seppoman

sounds like you activated the SuperPoly mode while only listening to one SID pair. The dynamic voice allocation would probably assign the notes you play to every SID (one after another) until the circle is completed. Go to the ENS menu (press first Menu button) and make sure that the SPV value is set to "off". S

I don't think that this chaining can be the reason for the noise. I'm using this solution on my Der Brat, too, without problems. I don't know if maybe 1 or 2 dB of s/n ratio is lost, but it definitely doesn't add enough noise that anyone would complain about it. S

would you mind describing your bipolar supply in detail? which kind of cirquit are you using (schematic)? single transformer, bipolar transformer, two transformers? Full or half bridge rectification? I still got the feeling your problem might be located at the PSU - like e.g. the PSU delivers its voltages only when no load is applied. Some hires pics of both PSU and AOUT_NG from both sides also could help getting an idea what's wrong - at the moment, I can't make much sense out of the effects you're describing... S

I was asking because you said both pos and neg rail read 11.7V. So the neg is minus 11.7V measured towards GND, i.e. between the two voltages you measure 23.4V, right? Ok. You need to narrow down the problem a bit. As said before, please leave all jumpers open until the problem is found. that way, the DAC or other mistakes on the digital part can be left out of the search. Also remove the TL074s from the sockets. Is the voltage drop still present without tl074s? Does the 7912 get hot when the PSU is connected? Can you measure if the board takes excessive power from the negative rail? S

I hope the negative rail reads -11.7V? ;) As long as there's troubles with the supply voltages, you can't expect any reasonable behaviour. If you want to check if the DAC alone works correctly, you could remove all jumpers and measure the JP1/JP2 pins coming from the DAC (against GND). This should give values between 0V and 4V when you change the values in your app (is the module already connected to the core and is some app running?). Make sure the bipolar PSU really works fine, recheck all soldering, parts orientation, parts values etc. I would definitely sort out the problems on the analog part before reconnecting the jumpers. The DAC probably wouldn't like it very much if e.g. it gets 12V or -12V fed into its outputs. S

PLEASE don't kill any working ESQ1s for that IC, they're just too fantastic to be slaughtered. A lot of information like all the Ensoniq schematics, DOC datasheet etc, can be found here: http://www.buchty.net/ensoniq/index.html S

Haha, 10 minutes ;) Stryd isn't that fast ;D - That isn't some automated system, just an adress styd_one is regularly checking and then uploading the stuff himself. S

und hast dann nur noch den halben Wertebereich, also besser nicht machen ;D An der Genauigkeit ändert 5k oder 10k nichts. Nur der Stromverbrauch der Fader (einleseseitig, also nicht der Motor) verdoppelt sich (mit 1mA aber immer noch so wenig, daß es nicht wirklich ins Gewicht fällt). Funktionieren sollte 5k wahrscheinlich genauso gut (ohne Garantie, weil nie selbst getestet) S

Und was willst Du uns damit sagen? ;D die Dinger in der eBay-Aution sehen eher wie 2x24 aus und haben außerdem keine Hintergrundbeleuchtung... Klar kann man auf eBay auch gute/ähnliche Displays mit etwas Geduld günstiger schießen, aber im Vergleich zu üblichen Ladenpreisen sind 12€ sicher ok. Kein Grund also, hier rumzumeckern ;) S

Hey NV, you really are starting to make things more complicated than they are - I think all you need to know has been said before now ;) Except: Ratings of bridge rectifiers are just the maximum allowable values, i.e. a B40C800 would take 40V and 800mA max, so as the prices don't differ much als long as you're not going for a HUGE PSU, just use e.g. a B80C1500 or somthing like that. The basic principle of Shum's schematic in fact is the same as the first one from the Wiki except the missing secondary 100nF caps (which you should install, too). The cap values of Shum's schematic are quite sensible, so just take them and add these secondary 100nFs. About the transformer: 2x14V or 2x15V is definitely enough, if you're going higher you only generate more heat by that. Use e.g. the 14A-20-28 or the 14A-30-28 from that PDF, or from the Pulse/ERA PDF from last week, the 039-5311.0 (30VA). As long as you're not hooking up a modular synth to that same PSU, even the 039-5104.0(14VA) would suffice. Just choose one of them now and get going ;D ripple: yes, ripple means noise, so it's something you want to keep reasonably low :) S

Not necessarily an AOUT_NG, but of course you need some AOUT to control the filter :). You could also use two (!) AOUT_LCs or the "old" AOUT (but in this case you'll need to add the bipolar option at least onto two of the channels). If you don't have any AOUT yet, the NG is well suited for the purpose and has probably the best price/performance ratio :) S

Currently I'm overworking the PCB a bit e.g. to give the capacitors more room. There'll probably be a bulk order for the PCBs "soon". Having seen what happens with bulk orders nowadays, I should probably point out: I am giving no definite date when this will happen, an NOT taking any orders so far and it definitely makes NO sense to post any "I want two" stuff to this thread ;D S

Try "OSC" - second hit ;) S

Just PM him ;D

Fantastic box, I love it :) also the blue lines on the panel go together very well with all the red lights. Where did you get the panel made? S

as stryd already pointed out, this is quite the same as the second one on the bipolar wiki page. I guess it would work but would give more ripple on the supply voltage. so there's no real reason not to use the 14VA transformer you found in the first place (or the 15V version from the same series) :) correct. and maybe 9V is better after all. I used a 7.5V transformer before without problems but the margin is maybe a bit slim considering the voltage drop over the rectifier. I'd go for an at least 1 A, better 1.5 A transformer, especially for the Seq. That's right. Depending on what you want to control with the aout_ng and if you want to power that stuff from the same PSU, you could either use the 14VA transformer or go for a slightly higher rating. Nothing complicated about that. just connect them in parallel. On the secondary side, if you use that dual transformer, you need to take care that you connect the end of one coil to the beginning of the other. Don't make the "ground" connection at the same side of the coils or you'll get the transformer humming and getting hot. but if it's wired the wrong way, you'll notice that effect very fast :) S

Do you see any IC on the schematics in this thread that even remotely looks like it could be a DAC? :D S

Hi, I'm offering a Yamaha SY35 synth. It's neither analog nor in the same league as contemporary Workstations or VAs, but for slightly trashy 80s/90s stuff the sound is quite nice. The sound engine is a mixture of FM and crude samples, combined via vector synthesis. The keyboard (61 keys with aftertouch) is quite good, definitely better than the usual crappy USB Midi controllers. Of course fully functional. 120 Euros including shipment (within Germany - I suppose international shipping and Paypal fees would make it too expensive and complicated to be a good deal anyway, so I'd prefer not to sell it internationally) Seppoman

oh yes - it starts with the fact that the OPL3 uses an unusual sample rate of 49.something kHz so when you record it back with a different sample rate, the signal isn't the same anymore. Together with the two channel samples possibly coming out of the OPL3 with a slight delay, a few things happening in the analog domain, then sampling it back with a different rate, maybe even using the input of the SB16(?) which has a really BAD CODEC could among other things lead to additional time offset if e.g. the codec also samples the cannels one after another and maybe uses another channel order for that... So it's quite possible all these digital and analog things happening to the signal would lead to an offset of one sample. Anyway, I think stryd has proven that this is the case on your recording. If you happen to like what this does to the sound, you should check the stuff I wrote about comb filtering and find a way to reproduce it in a more hifi way than voice cancellation is capable of, rather than using up all your time with questioning the why and how over again :) S

Sadly, the link for the YAC512 datasheet is down. But from the OPL3 datasheet you can see there's no data line to trigger a synchronous update of the DAC channels. So maybe this means that the update of the two channels happens with a slight delay between the two. Depending on the serial clock frequency between OPL3 and DAC which isn't specified in the datasheet, I guess that delay might be up to a quarter of the 49kHz sampling frequency. So when sampling this stereo signal with e.g. 44.1kHz, this might lead to some samples being off one cycle. Note that this is only a theory, maybe the DAC's (unavailable) datasheet would mention that the outputs are only updated after the second value update... Anyway, having a minimal phase difference between the two channels does lead to the result that your phase cancellation method a) doesn't cancel out the sound completely (-30dB is still very much) and b) leads to a so-called "comb filtering" effect, i.e. some frequencies are cancelled out more than others. http://en.wikipedia.org/wiki/Comb_filter. This effect can be imitated by either a comb filter FX plugin (surprise ;)) or, more or less, by a combination of notch filters. I think it's safe to say that such effects of the OPL3 are definitely not made on purpose but maybe simply to save costs by omitting a signal line for synchronous update. This was a budget mass product. And if you want to have that effect, the signal quality would degrade much less if you use FX instead of your cancelling method. Oh and btw, CL have my full sympathy for not answering extensive and philosophical emails about minor design flaws of a fifteen year old chipset they didn't even develop themselves :D S

Well as I said, a second transformer will help avoiding heat anyway. But for a FM using that display, the 30VA transformer/NLX cirquit would be ok. You could omit the 7809 part because you don't need 9V. Instead of the high power resistor you could also use a 7809 like shown here (for MBSID): http://www.ucapps.de/mbhp/mbhp_core_power_fix.pdf. The resistor will work fine but become rather warm/hot, and it's easier to mount a 78xx to a heat sink than a resistor. The FM would also benefit from a second transformer, but for a SEQ I'd really recommend using one (two displays, more LEDs, more of them staying on at the same time etc). 7.5V is even better than 9V, they're not that uncommon. The PSU for this second transformer is already integrated on the core module, and for the bipolar supply you could go for the first schematic on the "bipolar 12 V" wiki page. So the two transformers method even makes the PSU more simple. A rating of e.g. 15VA would be sufficient for a SEQ (that equals 1.66A with 9V or 2A with a 7.5V transformer). For the FM, about 10VA are plenty. S

leider nicht: für Cutoff steht da -120 bis +180 mV (direkt am Beinchen). Thorstens Lösung würde ich auf jeden Fall mal ausprobieren - wenn das Ergebnis gut ist, wäre es auf jeden Fall der geringste Aufwand. Allerdings steht im Datenblatt des DACs min. Lastwiderstand 2kOhm, also sollte auch der Poti wenigstens diesen Wert haben. Wie sich der Kurvenverlauf ändern würde, weiß ich leider nicht. Ansonsten besteht natürlich die Möglichkeit, die Schaltung aus dem Datenblatt bzw Fonik-PDF nachzubauen. Diese Schaltung habe ich auf dem Board weggelassen, weil sie im Zusammenhang mit einem AOUT mit Bipolar-Option überflüssig ist, Platz und zusätzliche Bauteile braucht und ansonsten nochmal eine Schaltung ist, die man kalibrieren muß. Im Prinzip ermöglicht diese Schaltung, reguläre (unipolare) CV zu benutzen (auch mehrere davon, also auch z.b. ein poti). Der eingezeichnete Offset-Trimmer ist dafür verantwortlich, daß am IC trotzdem eine bipolare Spannung ankommt. Noch ne Idee: Ich hatte Dir ja neulich empfohlen, mal über eine MBSID ohne SID als Steuerung nachzudenken. Neben diversen anderen Features, die MBCV nicht hat (Routing-Optionen, LFOs, per Midi triggerbare Envelopes etc) gäbe es da auch die Möglichkeit, entweder 4 Potis anzuschließen (wenn die Filter immer stereo benutzt werden sollen) und diese übers KNOB-Menü auf die CVs zu routen. Oder man könnte einzelne Kanäle per Encoder einstellen, indem Du ein 2x40-Display mit 10 Encodern drunter baust und diese alle als Soft-Encoder definierst. Dann könnte man während man auf der EXT-Seite ist, alle 8 CVs getrennt beeinflussen. Praktischer und auch von der Einstellung geschmeidiger wäre aber wohl die Poti-Lösung. S

I forgot to answer about the two transformers you've found: If you use a separate transformer for the 5V rail, the 14VA one is more than sufficient. If you decide to go the NLX way, the 30VA should be ok as long as you don't use a lot of superbright LEDs (better anyway so you won't need sunglasses ;)). Usually LCDs are between 200 and 500 mA, the rest doesn't need much. So there'd be around 500 mA left for LEDs. S

yes, in the meantime I already noticed that issue - but instead of using a fat transformer I'd recommend using a second (7.5V or maybe 9V) transformer for the 5V rail. Nothing personal against NLX, but that construction only introduces troubles. It's loading the transformer very asymmetrically, plus there's a huge amount of heat to be dissipated from the 7809/7805. Best thing would, of course, be a single transformer like that Pollin one, but they're quite hard to find... S

yeah you're of course right - only in the sense that you could connect the digital control lines for an AOUT module there. But there's no reason to do so, and in contrast to the other variants the J5 pins themselves can't output analog voltages. That's what I meant :) S