Wilba

sammichFM

79 posts in this topic

Well it took two late nights but my sammichFM now powers up and shows Ready! I'll be trying to load the firmware today, though I haven't been brave enough to supply power to the FM chips just yet.

Wilba, you did a fantastic job with the kit! It has all the wonderful details that made building it fun and even relaxing. The little things, like having the header pins snap-in (which meant I didn't have to take the header down, tack it, then burn my finger while trying to adjust it so it's vertical) and having snap-in sockets. Very cool, and the LCD looks sexah too!

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WOW... Impressive..

Congratulation for this beautifull little box.

I'll definitely have to order one... maybe next month.

I'm surprised to read in the feature list:

"4 simultaneous instruments of 6 voice polyphony each, plus drum kit. Each voice is a 4 operator waveform."

That makes 24 voices of 4 operators + drum kit ??

That sounds much more than in the opl3 spec:

"6 four operators melody sounds + 3 two operators melody sonds + 5 rythm sound".

Did i miss something ?

Thanks,

Xavier

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No, you're right... I'm paraphrasing TK's MIDIbox FM specifications here: http://www.ucapps.de/midibox_fm.html

Maybe it should be written as "4 simultaneous instruments of up to 6 voice polyphony each, plus drum kit. Each voice is a 4 operator waveform."

Or you can propose an alternative.

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OK. thanks for the clarification :-)

Maybe something like :

"6 four operator voices played by 4 simultaneous different instruments plus drum kit."

Xavier

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I think there is an error in the voltage testing picture (the one with the colored dots) for the base PCB. Pin 2 of IC9 (2nd from the top on the left row) is connected to GND and not +5V. I noticed that during the voltage/continuity testing phase and looked it up in the PCB layout PDF.

Regards

trilader

Edited by trilader

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Are you using the 1.0 version of the build guide? I believe that issue has been fixed in that version?

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I emailed the link to the v1.0 build guide but forgot to update the link in the wiki. Fixed now.

Also, until the build guide is updated again, I recommend MIDIbox FM v1.4c which fixes issues with short notes for drum sounds.

http://www.ucapps.de/mios/midibox_fm_v1_4c.zip

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Crikey! I slack for a few months and come back and Wilba's gone and designed a whole new project. Beautiful job as always!

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Ok, no problem then. I was on my desktop and didn't look at the version number.

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That looks like a switched PSU to me (though I'm having Google Translate fail). You'd want a linear regulated PSU as the best option typically. Switchmode will work, but can induce noise (and usually causes a big flame-war here on the forums about half the time it's mentioned :) )

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Also quite often, voltage-switchable psus like the one you mentioned do provide the maximum current (1A from specs) only at the lower voltage settings.

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@m00dawg: Well, the description says "stabilisiert" i.e. "stabilized", which to me indicates that it's a transformer based psu. Do switch-mode PSUs need to be stabilized? Probably not. But I'm not sure about this. The product description is quite poor.

@Hawkeye: The sammichFM draws about 200mA according to the sammichFM building guide. If 1A is provided only in the lower voltage range, I guess at least 200mA should be provided at 9V. But still guessing...

@all: Any recommendations for a transformer based (linear) power supply here in Germany/Europe? :clover:

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Don't you guys have local fleamarkets? There are lots of those PSUs available round here...

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Regarding a linear psu, you can also build them yourself (but be careful with the high voltages) for low credits.

http://sound.westhost.com/power-supplies.htm for an overview

Coils are available at Reichelt "Flachtransformatoren" for 5-8€ a piece.

Linear PSUs are difficult to get (or expensive, 80€+), because they are considered special nowadays, switching PSUs normally do the job more efficiently (albeit for a few audio audio people who hear ´em :-)).

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@imp: We sure have, but I'm too lazy to visit one. Why leave the house if the mailman can bring me one ^_^

@Hawkeye: You have a great DIY-attitude :-) But with my experience, I will likely blow the sFM into pieces instead of powering her. Therefore I will stick with my switch-mode PSU first and see if induced noise will occur. If so, I'll try the Pollin PSU and report on the forum.

Edited by kristal=

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Try looking at the Boss guitar pedal range of PSU's, no doubt you'll find one to match.

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I recently discovered a 9V DC 300mA plugpack worked perfectly.

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Regarding a linear psu, you can also build them yourself (but be careful with the high voltages) for low credits.

http://sound.westhost.com/power-supplies.htm for an overview

Coils are available at Reichelt "Flachtransformatoren" for 5-8€ a piece.

Linear PSUs are difficult to get (or expensive, 80€+), because they are considered special nowadays, switching PSUs normally do the job more efficiently (albeit for a few audio audio people who hear ´em :-)).

That's usually my favorite option, though for the Sammich I didn't want a huge power brick as I can't build my own PSUs smaller than a commercial solution. Plus, there's that epic thread about adding circuit protection stuff and all that so I figured the Sammich might be best served via a $20 regulated power brick someone else built.

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I haz Sammich! Just arrived this morning. Haven't checked contents, but I'm sure it's all here.

a|x

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I haz sammichFM too! I just picked it up today from the german "Zoll". Seems everything to be there. Now please...another batch of sammichSIDs...my 8580s are freezing alone in the box... :brr: ;)

Maybe some kaffeSEQ too? :tongue:

Edited by pulsn

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I can not edit in the wiki!

here a link for a PSU that works fine with both sammichSID and FM :clover: (Europe/Germany)

VOLTCRAFT® USPS-600

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I can not edit in the wiki!

You'll have to log in with your forum's username and password first. Go and try :smile: !

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The PSU from Pollin turned out as a switch-mode PSU from goobay. But I do not notice any noise. At least when no sound is generated. In contrary to my sammichSID, where I always noticed a slight hum even when no sound was generated. So my question is: how do I have to understand the sentence "They generate far too much noise in the audio." from the building guide? Only noise within the sound generation or a general noise on the audio outputs?

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