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  • @wuemura according to your own researches, they *are* wrong (EDIT: to better clarify, "they" is referred to ValleyBell and superctr), because as you can clearly read in ValleyBell's information, the phase shifting is done *in software* and not on an outside board and, again, as stated in the quote I made above, the QSound chip does actually that, it *decodes* the audio and the result, as once again stated, is a simple stereo track which just needs to be played back. And this is really the last f…

  • for @wuemura and all other people how might be interested in the discussion that arose earlier: I've reached out to ValleyBell asking to shed some light (at least for me) on the QSound situation both regarding MAME and how it works and he has given me permission to copy-paste his reply here: Quote from "ValleyBell": “Hi donluca, let's begin with the MAME story: Initially, one of the MAME developers didn't want to accept superctr's submission, because he wanted a reason to finish his DSP16A dynam…

  • Artemio measured how much current it drew and it was 0.665A twitter.com/Artemio/status/1191839819665686528?s=20 As said before, the components can work up to 16V DC IRC. But yeah, a common 12V DC should be enough bypassing the rectifier.

  • Fair enough. I know there's been lots of drama involving the MAME dev team and this is not the place to discuss this as I don't want to derail the thread (which has lots of meaningful and important information). They have their own way and let's just stop here. Some people don't like their way and that's 100% fine, I can see why, not going to defend them or anything. I know libvgm quite well and check it from time to time, I'm always interested in seeing how those evolve and each step towards a …

  • Dude, all that anger towards something so meaningless doesn't do you well, it's bad for your health. Take a deep breath. Chill. Now... QSound amps have been around forever (and people have possibly been frying them by feeding them 18VAC, but that's another story) and by now people would have found out if there was a matrix decoder (big spoiler: there isn't), but if you're so sure of it, then by all means, do not hoard this for yourself but submit your findings to the MAME team, open a ticket on …

  • Quote from wuemura: “Looks like you don't know what a R-C phase shift network do...learnabout-electronics.org/Oscillators/osc31.php ” And you're still failing at understanding the fundamental difference between a resistive load and a reactive one and how you can't just apply an R-C filter to obtain a phase shift when you have a resistive load. Since I'm talking to, as you stated yourself, an "hardware developer" (which means absolutely nothing unless you're more specific, you could be someone wh…

  • @wuemura I'm wondering if I'm getting trolled or if you're serious. For once, since we're having a civil discussion, I'll give you the benefit of doubt and believe that you actually know what you're talking about but I need to point out that the first circuit you've shared could work only if we're having a reactive load on one end which this is not the case as speakers are resistive loads. This means that if you actually want to produce a phase shift you need active circuitry and not just a netw…

  • That's going to wrap it up. If I had one of those I'd just bypass the rectifier and send 12V DC from the cab's PSU and call it a day. No one will ever need the full 45W output of the power amp in a cab.

  • 12V DC might be a tad too low. An educated guess would be that each diode causes a 1V drop, so a bridge would be 2V, hence you need at least a 13.2V DC PSU. The issue here is that this is pretty scary as the board doesn't have any kind of voltage regulation that I can see. Personally, I'd just redo the entire PSU section with a proper, regulated one to avoid frying good boards.

  • Quote from Jdurg: “Right now, I would KILL for an alternative way to power the amp. I've just been told that US Customs has destroyed my transformer. (Drilled a hole right through it). We need to find a transformer that can be used as a replacement for the original as it looks like they cannot be imported anymore. ” @Artemio finally measured the voltage going from the original transformer and it read 11.2V AC twitter.com/Artemio/status/1191544118817755136?s=20 Knowing this, we may calculate the …

  • No problem, glad to help. I took the 8Ω version because I have a small custom amp inside which works better with 8Ω speakers. The original Astro ones are 4Ω IIRC, so you might want to go for that.

  • Quote from hardyhell: “@donluca May I ask which speaker you bought to replace the ones in the Astro? Thanks ” Sure, it has been a very unpleasant search due to people suggesting crappy computer speakers and other stuff I wouldn't touch with a stick from a mile away. That really angered me as there's a thread on (IIRC) AO where, following OP's advice, several people dumped their money on those Logitech PC speakers and some crappy Chinese ones form Aliexpress and were sorely disappointed with the …

  • Quote from SmokeMonster: “So far, no one has it working with any PSU besides the original transformer. ” I've looked at pictures of the transformer and it looks like your typical, average transformer. Has anyone actually measured the voltage it outputs? I mean... there's no magic in electronics, it's just math. Once you've discovered the voltage range at which the components work, you feed it and you're good to go. @wasspat, replying to your points: - The improvements can derive from a very simp…

  • Trust me, once you got the amp in your hands and know the specs of its components it's a matter of rustling through your PSU box to get the right one. That's why I really want one. Unless there's something really fishy going on (and it might be, I had a Cambridge Audio Phono preamplifier which had the strangest power supply section I've ever seen in my life) it shouldn't pose a problem. The real issue is that there might be different revisions of the board, with each needing to be fed different …

  • The op-amps are simple buffers, they have nothing to do with equalization. I've understood what you're trying to say, but you need more advanced circuitry to achieve what you say. Most of the caps and resistors are required to bias the opamps and adjust the gain stage and make them work without oscillating. There are surely some low pass filters there but that's it. Btw, you guys are really making me want to get a Qsound amp just to play with it a bit. I'll put an alert on ebay and see if I can …

  • @l_oliveira there's absolutely no equalizer whatsoever on the Qsound amp board, you can see that yourself, there's a clear picture of it. The DSP is located on the main board and can work with any amplifier, not just Capcom's. The amp is one of the most classic, straightforward designs, with two op-amps acting as buffers, two power amps on the heatsink and all the various caps and resistors for noise filtering. And now that I come to think about it... I think @SmokeMonster already busted this my…

  • Quote from Jdurg: “Just curious, but what are your qualifications for stating this? ” I could tell you I've worked with audio for years and seen and repaired countless DACs, ADCs, pre-amplifiers and power amps, and that would be as good as saying I was an ex-Capcom employer, but honestly I couldn't give a flying fuck about it, so just take a look at the board and see it for yourself: arcade-projects.com/forums/ind…p/&postID=17063#post17063 (thanks to @acblunden2 for the pic) Nothing magical, tha…

  • @wasspat, don't take this a personal attack, but rather a warning to all other potential buyers to avoid the spreading of misinformation: the "Q-Sound" amp provided by Capcom is an absolutely standard stereo power amp with no custom circuitry or IC on it. The entire Q-sound improving thing is on the CPS1/2 motherboard themselves, you can use any amp and enjoy Q-Sound. You've swapped the amp so that was bound to change the way the sound it's reproduced, but it has absolutely no impact whatsoever …

  • You surely got the most... interesting, if not unique things over there. Is Zenit the same company which makes the russian camera lenses? They made copies of Zeiss lens back then and they were pretty good and still quite looked after today.

  • ad nauseam: github.com/mamedev/mame/blob/m…mame/drivers/segas16b.cpp I feel like this has been posted at least 4 times and sometimes I still get people PMs asking me for help when it's already all nicely explained, as I was the driver developer or something. And just to make sure: I'm not the Luca who's one of the MAME devs. I've just contributed once in the past (quite a lot time ago actually) and that was it.