mind at ease. The digital filters work great for me by the way!


I’m happy to help :blush: The rear of the original SP1200 indicates this as well. If you want to bypass the low pass filters on the 2 of the 8 outputs on the SP1200 you need to use tip/ ring/ sleeve 1/4" inch cables and only plug the cables in half way to avoid the outputs lowpass filter. I’m not sure if Isla Instruments S2400 implemented this but that’s how the E-MU SP1200 works. Enjoy the S2400 there’s nothing wrong :partying_face: :tada: :piñata: :confetti_ball: :beers: I’m still waiting for my S2400 to arrive. I’m excited! I miss my SP1200. I sold it for $5000. on craigslist in 2020


On the s2400, there’s a menu to turn on/off the analog filters. No need to adjust cables.
Enjoy your machine when it arrives :slight_smile: