Before there was Pinwoofer, before Flipper Fidelity, before even PinballPro, there was the original DIY: my amplified AFM that I hauled to Expo 20 years ago.

There was nothing else like it... you could hear martians dying clear across the hall. Most people really enjoyed it and I brought it back for a couple more Expos. This is the game that started the trend for better pinball audio. I documented the build on RGP for others to use, and later did my Demo Man and STTNG. Eventually PinballPro came out with their original unamplified kits, and the pinball audio aftermarket was born. The AFM upgrade still works great!

(Also includes an early flipper cooling prototype!)

afmaudio (resized).png

For current upgrades, HocusLocus has the right idea with purchasing a speaker-level to line out converter. This lets you connect directly to the backbox speaker leads and avoid messing with the Spike2 board. Get one of those, connect the inputs to the backbox speaker leads, and run the line out to your amp. Nowadays, the amplifier/equalizers I used aren't available, but there are plenty of small 2.1 amps to use, like this Lepai model:

https://www.parts-express.com/Lepai-LP-168HA-2.1-2x40W-Amplifier-1x68W-Sub-Output-310-308

You would connect the Lepai directly to replacement backbox speakers and a new cabinet subwoofer. Here are all of Parts Express's 4" speakers:

https://www.parts-express.com/car-audio/car-speakers-subwoofers/dash-door-deck-car-speakers/speakersize/4.0

Lately I've been getting the Visaton FX-10s. These have the tweeter flush with the surround ring, so you can install them behind the Stern grilles no problem. They sound good and are only $20ea.

https://www.parts-express.com/Visaton-FX10-4-Coaxial-Speaker-292-674

For the cabinet sub, you don't really need to spend a lot. $20-$30 subs work fine. Here are all of Parts Express' 8" subs:

https://www.parts-express.com/car-audio/car-speakers-subwoofers/car-subwoofer-speakers/nominaldiameter/8

This Pyle is only $20 and would be fine in a pinball application. You can always spend more but I have yet to blow a sub in a pinball.

https://www.parts-express.com/Pyle-PLPW8D-Power-8-800-Watt-DVC-Subwoofer-267-7452

I recommend removing the plastic grille to keep the sub cone from buzzing it. Also, if the game is a Spike 2, go into the settings and set for 4 ohm and remove any equalizer or filter settings. Use the bass/treble/sub controls on the amp to adjust the sound... I wouldn't trust the digital adjustments the game makes.

I may have been first, but TheKorn completely knocked it outta the park later on.. (2nd pic)

https://www.pinballnews.com/shows/expo2010/index2.html

Gogo: I bought a similar "better" amp from parts express for my Maiden, and it shit the bed after about 10 months. The cheap Lepais are still working fine, except for a little noise in the controls. Even when it worked, the bigger amp didn't sound noticeably better than the cheaper one.

This is the one that failed early: https://www.parts-express.com/Dayton-Audio-DTA-2.1BT2-100W-2.1-Class-D-Bluetooth-Amplifier-with-Sub-Frequency-Adjustment-300-3831 The one you're looking at probably has the same innards (both are 24v, etc)

Yes, I've found on the newer Spike and SAM games, you have to connect the amp chassis to the game's ground braid, or else you get a hum. The older WPC games didn't have this issue as much. Some amps have a ground screw to use, but if it doesn't, just back one of the housing screws out and connect the wire to it, then to the ground braid.

If you're just replacing speakers, Spike gives high/low filter options in the sound setup. Enabling these should remove the need for crossovers, but installing one certainly won't hurt.

Rick and Morty owners already fought this battle, and the consensus is: snip the ends off zip ties, and insert them between the glass channel and the cabinet wood. Use a half dozen or so for each side. Don't have to worry about removing them when glass comes out because they're under the channel.

With the external amps you can adjust the tone controls to bring back the mids. You'll need good backbox speakers to reproduce them. There's also the Spike EQ but I prefer to have the game output completely unaltered audio and rely on the amp for tone and level controls.

What I'd most like to see in this thread is a comparison of quality, externally amplified 4" speakers vs quality, externally amplified 5.25" speakers. Right now I'm putting in good 4" units with amps and it sounds good, but I think the bigger 5.25 speakers would fill the midrange even better. Want to know if it's worth getting adapters and upgrading to 5.25s.

There are a lot of audio settings in Spike2, including an EQ and some high/low filters. Go into these settings and make sure that everything is set to flat output, no filters. I've disabled all the filtering and EQs, then connected my line-level converters to the backbox speaker outputs. My Iron Maiden sounds fine this way, and has plenty of mids.

Is that in your GTB Rock game? Guessing from the view inside the door...