Speaker problem

[monkey puzzle]

I have a pair of standard Dell PC stereo speakers that I thought were plenty loud enough for my mame cab. I broke the cases open with the intention of mounting the actual speaker parts in my speaker shelf. Before drilling any holes in the speaker shelf I tried the speakers without their cases. To my suprise the speakers sound awful without the case. I assume the cases are need for acoustics etc.

I was wondering what the speakers would sound like once fitted to my cabinet. Would they sound ok, or would I need to build a small box around the back of them? Or would it just be best for me to buy a new set of speakers that I can fit without de-casing?

[compute]

Since they're already out of the case, I think it would be worth mounting the speakers in the cab and giving it a shot.  Depending on where/how you mount the speakers, the cabinet may provide the covering you need for the speakers to work well.  Neither of my cabinets have any cover over the back end of the speaker.

[BobA]

Worst case can you glue the back of your speakers over the speakers when they are mounted in your cab?  Speaker mounted with back enclosure upper left of picture.

[monkey puzzle]

Worst case can you glue the back of your speakers over the speakers when they are mounted in your cab?  Speaker mounted with back enclosure upper left of picture.

It's a bit late for that now. I had to destroy the cases just to get into them. And then I threw the broken parts away.
Not sure if I should try mounting the speakers if there is a chance they are not ok. The holes might not be correct for the speakers I end up using if these ones are no good.

[Xiaou2]

Sometimes speakers are very optimized to their container air volumes.

 However, sometimes the makers opt for smaller package design, so they are not fully optimized.  Such was the case when I actually improved my Pc speakers, by making my own wooden boxes for them.

 Many of them also have Bass Ports.  Holes specifically designed to create a certain tone when air flows out of it.   You can sometimes remount the port, but you dont always need it.  In my case, I left the rear of my speakers open-backed, as that sounded best.

 When I rebuilt my speakers, I used several oversized pieces of wood, and moved them around, holding them in place while playing audio to find the best air volume and thus best sound output. Then I marked and cut them to spec.

 When mounting them in a huge wooden box like an arcade cabinet, the entire cabinet becomes a speaker.  It can amplify the speakers effect.  So even though your speakers dont sound right to you unboxed... they will probably sound really nice in the arcade cabinet.  And if somehow it doesnt, you can add your own back box with roughly the same air volume of the originals.

[codefenix]

It's really a shame you decased the speakers.  I mounted a pair of Cyber Acoustics speakers, unmodified, in my cabinet.  The speakers came with a subwoofer which sits in the bottom corner of the cab.  The speakers themselves are held in place by a set of crude brackets I fashioned from pieces of scrap metal.  No vibration noise because I applied some foam tape between the brackets and the speakers.  Finally, I mounted 2 4x6" car speaker grilles to cover them.  End result sounds and looks great.

[Xiaou2]

FYI: Real Arcade speakers have no backing-case.  They are simple 10 to 15 watt speakers, and use the cabinet as the 'case'.

 Unless you are looking for Audiophile quality sound, then its doubtful any you have anything to really worry about.

 (and even then, most cheaper consumer level speakers are not Audiophile level quality anyways)

 The greatest part about classic arcade games was the sound resonating the entire cabinet.  Usually volume has to reach a certain level for you to get the resonance, but once you do, its a beautiful thing 
 

[boardjunkie]

Any (woofer) speaker will sound like crap without an enclosure. That is because you get phase cancellation from the lack of any sort of baffle. Sound waves from the rear of the speaker cone are opposite in phase from the ones from the front. So when you combine those waves in open air operation, they cancel out. An enclosure only allows the speaker to move air from the front of the cone for the most part, and the enclosure's internal air volume *should* be calculated to optimize low freq response according to the speaker's datasheet.

Since the speaker in an arcade cab operates free-air (the cab doesn't act as an enclosure, only a baffle), not every speaker will sound great this way. Depends on how much low end you want.

[monkey puzzle]

Thanks for the advice guys. I'm fitting my speakers now (without box at first). I will keep you updated.

[Xiaou2]

That is because you get phase cancellation from the lack of any sort of baffle.

 I wont claim to be a sonic expert, but thats seems like a weak argument IMO.

 An electric guitar without any power, sounds pretty lame (quiet, undefined) compared to an Acoustic.  The reason, it seems, is because the chamber of air+material type, causes an amplification effect.

 Air is pushed and compressed, and vibrations are transmitted to the cabinet.  The entire cabinet resonating, is greater than merely the strings resonating, for example.

 The electric guitars strings will still resonate the surface of the guitar, but the volume is still very low, because the material isnt able to resonate very much compared to a full hollow thin body of moving air.

 
 Too little air in an enclosure, and the volume and resonate effect is reduced.  Too much air, and you will need more power to create the resonance.  There can be echos, distortions, and transmission losses because the vibration forces cant reach all the sides of the box well and fast enough.  Echos and slight distortions are common with arcade cabinets.  Its more of a feature, and Id be willing to bet that a lot of the sounds created were actually tweaked and optimized for the cabinets resonance.

 Phase isnt really much of an issue.  Its very hard to nullify sound.  Even if you wire two speakers out of phase, the nullification is very minimal.  To make noise canceling stuff, requires very acute capture of the sounds based on sampling the sounds at a specific point in space and time. It creates a lot of pressure, and seems to only operate decently in enclosed situations... such as headphones. Its also very far from perfect.

 I could be wrong on this, but thats how it appears to me, based on what seems logical..

[boardjunkie]

Apples/oranges. Guitars are not speakers and don't operate on the same principal.

Its just plain bad advise to say that hooking up 2 spkrs out of phase doesn't make much difference. It makes a *huge* difference. Not only does it cancel out all the low end, you end up with a comb filtering effect through the mid freq's. It sounds bad....plain and simple. Maybe you can't tell the difference, but I can. I'm a pro audio repair technician, so its my job to know these things.

Not long ago I had a customer picking up some PA speakers that needed the horn drivers replaced. When he came to pick them up, I demo'd them for him. He listened for a minute, then said they sounded strange, like something was out of phase. Sure enough....one of the midrange drivers was hooked up backwards from someone else's mucking around. I wasn't listening for detail, I just verified that the horns works as they should so I could get them out of my way.....they were *huge*.

Woofers *require* a baffle to minimize phase cancellation with itself. An enclosure is required to obtain the spkr's advertized SPL and freq response. The internal air volume and port dia/length (when applicable) is determined by the speaker's specs (Thiele-Small parameters) as detailed in its datasheet. The speaker's specs even determine what type of enclosure the speaker is intended to operate in (Qts spec).

http://en.wikipedia.org/wiki/Thiele/Small

As far as ports go, they don't "emit a tone", rather they emit low freq sound within a specified passband. The port works with both the speaker and enclosure to tune the enclosure to the speakers free-air resonance frequency.

Enclosures ain't s'posed to resonate. If they do, its a horrible design. Any perceived  resonance in an arcade cabinet is from reflections inside the cabinet that find their way out thru the speaker. This can even happen outside the cabinet. Midway cab's like Pacman and Galaga have a resonance that occurs around the monitor area of the cabinet. The reflections created in that arrangement result in a very recognizable "signature" sound.

[Xiaou2]

Apples/oranges. Guitars are not speakers and don't operate on the same principal.

 Anything that makes sound, can pretty much be compared to a speaker.  Most especially things with a hollow chamber.

Its just plain bad advise to say that hooking up 2 spkrs out of phase doesn't make much difference.

 Never said it didnt have any difference.  The point I was making, was that out of phase or not, theres still plenty of sound.  That if you take the speaker out of the enclosure, out of phase or in phase, it will be a very quiet and undefined... similar to an un-amped electric guitar.

Woofers *require* a baffle to minimize phase cancellation with itself. An enclosure is required to obtain the spkr's advertized SPL and freq response. The internal air volume and port dia/length (when applicable) is determined by the speaker's specs (Thiele-Small parameters) as detailed in its datasheet. The speaker's specs even determine what type of enclosure the speaker is intended to operate in (Qts spec).

 I understand, however, its not always the case.  As said, Ive improved computer speakers bass response by making my own enclosure that had more air volume.  Furthermore, as said, Arcade machines are NOT high precision instruments. They are not sonically optimized, they dont have expensive powerful high def speakers either.  Nor would it even matter much, considering that you are inches away from the speakers.

As far as ports go, they don't "emit a tone", rather they emit low freq sound within a specified passband. The port works with both the speaker and enclosure to tune the enclosure to the speakers free-air resonance frequency.

 Sue me... for getting the incorrect Terminology.  Isnt a tuned frequency the same thing as sound?  Open your mouth wide and blow air out of it... and it will sound one way.  Close it partially, and it will sound different.

Enclosures ain't s'posed to resonate. If they do, its a horrible design. Any perceived  resonance in an arcade cabinet is from reflections inside the cabinet that find their way out thru the speaker. This can even happen outside the cabinet. Midway cab's like Pacman and Galaga have a resonance that occurs around the monitor area of the cabinet. The reflections created in that arrangement result in a very recognizable "signature" sound.

 As said, the sound is amplified by the chamber, however, the chamber of an arcade machine is so large.. that it takes a decent volume before the cabinet reacts.  It goes from sounding like only the speakers are producing sound... to the entire cabinet making sound.  A very dramatic boost in power and effect, some echoing and vibrations.

 Its what we want, if we are recreating the arcade experience.

 If we were creating an audiophile batcave, then yeah, we would want precision designed speaker.  However, that usually isnt the aim of an arcade machine.

 I cant recall One arcade machine that had acoustically designed enclosed speakers, let alone acoustic stuffing, dampening material, sealant, crossovers, etc.


 I can play mame thru my Sennheiser HD 595 audiophile quality headphones, which are pretty much unmatched by ANY full size speaker system... but playing games like Konkey Dong, Ms Pacman, Spy Hunter... etc.. they dont sound Anything like the real machines.

 The 'acoustically flawed' arcade cabinet sound is unique, and is part of the replication of the experience.

[boardjunkie]

Ok.....let me go all Mr Wizard on you then. Here's a simple experiment anyone can try.

Take a piece of cardboard about 12" square and cut a hole in it to fit any old speaker you have lay'n around. With the speaker connected to an amplifier, play music thru it while holding it in your hands facing up. Sounds crappy right? Now lay the cardboard on yer lap, and (music still playing) lower the speaker into the cardboard. What happens? It gets louder and fuller sounding. How can this be when there's no enclosure to "amplify" the sound? Speaker baffle theory 101.....you isolate the forward firing sound waves from the rear firing sound waves. This results in a properly phased output.

[monkey puzzle]

Ok, things are getting a little too technical for me so I thought I would just fit the speakers and give it a try. I fitted the speaker shelf to the cab and they sounded ok. I don't have a marque yet so I covered the hole with a peice of wood and the speakers sounded better. I wouldn't say they sound fantastic, but they do sound adequate so I think I will leave them for now. Maybe when everything else in finished I will go back to them and upgrade to 2.1 speaker system.

[Xiaou2]

Those speakers look pretty tiny.

 Most arcade machines use a speaker that is at least 4".

[eds1275]

Most arcade machines use a speaker that is at least 4".

True, but then again, most speakers in arcade machines were fighting for volume with the machines around them. Besides, speaker size does not matter so much. If those speakers can push a decent volume over a short distance with a reasonable frequency response I'd say go for it. I can't remember ever seeing a decent sound system in an arcade!

[monkey puzzle]

Yes, the speakers are more than loud enough for my needs (unless I want the neighbours complaining) and there is no distortion when turned to maximum volume. Maybe in the future I would upgrade to a speaker system with a bass subwoofer for a fuller sound though.

[Xiaou2]

True, but then again, most speakers in arcade machines were fighting for volume

 I didnt mean volume.  The larger the diameter, the more bass response you can get, and the more air that is moved as well.

 Personally, Im not a big fan of subwoofers.  They often tend to muddy the sound more than add to it.  I prefer a decent clean & tight woofer instead.

 And if you want strong vibration effects, a tactile transducer will be the best.
(such as the Aura Bass Shakers, Buttkicker...etc)