(Topic ID: 293026)

WPC Where should the Sub Woofer go?

By Budwin

2 years ago


Topic Heartbeat

Topic Stats

  • 15 posts
  • 7 Pinsiders participating
  • Latest reply 2 years ago by jwill370
  • Topic is favorited by 2 Pinsiders

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Topic poll

“Where is the best place to install a Sub Woofer in a pinball machine?”

  • Internal Sub Woofer 5 votes
    31%
  • External Sub Woofer 11 votes
    69%

(16 votes)

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#1 2 years ago

Ok, there are so many ways to improve to the WPC era sound for pinball I almost hesitate to add another, but why not too much info is better than not enough.
So first my goal for my particular situation is that I was underwhelmed by my Party Zone sound. (like many others)
This pin has some good tracks, like Hendricks an Who, so why not make that sound better? (stock sound is pitiful)
First of all I have to manage my expectations since this pinball machine is NEVER going to be a quality stereo system.
Also I am no audiophile, so not looking for too much with this modification.

That being said, I have played new Stern and JJP machines and they sound WAY better.
But, I'm a serious cheap skate and a pre-fab aftermarket solution like PinWoofer or Pinball Pro are outside my price range.
(I will say after going through the process those products look very attractive after the amount of work required for DIY)

OK, the first thing to do was replace the original speakers, obvious move.
I felt lucky to find speakers that matched the bolt patterns of the originals from Parts Express.

Cabinet 6 1/2 IN Woofer $26.98
https://www.parts-express.com/Dayton-Audio-DC160-8-6-1-2-Classic-Woofer-295-305
(no modification bolt pattern aligns perfect)

Mid Range $26.98
https://www.parts-express.com/Dayton-Audio-PA165-8-6-PA-Driver-Speaker-295-015
(a little modification to the head to make room for the really big magnet, cutting a notch in the wood cross member)

Tweeter $3.00
https://www.parts-express.com/T-25-2-1-2-Paper-Cone-Tweeter-8-Ohm-279-452
(Very slight modification to ream out one of the holes to fit the bolt pattern)

After changing the speakers there was no noticeable improvement
The sound from the cabinet speaker was almost non-existent.
OK, searching Pinside I found a link for improving WPC sound by attenuating the top speakers so you can hear the woofer.
Guide to add L-Pad - http://www.dziedzic.us/wpc_speaker_sound_info.html

Did that and there was some improvement, but nothing that made all the changes to this point worth it.

OK, time to get serious, I'm adding a Sub Amp - I am determined to hear some bass.
This is when the choice of a external sub woofer or internal has to be made. (you can do either with about the same cost)
I'm sure adding an external is easier, but I have a personal preference to keep the pinball machine looking stock if at all possible.
Maybe I'm stupid for having that in my head. I decided to go internal.
Well there are many options to make that happen, but being a cheap-skate I go to Amazon for an Amp that would drive my 50W cabinet speaker.

Anyway here is the China Sub Amp $16.98
https://www.amazon.com/dp/B01N5DGK37

Well not quite that simple because the input of that amp it designed for a high impedance and the WPC amp is a low impedance output. So, I ordered the cheapo China impedance converter from Amazon.

Impedance Converter $8.99
https://www.amazon.com/dp/B009T5S3HE

IMG_3388 (resized).JPGIMG_3388 (resized).JPG

I had a 19V laptop power brick that could deliver >6 amps, so that should more than cover the 50W I am looking for.
That brick power supply mounted easily into the cabinet beside the transformer. (wired to curtesy plug)
Alright I've got some power NOW !
I wired the output of the early WPC amp to the impedance converter (I just soldered the wires to the PCB).
Then I soldered the wire harness included with the amp to the RCA jack of the impedance converter. (mono only one RCA needed)
The impedance converter has a potentiometer to adjust level, so I did that.

Now I went into the 'test' mode for audio and put this new configuration through its paces.
Freakin Aye, now that woofer is thumping !
Oh, damn now the whole pin is shaking like there an Earthquake ! (mostly the playfield glass, it is bulging like it is going to burst)

OK, how am I going to fix that?
Well all that air pressure from the woofer needs to be re-directed outside the cabinet.
Maybe a pre-fab woofer box would keep that pressure from the inside of the cabinet and shaking the playfield glass.
Do I have room inside for a box? Looked around and found a small box designed for 6 1/2 speakers.

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Rhino Base Box 6 1/2 IN $70 for a pair
https://www.rhinobassbox.com/productdisplay/65-single-hole-speaker-box-poly

Got a pair of those from eBay for $50
Unfortunately, when I place my 6 1/2 IN woofer in there it did not quite fit. (5.5 IN diameter hole speaker fit diameter 5.7 IN)
So, I broke out my hole cutter and drill press and opened up the hole by 0.2 IN
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Now the speaker fits perfect.
OK, I did some re-engineering of the bottom of the cabinet to mount the new box. (pried up the speaker ring and screwed that to the box)
The speaker and box are now a removable and serviceable module.
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Installed that and discovered a ton of blow back air escaping around the speaker terminal connections on the back of the box. UGH

Alright I need to get the power of all that air behind the speaker into my ears, ported woofer !
How to add a port without making the pin look like a kludged Frankenstein?
Rummaging through my junk box I found a drain elbow from my new garbage disposal I never used.

Garbage disposal elbow $8.88
https://www.amazon.com/gp/product/B07BF2R9LZ/ref=ox_sc_act_title_2

I just drilled a 1 1/4 IN hole in the side of the box and screwed the elbow pipe into the box.
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Now I have a ported speaker box.
IMG_3348 (resized).JPGIMG_3348 (resized).JPG
Then drilled a 1 1/5 in hole in the bottom of the cabinet.
Mounting required some T-nuts and #8 1in long screws with 1/4 IN hex heads. (hard to get a screwdriver to the corners, used 1/4 IN wrench)
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With all that mounted and the volume turned up the glass is not vibrating and the bass thump is satisfying.
Now that extra air is blissfully blowing out that port with enough pressure to blow women's clothes off
The L-pad also allows me to balance the head speakers volume to the woofer.

Still this setup is in no way a high fidelity setup, but it is as far as I think I need to go for a pinball machine.
My overall look back at this mod is that it was pretty difficult and I might have been better off going external on the Sub.
Still, the idea of hauling around an external Sub with the pin does not appeal to me.
So, maybe this is OK.

#2 2 years ago

God, I'm freekin exhausted!

#3 2 years ago

I just add a polk psw-10 and call it good enough. Drilling holes in the bottom of the cabinet is not “looking stock”, but if your happy with it, that’s all that matters.

#4 2 years ago

The sensitivity on the woofer you selected for the cab is quite low. Id imagine that played a role in it’s absence pre amplifier. I like the box you constructed. It reminds me of what spooky does w/ their games. I never understood why other manufacturers don’t do this. A mod like that would likely sell well if it bolted into the stock framework.

#5 2 years ago

I'm not sure I follow all the effort. My AFM came with a flipper fidelity kit installed. I can crank it up enough to feel like a shaker is installed. The woofer can definitely be felt. I don't think the kit is expensive but maybe I'm wrong. Looks great anyhow, nice work

#6 2 years ago

This picture shows the counter sink wood screws that hold the box to the speaker.
I added a poll to see how folks feel about internal vs. external sub woofers.
Really I may try an external sub for the next sound re-work on a pin.
If I don't like it I could always make another box.

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#7 2 years ago

I found an old thread where somebody did something similar here:
https://pinside.com/pinball/forum/topic/my-popeye-custom-modified#post-622602

#8 2 years ago

Here is the woofer and port side.

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#9 2 years ago
Quoted from tilted81:

The sensitivity on the woofer you selected for the cab is quite low. Id imagine that played a role in it’s absence pre amplifier. I like the box you constructed. It reminds me of what spooky does w/ their games. I never understood why other manufacturers don’t do this. A mod like that would likely sell well if it bolted into the stock framework.

Do you have a recommendation for another 6 1/2IN woofer that would have a better response?
Also my original thought was to clamp the box assembly with wood screws from the inside using Z brackets.
I got a little lazy and did not make (or buy) a set for brackets. Now I wish I did so there would be nothing different on the bottom except the port hole.
The bolts I used were sort of blocked by the box corners so accessing them was not great.

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#10 2 years ago

Does anyone know of a good response (quality) 8 OHM woofer speaker for WPC?
I would be interested in 6 1/2 inch speakers only.

#11 2 years ago

Oh, I just realized my China Amp is rated for 2-8 Ohm so I guess that opens up the options for a 6 1/2IN woofer.
Anyone have experience with small woofers?

#12 2 years ago

I guess as long as the rest of the game has this much attention, go for it.

#13 2 years ago

I'm looking at this one on Amazon.
https://www.amazon.com/Lanzar-6-5-inch-Subwoofer-Speaker/dp/B001L5FQ0M/ref=psdc_1294866011_t3_B06Y1F1XVP
No idea how to read the specs compared to the Dayton Audio woofer.
https://www.parts-express.com/Lanzar-MAXP64-6.5-600-Watt-Woofer-292-2590
https://www.parts-express.com/Dayton-Audio-DC160-8-6-1-2-Classic-Woofer-295-305
I would be willing to spend a little more if someone knows of something better.
Or, I could just stick with the Dayton Audio DC160-8

#14 2 years ago

I have decided the Dayton Audio DC160-8 woofer is fine, I can't see making the bass much better with a different woofer.
I'm installing the same mod on my Dr Dude, I'll update this thread as I make progress.
Maybe I'll start selling an after market kit for woofer boxes on SYS11 and WPC.
Or not.....

3 weeks later
#15 2 years ago

My STTNG's cabinet speaker was shredded when I got it. It looked like someone had kicked the protective screen hard enough to tear through it and rip the speaker cone. Out of curiosity I took a 12" subwoofer out of a car speaker box and set over the cabinet speaker hole. I hooked it to a car stereo amp then hooked cabinet speaker wire to the amp. I powered it off AC using a 12v transformer. STTNG has a lot low frequency sounds that can really rumble the cabinet. I liked it and left it like that for a number of years. Finally I got enough ambition to make it permanent. I enlarged cabinet speaker hole to fit the 12" subwoofer. I bolted it in with the grill from the speaker box inplace to protect it. I used a chinese amp similar to yours and powered it with a laptop PSU. This really kicked up the rumble. I had to put tape on the edges of the glass to keep it from rattling. Sometimes I can hear the balls in the hopper of the pachinko machine next to the game shifting. Some of the modes have ship engine sounds which you can feel through your hands resting on the game. It's not something you get from a shaker. I have a 10" external sub and a shaker for Mettalica. It does not compare to STTNG with the internal sub. DCS sound is probably better than SAM sound. I kind of doubt pre DCS WPC sound would work as well as STTNG. I have not done this to any of mine. I think I would use a woofer rather than a sub if I did try. I also replaced the backbox speakers in STTNG. I didn't notice a dramatic difference there.

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