2m or 2.2M linear pots needed, small? PC mount?

[cslammy]

I found some 2W panel mount honkers on ebay. They work, but are really big

Linear or audio taper, audio preferred.

Anyone have any for sale? Trade? Know of a place to get some of these? PCB mount would be best. If not, panel mount will work.

Can't find them in the usual spots.

Thanks.

[donpachi]

I also could not find a small 2M pot. But the two sections of a stereo 1M pot can be chained in series as a workaround. What I used is this:
https://www.uk-electronic.de/onlineshop/product_info.php?products_id=3424&language=en
HTH

[cslammy]

[donpachi]

[cslammy]

[gabbagabi]

since tau=R*C,
an other workaround is to just increase the cap value,
which is usually easy-er to do

e.g. 1M/1µF shold act same as 100k/10µF

let me guess rene schmitz adsr?

[PHOBoS]

[cslammy]

Yes Rene ADSR.

I wanted to keep the RC curve cap as small as possible, thinking a small cap maximizes the real-world speed of a rapid attack. math wise it should sound the same (right?) but working with other ADSRs I have not always found that to be the case, at least to my ears.

I haven't A Bd the Rene-DSR circuit with both possibilities to see if I can hear a difference.

Once I get the 1M pots, different flavors are on their way from Mouser, I will A B them. I should be able to put a couple of Rene ADSRs side by side.

[PHOBoS]

[gabbagabi]

this is, of course!, the case,
since our opamps are a limited source of current (ive had a look into the TL07x Datasheet, but couldnt find the exact value )

Once i tought one could replace the typical Attack-Diode with a transistor going to Supply, but ive never tested it, it works in the simulator

just some things:

if u are looking for very fast attacks, ur usually look for percussive-like sounds, means u dont have 10ns Attack and then 10s Decay --> so u could make it switchable (like in the yusynth ADSR)

an other idea is, if u need it fast: not to charge the Cap up to 2/3Supply, just charge it to say 1V, but i guess then you need a different design - not based on 555

concerning renes design, the Decay and the Release-discharge is realized with a diode which results in an issue which is described (and solved) here:
https://kassu2000.blogspot.com/2015/05/precision-adsr.html

[Grumble]

You could also use an opamp with a fet based current source, that way you can increase the current beyond what the opamp can supply so the potmeter can have a smaller value while the capacitor can be increased.

[cslammy]

To better understand all of this I built a Rene ADSR with 2M audio taper and 2.2uF/10uF cap. Post is here:

http://audiodiwhy.blogspot.com/2019/01/renaydsr-zen-and-art-of-tau.html

Favor: if someone who is good at EE can look at the middle of this post and check the math I'd be grateful. Be gentle please, it's my first time.

Thanks.

[gabbagabi]

congrats to the build

some things:
the thing with tau, the rule say after 5*tau a cap is charged, that means it is then 97% charged,
if u take math a cap would never be charged 100%, a tiny tiny fraction would always be left - until we reach eternity
if u are the electronic guy u could say ( like the best teacher in the world have said to me, once upon a time) if the last electron is on the disk - its on, there are no half electrons!


as i was building the yusynth adsr i also burned some 7555, they seems to be extremly sensible, i dont like them
here: http://electro-music.com/forum/topic-70684.html
JovianPyx describes very well the problem that normal 555 have, may u will need that information one day

can one adsr "sound" different to the other?
i would say only in the extrems, specialy if we go short`n`low,
short means what is the shortest attack time? that is quiet clear i guess, since people are even designing zero-attack-envelopes it is important to archieve a fast Attack for the ultimate percussion sound.

Low means: does decay goes to zero - and how fast it does (same with release- but imo it is not so important as for the decay)?
u can test it: set Sustain to zero and release to zero, u should have a AD Envelope now. But discharging with a standart diode results in an extended discharge time (view also the link ive postet earlier)
This often results in a audible effect when the gate goes low, as a workaround i used to open the release a bit to "soften it out", this effect u could even find in the stock ADSR of the https://vcvrack.com/
can you hear it too in your build?

Lin vs exp response Potis, imo especially in envelopes exp-pot making sense, cos the interesting things are happening fast, no-one is speaking about how nice slow his envelopes are, so with exp-response u can be very precise "in the beginning" means u can adjust very well between eg 1ms and 1,5ms, but u are going to be unprecise towards the end where it does not matter so much if u have 8000ms or 8200ms of release

altought it could handle math iam not in love, but i can remember that it was kind of interesting where the units are coming from, since tau is a time: where time is coming from if u calculate a resistor and a capacitor?
Then (once upon a time) the best teacher in the world used to say: there was a clever guy back then who had the same problem, so he decided to include time in capacity so the guys in the future (us) dont have to worry about that, since then capacity could be written as (A*s)/V

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[gabbagabi]

even the bloody simulator can reproduce this behaviour

on the left side my "normal" AD circuit, the decay discharge is realized with a transistor, is represented by the red graph

rigth side, same circuit but "modded" to discharge-over-diode-thru-opamp, is the blue graph

you can see very good first the deformation and may more important that it takes much longer to reach zero, in this example it couldnt even reach zero

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[cslammy]

Thanks for all the advice and input.

I ended up building 3 Renay-DSRs using pretty much his stock design, and for my application--for this, trying to emulate 70's sounding synths, I think it sounds good.

Each has different realization of "tau", but all can be made to sound pretty much the same to my ears.

Here is my wrap up, including very basic sound samples.

https://audiodiwhy.blogspot.com/2019/02/renedsr-fastest-envelope-in-west.html

My next envelope projects: quad digital AD or D that will work with standard Expo VCA; gate modifier, and cloning the ADSR in the SH5. No idea when I will get to them

[gabbagabi]

if you like to test "the probably fastest non zero attack envelope" --> tpfnzae

i would prepare the schematics for you

[cslammy]

[gabbagabi]

will do so