Fixing crackling sound when Iron Maiden is turned way up

(Topic ID: 218688)

Fixing crackling sound when Iron Maiden is turned way up


By vireland

3 months ago



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  • 15 Pinsiders participating
  • Latest reply 77 days ago by TheCount
  • Topic is favorited by 26 Pinsiders

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13
#1 3 months ago

The crackling sound when you crank Iron Maiden is most-likely clipping of the on-board amp that is not up to the task of driving the JBL speakers. Fun fact: There is no standard for audio output (and mix levels?) levels between each Stern release. That can cause problems like this.

The solution? Use the line level output and hook up a small, inexpensive external amplifier in the head.

This took a while to round up because my first efforts were using the specs in the Iron Maiden manual. Silly me. The line out CN5 connector specs in the Iron Maiden manuals are wrong. This thread has the RIGHT specs for CN5, including two versions of the connector.

THESE INSTRUCTIONS ARE SPECIFIC TO IRON MAIDEN. The Line Out has changed all over the place on the Spike/2 boards, so the details need to be adapted for other Spike/2 machines.

The built in amplifier on Iron Maiden shows strain when paired with the JBL Studio speakers, clipping when the volume is turned up into the 30s or so. The solution? Get a cheap external amplifier that can drive the JBLs better. To do that, you need to use the Line Out connector on the Spike/2 board. Pro owners can also upgrade their speakers AND amplifier to get sound better than the LE comes with.

I'm still waiting for parts to finish the Pro conversion, which I'll add to this when they come in, but I have the information and parts for the cable that adapts the pinouts to an RCA cable you plug into the amp, which you then plug into your existing LE JBL speakers. So let's get that info out!

To make the adapter, you need an RCA cable (I grabbed one out of my abandoned wires box):
rca_cable (resized).jpg
a connector housing (this is the 6 pin version) - Digikey Part number 281838-6
connectors (resized).jpg
some molex pins - Digikey part number 0016020087
molex-pins (resized).jpg
and some shrink tubing (not pictured, harbor freight has variety packs)

There are TWO kinds of boards in the Spike/2 Iron Maiden run. Both have a CN5 connector, but one has a 6 pin CN5 and one has a 7 pin CN5 because the woofer output was added. You first need to figure out what kind of board you have. Look at the area below the CPU on the Spike/2 main board. The area highlighted in this picture is the revision:

boardID (resized).jpg

Revisions 520-7031-01A, B, C, D or 199-7031-00A have a 6 pin CN5 connector and the pins are arranged like this:
Correct_Line_Out_Pinouts (resized).jpg

Revisions 520-7031-01E or 1997031-00C have a 7 pin CN5 connector, and the pins are arranged like:
alternate_line_out (resized).jpg

Revision 199-7031-00B was never produced, according to Stern.

So, cut the RCA cable, leaving about 18 inches from the cut to the RCA ends of the wire:
cut_rca (resized).jpg
Separate the wire halves for about 2 inches, then strip the insulation off each one. On each wire, you'll have a "loose" insulation wire and another, smaller insulated wire inside. Twist the copper "loose" wire so it's in one piece on each of the wires.
stripped-wire (resized).jpg

Twist the two copper wires together and put some xtra-small shrink tubing over it (not shown), leaving a little bit of the copper peeking out the end. Shrink the tubing over the copper (ground) lead.

Cut a piece of small shrink tubing and slide it out of the way on the RCA wire so it's there for later (copper wire does not have small shrink wire on it in this pic):
shrink-tubing (resized).jpg

Crimp the molex pins on the Left (white), Right (red), and copper lead. These pins are SMALL. I used a magnifying glass.
molex-on (resized).jpg

The two (legs) on the top and bottom of the connector FACE the CN5 connector, so they should be pointing right if you have the connector vertical in your hand.
numbered-plug (resized).jpg

In that orientation, plug the red into the top, white next, then the copper lead in the 3rd position from the top. They should "click" and you should not be able to tug them out. Slide the shrink tube up so it's snug against the connector and shrink it to the wires.
connector-on (resized).jpg

Your adapter is done, and you're ready to plug it into the Spike/2 board in the backbox. Turn off the machine and plug it in, like so:
spike-board-adapter-plug (resized).jpg

Then plug the RCA connectors into marked L/R input jacks on the back of the Pyle amp you got from Amazon (amazon.com link ») :
pyle-2 (resized).jpgpyle-3 (resized).jpg

Then make a speaker cable adapter to plug into your JBL speakers and connect those wires to the output clips on the pack of the Pyle amp. You are good to go at that point. Make sure the amp volume is ZERO when you initially turn the machine back on, then slowly increase it until you get the level you want. This amp can overdrive the JBL speakers, so you won't be able to run it at max.

I'll add the Pro conversion to 5.25" speakers when the rest of the parts arrive, but this will help those of you with an LE and the clipping/crackling speakers at high volume.

Now that this project is done, how about these projects?

Reinforce the crappy Stern leg plates so the newer cabinet wood doesn't split at the corners:
https://pinside.com/pinball/forum/topic/reinforcing-stern-cabinet-legs-step-by-step

Replace the noisy stock spike power supply fan with a much quieter one:
https://pinside.com/pinball/forum/topic/replacing-stern-spike-noisy-ps-fans

Fix mid-game Spike resets:
https://pinside.com/pinball/forum/topic/fixing-stern-reboots-on-spike

Fix your LEDs and LED Flashers in spotlights so they don't pop out unexpectedly:
https://pinside.com/pinball/forum/topic/fixing-led-bulbs-flashers-that-fall-out-of-spotlights

#2 3 months ago

Nice write-up once again, thanks Vireland! Is that a cropped version of the schematic for the Spike 2 CPU board!? How'd you get your hands on that, and can you post the full schematic?

#3 3 months ago

Awesome job man, will be doing this soon.
THANK YOU!

#4 3 months ago
Quoted from andre060:

Nice write-up once again, thanks Vireland! Is that a cropped version of the schematic for the Spike 2 CPU board!? How'd you get your hands on that, and can you post the full schematic?

What's here is all that Stern's allowed out, for whatever obscure reason. No competitor is clamoring to duplicate the fussy Spike/2 system.

#5 3 months ago

Made myself the cable as per instructions - thanks Vireland! Really trivial if you have some .100 connectors on hand. In my case I routed the cable out of the top backbox hole (used for the topper wiring) as I am connecting the game to external amplification in the room.

Interestingly (and unfortunately), it is a volume-adjusted line out, meaning the volume + bass + treble settings of the cabinet speakers control this output. This is not ideal if you want to leave the stock sound system wired in the game at the same time and use this as a line-out to external speakers in the room. I'm having to turn the external amp volume WAY up as I have the game volume level set to not blast my ears out with the built-in amp+speakers

So, it looks for my purposes like the headphone out would be a better solution, as the system allows independent control of the speaker and headphone volumes.

Vireland, since it looks like you had access to a schematic, any chance you can dig up details on the CN3 headphone connector? I'd like to fabricate my own. Interested in particular on details on how the Stern kit's volume control is wired up - presumably just a pot, but it would be great to get the specs on it.

backbox.jpgwire (resized).jpg
#6 3 months ago
Quoted from vireland:

What's here is all that Stern's allowed out, for whatever obscure reason. No competitor is clamoring to duplicate the fussy Spike/2 system.

Interesting. Nothing on CN3 eh?

Didn't Gomez promise better Spike documentation at TPF?

#7 3 months ago

Hey Vireland I never got any clarification on my question about why the music itself doesn't really clip (at 46+ it does), but at 33+ the fx clip horribly. Same answer---amp can't drive speakers?
The audio mix itself seems off. Speech attenuation does not resolve fx clipping. I've taken speech completely out and fx still clipping.
Just wondering yer thoughts on this.

#8 3 months ago
Quoted from Gryszzz:

Hey Vireland I never got any clarification on my question about why the music itself doesn't really clip (at 46+ it does), but at 33+ the fx clip horribly. Same answer---amp can't drive speakers?
The audio mix itself seems off. Speech attenuation does not resolve fx clipping. I've taken speech completely out and fx still overbearing.
Just wondering yer thoughts on this.

It's probably the internal mix. No way to tell if it's the internal amp not keeping up or the pre-processing falling down until an external amp is installed. Once I have the rest of the parts to convert the Pro over to 5.25" speakers, I'll be able to do more testing. This how-to is only the half of the project (the part LE owners need), but I wanted to get the information out there until I get the Pro/Prem part done.

#9 3 months ago
Quoted from andre060:

Vireland, since it looks like you had access to a schematic, any chance you can dig up details on the CN3 headphone connector? I'd like to fabricate my own. Interested in particular on details on how the Stern kit's volume control is wired up - presumably just a pot, but it would be great to get the specs on it.

Hahaha, funny you should ask. Getting a headphone output wired up is on my "to-do" project list. Should get it done pretty soon.

Quoted from andre060:

Interestingly (and unfortunately), it is a volume-adjusted line out, meaning the volume + bass + treble settings of the cabinet speakers control this output. This is not ideal if you want to leave the stock sound system wired in the game at the same time and use this as a line-out to external speakers in the room. I'm having to turn the external amp volume WAY up as I have the game volume level set to not blast my ears out with the built-in amp+speakers

Well, you could work around that by splitting your RCA output to a small cheap pyle amp in the head that is wired to the existing speakers, bypassing the internal Spike/2 amp entirely, then set the level for your machine's speakers low and your external speakers higher, and turn up your machine's volume output that feeds the speakers.

#10 3 months ago

I put the line-out on my Aerosmith into a headphone amp and listened with some good headphones - definitely doesn't sound super clean. Lots of distortions in the sounds which is either intentional per the sound designer, or distorting in the mix before amplification. A bit disappointing, but it's not the end of the world, still love the sound and music in the game. For my ears though I think Ghostbusters is the best sounding game from Stern I've ever heard.

#11 3 months ago
Quoted from vireland:

Hahaha, funny you should ask. Getting a headphone output wired up is on my "to-do" project list. Should get it done pretty soon.

Awesome. And actually I just bit the bullet and bought one of the Stern kits, so I should be able to reverse engineer it as well if it's as simple as it looks.

#12 3 months ago

Andre you already got this jamming?
How does it sound man? Clipping lessened at high volume?
Shazam yer fast!
Edit: reread yer post about going line out to external speakers. C'mon man switch it up to bb for us homie! Inquiring minds wanna know!

#13 3 months ago

If I buy a flipper fidelity speaker and sub kit should I still add one of these amps to my premium to improve sound?

Or should I buy some other type of speakers? I already have an external sub

#14 3 months ago
Quoted from Gryszzz:

C'mon man switch it up to bb for us homie! Inquiring minds wanna know!

I have the high-output 8" flipper fidelity kit in both Aerosmith and Iron Maiden. My volume settings is -14 bias to cabinet woofer (for bass, you can barely hear it at even 0 balance), and volume set to 20-25ish. At those volumes, there is no clipping from the on-board Stern amp, so not much point to piping the line out to an external amp wired to the cabinet speakers.

Like I said with Aerosmith there is some distortion in the sounds - I was pretty sure from listening it wasn't amp clipping, and listening to the line out wired to a headphone amp confirmed this.

That said I concur with Vireland: if your sound is noticeably worse at high volume *only* and not lower volumes (just like Vireland says in his original post), you can probably benefit from adding an external amp wired to the cabinet speakers. But that would only be at seriously loud volumes, especially with the stock Stern speakers which are way more efficient than the Flipper Fidelity ones (quality comes at the cost of efficiency as a general rule of thumb with speakers).

#15 3 months ago
Quoted from andre060:

at high volume *only* .

Wait...there's another way?

#16 3 months ago
Quoted from Gryszzz:

Wait...there's another way?

Hahaha Yes, yes there is. I for one would like to keep my hearing for as long as possible. Once it's gone it doesn't come back...

#18 3 months ago

You're either pretending you can't hear me from hearing loss, or we're totally not on the same page By "is there another way?" it sounded like you were implying loud is the only way to go

#20 3 months ago

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#21 3 months ago

Why in the hell would you guys buy parts & hack your $9K pin when Stern needs to make this right?! I have a LE,but there's no way in hell I'm doing this nonsense... Think about it.. Stern has to fix it..

#22 3 months ago
Quoted from Strummy:

If I buy a flipper fidelity speaker and sub kit should I still add one of these amps to my premium to improve sound?

Nah,
The Flipper Fidelity kit alone sounds so much better than the crap 25 cent stock speakers you won’t even need to crank it past 28.
Dare I say they sound even better than the JBL’s they spec’d on the LE?

Once you dial in the upper and lower speakers’ bass, treble and cab balance via menu, it really doesn’t need the external sub, OR amp.

It takes a bit of time to get everything “just riiiiight”, but the end result with the sounds, callouts and music is simply EPIC.

#23 3 months ago
Quoted from Breadfan:

Why in the hell would you guys buy parts & hack your $9K pin when Stern needs to make this right?! I have a LE,but there's no way in hell I'm doing this nonsense... Think about it.. Stern has to fix it..

You're not hacking any of it. No part of the machine is cut. It's all plug-reversible.

#24 3 months ago
Quoted from andre060:

I put the line-out on my Aerosmith into a headphone amp and listened with some good headphones - definitely doesn't sound super clean. Lots of distortions in the sounds which is either intentional per the sound designer, or distorting in the mix before amplification. A bit disappointing, but it's not the end of the world, still love the sound and music in the game. For my ears though I think Ghostbusters is the best sounding game from Stern I've ever heard.

Hmmmm, Spike 1 game.

Funnily enough I think KISS ( also Spike 1 ) sounds night and day better than AS and Maiden ( Spike 2 ). For me KISS is the best sounding Stern I have heard.

No clue why.

#25 3 months ago
Quoted from Breadfan:

Why in the hell would you guys buy parts & hack your $9K pin when Stern needs to make this right?! I have a LE,but there's no way in hell I'm doing this nonsense... Think about it.. Stern has to fix it..

The stereo in my truck needs an upgrade too

#26 3 months ago

Just talked to Stern in they said there's a software update coming soon to fix it and it's not the amplifier.

#27 3 months ago
Quoted from Breadfan:

Just talked to Stern in they said there's a software update coming soon to fix it and it's not the amplifier.

Nice

#28 3 months ago

Even if they fix the audio mix, I still prefer to have these speakers driven by an actual amp, not a power supply board. The Stern "amp" can't handle these speakers. It will only make it sound better. And most importantly, louder AND better.

#29 3 months ago
Quoted from Breadfan:

Just talked to Stern in they said there's a software update coming soon to fix it and it's not the amplifier.

Awesome!
My premium sounded like absolute ass out of the box compared to my GBP and SW pro, which coincidentally, still have their stock speakers intact...
The FF kit I purchased in my above post helped immensely on the latest 1.0 code but, I’m glad they will finally address the audio deficiencies for those folks that continue to use the original set.

#30 3 months ago
Quoted from NimblePin:Awesome!
My premium sounded like absolute ass out of the box compared to my GBP and SW pro, which coincidentally, still have their stock speakers intact...
The FF kit I purchased in my above post helped immensely on the latest 1.0 code but, I’m glad they will finally address the audio deficiencies for those folks that continue to use the original set.

So I did order my first set of flipper Fidelity speakers today and I'm psyched that they will sound even better with future codes!

#31 3 months ago
Quoted from Breadfan:

Just talked to Stern in they said there's a software update coming soon to fix it and it's not the amplifier.

Interesting. Wonder if this is specific to Iron Maiden, or if it’s a system fix that will apply to other spike 2 games...

#32 3 months ago
Quoted from Breadfan:

Why in the hell would you guys buy parts & hack your $9K pin when Stern needs to make this right?! I have a LE,but there's no way in hell I'm doing this nonsense... Think about it.. Stern has to fix it..

Haven't they promised software fixes for hardware issues in the past?

#33 3 months ago
Quoted from TOK:

Haven't they promised software fixes for hardware issues in the past?

"As designed" plus a software kludge is a clear and present danger whenever there are hardware problems.

#34 3 months ago
Quoted from andre060:

I just bit the bullet and bought one of the Stern kits, so I should be able to reverse engineer it as well if it's as simple as it looks.

Update: Ordered from the Stern shop, got an email the next day saying the kits are back-ordered with an expected stock date of early July.

#35 3 months ago

New code came out today & now you can change the ohms from 8 to 4 to fix the sound clipping.

#36 3 months ago

I have mine on 8ohm and at 38 volume no clipping....FUCKIN A.
My other settings:
Music attenuation: -50
Speech attenuation: 5
Bass: 90
Treble: 80
Gonna keep going up on volume and find the breaking point. Still interested in installing external amp.

#37 3 months ago

Changed them out. Much better. Hope the new code helps too. I still have the external sub hooked up as well

20180616_002120 (resized).jpg20180616_003140 (resized).jpg

#38 3 months ago
Quoted from Strummy:

Changed them out. Much better. Hope the new code helps too. I still have the external sub hooked up as well

BEEFY

#39 3 months ago

Well some of my stuff showed up today, I went with the Flipper Fidelity 10 in Sub upgrade. It comes with a mounting bracket, I can wait to hear it cranked up!

20180621_153708 (resized).jpg
#40 89 days ago

So with 1.0.1 code I have my LE set to 4 ohm with:

Volume 40-45
Head treble 80
Head bass 50
Cab bass 110
Cab treble 20
...and the woofer connected to a Polk 10” powered sub cranked about 50%.

This thing absolutely rocks! The bass guitar parts are clear and distinct and whole thing just rumbles at all the right places.

#41 88 days ago

I have my settings at 11.

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#42 86 days ago

What's a good speaker replacement for my IMDN pro don't want to get anything that needs to many watts. Just want to replace the head speakers.

#43 86 days ago
Quoted from cjpins:

What's a good speaker replacement for my IMDN pro don't want to get anything that needs to many watts. Just want to replace the head speakers.

Here too.....using factory mounting.

#45 80 days ago

They're a little (okay a LOT) skimpy with the speaker specs. What's the frequency range of those, and what's the sensitivity? Some basic speaker specs on their site would be useful for people making a decision.

#46 77 days ago
Quoted from vireland:

Some basic speaker specs on their site would be useful for people making a decision.

They don't want people buying the same speakers without the FF logo for half price.

#47 77 days ago
Quoted from yancy:

They don't want people buying the same speakers without the FF logo for half price.

But it's stupid that you can't even compare to other products without even basic things like frequency range and sensitivity.

#48 77 days ago

I personally have never bought a pin speaker kit form FF or anyone else. I never liked the idea of buying without knowing the specs.

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