Hi all,
I have a Recroommasters Xtension 32" cabinet on order:
32" Pro Upright Xtension Arcade Cabinet Emulator Edition
There are four speaker cutouts - two under the marquee and two on the sides. (The ones under the marquee have the same panel slots as the sides, just covered with a grille for asthetics).
This cabinet is designed for a PC running arcade machine emulators. The rear of the cabinet is open for access to the equipment, and I plan to keep it that way:
https://youtu.be/PkvkJ6sFrnU?t=161
Because my source is a PC, I'll have the usual 3.5mm stereo jack outputs - front L/R, rear L/R, and sub out. The sound drivers will likely provide basic equalizer controls along with some 4-channel sound effects.
For my last cabinet (similar to this but narrower), I just bought a cheap set of Logitech speakers and laid them in the marquee area. Inelegant, but it got the job done. But this time, I'd like to do something nicer.
I was going to get two Lepai LP-2020TI amplifiers, but because the PC should provide some equalization features, I went with two TDA7297 2x15W digital amplifiers instead. (Two of them cost me a whole $5 shipped!) I'll make a little module for them that I can sit behind the PC's fan, so they get airflow. Right now I'm thinking of powering them from the PC's power supply, since its 12V rail will have far more current capacity than these things could ever consume. If that provides problematic, I'll use a separate 12VDC supply instead.
Now, on to speakers... The primary consideration is that the cabinet is open. The second consideration is - well, I just want it to sound like an arcade machine, but with decent sound.
My listening setup is a Sunfire Cinema Grand powering Magnepan MG3.6 planar speakers. Playing MAME on that setup is piercingly harsh; digitally generated sound just isn't meant for that level of fidelity. So, I'm not looking for hi-fi, but I am looking for a good-quality rich sound without resonance, boominess, hollowness, etc.
At first I was looking at some full-range Visaton drivers from Parts Express, because it looked like the surround didn't protrude past the front plane and I'd be able to just mount 'em right behind the panel speaker slots. But then, what about soundwaves back into the cabinet?
That got me to thinking about perhaps making little mini-enclosures (with insulation too?) and attaching them at each speaker opening. Then I could control box volume, porting, etc. But then which speaker would be best? Full-range? Automotive 2-way? Should I do full-range at the top and mid-bass on the sides? Should I do four identical speakers top and sides, and a sub in the cabinet? The PC sound drivers do support a subwoofer out with controllable crossover frequency, and I'd just be another Ebay amplifier board away...
Plus I see various foam and plastic "speaker baffles" on Ebay and other sites designed to mount behind speakers. Is this just for weather protection, or is it meant to help acoustics too?
So that's where I am. Basically, I'm using a PC to provide sound with whatever controls its sound driver provides, and I need to figure out how to provide decent, solid sound from behind four slotted speaker openings in an open-rear cabinet.
I have a Recroommasters Xtension 32" cabinet on order:
32" Pro Upright Xtension Arcade Cabinet Emulator Edition
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
There are four speaker cutouts - two under the marquee and two on the sides. (The ones under the marquee have the same panel slots as the sides, just covered with a grille for asthetics).
This cabinet is designed for a PC running arcade machine emulators. The rear of the cabinet is open for access to the equipment, and I plan to keep it that way:
https://youtu.be/PkvkJ6sFrnU?t=161
Because my source is a PC, I'll have the usual 3.5mm stereo jack outputs - front L/R, rear L/R, and sub out. The sound drivers will likely provide basic equalizer controls along with some 4-channel sound effects.
For my last cabinet (similar to this but narrower), I just bought a cheap set of Logitech speakers and laid them in the marquee area. Inelegant, but it got the job done. But this time, I'd like to do something nicer.
I was going to get two Lepai LP-2020TI amplifiers, but because the PC should provide some equalization features, I went with two TDA7297 2x15W digital amplifiers instead. (Two of them cost me a whole $5 shipped!) I'll make a little module for them that I can sit behind the PC's fan, so they get airflow. Right now I'm thinking of powering them from the PC's power supply, since its 12V rail will have far more current capacity than these things could ever consume. If that provides problematic, I'll use a separate 12VDC supply instead.
Now, on to speakers... The primary consideration is that the cabinet is open. The second consideration is - well, I just want it to sound like an arcade machine, but with decent sound.
My listening setup is a Sunfire Cinema Grand powering Magnepan MG3.6 planar speakers. Playing MAME on that setup is piercingly harsh; digitally generated sound just isn't meant for that level of fidelity. So, I'm not looking for hi-fi, but I am looking for a good-quality rich sound without resonance, boominess, hollowness, etc.
At first I was looking at some full-range Visaton drivers from Parts Express, because it looked like the surround didn't protrude past the front plane and I'd be able to just mount 'em right behind the panel speaker slots. But then, what about soundwaves back into the cabinet?
That got me to thinking about perhaps making little mini-enclosures (with insulation too?) and attaching them at each speaker opening. Then I could control box volume, porting, etc. But then which speaker would be best? Full-range? Automotive 2-way? Should I do full-range at the top and mid-bass on the sides? Should I do four identical speakers top and sides, and a sub in the cabinet? The PC sound drivers do support a subwoofer out with controllable crossover frequency, and I'd just be another Ebay amplifier board away...
Plus I see various foam and plastic "speaker baffles" on Ebay and other sites designed to mount behind speakers. Is this just for weather protection, or is it meant to help acoustics too?
So that's where I am. Basically, I'm using a PC to provide sound with whatever controls its sound driver provides, and I need to figure out how to provide decent, solid sound from behind four slotted speaker openings in an open-rear cabinet.
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I'd look at 6" car stereo coax drivers for the valance - they tend to be designed with "aperiodic" or at least very leaky areas such as doors, side or rear decks - and not worry too much about futzing around with modifying the cabinet for "better" sound - whatever that might be for this type of application.
However, you might find the power level of only 15W a bit on the light side. Some of the latest generations of Class D modules, such as by Sure are silly good bargains. Last summer I built a 4 x"100W" unit for bi-amping, with the addition of a passive line level XO. Altogether the amp and switch mode power supply set me back approx $100 USD. A decent fancy chassis could easily cost more than that.
Even though the power ratings on this class of amp could be considered "optimistic", and can depend on the available power supply VA rating, this one works quite acceptably for the mostly background level listening the system is tasked for.
However, you might find the power level of only 15W a bit on the light side. Some of the latest generations of Class D modules, such as by Sure are silly good bargains. Last summer I built a 4 x"100W" unit for bi-amping, with the addition of a passive line level XO. Altogether the amp and switch mode power supply set me back approx $100 USD. A decent fancy chassis could easily cost more than that.
Even though the power ratings on this class of amp could be considered "optimistic", and can depend on the available power supply VA rating, this one works quite acceptably for the mostly background level listening the system is tasked for.
Thanks for your thoughts, chrisb. You raise a good point about looking for automotive drivers designed to be more forgiving of their environment.
And you are right, I'm still trying to figure out what "better" means for this application. Something that gives terrific fidelity for a 90s arcade game might sound absolutely harsh and piercing with an early 80s arcade game.
It seems like many arcade machines use simple full-range 4" drivers. I decided to go a bit bigger and go with 5" drivers. I ordered four of the Visaton BG13P 5" full-range drivers:
Visaton BG13P 5" Full Range Speaker 8 Ohm
and also grabbed this 12VDC 5A supply to power the TDA7297s while I was at it:
Talos Security SP1245 CCTV 12 VDC Switching Power Supply Adapter 4-Output for Camera
(It has multiple outputs, so I can power other parts of the arcade machine such as both coin door lights. Handy!)
Installing the Visaton BG13P drivers in the cabinet should be easy enough. Then I'll need to decide whether further treatment is necessary. None of this will be visible, so I'm pondering things like installing a box/bowl made of wood/ABS plastic over the driver with some insulation in it. It could be as something as simple as a plastic mixing bowl from Walmart with the required volume and sufficient rigidity! Who knows. 🙂
The Parts Express product page for the BG13P provides box volumes for sealed and vented use. But if I choose vented, how do I know what port diameter and length to use?
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I agree about not needing extreme resolution for old arcade games. You also need very little power, since your ears are only about 40cm from the speakers, and the crunchy 8-bit sound effects often seem louder than a clean sound would.
Seems like a good choice. They'd probably make decent (cheap) car speakers, too.
Total Q (Qts)1.042
This value indicates the speaker should work well in a very large or open-backed enclosure. You could simply screw the drivers to the insides of those cutouts.
Assuming your ears are about 40cm from the speakers, and the output from the rear of the speaker has to travel 120cm to reach your ears, the rear output should be relatively low in level, and (with a delay of about 20 milliseconds EDIT: about 2 milliseconds) should be perceptually blended with the front output.
Some nerdy reading on (non) perception of delay
Don't choose either. I'd suggest a very simple open backed option.
If the reflected sound does bother you, I'd hang a rug on the wall behind the cabinet, or add a stuffed (but still open-ended) tube to each driver. It wouldn't need to be rigid. e.g. found materials such as an empty yogurt container + some pillow stuffing would be fine.
Seems like a good choice. They'd probably make decent (cheap) car speakers, too.
Total Q (Qts)1.042
This value indicates the speaker should work well in a very large or open-backed enclosure. You could simply screw the drivers to the insides of those cutouts.
Assuming your ears are about 40cm from the speakers, and the output from the rear of the speaker has to travel 120cm to reach your ears, the rear output should be relatively low in level, and (with a delay of about 20 milliseconds EDIT: about 2 milliseconds) should be perceptually blended with the front output.
Some nerdy reading on (non) perception of delay
Don't choose either. I'd suggest a very simple open backed option.
If the reflected sound does bother you, I'd hang a rug on the wall behind the cabinet, or add a stuffed (but still open-ended) tube to each driver. It wouldn't need to be rigid. e.g. found materials such as an empty yogurt container + some pillow stuffing would be fine.
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That is one of the reasons I chose this driver! It *looks* like there might be sufficient offset from the face frame to the driver that I can screw it directly onto the inside surface. If the whizzer sticks out a bit proud, I can run some weatherstripping around the speaker frame before attaching it.
One of the fun aspects of this "build" is that there are four speakers - two top, two side. The Realtek HD Audio drivers have a number of equalization and surround-sound effect settings that will be fun to play with. I could try emulating various spaces with the four channels. Or, I could play a low-level looping "80s arcade" background sound effect out of the sides while playing the emulator effects through the top. The sound leakage out the back might even help with these things. Who knows!
Thank you! I was originally worried about reflection into the cabinet, but if the driver prefers open-backed, then that makes life easy. Worst-case, I can use short scraps of corrugated black drainage pipe as tubes. It cuts easily with a utility knife, and I can cut discs of mineral wool insulation that the corrugations would hold in place.
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