The Akai S900/S950 Low Pass Filter

Thoughts, tips and tricks, post here.

Well, only have just received the s900 (same filter i believe) had to mod the receptacle!, the filter i think is a cross between digital/analog, it seems to be very effective around the 20-35 value, especially when sampling at the lower freq rate, gives some interesting artifacts, that can't be emulated on software. made a ripper tune last night only sampling drums and bass (only one bass note) but boy it was really thumping. It seems the midi timing is very accurate.

wavemartian wrote:Well, only have just received the s900 (same filter i believe) had to mod the receptacle!

The power socket?

If so, you could have gone to Jaycar and purchased the correct power cable.

wavemartian wrote:Well, only have just received the s900 (same filter i believe) had to mod the receptacle!, the filter i think is a cross between digital/analog, it seems to be very effective around the 20-35 value, especially when sampling at the lower freq rate, gives some interesting artifacts, that can't be emulated on software. made a ripper tune last night only sampling drums and bass (only one bass note) but boy it was really thumping. It seems the midi timing is very accurate.

There is no Low Pass Filter on the s900! I think your talking about adjusting the bandwidth (aka sampling rate). Which is ironic because the aliasing your jazzed about is entirely digital and very easy to replicate via software.... Simply because its software in the first place making that sound not the analog components.

Clint wrote:Thoughts, tips and tricks, post here.

-a lot people report a high frequency noise when the filter is closed. I noticed with samples @ 19200 bandwidth(max samplerate) you can get a much larger filter range without running into the high frequency noise. I would definitely choose 19200 for single cycle wave forms

m56p87 wrote:

wavemartian wrote:Well, only have just received the s900 (same filter i believe) had to mod the receptacle!, the filter i think is a cross between digital/analog, it seems to be very effective around the 20-35 value, especially when sampling at the lower freq rate, gives some interesting artifacts, that can't be emulated on software. made a ripper tune last night only sampling drums and bass (only one bass note) but boy it was really thumping. It seems the midi timing is very accurate.

There is no Low Pass Filter on the s900! I think your talking about adjusting the bandwidth (aka sampling rate). Which is ironic because the aliasing your jazzed about is entirely digital and very easy to replicate via software.... Simply because its software in the first place making that sound not the analog components.

the S900 has the filter if you upgrade it to OS4... in order to use OS4, the S900 must have EPROM chips that are 1.2 and you can load OS4 from a floppy disk on startup.

crossings wrote:
the S900 has the filter if you upgrade it to OS4... in order to use OS4, the S900 must have EPROM chips that are 1.2 and you can load OS4 from a floppy disk on startup.

good to know! I was going to add, the s900 service manual shows nine MF6CN-50 filter chips, just like the 950.

the only thing is, there are a lot of S900s out there that don't have the 1.2 EPROM upgrade... and i don't think you can buy those EPROMs anywhere now... so not everyone can use OS4.

m56p87 wrote:There is no Low Pass Filter on the s900

I was gonna correct this misconception, but others have already stated the facts. Some S900's won't have the filter, it needs the OS upgrade to get certain S950 features. The 1.2 OS is available on eBay if you look in the right places...

How common is this? I've used a few 900s and haven't ran into OS4 yet.

i've owned a total of three S900s in my years... 2 of them had the 1.2 EPROMs... so in my experience 2 outta 3. you need to get your hands on the OS4 disk though... OS4 can only be loaded from floppy on startup.

http://akai-s900.blogspot.co.uk/2008/02 ... -s900.html

2wice wrote:I found this on the Akai maling list it seems to sum this up pretty well...

S9V4.0
SYSTEM DISK FOR S900

INTRODUCTION
Thank you for purchasing the S9V4.0, an exclusive system disk for the
AKAI S900.
The S9V4.0 has been developed to augment the functions of the S900.
By loading this system software onto your S900 V1.2 (1,2), you can
obtain the following additional functions and upgrade the musical
expressiveness of your S900.
1. Pre-trigger recording
2. Special one shot mode
3. Crossfade looping
4. Dynamic Filtering
5. Automatic locating of start point
6. Velocity release by note on
7. Combine two samples for velocity crossfade type samples
8. Changing the velocity mix curve for velocity crossfade
9. Time skew for velocity
10. Key group copy function
11. Disk mode: Compression of sampled data
When using S9V4.0, please make sure you have fully mastered the basic
operation of S900.

WARNING
* The S9V4.0 cannot be loaded unless your S900 is V1.2 (1,2).
* The S9V4.0 cannot be copied. If you have trouble with your disk
under normal use, please consult the Service Division of AKAI's Head
Office through the store where it was purchased.
* Because of the augmented MIDI exclusive function, you may get an
error message if you load an editing software which was not created
by this system software. Please be sure to load this system software
before using editing software and sample data created by S9V4.0.


>Simon
>Canberra
>AUSTRALIA

Can we concentrate on the actual FILTER here, I've amended the thread title.

has anyone managed to modulate the filter cutoff from an mpc?

soundtech wrote:has anyone managed to modulate the filter cutoff from an mpc?

Velocity and midi note number is the only way I can think. What's nice is having a full ADSR envelope the note duration can factor into the filter sweep


I'm not sure if my ears were just playing tricks on me but I also think it is possible to use velocity--->attack, and modulate only the filter ADSR, the volume ADSR attack time is unchanged if left at 0.

I upgraded the s900 to OS4, which has the dynamic filtering, you need to use omniflop program and have an old computer with a floppy drive. I didn't realize you could get those funny 2 prong cords locally. When i was putting together a program last night i noticed some weird characters after the sample name
ie sample name: snare3 ^x at C3. Its the cross with the hat on; anyone know what this means. i will post a sound clip of sound examples of S900