I get this question pretty frequently, so I figured I would post a how to guide on getting the most out of the audio system on your Total Nuclear Annihilation pinball machine.
Do this at your own risk as this has the potential to damage your amp and/or speakers if set too high. But please do not do this unless your amp settings get totally out of whack.
Warning, this setup procedure is going to be loud, so warn the people around you.
Subwoofer Physical Adjustment (do this first):
You may notice some strange distortion coming from the subwoofer… These subwoofers are interference type speakers which means that upon loud use, the speaker cone extends beyond the mounting bracket plane. This will cause the cone to come in contact with the speaker grill and potentially the edge of the bottom of the cabinet. You can get a 10 inch speaker spacer online from various places that will make sure the speaker has enough space to move freely.
Sub Chamber Sealing:
A pinball machine makes a TERRIBLE subwoofer cabinet for a number of reasons, but here are a few. The main reason being that every subwoofer has a recommended cabinet volume specification. These pinball cabinets are MUCH MUCH larger than what the subwoofers call for. The next reason is that pinball cabinets are full of crap that can rattle around upon vibration from the subwoofer making terrible sounds. Another big reason is that pinball cabinets are basically the most leaky thing ever. Porting subwoofer cabinets is important, but having the sound leak out from ever little hole and crack is awful.
OK, so what do we do about this…. In TNA I created a Sub Chamber in the cabinet. This is basically a box that goes around the subwoofer that is pretty close to what the subwoofer wants for volume. This box idealistically will push all of the bass out the bottom of the cabinet. This is great, but unfortunately, it is not perfect in production. The production sub chambers leak a bit as they were not sealed with silicone sealant.
Easy fix though. While you are in there putting a spacer under your subwoofer, it is a great time to pick up some silicone sealant and seal up the inside of the box. I recommend pulling all the screws out from the bottom of the cabinet and removing the Sub Chamber completely. You can then squish this silicone sealant into every join on the inside of the chamber. Once you go to reassemble it, put a bead of silicone on the bottom side where the chamber attaches to the bottom of the cabinet. This will ensure a great seal and improve the sound of the subwoofer.
Adjusting the Amplifier:
Step 1: With the game on, take the backglass out and press the volume up or down button on the back of the LCD and bring the pre-amp volume down to 11. It will show on the screen. This is probably set high from the factory, but I found reducing this made the audio quality slightly better.
Step 2: Put the backglass back in.
Step 3: Turn every knob on your amp all the way down until it stops.
Step 4: Go to Music Test in the service menu and select reactor 3 by pressing the start button a few times.
Step 5: On the coin door, press the volume up button until it reaches 11.
Step 6: On the amp, turn the second knob from the left (sub crossover) up about 1/8 turn.
Step 7: On the amp, turn the treble just past half way up.
Step 8: On the amp turn the Bass knob up about 1/8 turn. Keep this low as this is controlling the bass output to the upper speakers and could damage them or the amp if set too high.
Here is where it is going to get loud…
Step 9: On the amp, turn up the sub volume very slowly until just before you hear a bit of distortion. This will be pretty loud.
Step 10: On the amp, turn up the Volume knob slowly until before you hear distortion or you feel that is the loudest you would ever have the machine. This is also the time where adjusting the treble up or down should be done.
Important note! If the amp cuts out during any of these last 2 steps, you went too high with the volume and/or Bass knob. Bring these back down so the amp does not cut out as this could damage it.
Step 11: On the coin door, turn down the volume back to a reasonable level and enjoy.
Again, please do this at your own risk. You can damage your amp and/or speakers messing with this stuff. I am not an expert audiophile or whatever it is called, I am just knowledgeable enough to be dangerous here. Don’t blame me or Spooky if you break something. 
Using an external subwoofer:
If you just cannot get your subwoofer sounding awesome, the easiest thing to do is install an external sub. These are pretty affordable and I recommend using the Polk Audio PSW10. All you do is disconnect the amp output wires on the internal subwoofer and run a new set of wires down to the PSW10s Speaker Level Inputs. You can then do that amp adjustment procedure again without the internal sub hooked up.
Conclusion:
I hope this helps you getting your TNA to sound awesome. If you have any questions or find any errors or better ways of doing this, please contact me and let me know. Enjoy!
Final note: I put a few Amazon links in this blog post that are linked to the Danesi Designs Affiliate Program. I did this to hopefully help generate a little bit of passive income. Thank you everyone very much!
