Home | ER-101 | ER-102 | ER-301 | Wiki | Contact

ER101/301 100-Sample Drum Machine

Hi everybody! I’ve been building an ER301 drum machine sequenced by a ER101/102 and could use some help to get it working better. The goal is to have the ER101 index values (which are between 00 and 99) select corresponding slices between 1 and 100 of a varispeed player on the 301.
I prepared some folders with 100 kicks, 100 snares etc and loaded the contents of each folder onto a vari-speed player. So the slice control on the ‘kick’ vari-speed player chooses which of the 100 kick samples to play.
The first snag I ran into is that the ER101 does not have a default table mapping all index values to its full output range. The Linear 8 table is in 100 mV increments meaning that index values do not output different voltages after 80. Can anyone share an ER101 index table of 80 mV increments, where the full 0-8v output range is mapped linearly to indexes 00-99?
For the time being I’m using the 24-ET table to select slices. However the slices on the 301 are not being reliably selected. As a sequence loops, wrong slices are played occasionally and randomly. I don’t know if this is because I need to introduce a delay on the trigger input so the slice voltage is received first or because I have not mapped my 301 gain/bias parameters in the best way. It might be that some input voltages are corresponding to the border between 2 slices causing it to randomly select one or the other.
For slice selection I created a top level control on a mixer unit with a range of 1-100. The varispeed player feeding this mixer takes this slice control and uses a rational VCA dividing by 100 to bring it back to the expected range to select the slice. Should I be doing this a different way? Works fine when I manually select a slice with the bias control, but not when selecting slices with sequenced voltages. Do I need to quantise the input voltage to a 100 step range somehow?
Any tips would be much appreciated!

If you use 12ET on the ER-101 and CV-to-Slice-Mapping = 12TET on the ER-301, then you will have access to 98 (i.e. index 0 to 97 on the ER-102) slices without having to deal with custom voltage tables or scaling the slice selection voltage.

This is definitely required. There is a lightweight delay unit called uDelay for this purpose:
And here is a description of why:

If you really want to use 24ET on the ER-101 then set the slice modulation gain to 2 and set the CV-to-Slice-Mapping to 12TET. Multiplying by 2 effectively converts 24ET to 12ET.

Thanks for the quick response and helpful suggestions. I’ve implemented the 12TET slice mapping on the ER301 and added an additional 2 semi-tones to the ER101 12-ET index which means I can select 99 slices/samples which is great. I added 10ms micro delays before the gates and everything seems to be behaving as expected! It’s a lot of fun to program rhythms on the 101 and use the math transform to randomise sample selection. Instant inspiration machine.