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Resurrecting an old thread. How do you wire an l-pad to a DCS game, using the original backbox speakers? It appears that the speakers are 8 ohm in parallel, so it’s presenting a 4 ohm load to the sound board. And I don’t see a 4 ohm l-pad device?
Starting to seem like it’s easier to just add an external sub. Ha...
Thanks. I think, if I’m reading things correctly, all of the data is based on replacing the backbox speakers. I’m trying to avoid that. Either way, I thought the l-pad stuff all assumes an 8 ohm load, which I think is not what DCS has for the backbox speakers. I’m not sure if an 8 ohm l-pad will work with a 4 ohm load?
I know there have been other posts about modifying the sound board resistors to accomplish the same thing. Maybe I’ll go that route if I can’t figure out the l-pad solution...
Quoted from northerndude:The following is from the very first post - looks to be easy!
"DCS games (includes wpc95):
For those that may ask, there is a simpler solution for DCS and WPC 95 games. Simply swap the cabinet speaker with an efficient 4ohm sub. You don't even need a crossover because the cabinet speaker is already electronically crossed over at 300hz. There are two amps in the DCS games. This allows you to only worry about the subwoofer swap without backbox impedance and rewiring. If the cabinet speaker you choose is efficient enough, you can be done. But if not, you can add the L-Pad above or maybe just add a 20 ohm resistor (http://www.parts-express.com/pe/showdetl.cfm?partnumber=017-20) to lower the backbox volume.
If you choose to add the resistor, you would desolder the two wires that go to the 5.25" left speaker on the backbox. One goes to the amp, one goes to the right speaker. Separate the wires. Solder the resistor to the + lug of the 5.25" speaker. Solder the wire that goes to the + of the right speaker also to the + lug of the 5.25" speaker. Solder the wire that came from the amp to the other end of the resistor. That's it.
Finally, for DCS games you'll want to choose a decent and efficient sub. The wh88 will work pretty well as it is extremely efficient. However, it's 8 ohm so it takes some power from the amp away in impedance. I recommend using one of these MCM 10" speakers: http://www.mcmelectronics.com/product/55-3211. They are 95db efficient so you may not need any resistors if you use this. You will lose some volume form the small 6" cutout on your cabinet but it's fine. If you choose this option, your entire cost for the DCS addon is around $15 shipped.?
I was trying to do it on the cheap. I have a new sub on the way for my sttng, just hoping to gain some control of the balance between treble and bass...
The damn polk subs went up a lot in price this year, at least the one I own for my tv did..
How do you guys get the wire outside of the cabinet for an external sub? I don’t like the idea of drilling a hole, ha.
I have an odd problem, hoping someone has seen it.
When I power off a few of my WPC machines, my subs often begin humming. A low volume, low bass growl.
I did some experimenting tonight to see if I could figure it out. When I turned off TZ, the humming began. So, I disconnected one of the input wires at the sub and the humming stopped, as expected. I reconnected it and it resumed. So, I unplugged TZ thinking that the removal of power to the machine would stop whatever feedback it was getting. Even with TZ unplugged, it continued. Odd. That makes me think it’s some sort of radio interference.
I tried to see if I could find external interferences like LED lights or my phone. No dice.
To be fair, the wire from the game to the sub is unshielded wire. Maybe that’s my problem.
My setup is 10” Polk subs, one per machine.
Quoted from nerbflong:I have his issue with Gottlieb games mostly. The speaker in the lower cabinet acts like microphone and the gain on your sub must be high as its amplifying the sound to create a feedback loop. Doesn't matter if the game is on or off. On some of my games you can slap the cabinet and it will start humming. I solved it my plugging the subs into the service plugs inside the game if it goes on/off with the game, or wiring in a 110 plug on the switch side of the pinball machine. So when you flip the pinball machine off, the sub is off.
Thanks, that makes sense, and I'm not sure if I ever would have put those pieces together myself. You're 100% correct, I can nudge my machines and the sound comes/goes. It's odd, to say the least, but what you outlined explains it.
I'll have to think about how I'm going to address it. Unfortunately, in the pre-DCS games, unplugging the sub in the cabinet isn't an option due to how they wired the speakers in series. And one of my games is an import without a service plug.
Back to the drawing board. Unfortunately, I don't want to live with it as it's annoying, at best. =(
Just curious, has anyone utilized J509 as a line-out audio source on pre-DCS boards? Just thinking it’d be less of a hack. But I don’t want to blow up my sound board in the process of trying...
Quoted from colofan:Actually sounds like a ground loop problem. Are your subs plug into a different outlet than the game. This means the grounds are not the same and thus creates a 60Hz hum. Measure the ground on the sub and measure against the ground on the game. Also loose grounding straps can also cause this issue to come up.
I considered that too, but it happens when a game is totally unplugged. So there’s no ground reference at all for the machine, other then the legs on the carpet. Maybe that’s enough? I still think it’s the speaker acting as a microphone....
I bought some better signal wire that is shielded with a grounding wire. I’m going to try the J509 plug and will report back on the results.
Well that was an epic failure. I tied into J509 and used it to see my sub. It made...no sound. Zilch. Nothing. Ugh.
Back to the drawing board again....
I wonder what J509 is supposed to do. I know clays guide has a hack around r102. Maybe that’s my next step. But what was the original intent of J509, without the hack? Clearly it’s tied into the sound circuit...
Some more info from my experimentation.
Keep in mind my goal here is to get a useable “line out” signal from a WPC pre-DCS game so that I can feed it into my subwoofer. I know a lot of people simply pull the signal off of the subwoofer wiring. For me, I got a lot of feedback / hum when I tied into the subwoofer wiring. So I wanted to explore J509, the theoretical “line out” connector on the sound board.
My first experiment was to tie into J509 without an board modifications. I did that, wiring pins 1 & 3 on that connector to the RCA input on my powered sub. Zilch. Nothing. If my sub was making any sound, I couldn’t hear it over the machine. Back to the drawing board.
In Clay’s guide, he recommends removing resistor R102 from the sound board, and then connecting the negative side of C21 to pin 3 on connector J509. Supposedly that gives you a “line out” that’s not effected by volume control. I made this mod today to my CFTBL and once again wired it to the RCA input on my powered sub. Shazam. This seems to work.
Right now I’m not hearing the hum / feedback. I’m using a shielded cable but thus far haven’t grounded the shield.
I’ll post more feedback after testing this setup for a while. I modified my TZ sound board too, so it’s next in line to get a sub wired up like this.
81673132-5B20-4020-BDF3-0694CDE4CD70 (resized).jpegC80D53FC-8B65-4B2D-90CD-2ED8CBAC8AFC (resized).jpegD8DE9427-73D1-44A7-ACC6-63F69896FAE4 (resized).jpegED9EA099-818B-45AE-B053-98AB3592B1A8 (resized).jpegJust another follow up. My TZ and CFTBL (pre-DCS games) have the J509 hack that removes R102 and ties into C21. From header J509, I have a shielded cable that ties into an RCA connector on my Polk 10” powered sub. Both games sound great.
On my STTNG (DCS), I added a header to J6, and once again added a shielded cable that feeds an RCA input on my Polk 10” powered sub.
All 3 seem to work as anticipated. And there’s no hum when the machines are on or off. So far, this is a success.
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