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Speaker problem
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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:

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

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


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

 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.


--- Quote ---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).
--- End quote ---

 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.


--- Quote ---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.
--- End quote ---

 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.



--- Quote ---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.
--- End quote ---

 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".
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