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Williams Sound Amp Project

lukewells

lukewells

Registered
Joined
May 1, 2012
Messages
2,376
Location
Blackpool, UK
Hi everyone,

As already mentioned in the Sony speaker thread, I ironically already have a project underway, to create a 3 channel sound amp with active low pass filter for Williams pinball machines.


So why do you want one?
  • Less heat
  • Lower Power consumption
  • 3 independent channels (2 backbox 1 sub)
  • Adjustable sub volume on board
  • Adjustable active low pass filter (to tune the subwoofer)
  • 2 backbox channels, means double the power of the original sound board (which only had 1 channel)
  • Double powered sub woofer channel
  • No more need for separate crossover
  • No more need for an L-pad for sub volume



The first prototype will be arriving on my next panel from the PCB fab, so I will soon be experimenting with the filters.

With my projects, the key phrase is "low cost" so my initial target is ideally under £30 is possible (component selection will affect this during the testing phase)

Please register your interest here
 
Surely you are going to have to go class d? Since the lm1875 and tda2030 are fine chips, almost hifi standard, just badly implemented (also with crap speakers) in Williams tables.

Infact, sod it, dont reinvent the wheel. Just do a 2xtda2030 and 1xtda2005 for bass. If it's well executed it'll be great.

Also, will there be enough current on the 12v line?
 
Interested.

Assume this means i could buy your amp, then add my own [Sony?] backbox speakers and [generic/suggestions] cabinet Sub.

Any way to cost effectively beef-up the audio on games is a big win in my books.

Any interest in a similar thing for modern Sterns, or would you say they don't need this?
 
Monkeyboypaul said:
Interested.

Assume this means i could buy your amp, then add my own [Sony?] backbox speakers and [generic/suggestions] cabinet Sub.

Any way to cost effectively beef-up the audio on games is a big win in my books.

Any interest in a similar thing for modern Sterns, or would you say they don't need this?
Click to expand...
Given that the cost of an l-pad and crossover is about £20 then this is a no brainier. Will the design also include a method of lowering the backbox speaker output? Anyway, I'm in.
 
if you can make it easily accessible/adjustable just inside the coindoor, even better.

A gripe with the FF kits is the backbox volume knob mounts in the top right corner of the backbox, so it's not easily tweaked mid-game. FF sell extension kits for this knob, and i could do it myself, but i haven't and probably won't.
 
abaxas said:
Surely you are going to have to go class d? Since the lm1875 and tda2030 are fine chips, almost hifi standard, just badly implemented (also with crap speakers) in Williams tables.

Infact, sod it, dont reinvent the wheel. Just do a 2xtda2030 and 1xtda2005 for bass. If it's well executed it'll be great.

Also, will there be enough current on the 12v line?
Click to expand...

You can build yours with TDA's if you want ;)
 
Eddie Twadds said:
Given that the cost of an l-pad and crossover is about £20 then this is a no brainier. Will the design also include a method of lowering the backbox speaker output? Anyway, I'm in.
Click to expand...

There will be a gain and cuto-off control for the sub, so yes in effect you can raise/lower the volume of the sub to balance it against the backbox speakers
 
Monkeyboypaul said:
if you can make it easily accessible/adjustable just inside the coindoor, even better.

A gripe with the FF kits is the backbox volume knob mounts in the top right corner of the backbox, so it's not easily tweaked mid-game. FF sell extension kits for this knob, and i could do it myself, but i haven't and probably won't.
Click to expand...

Unfortunately not, certainly not in that price range.

With my design, the controls will alter the gain on the line-level side, so running wires up to the coin door would introduce huge amounts of noise into the signal. The correct way to do remote adjustment would be to use electronic potentiometers, and then control them via serial from a remote mounted board on the coin door. I could look at pricing that up as an option if it is something a few people would want
 
abaxas said:
Nowt wrong with the tdas if implemented well. Also anything decent for bass is a waste of money and time.
Click to expand...

On the 2030, as your approach 8w, the current draw, power dissipation and distortion increase exponentially. At full power a TDA2030 can draw 3.5a, and there is not 10.5amps of +/-18v available in a pinball machine to run 3 of these or similar.

If you want to run more power with a lower THD, using the pre-existing available power circuits in a pinball machine then it is class-D, or stick with the original highly limited amplifier circuits
 
Luke,

You gonna take the Pre-outs from the board then? Just wondered as thats common to all sound boards (a pre-out) and would give a decent line output, however will need hardware or connections on the board, rather than the standard connectors out.... Just makes things a little more difficult for the standard "installler" ;)
 
lukewells said:
Unfortunately not, certainly not in that price range.
Click to expand...

Fair enough - just saying' a little 'volume/mixer' in the coin door would be useful, especially on days when i just crave BASS. And if you can make the design modular so this is an affordable but not essential option, well, i for one would give it a go, but it's not a deal breaker by any means.

While we're on it, this is a really great idea and I'm really surprised it hasn't been done before by other similarly minded [clever] people.
 
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I can see there being a huge market for this, could become a full time job building them if that's what you want.
 
Glad too see there is a lot of interest in this one guys :thumbs:

(I've actually got multiple projects in prototype stage - it's hard to stick to one lol)

I'm going to be doing some experimentation with the filtering to get things sounding as good as I can. Once they are ready for production, I will of course be able to demo them on my own machines for people who can make it over here.

I'm planning on pairing this amp up with the £10 Sony speakers, I will also find an appropriate low cost sub that pairs well, then we can all have improved pinball sound hopefully for under half the price of importing one of the pinball pro / flipper fidelity type kits, including an amplifier upgrade!
 
lukewells said:
Glad too see there is a lot of interest in this one guys :thumbs:

(I've actually got multiple projects in prototype stage - it's hard to stick to one lol)

I'm going to be doing some experimentation with the filtering to get things sounding as good as I can. Once they are ready for production, I will of course be able to demo them on my own machines for people who can make it over here.

I'm planning on pairing this amp up with the £10 Sony speakers, I will also find an appropriate low cost sub that pairs well, then we can all have improved pinball sound hopefully for under half the price of importing one of the pinball pro / flipper fidelity type kits, including an amplifier upgrade!
Click to expand...
If you need any other test machines all mine are offered up.
looking forward to this and more importantly how it's going to sound.
Keep up the good work buddy.
 
ronsplooter said:
@lukewells what systems will this amp be compatible with? If it'll work with my TAF and my Banzai Run then put me down for a couple :thumbs:
Click to expand...

Theoretically any system, I just need to work out a clean way to tap into the audio on each different audio board. It will generally be the case of either adding a pin header (on boards where the pads exist for pre-amplified audio already) or soldering a couple of wires onto most other boards. For anyone not comfortable in doing that, I guess you could send your sound boards to me for modification
 
Put me down for one and I am happy to test and review install/manual etc.
 
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