MOTM

Just like I responded to the request for the ARP filter (I hope to have prototypes by mid-Nov), I
am in 'contact' with a potential source for a digital delay and sampler/looper MOTM delay module.
Stay tuned for more info as this progress.

I'm trying to do one with at least 2 CV "parameters" for <$400 (assembled only, as it's all SMT).
I'd like to get $300, but I don't think I can liscensing another design.

So, fell free to start posting "list of desired features". I can't say how flexible I can be in
changing the DSP code.

Paul S.

On Friday 31 October 2003 18:24, Paul Schreiber wrote:
> Just like I responded to the request for the ARP filter
> (I hope to have prototypes by mid-Nov), I am in 'contact'
> with a potential source for a digital delay and
> sampler/looper MOTM delay module. Stay tuned for more
> info as this progress.

Ohhhh, a MOTM *looper*. :))
I own two Repeaters and a Lex MPX-G2 with 10 secs of delay, 
but having this in MOTM format with sounds *very* nice.

>
> I'm trying to do one with at least 2 CV "parameters" for
> <$400 (assembled only, as it's all SMT). I'd like to get
> $300, but I don't think I can liscensing another design.
>
> So, fell free to start posting "list of desired
> features". I can't say how flexible I can be in changing
> the DSP code.

For a good looper you need aprox 10 secs delay, \ufffdthe more 
the better.

You'd need CV feedback conyrol. By reducing the feedback, 
you get the chance to 'clean' the loop and make room for 
new material to be fed into the loop.  

A CV record/play mode switch is needed. 

When  switching in/out record mode, no clicks/ticks/whatever 
should be produced.

No clicks/ticks must be heard when the loop 'returns' to the 
start of the buffer, even when a long ambient sound is 
recorded.

A lowpass filter for emulating an analog delay is needed, 
with CV control. But because we all have filters around, 
maybe it is possible to insert a filter into the loop 
signal. That takes an DA and DA converter, so the built-in 
LPF is probably a better choice.

- Robert

> So, fell free to start posting "list of desired features". I can't
say how flexible I can be in
> changing the DSP code.

V/8ve input!  Perfect for waveguide type stuff...

Harry

On Oct 31, 2003, at 9:24 AM, Paul Schreiber wrote:

> Just like I responded to the request for the ARP filter (I hope to 
> have prototypes by mid-Nov), I
> am in 'contact' with a potential source for a digital delay and 
> sampler/looper MOTM delay module.
> Stay tuned for more info as this progress.

I am very, very happy to hear to this!

> I'm trying to do one with at least 2 CV "parameters" for <$400 
> (assembled only, as it's all SMT).
> I'd like to get $300, but I don't think I can liscensing another 
> design.

Delay time and feedback would be my vote for delay parameters. Price 
sounds fine by me, lower is always better, but 400 doesn't sound too 
high.


> So, fell free to start posting "list of desired features". I can't say 
> how flexible I can be in
> changing the DSP code.

I think keeping the feature set to things that make since *within* the 
modular signal chain as opposed to pre/post processing is pretty 
important. There are plenty of other fx processors to handle those 
tasks. It doesn't need a reverb, for example. It also shouldn't try to 
replace your guitar looper, there are better tools for that.

Most importantly: This delay must never, ever, ever, ever digitally pop 
or clip. Ever. At all. No matter how it's abused.

The feedback should be literal, that is, the final output stage of the 
looper should have two outs and two inputs. To do feedback you take one 
output, route it back into the CV controlled input and it's 
remixed/limited/filtered with the main single. This allows for doing 
things to the feedback signal in unusual ways, like passing it through 
a '440 on an LFO'd cutoff . There is an ocean of sounds to be made from 
screwing around with the feedback before it gets pushed back into the 
delay line.

Changes to delay time should not clip. Play with the delay on the 
access virus for an example of a very nice delay. Delay time should be 
CV controllable, and sync-able.  In other words, a re-trigger signal 
for the delay. One should be able to sync delay to an LFO or pulse 
wave, etc. Fun sampling like effects could be done with this.

There's certainly room for more than one kind of delay in the MOTM line 
too ;)

--- In motm@yahoogroups.com, Mike Estee <mikest@a...> wrote:
> The feedback should be literal, that is, the final output stage of the 
> looper should have two outs and two inputs. 

Love the idea of it just being a delay line with no other features. Patch it into an echo 
with whatever other modules you want. I do this all the time. The only drawback is 
that it's way lo-fi compared to feedback done in DSP. As long as you could turn the 
mix to 100% wet and feedback to 0% I'd be happy.

How about dual synced delay lines with windowing functions for granular effects? 
Ow! Who just kicked me?!?!

Max

On Oct 31, 2003, at 12:07 PM, rreprobate wrote:

> --- In motm@yahoogroups.com, Mike Estee <mikest@a...> wrote:
>> The feedback should be literal, that is, the final output stage of the
>> looper should have two outs and two inputs.
>
> Love the idea of it just being a delay line with no other features. 
> Patch it into an echo
> with whatever other modules you want. I do this all the time. The only 
> drawback is
> that it's way lo-fi compared to feedback done in DSP. As long as you 
> could turn the
> mix to 100% wet and feedback to 0% I'd be happy.

I would argue that it's not *that* lowfi ^_^, but yeah, you'd get 
coloration over time as the delay line loops. Anyway, there are much 
better toys for looping. I totally love the idea of just a delay line. 
In addition, I very much like the idea of keeping the things analog 
does well in the analog domain and the things digital does well in the 
digital domain.

For example, I think it's silly to do the filtering with a DSP 
algorithm, you end up having to code back all the variances and 
imperfections found in a real filter that make them sound good. You'll 
get better filtering from any of the 400 series anyway. Same applies 
for the mixing. What happens when the feedback overloads? In a digital 
algorithm? In a analog circuit? I think those edge conditions are 
important.

Time scaling resolution should be high enough to avoid zippering. 
Ranges are fine way to overcome this.

Just the thought of a feedback delay line that incorporates a 440 makes 
me drool ^_^

ps: has anyone else here played with the evolver? it's a dsp/analog 
hybrid.

> I'm trying to do one with at least 2 CV "parameters" for <$400 (assembled
only, as it's all SMT).
> I'd like to get $300, but I don't think I can liscensing another design.

Hey, that's less than I paid for my TC Electronic D-Two!

The good thing about a Delay as a part of a _modular_ synth is that you can
add a lot of features just as you need it, with other modules. Don't worry
about the "right" Loop filter for these echoes growing "distant" (loosing
bass and treble) - you can patch this up with any regular VCF in the system.
Well, you might provide a simple 6dB rolloff with variable corner frequency
for the simple stuff. Other than that, just make the feedback loop "open"
such that you can patch in whatever you need. Ever tried a frequency shifter
in the feedback loop? Or a simple ring modulator? Hmmm ...
What you *do* need is a _limiter_. Really. Especially with a lot of
external stuff patched in, which will push the loop gain above unity
easily, you want a limiter. Digital, part of the DSP code.
And provide a lot of Delay time. 20 seconds minimum. RAM is cheap
nowadays, and all the Loop Artists will run and buy a MOTM delay
if they can use it as a Looper. Provide switches for clean doubling
and halfing (is that the word?) of delay time, in addition to CV inputs.
Loopers like this. And a CV input for adding Tape-echo-like wow and flutter.
Make it stereo, if it's possible.

JH.

> V/8ve input!  Perfect for waveguide type stuff...

Right, almost forgot that!

BUT! If you want to use it for physical modelling, the V/8ve
input must be compensated for the fixed delay of the ADC / DAC
process! Implement it such that it goes down to 1ms or less,
and that the whole chain (ADC, RAM-cycles, DAC) tracks
to 1VOct, _not_ just the RAM part!

JH.

> The good thing about a Delay as a part of a _modular_ synth is that 
> you can
> add a lot of features just as you need it, with other modules. Don't 
> worry
> about the "right" Loop filter for these echoes growing "distant" 
> (loosing
> bass and treble) - you can patch this up with any regular VCF in the 
> system.

Amen! This is exactly what I'm talking about.

> What you *do* need is a _limiter_. Really. Especially with a lot of
> external stuff patched in, which will push the loop gain above unity
> easily, you want a limiter. Digital, part of the DSP code.

Unless the feedback path is all software, wouldn't the limiter need to 
be before the AD? :( Saturated ADs sound horrible :(

> And provide a lot of Delay time. 20 seconds minimum. RAM is cheap
> nowadays, and all the Loop Artists will run and buy a MOTM delay

You know, you could probably get away with supporting regular DIMMs and 
adding a bit of glue to make delay time dependent on how much Joe MOTM 
User is willing to pony up for RAM. This pushes the cost of RAM down 
through volume ;) Heck, can you even *buy* a 16MB simm anymore? In my 
music I personally have never found a use for a delay longer than about 
4 seconds, but for looping 20 seconds is probably scraping by. Be the 
first on your block to have 1GB delay/looper ^_^

> if they can use it as a Looper. Provide switches for clean doubling
> and halfing (is that the word?) of delay time, in addition to CV 
> inputs.
> Loopers like this. And a CV input for adding Tape-echo-like wow and 
> flutter.

It seems to me like a delay and looper probably belong in different 
modules. There are a certain class of features you want for looping 
that aren't all that interesting for a delay line, and vise versa.  I 
have to admit, my lack of imagination is drawing blanks as to how a 
looper would be really useful within the signal path of a patch. It 
seems like more of a post processing toy. I can certainly imagine using 
an electrix repeater with a motm during a performance, but I have a 
hard time imagining how it would make sense within a patch.

Anyone care to enlighten me?


> Make it stereo, if it's possible.

I really like Paul's multi-use format modules. It's a VCA, but a two 
channel VCA with slightly different behavior for slightly different 
problems. Or the filters with their double duty as clean sine wave 
generators with 1V/Oct control. Or the White/Pink/Slow/Vibrato/S&H 
module. I get good milage out of that one ;)

--mikes

OK, I'll try this *again*.

The basic feature set (algorithms, delay times, delay length) I *cannot change*. If it loops,
then it *loops*. If the filters are in SW, *so be it*. There are some things I can add around the
"core" DSP/codec section, but there's not much I can do (right now) about the DSP code.

Paul S.

Maybe it would help if you tell us what is in the DSP code so we 
could talk around that?  I've heard some really good suggestions 
(two inputs, two outputs for full control of feedback, etc.)  It 
would be nice to know what's etched in stone and what isn't.  

Or did I miss that post?

Mike

Happy Halloween!

--- In motm@yahoogroups.com, "Paul Schreiber" <synth1@a...> wrote:
> OK, I'll try this *again*.
> 
> The basic feature set (algorithms, delay times, delay length) I 
*cannot change*. If it loops,
> then it *loops*. If the filters are in SW, *so be it*. There are 
some things I can add around the
> "core" DSP/codec section, but there's not much I can do (right 
now) about the DSP code.
> 
> Paul S.

Lotsa good ideas rolling around on this.

I just wanted to ask - and maybe I missed a post on this or whatever -
 
Are we talking a 'stereo'  delay?  I ask this because, as I babbled 
on before about how delays and 'time shifting', etc - REALLY open up 
a lot of new sound possibilities...these possibilities are seriously 
diminished however - with a mono concept.

I realize this may offend any hard core 'analog' disciples - and you 
can always just buy 2 (which is good for the revenue stream, but less 
likely to happen on the part of the buyer)  yet I thing this issue 
should be dealt with from a 'biggest bang for the buck' sort of basis.

Or most importantly -  the biggest 'aural capabilties' for the buck

Somehow or other my MOTM is going to be stereo- "end of 
discussion...for me anyhow" - and I know we all know of various ways 
to accomplish this - but delays, are REALLY a whole new world, in the 
stereo domain.  And they get pretty boring -in mono, especially when 
you got a Lexicon (a few really good ones for really, really cheap 
comparatively speaking to yester-year)

Plus being somewhat of an anal 'supreme audio quality idiot' and 
having performed one too many times through Fender Twin Reverbs,etc 
(with 20 grand in keyboards or such) - I have long since determined 
that even my on-stage monitors be stereo.  Its just too damn 
depressing to have your $10K Kurzweil, Triton, etc.. coming out mono -
It drive me to pyschopathic proportions...and makes me want to kill 
all guitarist and anybody else who can sound great via a mono signal 
path!

I'll leave any discussiom on dolby 5.1 for a later date----lol

My 2 cents - 
(Thats all I have left - after buying way too many toys.!!!)

Rog

>The basic feature set (algorithms, delay times, delay length) I *cannot
change*. If it loops,
>then it *loops*. If the filters are in SW, *so be it*. There are some things I
can add around the
>"core" DSP/codec section, but there's not much I can do (right now) about the
DSP code.

What sort of features are possible for us to request? I'm VERY excited about
this module, but I'm not sure what kind of features are possible for you to
work around in the core DSP. My ignorance, sorry. Can you go into it a
little more? I have a feeling for what's NOT possible in this situation, but
what IS possible for us to chime in about?

FWIW:
Robert's suggestion of having an insert available for filters is stellar. I
would prefer an insert over having a built-in LPF, because I use LPF just as
often as BP or HP with regen'd delay. Also, I'd love to be able to insert
chorus in there, some gain modulations (so delays become grainy over time!),
a digital resampler (lower the bit depth with each delay!), or some
reverb... Man, that would just open up so many possibilities. Is it
possible?

best,
- Scott
____________
http://www.red-noise.com
http://www.strawberryplanet.org

> on before about how delays and 'time shifting', etc - REALLY open up
> a lot of new sound possibilities...these possibilities are seriously
> diminished however - with a mono concept.

Not necessarily... Different techniques call for different tools. It depends
on how you mix and what your arrangement is like. If you're just working on
a single sound, sure, one mono delay is going to be flat. But if you have a
busy mix, a stereo delay could easily make the track feel cluttered and
murky.

best,
- Scott
____________
http://www.red-noise.com
http://www.strawberryplanet.org