Space Duel/Gravitar sound question

gorfchampion

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My Space Duel is in a Gravitar cab. I read in a recent thread that SD has 4 speakers. This Gravitar cab has 1 speaker(same setup as Centipede it looks like), and it sounds like crap. I realize I must be missing out on some great sound: 4 speakers compared to 1?

These cabinets are the same, right? So would I be able to mount 4 speakers in there if I wanted the true Space Duel setup? Are the 4 speakers the smaller round ones? The one in there now is larger and oval shaped. Can I hook up 4 speakers without having to worry about more power from the supply?

I need the expert's opinions here. Thanks
 
My cocktail SD had only one speaker in it John, can't confirm the settings on an UR. It sounded fine on one speaker for me!
 
I got a couple Atari speakers from a Battlezone if you need one.
 
I think you'll find that you have space for 2 speakers on the Gravitar cab. One below the CP and one below the marquee. You could add one extra speaker without making a mess of your cab. You'd need to find 4 ohm speakers though. Using a 4 speaker set up would be difficult. Easier to find a Space Duel Cab. Also, the Gravitar cab is rarer so it would be a shame to cut it up. I will agree, however, that the 4 speaker sound on a factory Space Duel cab is great.
 
I think you'll find that you have space for 2 speakers on the Gravitar cab. One below the CP and one below the marquee. You could add one extra speaker without making a mess of your cab. You'd need to find 4 ohm speakers though. Using a 4 speaker set up would be difficult. Easier to find a Space Duel Cab. Also, the Gravitar cab is rarer so it would be a shame to cut it up. I will agree, however, that the 4 speaker sound on a factory Space Duel cab is great.

Just looking at my cab and pictures of a SD cab, they are not the same? Man it sure looks like there is the same amount of space below the marquee. There must not be if you say there isn't, though. No, I'm not going to cut up my cab, believe me. Not sure what I'll do yet...
 
Space Duel & Gravitar have very similar upright cabinets. The one obvious difference to a glance is that Space Duel has 4 speakers (all 4 ohm) - two below the control panel and two below the marquee - while Gravitar has 2 speakers (both 8 ohm) - one below the control panel and one below the marquee.

Do you have a perforated metal grill below your control panel and another grill between your monitor and your marquee?

The cutouts on Space Duel are sized for about a 4x6 speaker. However, they mounted 6x9's behind them.

Bad sound could be due to many things. A bad TDA2002 on your A/R-II board. Bad wiring. Bad volume pot (common). Bad speaker(s). Wrong speaker(s). Issues on the game pcb...

First thing is to determine conclusively if you have two speakers present, that they are both connected, and that they are both 8 ohm. You should also look at the condition of the speakers. I've seen 6x9's in old Atari games that are literally disintegrating from age.
 
Space Duel & Gravitar have very similar upright cabinets. The one obvious difference to a glance is that Space Duel has 4 speakers (all 4 ohm) - two below the control panel and two below the marquee - while Gravitar has 2 speakers (both 8 ohm) - one below the control panel and one below the marquee.

Do you have a perforated metal grill below your control panel and another grill between your monitor and your marquee?

The cutouts on Space Duel are sized for about a 4x6 speaker. However, they mounted 6x9's behind them.

Bad sound could be due to many things. A bad TDA2002 on your A/R-II board. Bad wiring. Bad volume pot (common). Bad speaker(s). Wrong speaker(s). Issues on the game pcb...

First thing is to determine conclusively if you have two speakers present, that they are both connected, and that they are both 8 ohm. You should also look at the condition of the speakers. I've seen 6x9's in old Atari games that are literally disintegrating from age.



Thank you for this info; I will check all these things first and then go from there. I Appreciate the help!
 
Space Duel & Gravitar have very similar upright cabinets. The one obvious difference to a glance is that Space Duel has 4 speakers (all 4 ohm) - two below the control panel and two below the marquee - while Gravitar has 2 speakers (both 8 ohm) - one below the control panel and one below the marquee.

Do you have a perforated metal grill below your control panel and another grill between your monitor and your marquee?

The cutouts on Space Duel are sized for about a 4x6 speaker. However, they mounted 6x9's behind them.

Bad sound could be due to many things. A bad TDA2002 on your A/R-II board. Bad wiring. Bad volume pot (common). Bad speaker(s). Wrong speaker(s). Issues on the game pcb...

First thing is to determine conclusively if you have two speakers present, that they are both connected, and that they are both 8 ohm. You should also look at the condition of the speakers. I've seen 6x9's in old Atari games that are literally disintegrating from age.

Ok, mine does have a speaker grill below the cp, no speaker there, though. I'm assuming the one below the marquee is an 8ohm; though I could be wrong. Not sure why it sounds crappy. I just replaced one in my Battlezone cabaret that had the same crappy sound. The speaker was really old and brittle. I'm thinking this might be the same problem.

First of all, where can I get new ones? Secondly, how do I go about wiring in a second speaker(below the cp)?
 
Ok, mine does have a speaker grill below the cp, no speaker there, though. I'm assuming the one below the marquee is an 8ohm; though I could be wrong. Not sure why it sounds crappy. I just replaced one in my Battlezone cabaret that had the same crappy sound. The speaker was really old and brittle. I'm thinking this might be the same problem.
First of all, where can I get new ones? Secondly, how do I go about wiring in a second speaker(below the cp)?

Here's what I would do:

First, check your top speaker to make sure it's in decent condition, hooked up with the proper polarity (white wire to positive terminal) and that it's 8 ohm (impedance should be stamped on the magnet). You'll need to remove the marquee, and then pull out the light/speaker assembly. See page 3-6 in the Gravitar manual.

If you don't have a manual and schematics, you can download them from
http://arcarc.xmission.com/PDF_Arcade_Atari_Kee/Gravitar/

Next, if you haven't done so already, rebuild your A/R-II board. The big electrolytic capacitors in the audio amp circuitry are far past their lifetime. I recommend Bob Roberts' kit - "Atari A/R II-02 to -06 Repair Kit (Caps+Q2/3/8/9+R30) $12.00" at
http://www.homearcade.org/BBBB/parts.html
You'll also need some TO-220 and TO-3 mica insulators and some heat sink compound.
(This assumes that you have appropriate equipment and are comfortable with desoldering and soldering components.)
You may want to also order two of "TDA 2002 Atari A/R bds & others sound $3.00" just in case your problem stems from bad audio amps.
After the rebuild, be sure to check and adjust for a good +5V on the Gravitar pcb.

If you're doing that much, you might as well bring the rest of your power system up to spec. Get "Atari AC Power Supply Repair Kit + 8' Line Cord $27.00". That gets you the parts to fix up your transformer block (filter cap, bridge rectifier, fuse block, fuses, power cord).

Next, it sounds like you have an empty hole where you should have a lower speaker. Are there screw holes where it looks like a speaker was once mounted? If so, look to see if the speaker wires are dangling loose around there somewhere (a white wire and a brown wire), or, check the nearby wiring bundles to see if the wires are there, but got snipped off.

If the wires are there, you'd just need to screw a speaker in place and connect it. If the wires aren't there, then you'd have to splice some into the harness - easiest spot would be at the 12-pin molex connector going to the service panel.

For replacement speakers, Bob sells those too:
"8 ohm 15 watt shielded 6X9 speaker $10.00"

Note - you may find this restoration thread of mine helpful:
http://forums.arcade-museum.com/showthread.php?t=104226
 
MNRocketry, thank you for your help! Although I personally don't have the skill to rebuild the boards, I have friends that can. I will do all of these things and have a better game in the end. Maybe I can learn something along the way, too. Thanks again!
 
Ok, I got it fixed. No board problems. Seems to have been a sticky volume pot. I worked it back and forth and it seems fine. I still ended up taking the speaker that was under the marquee and mounting it below the cp, where both wires were hanging nicely. I took a used speaker I had in my spare parts(8 ohm) and mounted that back up top; works nicely and it sounds great! Thanks again everyone for the help. I did learn quite a bit.
 
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