(Topic ID: 282784)

Speaker re-design for pinball

By colofan

10 months ago


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  • 36 posts
  • 17 Pinsiders participating
  • Latest reply 8 months ago by colofan
  • Topic is favorited by 22 Pinsiders

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Indiana_Jones_impedance (resized).JPG
WCS_impedance (resized).JPG
Goldeneye_impedance.JPG
Woofers_impedance (resized).JPG
Goldeneye Backbox imp (resized).JPG
Goldwood_Pin_spl_sim.PDF (PDF preview)
Simulation diagram (resized).jpg
WCS_Backbox_SPL (resized).png
DSCN2966 (resized).JPG
Indiana_Jones_and_WCS.PDF (PDF preview)
Indiana_Jones_backbox_imp (resized).JPG

#1 10 months ago

It's been 6 years since I have been back. Life got in the way. But this is a thread that I will start to walk through the redesigning of Loudspeakers in that are used in pinball machines. I have 90's version of machines. I will leave out the designs that have external speakers since that is already well covered elsewhere on the internet.

My information will come from Goldeneye, WCS (Bally) and Indiana Jones (Williams) machines.

As a reference I have been doing loudspeaker design since 1973 and do this as a side business for custom work for business and home applications.

First I will start to post testing of said above machines.

Impedance curve for the backbox of IJ.

Indiana_Jones_backbox_imp (resized).JPG
#2 10 months ago

will be watching. always would like the games to sound better.

#3 10 months ago

Watching too, I always put better speakers in. Custom.
I recently added RoboWar and Robocop to my collection and they make 90’s wpc machines sound like crap with standard speakers in.

#5 10 months ago

I'm curious to read about your testing and thoughts for sure... but most interested in seeing how your thoughts on speaker design can help overcome the lack of quality of the sounds at the source. My uneducated inclination is that at the end of the day there has to be a limit to how good it can sound due to that poor/low quality of the recordings.

#6 10 months ago

Here are Indiana Jones and WCS on same graph. Similar curves but resonance peak for IJ much higher.

Source material is also a concern. As I said first to step through and improve where is there first then deal with the source issue.

I saw on this board a few times about references to impedance as a single digit number on the back of the driver. Clearly over the frequency band it is not constant. Also my understanding is the power amplifiers on the machines are designed to run with a 4 ohm load.

Indiana_Jones_and_WCS.PDF
#7 10 months ago

The redesign process that I will do is :

Characterize the current system both electrically and acoustically.

First is to examine the backbox and down firing speakers both impedance and also an pink noise rta spl measurement at the distance where the user of the pinball will be standing.

Measure the lower box to determine volume and also how "leaky" it is with all the perforations in the playfield and all the leaking around the seams. This will affect mostly the efficiency of the system.

After that I will then start to model the environment with "LEAP" and look for a better drivers. to replace the current models.

Install new drivers with new crossover designed. Test the system and see if some "tweeks" are needed for phase response mostly.

#8 10 months ago

Wow,I can say for sure that Spooky sure doesn't have a clue on this with the new R&MBSE!! You should educate them as well!!

#9 10 months ago
Quoted from colofan:

The redesign process that I will do is :
Characterize the current system both electrically and acoustically.
First is to examine the backbox and down firing speakers both impedance and also an pink noise rta spl measurement at the distance where the user of the pinball will be standing.
Measure the lower box to determine volume and also how "leaky" it is with all the perforations in the playfield and all the leaking around the seams. This will affect mostly the efficiency of the system.
After that I will then start to model the environment with "LEAP" and look for a better drivers. to replace the current models.
Install new drivers with new crossover designed. Test the system and see if some "tweeks" are needed for phase response mostly.

What will be an outcome? A custom speaker set and/or rheostat and/or built-in amplifier?

#10 10 months ago

It's only pinball. This isn't Altec-Lansing's "Voice of the Theater" speakers.

#11 10 months ago
Quoted from KenLayton:

It's only pinball. This isn't Altec-Lansing's "Voice of the Theater" speakers.

The difference between factory setup and entry level speaker/rheostat is day and night (even with original soundboard).
Good sound is part of the fun.

-2
#12 10 months ago

PinWoofer has solved these problems, and more! You'll get the best possible sound out of your WPC title with separate backbox and cabinet leveling, tone and equalization controls, auto muting (to get rid of the hum / buzz) and speaker upgrades. Plenty of power to play it loud, or play it clean at low volume levels with ample dynamic range to hear new things in your track:

https://pinwoofer.com/pinwoofer-gt-8in-5-25in-wpc-super-kit/

Easy to install in just a few minutes with detailed instructions.

DSCN2966 (resized).JPG
#13 10 months ago
Quoted from PinWoofer:

PinWoofer has solved these problems, and more! You'll get the best possible sound out of your WPC title with separate backbox and cabinet leveling, tone and equalization controls, auto muting (to get rid of the hum / buzz) and speaker upgrades. Plenty of power to play it loud, or play it clean at low volume levels with ample dynamic range to hear new things in your track:
https://pinwoofer.com/pinwoofer-gt-8in-5-25in-wpc-super-kit/
Easy to install in just a few minutes with detailed instructions.
[quoted image]

Let's see the results by colofan. Hopefully he will come up with much cheaper solution.

18
#14 10 months ago
Quoted from PinWoofer:

PinWoofer has solved these problems, and more!

If only we could solve the problem of people showing up in creator's threads to advertise their products. You got anything for that?

#15 10 months ago

Measurement at 48 inches which is the approximate distance player would be standing from backbox. This is for WCS game.

This was with white noise input and using RTA for the frequency spectra. Speaker was driven from an 50watt instrument amplifier, Amplitude was chosen to be 50 dB above background noise.

WCS_Backbox_SPL (resized).png
#16 10 months ago

Smoothing was done with 1/24 octave setting. Not a very smooth curve but for speakers made in the early 1990's not all that unusual for lower end drivers.

Maybe someone has the frequency curve for the amplifier on the sound board. When I do the tests on the lower frequency driver we can meld the curves together to get a system view.

#17 10 months ago

Following

#18 10 months ago
Quoted from Aurich:

If only we could solve the problem of people showing up in creator's threads to advertise their products. You got anything for that?

Exactly -

Following your thread colofan

#19 10 months ago

As an example of what I will be doing is to eventually get to a simulation of audio output from a pinball game based on the environment the player is experiencing.

Since an earlier poster stated they already have a solution I will briefly simulate with the data I have on this pinwoofer solution from an acoustic perspective.

The drivers used are a Goldwood GW-8024 (Based on data from a spec sheet on Parts Express website) for bass in cabinet and the Backbox speakers are Pyle PL53BL. It should be noted that the Pyle typical for mobile application has very incomplete spec sheet since it provides not enough information as to on-axis and off-axis performance. An example I provided above about Impedance being a single number and sensitivity is a single number.

Only way to simulate the Pyle drivers is to get one and test it to find out what it really is.

I am going to provide the layout for the simulation and then the SPL output from the Goldwood driver at the players location.

Input power was 2 watts which a 2.83volt input form the amplifier. No electronic filtering is applied.

The 2 curves for spl is on-axis (red) which shows the diffraction effects of the cabinet. The blue curve is a power response which is the long-term(100ms) response which is more representative of constant output from the driver versus the transient response from on-axis provides.

On final note is the cost of both Drivers(Pyle sold as a pair) ; Goldwood is $25.96 , Pyle $18.98 prices from Parts Express

Goldwood_Pin_spl_sim.PDFSimulation diagram (resized).jpg
#20 10 months ago

I'm not an expert but I know a couple things. I always see these car audio speakers put in with these speaker kits and I don't get it. I feel like with pinball, a full range driver with high sensitivity would be ideal.

Maybe things change a bit when you add a real amp into the equation, but even still probably a co-ax is all you need. Pinball machines are not covering a wide range of frequencies. You're not gaining anything by adding extra tweeters and whatnot, but you certainly lose a bit of performance (reduced cone size, blocked sound waves, ect). I'm sure size is a limiting factor as well, because pinball sizes are much more common in automotive applications. I imagine its also easier to sell a product as "high end" when it looks fancy compared to a standard (but quality) paper cone speaker, even if the performance is actually worse.

One of the main reasons I've never invested in aftermarket pinball speaker systems. I am intrigued by a plug and play amplifier options where you maybe supply your own speakers, instead of marked up low end car audio speakers.

We also can't forget that the source audio is very low quality. There is room for improvement, but without mods like a pinsound board, you could have the worlds finest speakers but it'll only ever sound as good as the garbage coming from the source.

#21 10 months ago
Quoted from Aurich:

If only we could solve the problem of people showing up in creator's threads to advertise their products. You got anything for that?

Meh...I don't get why PinWoofer's post is so offensive. Dan (PinWoofer) is a great guy with a great product. He is extremely low key, passionate and knowledgeable. This thread is clearly about analysis/design, NOT a "competing" product. Since PinWoofer has been in development for several years with great results, at a minimum, colofan can shoot high and see how his audio design work stacks up against PinWoofer (the best audio mod that's come out in many years). If it's as good (or better) for less $$, it's good for the community.

#22 10 months ago
Quoted from snaroff:

I don't get why PinWoofer's post is so offensive.

Because

Quoted from snaroff:

This thread is clearly about analysis/design,

and PinWoofer ’s post is about selling Pinwoofers.

#23 10 months ago

Hey guys - we certainly did not intend to over step - please, continue the creative discussion and we'll leave the thread. This topic is about the new ideas.

#24 10 months ago
Quoted from snaroff:

Meh...I don't get why PinWoofer's post is so offensive. Dan (PinWoofer) is a great guy with a great product. He is extremely low key, passionate and knowledgeable. This thread is clearly about analysis/design, NOT a "competing" product.

Then maybe he could have contributed with his analysis and findings... and not just "I already have the answer... buy this.."

#25 10 months ago
Quoted from flynnibus:

Then maybe he could have contributed with his analysis and findings... and not just "I already have the answer... buy this.."

I get it...if people want to have a thin skin, knock yourselves out!

All I'm saying is Dan *isn't* a rabid self-promoter...he's a good egg, and people shouldn't get bent out of shape. That's all.

If the op were selling a product, I would totally agree with you and others. The op is doing research and Dan is building/shipping product. Whatever...no big deal, since Dan has recognized the sensitivity. Fact is, when I was reading this thread, I thought about mentioning PinWoofer (since I have PinWoofer installed in many of my games).

#26 10 months ago

New impedance curves. First graph is the backbox of Goldeneye. Since it is stereo tested both speakers independently.

Second Graph is the impedance of all three woofers in there respective cabinets.

Goldeneye Backbox imp (resized).JPGWoofers_impedance (resized).JPG
#27 10 months ago

Taking a closer look at Goldeneye speakers. The natural resonance of the backbox speakers are 727 Hz and the woofer is 100Hz.

From an efficiency you typically do not have much output from a driver below resonance. Thus the crossover point is this setup means that the woofer goes up to at least 800Hz. The bad of this is sound is pretty directional above 100Hz which means the audio will shift in listening in this range. Another bad is woofer of the size of 8 inch has breakup modes that causes non-linear response to occur. This is more of a mid-woofer since below 100 Hz is not really there in output. I will be doing SPL measurements next.

Goldeneye_impedance.JPG
#28 10 months ago

WCS and Indiana Jones are mono. My understanding is though that they do a electronic crossover for the two different amplifiers which I confirmed off of the schematic. Again I will be doing SPL test in situ. Again though the woofer resonance is around 100hz which acoustically is more mid-bass region audio wise.

Indiana_Jones_impedance (resized).JPGWCS_impedance (resized).JPG
#29 10 months ago
Quoted from Davi:

What will be an outcome? A custom speaker set and/or rheostat and/or built-in amplifier?

Yes a custom design with all the details on how the engineering occurred. Best bang for buck. Outcome is to understand what the current system can do and what are the advantages on changing/adding parts. Big improvements can happen without a major investment.

Understanding the home environment where the games are being played. Like watching a movie audio is an important part of enjoying the experience of playing.

At the beginning it is capturing what the system is doing and then evaluate on next steps.

1 week later
#30 10 months ago

I know that mostly new back box drivers have centered on 5 1/4 inch sized co-axial drivers. I took measurements of my machines of the grill size hole.

Goldeneye about 3 5/8 inches in diameter which is roughly 92mm
Indiana Jones about 4 1/2 inches in diameter which is roughly 114mm
World Cup Soccer about 3 3/4 inches in diameter which is roughly 95 mm

The diaphragm of the speaker cone should not really be larger than the grill hole to not interfere with the upper midrange frequencies. The dispersion pattern of a driver especially in off-axis is correlated to diaphragm size and frequency.

A car 5 1/4 speaker has a working diaphragm size 113 mm. This would be okay for IJ but two large for the other games.

The desire for larger speakers is bass response is better. However based on my impedance measurements the need below 100 Hz might not be needed.

If someone knows what the frequency response from the games amplifiers that would be useful. If no one has that data I will measure it during game play and will look at the schematics to see what the filters they put in the inpuy to the output amplifiers.

#31 10 months ago
Quoted from Aurich:

If only we could solve the problem of people showing up in creator's threads to advertise their products. You got anything for that?

amazing post.

2 weeks later
#32 9 months ago

Slight delay because of holiday.

Next up this week will be test spl of Goldeneye system using pink noise and instrument microphone.

Going to be installing replacement backbox speakers with Dayton Audio CX120-8 4" Coaxial Driver with 3/4" Silk tweeter. This is a tweeter driver mounted co-linear in driver. Frequency response is on paper proper sensitivity to match current driver mounted.

Focus of woofer(not sub-woofer) selection will be aimed looking a pro-drivers because they have higher sensitivity, this is accomplished through a lighter cone mass and larger motor. This also drives up the Vas however considering how large the lower box not a problem with pinball machines that are solid state. Looking in the 40-50 Hz natural resonance (Fs) though I do not have data as to the frequency response needed for a game.

#33 9 months ago

Thanks for the thread, great insight and analysis - following

#34 9 months ago
Quoted from colofan:

Slight delay because of holiday.
Next up this week will be test spl of Goldeneye system using pink noise and instrument microphone.
Going to be installing replacement backbox speakers with Dayton Audio CX120-8 4" Coaxial Driver with 3/4" Silk tweeter. This is a tweeter driver mounted co-linear in driver. Frequency response is on paper proper sensitivity to match current driver mounted.
Focus of woofer(not sub-woofer) selection will be aimed looking a pro-drivers because they have higher sensitivity, this is accomplished through a lighter cone mass and larger motor. This also drives up the Vas however considering how large the lower box not a problem with pinball machines that are solid state. Looking in the 40-50 Hz natural resonance (Fs) though I do not have data as to the frequency response needed for a game.

I really like where this is headed. The Dayton speaker is a great choice although I am worried a little about the sensitivity being so low on it. Much better than the junk Pyle and Pyramid that a lot of the aftermarket companies use I think though. If you can push a little more juice to the speakers this is definitely going to be a killer setup.

I like the idea of a pro audio woofer as well. This is right in line with a lot of my theories but I have been not willing to sink the money into to test, and I don't have the equipment or level of knowledge as you. Please keep us posted, this is a great thread for audio nerds!

#35 9 months ago

.

3 weeks later
#36 8 months ago

I am having discussions with Misco company about considering a low frequency driver as a straight replacement for the OEM in the lower cabinet. Both 8 and 6 1/2 inch sizes. More of a vintage suspension system that would improve efficiency but with modern materials and magnetic motor.

This would need the large space thus not designed around mobile application which drivers are designed with a very small space.

In speaker parameters (Vas) will be a critical value for good performance in pinball machines. An example of a design like this is JBL Pro 2235H, though a 15 inch driver the lightweight cone (mms) and large magnetic motor gives a great lowend performance down into the 30-40 Hz range.

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