jrp
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Posts posted by jrp
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Ich hatte glaub ich im elko was gelesen. Ist auf jedenfall nichts ungewöhnliches, absolut machbar. 3500 ist nicht ideal, aber sehr gut. Ich würde eigentlich gerne ein paar mitbestellen, allerdings bin ich mir noch garnicht sicher ob ich in zukunft nicht mit dem MBCV und linearen vcos arbeiten kann/will.
http://www.midibox.org/forum/index.php?topic=9366.0
Dann könnte ein ganz simpler expoconverter für modulationseingänge ausreichen.
Wenn der ein bischen unberechenbar ist - umso besser...
Nochwas: Schau doch mal bei Electro-music.com ins diy-synth forum. Da dürften sich auch noch einige interessierte landsläute finden. Die 50 oder besser 100 sollten wir eigentlich schnell zusammen haben. Sowas kann man immer gut auf lager gebrauchen!
Ich wollte bei weltronic schonmal 3 stück bestellen. Hätte etwa 50 euro gekostet...
Vieleicht gibts auch irgendwann eine Sammelbestellung für SSM2210 dualtransistoren. Zusammen mit einem low ofset low drift opamp gibt das nen richtig guten vco!
An dieser stelle nochne empfehlung:
http://mypeoplepc.com/members/scottnoanh/birthofasynth/id28.html
Eigentlich nichts besonderes dran, ein tricore vco (besseres verhalten in hohen lagen als sawcore). Das besondere ist der diskrete comparator im eigentlichen oszillatorblock. Soll angeblich besser sein als ein standardopamp (und 1000* billiger als ein spezial komparator).
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i´m sure it is from the psu. multiples of 50hz - sounds a lot like a bad filtered psu.
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ich hab nurmal gelesen das man mit standardwiderstärnden (parallel und seriell) den tk beeinflussen kann. Genaueres weis ich aber nicht...
Und an anderer stelle das ein 3500er um welten besser ist als garkeiner...
Conrad hat welche mit 3850, um die 5 euro, einfach bei conrad nach platin suchen.
Die hab ich schon verbaut, hab aber nie genau gemessen wie stabiel das ganze ist. Kann ich mal machen. Ich hatte damals aufjeden fall zusätzliche widerstände mitverbaut. Ich weis blos nichtmehr wo ich das gelesen hatte...
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Für VCOs nehm ich an?
Ich könnte eventuell ein paar gebrauchen. Aber wird nicht meistens 3300ppm als besten wert angegeben?
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this is perfect (well, ok, storing within the MBCV would be perfect).
The Concepts of your work surprise and convince me more and more!
Maybe i just overlooked, but i hadn´t seen this in the MBCV ducumentation.
second look - it´s all there. Not in the feature list, but in the menues description.
Stupid me asking question already answered taking your time...
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and my oppinion is that building an aout and a vca is no difficult task. Not much harder than soldering a core or any other module.
It´s just like with all electronics: for easy troubleshooting you need to go step by step. Buld the sid, see if it works. Build the vca, can be a simple one, apply a voltage that should make it open, see if you hear something. Build the Aout (LC would be fine) and see if it outputs a cv. Connect everything and trim so that the vca is shut when no key is pressed. Ok, these are many more things to watch out for than building a simple setup, but if you go one by one nothing should go wrong.
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yes, of course, i hadn´t thought of that. Using different voices at one time this won´t work. Still i think the possibility to output the egs as cv is a very powerful feature! :D FM or Sid with minimoogfilter and tube vca 8)
Ok, a noisegate would be best. In a studio setup this would be the obvious solution. Wonder why this problem is not present when running the chip in a c64 though.
About the simple diode noisegate, i forgot to mention that low drop fast diodes should be used. BAT 43 work fine.
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i only now undestood, this is not seq speciffic but a mios feature.
So with this feature could be used to store and load different setups for the midibox-cv?
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Isn´t it possible to output a cv for a filter or vca? (with aout module)
or was that the fm?
If that is possible, and i bet it is, this could be a solution.
Make a vca follow the envelope of the sid´s soundpatch.
Or use a simple noisegate. If you like the sound to be dirty you can try the following:
A amp stage with variable gain, followed by two antiparallel diodes. Set the gain so that the softest part of the sound is just passing the diodes. Everything below +- 0,3v will be cut away. So you have to boost quite a bit. This is a great methode for distortion boxes, don´t know if you like the sound with the sid.
A real noisgate is more complex, but still a simple build.
basically a envelope follower to detect the amplitude, a comparator and a vca. if you can´t find a shematic i can have a look. (but i would have to look, that´s why i don´t post it now...)
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another old toppic, but i think i can add thome words to this that might be of interest.
First, LDRs are no good choice when it comes to linearity and exact values.
Of course. This disadvantage comes out strongest when you try to controll a stereo device, have two chanells behave exactly the same, etc.
Big Advantage: They work great, they are reall ohmic resistance (other than fets, otas etc). They do not produce distortion. They can handle rather high voltages (very important for the guitar amp). They are cheap. They come in different ranges. They are quite fast if you keep the led brightness between max and only rather dull. When you turn out the light completly many will wander in resistance for minutes. But they all have a range where they are settlet fast.
Parallel and serial resistors can improve the responce curve for your project.
For a Guitar amp i would go that way.
For a stereo amp i wouldn´t...
Another thing to look at are all the high performance VCAs/VGAs out there. Have a look at the AD or TI-BB chips. Some have excellent audio performance. Some are controlled by analog voltage, some digital, so there would be no need to build a DAC.
The BB Volume controll chips are some of the best out there.
Forget about stuff like the 13700 Ota. Nice for synth projects, but you wouldn´t like your amp after that.
But one thing: Replacing a resistor with an active component can get you in trouble, depending on the ranges and polarities of your signal.
One totally different thing: I play a lot and i wouldn´t want to replace the pots of my amp with encoders! Really! Really! On Stage you´ll hate it many times. Just the grip and responce of the pots, you need to relay on that. On stage less is more!
If you want to load different setups i would think about building a effect unit that has variable attenuation/gain, an eq, some fx loops that can be controlled, can switch and store the amps chanells, etc. Make a nice footcontroller for it that can load your presets, maybe has some pedals. Done.
Then your amp becomes the master soundshaper that you can set up according to your needs. Remember that settings, especially volume and eq, stored or remembered will have to be adjusted for every room you play.
So you could store sounds for different songs, parts etc in the preampbox, and still keep the amp to adjust everything for different playing situations.
And if you have a softwarecrash the unit can be rellay bypassed...
This is only my oppinion on this. Really don´t want to talk you out of anything. Do what you feel like! Modding the amp can be a cool project. But it could destroy the sound and the handling of the amp!
Second thought: A compromise could be to mod the amp, but keep the pots. A second row of encoders would be needed to make settings to be stored. Then you could have a footswitch to select presets OR the pots. A rellay can switch between the variable resistors and the pots.
For a guitaramp this might not be that great, but for some studio equipment it might be cool. Keep the original look and feel that you love for jamming of your vintage gear, and have the option to store settings with your midisequencer.
Have fun!
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I know that the MBCV can drive linear vcos. In therory this is very cool, because a linear (integrator-tricore) vco is simple and easy to build, requires no highfreq trimming and has no expensive, temperature depending expo converter.
A big polysynth could easily be built with the MBCV and this kind of vco.
But how are your experiances with this setup? How does it perform?
I recently started a discussion on this in the electro-music.com forum. A friend there pointed out that there can be problems with tuning to different ranges, and that the usable range is always limited more or less, depending on the dac used.
You might want to check if these MIDI controllers give you enough resolution for building linear frequency control. i.e. if it is possible in all frequency ranges to get a good enough tuning. This usually is troublesome with linear control from D/A outputs, it would be a bit sad to discover about this after all the work is done.and later another user added:
You're gonna want to use a multiplying DA for this. DAC0831 is a good choiceWhat interests me is this: I think for an analog synth it´s ok to be limited to 4 octaves at a time, but it´s important to be able to tune that range from low to high.
Now i can imagine that when an offset is applied to the cv, to transpose the whole range, that in that case the scale will get out of tune. Is that so?
How about pitchbend?
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Yes it is! I alsways had writing problems, so i bacame a musician...
And i must say one thing:
This pages have some of the best documented diy projects i´ve ever seen and a great community. I´m happy to contibute a little to this. But i would never have done this if you hadn´t asked if i could start a wiki page. Thats very cool. Good creative comunity spirit here!
If it´s not commercial it has to be that way.
good thing :)
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Hallo
Das ist ein alter post, aber ein für mich recht interessantes thema. Daher will ich das mal reaktivieren.
Zuerst: Wie ist es ausgegangen? Wie glücklich seid ihr mit dem handling?
Um auf die grundlegende funktionsweise einzugehen (vermutlich alles schonmal irgendwo erläutert...):
Ich hab mir die Dukumentation zum MB-CV nochmal durchgelesen.
Es ist doch so das man für jeden Ausgang eine keyzone definieren kann.
Also müsste die lösung doch so aussehen: Man hat seine gates mit festgelegten notenwert/kanal.
Man ordnet sich seine ersten 7 Analogausgänge und gates so wie man es braucht. Zb so das sie von unten an die festgelegten gates anschliesen. Den 8ten cv asugang lässt man auf velocity reagieren, und zwar auf die noten die für die statischen gates verwendet werden. Damit wird man in erster linie sounds ansteuern wollen die nicht (oder selten) gleichzeitig erklingen.
Wie gesagt, nach lesen der Doku erscheint es mir das das ohne weiteres mit der dout erweiterung gehen müsste. Und es geht noch mehr. Toll wie flexibel das ganze ist!
Meine anwendung soll zb so angepasst werden: Bassdrum, 3*HH mit eigenem gate cv. (Am Rande: Bei den 3 hihats kann man noch lustige logische verknüpfungen machen, so dass zb eine getretene hh eine offene abschneidet)
2 snares die sich eine velocity teilen.
Dann die toms. Die hören auf velocity und einen keyboard bereich von vieleicht einer oktave. Der Notenwert betimmt tonhöhe und stereopanning. Spart einige soundmodule!
Macht bisher 7cvs.
Ab da beginnen die dout gates mit ihren festgelegten noten. Das 8 cv wird so eingestellt das es immer der velocity auf diesen tönen folgt.
Wenn ich mich jetzt nicht sehr täusche müsste es auch alles im display der mbcv so einstellbar sein, das die sounds schön der reihe nach auf dem keyboard anliegen.
Wenn ich wie in meiner anwendung beschrieben zwei snares direkt nach der bassdrum haben will, je mit eigenem gate und gemeinsamer velocity (vom core modul, nicht vom dout) - bin ich mir jetzt nicht sicher obs geht, aber ich vermute mal das müsste hinzukriegen sein.
Noch eine kleine idee:
Normalerweise programiere ich sowas mit dem eingangsrouter des sequencers, aber wenns die drumbox schon mitbringt, umso besser:
Pro sound verwende ich zwei nebeneinanderliegende tasten des midikeyboards. Bei den Core-triggern kann man einfach die split zone entsprechend anpassen, bei den Dout triggern müssen halt je zwei mit dioden-oder zusammengefasst werden. Der Vorteil: Wesentlich besser auf dem keyboard zu spielen. Hihat figuren mit einer taste und einem finger gehen einfach nicht so gut...
Übrigens, wenns nicht reicht, ich sehe eigentlich überhaupt kein problem zwei midiboxcvs parallel zu betreiben. 16* cv/gate, mehr braucht man wirklich nicht.
Wenn man das ganze mal konfiguriert hat lässt man es so wies ist....
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ok, i´ve done a wiki page with all i know on the subject. Hope someone will correct if there are any misstakes.
The page looks messy, i´m not good at computerstuff...
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thanks for the info. Now at least i know that it could be done. I already notice, the more i learn about these projects, the more i understand that i´ll have to get some programming skills....
Ok, what about saving settings from the midicv? It doesn´t say anything about that in the documentation, so i guess it´s not implemented?
This is slightly off topic now, i know, but since i had the idea of sharing controlls i have come to the conclusion that it would be best to get rid of the lcd all together, since the mboxcv will have a special job and i´ll never use more than 2 or three setups.
If it´s realistic for me, i´ll try to find out how toi do it, once my cv is running.
My personall application will look like this: A big analog synth with 4 or 5 linear sawcore-oscillators, driven by a v/hz cv. That makes them simple and small and easy to use. No more tempcos and hi freq trimming.I want a poly mode for chords and an unisono mode. maybe also different split opotions. These settings can easily be configured on the midiboxcv. But that´s no good workflow. I guess there quite some turns and clicks to set up the box - every time. My aim is to get rid of the lcd once the midiboxcv is configured and have two or three buttons to load different (prepared) setups.
THis would be nice in any case, also when a lcd is being used. Just have quick access to the most often used settings.
We´ll see if i get to this, first i have to learn something about code though...
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One important thing i found out:
When transformers with no center tap are used, it´s very important that the load is rather balanced on both rails. Otherwise you get dc flowing through the transformer, it will get hot, too hot and fail.
don´t know if this is a problem here.
I was drawing some schematics and writing a description for the wiki. Could someone measure, under working conditions, how much current the modules that need +-12v draw on each rail?
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and here´s what we need to get +-12v out of 15vac (14v will also be enough)
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I´ll do that, glad to contribute. Don´t know how to write a wiki page, but i´ll find out.
Or maybe some links will do as well, since i never studied this or anything, i just collect information on the web...
But on the other hand, what i like about ucapps is that it´s all in one place.
Only thing i´m a bit afraid of is writing something that just isn´t true. I often think i know what i do in electronics, only to find out that the others know better...
So if i´m not sure about something i rather check the places in the web (or public library) that i trust.
Ok, i´ll do my best, show some different alternatives for psus and see that i find an expert for review.
I once blasted an elko and a 7812, that was no fun!
It suprieses me that the 7812/7912 are getting that hot. think they shouldn´t in this case. Are they getting hot with the 15v transformer only or with the 12v as well?
Can you still touch them? Could you meassure the current on both rails? maybe there is something wrong.
And yes, you´re right. Using a small print transformer and drawing little current is like using a higher voltage transformer - they always output much more. Sometimes even double to what´s printed on them.
Problem could be that when a really small one is used, one that delivers not much more than the power needed, the voltage will drop to the voltage rated.
Same may apply to big ringkern (english: ringcore?) transformers. If someone sees this schematic with the 12v transformer, thinks that this always works, builds a big psu for his whole setup he could get into trouble.
Also it´s important to know that one way rectification is only for small loads (although i don´t know how small)
just some links for those intersted:
http://www.powerstream.com/Wall-mount-FAQ.htm
One good descripion in german is here:
http://www.synrise.de/diy/supply/supply.htm
for more power... good info
http://sound.westhost.com/power-supplies.htm
basics
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hier das aout modul
http://www.reichelt.de/?ACTION=20;AWKID=11419;PROVID=2084
Ohne Flachbandkabel, ohne max-ics
Statt standard leds sind es LC-Leds, entsprechend auch 3*4,3k statt 470r
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Hi together
I just noticed that on the project pages a 2*12v transformer is used in the schematic for the +-12v supply.
Just like to point out that this can work, but is not recomendet (and not standard).
The 78xx regulators need an input voltage that is at least 3v higher than the output to work correctly.
Normaly this is ok, since the rectification will give us a higher pulsing dc level (something with *sqr(2))
But: - The diodes will drop our voltage by 1,4v
- Our mains supply is not stable. In germany +5%, -10% are allowed.
As soon as this is the case (propably more often than you think) it´s getting problematic.
Not that it won´t work - you will have noticed... but ripple and noise will increase, the 78xx won´t feel good.
So i suggest the use of 2*15v transformers.
A 14v transformer will work with one way rectification, i talked about it in another post, conrad sells 14v AC "Steckernetzteile" that should be sufficiant!
IF YOU THINK I MADE A MISSTAKE HERE, PLEASE TELL US!
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What a great Lo-Fi idea.
that´s why i like it!
But you´re right, mutilayer boards are difficult. But every trace that dissapears will reappear eventually...
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To my knowlege and experiance any opamp can be used with a single supply.
But: For an inverting opamp you need a voltage referance that is in the middle of the two rails. In an symetrical setup this is ground, in an unipolar this has to be created (voltagedivider)
Here we have noninverting amps, so that´s nothing to worry.
But: Most amps are not rail to rail. So they will not be able to go down to ground when powerd between + and ground.
Depends on what comes out of the ya chips.
About the +-12v supply
A regulated psu is easy to build. very easy. But care should be taken and it´s maybe better not to have to deal with mains. especially if you transport the synth, never know who´ll step on it, tear a cable and get shocked.
I wrote a message to tk about this idea already:
The easiest, safest and most available solution are AC supplys (whats the english word for steckernetzteil? Plug-psu?)
They are more rare than dc, but you get them. Conrad in germany has one with 14VAC. Perfect for us. lots of comercial stuff, phone stations etc have psus like that.
Plug it in and you get 14v without dealing with any mains supply.
14V can be one way rectified and regulated with 7812/7912 for a +-12v supply. We don´t need much current, so one way rectification is no problem here, but don´t forget to use cabs twice as large than witch bridge rectification.
Opter possibility: Two 12v dc supplys. Cheap and in every household. Should be two of the exact same type. Prefer regulated ones. If you use cheap unregulated ones you will get more hum and noise. A RC filter and a gyrator on each rail will fix that.
hey napierzaza. greetings to canada. I once lived in vancouver for a year, loved it! There must be some vendors that you can order from in canada. Can´t belive.....
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Thanks for your thoughts.
Well, it´s not about saving a buck really. It is about handling and panel space (and design, maybe). Just like the way those seq3s look.
My ios will be on the back, propably on a single connector. This is a studiosetup mainly, the connections i like to patch will be available as bananajacks on my modular synth.
But i had another thought. Is it possible to save the settings of a midiboxcv as sysexdump?
Programm and save the configurations i use and store them on the computer. Then i can remove the lcd, complete the whole unit and restore my settings via midi.
1K Tempco 3500ppm/°C
in Deutsch
Posted
sind die günstiger? 2210 sind wirklich sehr gut, ich denke es gibt noch andere günstige doppeltransistoren die eng genug toleriert sind.
Aber bei that gibts glaub ich auch 4 und 6fach transistoren. Eigentlich für vcas Das wäre super um gleich 3 vcos auf einem board zu bauen, mit nur einem transistorchip.
trotzdem würde mich interessieren ob man mit dem MBCV mit v/hz cv nicht ganz auf den expo converter verzichten kann, oder ob das eher eine notlösung mit gewissen einschränkungen ist.
Auf jeden fall denke ich das auch hier der rest der schaltung entscheident ist. Zb die widerstände im CV summierer und eben dieser selbst. Natürlich auch die versorgung und die spannungsreferenz. Kann also möglich sein das ein vca trotz tollem chip und tempco nicht richtig trackt, aber das ist ein anderes kapitel...