MUFF WIGGLER Forum Index
 FAQ & Terms of UseFAQ & Terms Of Use   Wiggler RadioMW Radio   Muff Wiggler TwitterTwitter   Support the site @ PatreonPatreon 
 SearchSearch   RegisterSign up   Log inLog in 
WIGGLING 'LITE' IN GUEST MODE

New module: Discrete Ladder Filter
MUFF WIGGLER Forum Index -> Oakley Sound Systems Goto page Previous  1, 2 [all]
Author New module: Discrete Ladder Filter
Synthbuilder
mooneh wrote:
It would be great if you could do more dry demo someday. Its easier for me to hear the character.


Dry did you say... without delay? Dead Banana

How's about this then?

https://soundcloud.com/takla-makan/oakley-sound-discrete-ladder-filter -simple-bass-sequence

[Sorry for some weird reason it's not linking properly in the embedded player]

A very simple sequence of three notes repeating. The patch is the standard subtractive thing: Two VCOs, one discrete ladder filter, VRG for filter envelope, ADSR/VCA for final volume control.

As the sequence is playing I'm tweaking the cut-off, resonance, drive and input levels to the filter.

Tony
mooneh
Thanks sounds great. Must have w00t

I guess the sound around 1.36 is made with the drive knob to overdrive the filter? So nice.
Noiseconformist
Synthbuilder wrote:
It's not terribly ground breaking but I'm trying out some ideas with printed circuit board design
that I thought I would try in 5U before I start putting them into a completely
new series of 5U, 19" and Eurorack designs that I'll be working on later in the year.


In fact, that's what I'd consider a major teaser! cool
Synthbuilder
Issue 2 boards should be available later in the month and the price for the bare board will be 20GBP. Issue 2 PCBs will be nearly identical to issue 1 boards but will allow the pots to be mounted as normal. If you want an issue 1 board to save a bit of money and don't mind the extra hassle in mounting the pots now is the time to get a board at the current cheaper price.

Tony
emi2345
Hi there. I am planning my first modular and am pretty set on the Oakley system. I've built guitar amps and pedals before. I'm a full-time musician in a band. My favourite synths that I've played are (rather unoriginally) the vcs3, minimoog and arp 2600.

I'm thinking of a simple starter package around 12U, with a view to future expansion to around 20U, along the lines of:

mididac, vco controller, 2x vco, filter, adsr, multimix?

I'm trying to decide which filter and format I should go for. Would the discrete ladder filter be the most appropriate for minimoogy/early arp2600 sounds or the transistor ladder filter? Is there much difference, apart from obvious features? And the other question I had was, are there any advantages to the 2U format DLF? Could I use it as a distortion/mixer unit if the filter is fully 'up' or will it always sound to some extent 'filtered'?

Thanks for the help and apologies if I've posted this in a bad place, I can't make a new thread yet.
Synthbuilder
emi2345 wrote:
mididac, vco controller, 2x vco, filter, adsr, multimix?


I'd add another ADSR or, my favourite, a VRG.

Quote:
I'm trying to decide which filter and format I should go for. Would the discrete ladder filter be the most appropriate for minimoogy/early arp2600 sounds or the transistor ladder filter? Is there much difference, apart from obvious features?


They do sound different and the Superladder does have the rather useful one pole and bandpass modes. But for older synth sounds I'd take the DLF.

Quote:
And the other question I had was, are there any advantages to the 2U format DLF? Could I use it as a distortion/mixer unit if the filter is fully 'up' or will it always sound to some extent 'filtered'?


The 2U DLF behaves much like a 1U DLF with a simple passive mixer in front of it. Personally, I'd have the 1U DLF and an additional Fourmix module. Having the mixer separately allows for filter free (and therefore very clean) mixing and allows flexibility later on when you add more filters to your system. The Fourmix also has an interesting overdrive mode as well as a useful way to add constant voltages to your audio which can create asymmetrical distortion.

Tony
emi2345
Thanks for the reply Tony!

That slope/bandpass pot in the TSL is really cool, I'm assuming it wouldn't be easy to implement it in the DLF instead of one of the CV depth pots?

One thing I'm not quite clear about the DLF is the way the CVs work, I'm guessing they both control the frequency and not the drive or the resonance like the TSL? Couldn't the same effect be produced by mixing two CVs together using a multimix and then patching that into one CV input?

The VRG is definitely on my long-list, I just want to get a simple system up and running first and then I can add each new module one at a time and learn it really well instead of having a tonne of complex stuff to learn in one go.

One final thought, and this may not be the best place to ask, does anyone know of a simple 2U or 3U loudspeaker/amplifier/headphone module I can get in the 5U format? I've been searching and I can't find one. One of the things I love about the VCS3, 2600 and Gleeman Pentaphonic is you can sit in a corner of the studio away from everyone else working on a patch without hogging the main studio speakers and making everyone else get itchy feet. They are complete instruments you can take anywhere and play without any external stuff. I'd be happy to try to build one from a schematic.

Thanks for all the help.
Synthbuilder
emi2345 wrote:
That slope/bandpass pot in the TSL is really cool, I'm assuming it wouldn't be easy to implement it in the DLF instead of one of the CV depth pots?


It would not be a trivial modification since you'd need another differential amplifier and a crossfader circuit. There's not a huge sonic difference between the sound of the TSL and DLF though - they are both clearly Moog ladder filters.

Quote:
One thing I'm not quite clear about the DLF is the way the CVs work, I'm guessing they both control the frequency and not the drive or the resonance like the TSL? Couldn't the same effect be produced by mixing two CVs together using a multimix and then patching that into one CV input?


Yes. Neither drive nor resonance are voltage controlled on this one. If you have a Multimix summing your cut-off CVs then the extra CV input on the DLF is superfluous. However, with the simple need for just envelope and keyboard CVs to control the filter there is no need for the Multimix - just plug them direct into the DLF and save that mixer for other duties.

Quote:
One final thought, and this may not be the best place to ask, does anyone know of a simple 2U or 3U loudspeaker/amplifier/headphone module I can get in the 5U format?


Inbuilt speakers and me don't get along well. I'd always settle for a nice little monitor speaker sat on top of my modular rather than one internal one taking up module space and which would inevitably not give the sonic results worthy of the modular connected to it.

A headphone amp and output module has been on the cards for some time.

Tony
Blake Smith
Quote:
A headphone amp and output module has been on the cards for some time.


That would be very handy.
emi2345
Well it seems like the best solution would be to get the DLF and then add a diode ladder later, which I think is similar to what the VCS3 has.

A 1U headphone output module would be great!
trebmonster
I'm a newbie so I'm not allowed to start a new thread...!
I'm just starting to build a DLF for use with my Moog Voyager. I shalln't be building a separate modular system but may add a couple of VCOs later. So I need to insert the DLF between the Voyager's mixer and filter. Moog kindly provide a jack for this purpose but the signal lever from it seems too low. I've not hooked up the scope yet but a DVM shows about 0.5v (AC) with all 3 VCOs on. My understanding is that the Oakley (and other MU systems run with analogue signals at around the 10V peak level. Is this right? So do I need to add an op-amp amplifier with gain of say 10 at the front and an attenuator at the end?
Many thanks smile
Synthbuilder
trebmonster wrote:
I've not hooked up the scope yet but a DVM shows about 0.5v (AC) with all 3 VCOs on.


The DLF is designed to work with signals ten times that, ie. 10V peak to peak. The input 'mixer' of the DLF will start to overload at around 8V peak to peak. Ideally then you need to amplify the signal with something like your mixing desk or an EFG module. Bear in mind that the output of the DLF will also be ten times what the Voyager wants on the way back in. So you'll need to cut it down a bit; a -20dB passive attenuator would be best. Not entirely straightforward then...

Alternatively, you could make the following resistor value changes to the DLF:

R18 220K, R24 15K - this will increase the input sensitivity by a factor of ten or so. I think this should work without introducing too much instability.

R27 3K3 - this will reduce the output by a similar amount.

I've not tested this so do let us know whether you get the results you are looking for.

Tony
trebmonster
Thanks Tony. I'll change R27 as you suggest, but as I may add some VCOs in the future, I'll leave the input sensitivity as it is and boost the Voyager with an Op-amp instead. Cheers.
trebmonster
All perfect. op amp giving gain of 10 on the input and your 3k3 change works spot on. Levels with Voyager just right. DLF calibrated perfectly - all trims to 0.000 V smile Sounds great. Love how you get resonance AND bass end at the same time. Many thanks.

905 clone reverb being built now when the tank arrives. But what next...???
MUFF WIGGLER Forum Index -> Oakley Sound Systems Goto page Previous  1, 2 [all]
Page 2 of 2
Powered by phpBB © phpBB Group