A while ago I spent a good amount of time looking around for reviews on lower end amps and most rate poorly. I found this Blaupunkt performed surprisingly well and cost the same as the one you mention. I have had on my list for a while, so haven't tried it for myself.
https://www.amazon.com/dp/B07Q28CNSN/

It's big and doofy looking, but should be way more clean sound than I can stand in a game. The only slight downside is that it doesn't have a line out for an external sub. My plan is to take the line out from the Spike2 board to the amp and y-split one channel to go directly to an external sub.

Speaking of external sub, I added one of these 4-way active mixers to connect four games to my extra obnoxious 12" powered sub. It has individual mixer controls to balance the sound between games. https://www.amazon.com/gp/product/B08393DLGV/ref=ppx_yo_dt_b_search_asin_title

I think I mentioned this somewhere before, but I ended up picking up a BLAUPUNKT AMP1604.
https://www.amazon.com/gp/product/B07Q28CNSN/ref=ppx_yo_dt_b_asin_title_o00_s01

Going through all the amp tests that I could find on cheap amps, this one stood out as fairly decent (the reviews of the others were not so kind). At $66 it's cheaper than the FOSI and should have much cleaner output. It's certainly overkill and much bigger physically. It has several nice built in features; speaker and line level input, adjustable low, and high pass filters with individual gain adjustments. The only thing I wished it had was a dedicated low level sub output passthrough, but it's easy enough to put a splitter in. I don't have it fully wired in yet, so can give any impressions. If you are considering putting a few more bucks in an amp comparison, you may want to give this one a good look.

Surely! I am testing first in my IMDN, so will use my own CN5 adapter. But if I like how it turns out, will likely add to Spike1 and SAM games as well.

Thanks for the note, but the seller details does not fill with confidence.

Easiest is to wire the amp's DC power supply directly to the cabinet power supply AC input. This is after the cabinet switch and will only provide power when the game is switched on.

I finished wiring up the BP car amp in my IMDN. It's not finished for mounting and cable routing, but I am happy with the results so far. Qualitatively, it has a very clean sound and pushes the speakers as loud as I can stand without any hint of clipping. Here's the basic of my setup;

1) BLAUPUNKT 4-Channel AMP1604 https://www.amazon.com/gp/product/B07Q28CNSN/ref=ppx_yo_dt_b_asin_title_o01_s01 $66
2) DC 12V 30A PS https://www.amazon.com/gp/product/B06XJVYDDW/ref=ppx_yo_dt_b_asin_title_o01_s01 $25
3) Cerwin Vega 4x6 backbox speakers. $40 I bought these cheap speakers to see what it would be like to make a 4x6 adapter instead of going to 5 1/4" Not the right choice for sound quality. https://pinside.com/pinball/forum/topic/3d-printing-sharing-thread-lets-better-the-hobby/page/24#post-6589169
4) Pyle 8" cabinet sub - https://www.amazon.com/gp/product/B007JV7F4W/ref=ppx_yo_dt_b_asin_title_o01_s00 $20

I made my own CN5 adapter to route pre-amp audio to the line level input of the amp. If you missed it, TinyBlackDog has a great write up here; https://pinside.com/pinball/forum/topic/the-official-rush-owners-club-1/page/37#post-6808277. I wired the power supply AC input to the game power supply AC input so that it will also switch on from the cab power switch. I wired the remote turn on for the amp directly to 12v so it turns on when power is applied. It's also feasible to wire the amp remote turn a spare 12v feed from the game and just plug the new power supply into the always on service outlet.

Some interesting observations;
1) I spent a lot of time futzing with the game audio settings. My main strategy was to zero everything out in the game and get as close to the sound I wanted by adjusting the amp settings first. I used amp channels 1/2 for the cab speakers. These can be set to high pass filter with adjustable frequency cutoff. For channels 3/4 driving the cabinet sub, there is a low pass filter also with an adjustable cutoff plus a separate bass 0-18db boost. Also each pair has their own gain settings for fade control. After that I started to shape the game EQ to fine tune the sound, but really wasn't terribly happy. It wasn't until that I *completely turned off the EQ and tone controls* that I got an obvious cleaner sound. I have come to really not like how the Spike system digitally manipulates the audio through these settings (including the suspect speaker impedance options).

2) I went a little conservative with my PS selection. I put a meter on the 12v power input into the amp and with it cranked up louder than I would ever have it, it peaked at 4.2amps. So....the 30A ps is certainly overkill. Next game, I'll drop down to a cheaper 8A (mayyyyybe 5A) passive cooling PS.

3) I used a 5pin connector housing for making the CN5 adapter as I didn't have any 7-pin laying around. It took a little sanding down on part of the connector to make it fit. You could get away with a 4-pin connector too.

4) I plan to still plug this into my 12" powered external sub for the extra low thud. The 8" cab sub sounds great, but just cannot compete on the really low frequencies. Also, I have found that after a certain volume, there is no hope of controlling glass or other cabinet rattles. I had to pull out my coin box because it would buzz at certain frequencies.

5) I put an early generation pinwoofer setup in my Metallica. It does sound good, but I figured I could put piece together a better setup for less. As it sits, this setup cost about $150 compared to $240 for the original pinwoofer (and $370 for the current version). I consider this a successful experiment.

PXL_20220313_051509430 (resized).jpg

Agreed. There is some software funny business going on with these settings. I prefer leaving the speaker settings to default 8 ohm. To me it seems that this is as close to the direct pass through and the 4ohm is some weird post pre-amp attenuation. The fact that changing to 4ohm for one of them affects the sound of the other is a hint that something is not quite right. When I moved both to 4ohm, and then cranked the volume back up, it sounded like the pre-amp was getting overdriven, and then attenuated so it sounded a bit muddy compared to the same volume with the 8ohm settting. This is all qualitative at this point, so I could be wrong.

That said, with the factory EQ off the sound is certainly much cleaner but depending on the game and the tonal characteristics of the replacement speakers, there may still be a need to shape the sound with an external EQ.

Just FYI, for my next install, I will probably be going with this 10A PS instead;
https://www.amazon.com/dp/B01E6RMASC/ref=cm_sw_em_r_mt_dp_ZDMEKM76TABVSDVJA9MB

The original one that I bought was 30A and certainly overkill for the needs. Going to 10A is still more than plenty and it is cheaper, smaller and passively cooled (no fan).

Noted. One of these means this manufacturer specifically? Also, curious how did you determine it was vibration failure?

Thanks for the comments on this. I settled on this MW power supply to run my amps. It even turned out to be maybe a dollar cheaper than the rando PSU I was originally looking at. These are 15v -7A which I am going to dial down to 13-14v.
https://www.amazon.com/gp/product/B019GYON9E/ref=ppx_yo_dt_b_asin_title_o00_s00

To keep the AC lines contained to the head and to reduce vibrations, I decided I wanted to mount it in the backbox. I designed and printed up my own mount.
Since the heads are metal construction, I had to figure out how to use pre-existing studs. This is what I came up with.

PXL_20220331_013639720.MP (resized).jpgPXL_20220331_013439199 (resized).jpg

This is how I wired in my additional PSU.

1) Unplug the game
2) Remove two nuts for the game PSU cover
3) Wire in to the game PSU ground/Neutral/Line

DSC09126_markup (resized).jpg

With the cover back on.

DSC09128 (2) (resized).jpg

Wiring directly to the switch is pre-fuse and pre-filter. I suggest wiring directly to the screw terminals on the game PSU where I have the arrow pointing.

EDIT: I might be wrong about the fuse. That could be just for the accessory plug. I will have to double check that. Either way, still think it's safer and cleaner to wire to screw posts behind a metal cover.

It's essentially the same wall power as coming off after the switch that feeds the game game's power supply. The difference is, you are doing yourself and the future owner a favor by not splicing the AC wiring in an exposed area. Just my 2cents worth.

Did the sound start to distort before the protection kicked in? Did you test this with all speakers running or just the sub?

Is your conclusion that the other mini amps that you tested are inferior in sound quality at elevated volumes to this Dayton?

Great run down. For TNA, the sub enclsore goes a long way to get the most sound out of that amp. It sounds good up to a point then it completely falls on its face and then full on clipping. The lowlights you list are exactly why I looked for an alternative . For about $25 more you can end up with the same car stereo solution that I settled on and have all the clean, distortion free power your ears can handle. On top of that you get much better noise rejection and crossover control. The 4ch amp I chose is flexible enough to allow either low-level (spike1/2) or speaker level (SAM, etc) inputs. I have this setup on 4 games so far and plan on at least 3 more. It would be interesting for you to try it out and give a back to back comparison.

https://pinside.com/pinball/forum/topic/improving-sound-quality-the-diy-route/page/8#post-6827701
https://pinside.com/pinball/forum/topic/improving-sound-quality-the-diy-route/page/10#post-6858259
https://pinside.com/pinball/forum/topic/improving-sound-quality-the-diy-route/page/11#post-6863467

No, I have it in 4 channel mode with the sub bridged on channels 3&4. Channels 1 and 2 are Left and Right back box speakers. I also have the RCA input to the amp split out and that goes to a powered sub to fill out the very bottom end.

I have had success using NinjaFlex 1.75mm filament between the cabinet and glass channel to eliminate glass rattle on my games. It's the same idea as the ziptie fix, but after adding car stereo amps to my games I needed something a little bit thicker than the zipties. The glass does fit pretty tight now, and 1.75mm is maybe jut a tad larger than ideal, but it is compressible enough to work. Other TPU filaments I tried were too hard and not compressible enough.

@pintweeter, I would like to know specifically what the claim is that necessitated a formal complaint to Thingiverse.

I think it is important to understand exactly what is being claimed against the DIYers in this specific thread by a well known vendor taking action to impede these projects. If there is another thread that explains what precisely Pinwoofer is accusing these folks of doing, I would be happy to jump over to it.

Thanks, but even though I stumbled into the conversation a couple days late I was caught up. I asked a specific question because the answers are not there... buy hey, why not just cut to chase. With the information given, I can't be certain which of these three scenarios this falls into.

1) The vendor has a patent on this design and the claim to Thingiverse was that these were infringements on intellectual property. There are different submission forms for copyright vs. IP claims. I highly doubt this is the case, but it is a possibility.

2) The vendor had originally shared design files and gave no license to share or alter those files after which they were uploaded to Thingiverse . That scenario would be valid copyright infringement claim but I also doubt this is what happened.

3) IF the claim to Thingiverse was indeed for copyright infringement simply on the basis that the uploaded adapters designs look similar and solve the same problem, then in my opinion this deserves scrutiny. US copyright laws provide ZERO protection for functional works (like a speaker adapter!). See the definition of "Useful Articles" https://copyright.gov/register/va-useful.html.
Anyone and everyone is welcome to take this vendor's adapter solution, reverse engineer it and make exact functional replicas down to the angstrom with no legal barriers for sale or free distribution. Either this vendor is ignorant of how copyright protection works, or they knowingly made false infringement claims to Thingiverse in an attempt to impair the ability of a DIY'ers or other vendors to provide originally created design files to others for free use. Sadly my guess is we are dealing with the latter case here and it sucks for anybody participating and contributing in this thread. I know there have been comments and conclusions made along these same lines, but I wanted to give the benefit of the doubt and give Pintweeter a chance to explain what the specific accusations were and the basis for the takedown requests.

I think it is important for anybody who dabbles in 3D printing for hobby or personal business to understand how these things work at least at a rudimentary level. No one wants to be found in violation unknowingly (because intent and actual financial harm are not required for punishment). On the flipside, one should not build a business around something that is easy for others to replicate with a false sense of legal protection.

On the plus side, Thingiverse does take real and fake complaints seriously. This is their warning for false claims;
"Please note that, pursuant to 17 U.S.C. § 512(f), any misrepresentation of material fact (falsities) in a written notification automatically subjects the complaining party to liability for any damages, costs and attorney’s fees incurred by us in connection with the written notification and allegation of copyright infringement."

To balance my last couple of posts with actual DIY audio contributions....

I adapted my car amplifier solution I use on multiple Spike games to my first SAM game (MetPro) a while ago. In an attempt to improve on the crummy SAM sound, I added this eq;
https://www.amazon.com/gp/product/B00S7G1TW2/ref=ppx_yo_dt_b_search_asin_title

It was a nice, cheap addition ($45 at time of purchase) and allowed excellent fine tuning of the tone. Next up, I think I will make myself a mono to fake stereo circuit to give a little more spatial element and take the SAM audio as far as it can go. I also had to design a new external PSU mount with the difference of how power lines are routed for the older games . For reference here's a summary of my previous posts on my car amp DIY solution. I have been nothing but thrilled with the results.
https://pinside.com/pinball/forum/topic/improving-sound-quality-the-diy-route/page/20#post-7159439

PXL_20231105_011549141 (resized).jpgPXL_20231105_011642656 (resized).jpg

Small point of clarification; Ground loops are formed from multiple parallel grounding paths. Shielding does not address ground loops, but instead protects against EM induced signal noise. Adding shielding can actually contribute to ground loop issues if the shielding is terminated to ground on both ends.

Not so say your harness doesn't solve a noise problem, just that the fact it uses shielding does not mean it solves any ground loop problems in the system.

I still see them here?
https://www.printables.com/model/313814-mounting-plate-for-525-speakers-in-stern-pinball-m/files