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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.
 
I just picked up a 12V AC transformer from Digikey. It was only $20. If it works, I'll post here and let folks know.
 
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
https://twitter.com/Artemio/status/1191544118817755136?s=20

Knowing this, we may calculate the voltage drop caused by the bridge rectifier so we can use a DC PSU as well.
Literally, a few posts up from yours I measured it with load and no load conditions in a Capcom Q25.

no load: 14.03VAC
Load and operational: 13.94VAC

So it looks like we have a decent operational range between both measurements. The 18VAC myth debunked.
 
Having an excuse to pick up little odds and ends that I needed anyway, at Mouser I saw a 14 V AC transformer that I will be giving a try. Once they arrive later this week, I'll be able to test them out both (The 12V AC one I got on Digikey and this one) and see if either works. I won't post any manufacturer or model information/links yet until I can confirm that they work.
 
Artemio tested three cabs under load and got 11.2V AC.

He is going to test again at the smoothing cap (bypassing the bridge rectifier) to see what the DC reading would be too.

15729875693681.jpg
 
Artemio tested the DC now too:

Transformer load or no load: 11.2V AC
Rectifier Output: 13.17V DC
Amps: 0.665

15729920147110.jpg
 
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.
 
Well this is interesting. Customs had disposed of the transformer I had ordered. Was looking around Craigslist in the area and saw someone who had a Big Blue cabinet listed for parts. I lucked out and was able to get that Kitamura transformer. I'm quite happy.

The audio difference isn't massively noticable, but I do notice certain instruments that I can honestly say I didn't really notice before. It's subtly different, but noticable.

I need to get a different volume potentiometer though. This thing is LOUD and I got no volume control from wiring it in before the signal gets to the amp. If I use the volume down controls on the main motherboard, however, it works perfectly and I can increase/decrease volume. Got it running now. This weekend I may end up tidying up the wiring inside of the cabinet a bit, and look into seeing about getting the digital volume controls from the CPS2 A-Board to the area behind the coin door.

I also need to return my transformer orders. Heh. I had ordered some connectors to wire the thing up, but was sent connectors far too small. Oh well.
 
For anybody else who is updating the amplifier in their cabinets to the Capcom Q-Sound amplifier board/transformer assembly, some advice based on my update.

1: Before you make the switch, reset the volume level of your CPS2/CPS3 board to the minimum. The Q-Sound amplifier isn't a weak little one so the normal volume level you were used to will be MUCH louder. I feared that I popped my speakers when I first turned it on. Haha. Thankfully, the speakers were fine and just really loud.

2: Spend the money on well shielded RCA cables. I first used cheap Radioshack A/V cables, and the static and humming and interference were pretty bad. Spent $20 on a shielded audio cable and there is no more humming, no more interference, etc. So cable quality is paramount.

3: Make sure everything is working beforehand. Lol. I didn't realize that the right audio channel on my CPS2 A-Board was funky. I re-soldered it and now it makes the solid connection.

4: Set minimal expectations. It's not actually that massive of a change (unless you are coming from a weak, crappy mono sound setup) but it is something that you can notice. Kind of makes you go "hm, that sounded different than I remember." The left-to-right spatial manipulation is pretty cool though. Especially on things like Dee Jay's projectile attack, or Dictator's psycho crusher. My little nephew, who is the proper height for arcade cabinets, said that if he moved back and forth the sound would change a bunch. So how you can notice the effects are likely also dependent on how tall you are, where you ears are, etc. In other words, don't go expecting a 7.1 surround sound style experience. Expect more of a subtle change to things you normally didn't notice.
 
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.
This is likely true for the majority of you using non Capcom QSound cabinets as they have your typical low power speakers.

Not the case for US Big Blue and Q GrandAm 25s. For Impress, no idea what they have for speakers.
 
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:
https://www.arcade-projects.com/forums/index.php?threads/capcom-q-sound-amp-help.1291/post-17063 (thanks to @acblunden2 for the pic)

Nothing magical, that would be the exact same circuit you'd find on low end amplifiers.

And just to make sure: all the filtering and phase shifting is done during the recording process and then you just need a stereo set up to enjoy it, otherwise you'd need special equipment and this wasn't the goal of this technology (to know more about this: https://en.wikipedia.org/wiki/QSound ), hence some albums were marketed as "recorded in Qsound" like The Soul Cages from Sting or Amused to Death by Roger Waters (i have both, nothing groundbreaking, although very well engineered, just like most material from that era).

But if you enjoy having a Q-Sound amp in your cab there's nothing wrong with it, but, IMHO, you'd better get a cheap modern amp and stick with it which will give you a better sound experience.
Sorry if I came late to the discussion, the forum didn't notify me about the discussion.

This it's not a personal attack, but I have to tell you the way it is.
I'm not a big fan of people that tell people "trust me because I'm this or that" I rather prefer strait up arguments based on facts instead of pulling rank over other people. I share the same opinion as @I_Oliveira, you are wrong in some many ways.

I don't like to "flash my badge" and use it as an argument but I'm a hardware developer, I've worked as a engineer in different companies in Japan, enough said. As I have shown at this post, you can download the sample and play it at your home to understand the very basics of QSound.

In fact, the QSound amp has a very simple design but, IT'S THE KEY COMPONENT TO DECODE QSOUND!
This is also disclosed at the Giant Bomb site:
https://www.giantbomb.com/q-sound/3015-3007/

The main problem with QSound as I've already told, you need speaker alignment with the listener to perceive QSound effects, this is why the Capcom big blue cabinet has that specific design, the speaker was face forward at the high of people ears, etc.

As @Jdrud put it, this it's not a 7.1 surround sound or any surround sound people know about, the amplifier decode QSound samples and if your speakers are aligned and you are aligned with the speaker(centered between the two speakers), you'll notice the effects and they are not subtle, it give you some depth perception, a wider stereo and people will notice sounds and effects they didn't hear before among with a noise cancelling sensation, like if you are in the middle of an empty acoustic space.

As phase shift goes...
phase-shift.png

This is a basic concept so, there is no need for anything "special" to shift phases.

in relation to QSound wikipedia and patents, the patents are not complete and are neither 100% correct, who handle emulation knows more about this in relation to real hardware and wrong information on the datasheets (Yamaha FM chips, anyone? YM2203 for example?).

The final words on this it's simple, to experience Capcom QSound you need that Capcom amplifier, end of story.
 
The final words on this it's simple, to experience Capcom QSound you need that Capcom amplifier, end of story.
And properly aligned speakers, which most people running these not in original cabs don't have which defeats the entire purpose.
 
So an new astro City will not be able to benefit of the Q Sound because the speakers are not alligned that way as in the Capcom cab?

i have a nvs 4000 in use with the cps2 and 3 and planning to get These amps running in my cab. but now i am not sure if it is any use.

or Change in Quality.

one think i can tell though that the "impress" Version of this amp which can be powered with jamma power was not use. total bad humming. returned it back then to the seller.
 
So an new astro City will not be able to benefit of the Q Sound because the speakers are not alligned that way as in the Capcom cab?
Probably not much benefit to be had if any.
 
The final words on this it's simple, to experience Capcom QSound you need that Capcom amplifier, end of story.
And properly aligned speakers, which most people running these not in original cabs don't have which defeats the entire purpose.
You don't need to run this on the original cab to proper hear the effects, all you need beside the Capcom amp, is to have a pair of aligned speakers facing you at your ears level.

Again, take the Ryu stage sample:
http://www.mediafire.com/file/3ey3fsutiwv1n3s/Ryu_Stage.zip

1. Play at your Smart TV, try Music, Movie, Game sound modes.
2. Mesure one arm length from the screen.
3. Make sure your stay at the center of the screen with the speakers at your head level.
4. Enjoy Qsound effects

To enjoy QSound this rules must be followed:

1. Aligned speakers
2. Speakers MUST face the player
3. Speakers installed at the player ears or head level
4. Use Capcom power amplifier

If people want to use a custom made speaker box, make sure they are time aligned properly. A good game to test/benchmark all QSound effects can deliver it's Street Fighter Alpha/Zero 2. Capcom uses all possible QSound channels with both music and effects with this game, if you want to show off QSound, this is the game.

Capcom didn't keep up with it because the arcade environment was too noisy so people couldn't hear any QSound effects or details, also, if the ambient was too noisy, it makes no sense to spend money to develop sound and effects for QSound if people couldn't hear it anyway. This is why Alpha/Zero 3 didn't receive the same sound treatment as Alpha/Zero 2 among other key factors, back in 97/98 Japan’s economy had slipped into its worst post-World War II recession.[1][2][3][4] Many companies start to move development and production to China because of cheap labor, taxes, etc, etc.

If people want to enjoy QSound without the Capcom amplifier, someone with electronic background need to copy/recreate that matrix decoder around those 6 opamp's so they can be used with any power amplifier they want or people from the emulation scene must include the matrix decoder output together with the QSound code.
 
So an new astro City will not be able to benefit of the Q Sound because the speakers are not alligned that way as in the Capcom cab?

i have a nvs 4000 in use with the cps2 and 3 and planning to get These amps running in my cab. but now i am not sure if it is any use.

or Change in Quality.

one think i can tell though that the "impress" Version of this amp which can be powered with jamma power was not use. total bad humming. returned it back then to the seller.
It depends on the type/model of the cabinet, the ones with speakers face forward over the player head, works just fine.
astro-city-01.jpg
 
You don't need to run this on the original cab to proper hear the effects, all you need beside the Capcom amp, is to have a pair of aligned speakers facing you at your ears level.
Sure, except most other cabs don't have this, so people putting them /in/ cabs aren't really gaining anything. That was my point.

For those who want to run it outside of a cab, sure.
 
You don't need to run this on the original cab to proper hear the effects, all you need beside the Capcom amp, is to have a pair of aligned speakers facing you at your ears level.
Sure, except most other cabs don't have this, so people putting them /in/ cabs aren't really gaining anything. That was my point.
For those who want to run it outside of a cab, sure.
If they want QSound effect on standard cabinets, all they have to do is to place speakers on the side of the cabinet facing the player at head level, if they don't want to drill the cabinet, get a speaker stand like the one used for home theater speakers or build an adapter made with a belt or something to be placed on the top of the cabinet.

Otherwise indeed it's useless, QSound will not work as expected or work at all.
 
That almost defeats the purpose of using the cab though, you know?
 
That are the rules for QSound, if you don't want it, don't use it, simple as that. Standard cabinets can't be used for QSound unless you apply some changes, there is no other way around it.
 
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