Adding a stereo amp to a New Astro City

[kidpanda]

…….

 

[gusmoney]

With thanks to @kidpanda, his thread here, and @hardyhell, I finally installed a stereo amp in my NAC. I wanted this setup for CPS2, MiSTer, Atomiswave, Taito F3, and Neo Geo.

I basically did as KP outlines above, built a connector to the PSU and another to the audio. Hooked both of these up to the amp. I hit some hiccups along the way with pins that didn't want to stay in the molex and wires that tended to break off from their internal pins inexplicably.

Here are some photos:

 

[Ivan87]

Hi @kidpanda , I am in this situation of putting a small LEPY amplifier on my astro city.
But I have a doubt: is the power supply capable of delivering the necessary amps?
To my knowledge, LEPY requires 2/3 amps
while the SEGA power supply should
deliver 1.5 amps in 12volt. Thank you

 

[jimmyjames]

Just a heads up I used this setup and it’s far superior to anything else ive seen. This setup has the ability to use the jamma by unplugging the 4 pin and making it stock. I also used a line level converter to convert the powered positive and negative to line level rca. This is an old trick we used in the 90s for car audio. You can add a filter to completely eliminate nose but I’m not really getting any whatsoeve. This is the proper way to do it. You have to manually unplug rca cords or switch plugs to go back to stock but it works really well.

 

[Ivan87]

Just a heads up I used this setup and it’s far superior to anything else ive seen. This setup has the ability to use the jamma by unplugging the 4 pin and making it stock. I also used a line level converter to convert the powered positive and negative to line level rca. This is an old trick we used in the 90s for car audio. You can add a filter to completely eliminate nose but I’m not really getting any whatsoeve. This is the proper way to do it. You have to manually unplug rca cords or switch plugs to go back to stock but it works really well.

my doubt is if the power supply is able to supply the right amps. These small amplifiers usually want 2/3 amp, while the power supply should only give 1.5 amp.

 

[jimmyjames]

my doubt is if the power supply is able to supply the right amps. These small amplifiers usually want 2/3 amp, while the power supply should only give 1.5 amp.

So I wasnt trying to answer your question just was showing a better way for people to hook all this up.

however I will answer it.
12vX3a=36watts@4ohm
12vX1.5a=18watts@hm
I am using 10 watt rms speakers at 4ohm I’m not worried as I can’t turn my speakers up even half way. I would honestly be better using 5watt ones as I would blow well before my amp hits 1.5a. I have a chance of hitting the 1.5a right before I blow them but it would be so loud. Also I’ve recapped my power supply and im not sure what would happen if I started clipping it as it’s never happened and they have been loud af a few times just to test this. I assume it would shut off because that’s what most power supplies do when clipped for even a millisecond.
if you want to get technical buy hm speakers at 5-8watts. You’ll prolly never even get them to the half way mark without blowing them.

I’m pretty sure I described this correctly from the last time I messed with all the ohms law, speakers and amps atleast this is how we figured our car audio when I was into it 20 years ago. It always made it so we didn’t blow our speakers and we got speakers that could take more than the amps could put out.

Also once you go past about 8 watts of power the thd (total harmonic distortion) is going to go up as you turn it up at about 18 watts it’s gonna be at 10% and sound like ish.

When you say something wants 2-3 amps it doesn’t it wants 12v it only draws what you decide it will draw and fortunate for us we have multimeters and we can see what the draw is while in operation. That’s always the best bet. Once it’s hooked up put a meter to it and see what you are drawing and as you turn it up mark on the dial where it hits 1.5 and the problem is solved. I use a multimeter for everything and before arcades I had never used one before in my life. In fact for the first ten years I owned cabs I didn’t own one. It want until I had a problem with a mvs cab in 2006 That I bought one. Get yourself one if you don’t have one. They are amazing for this hobby. The fact I would hook 100 dollar plus boards up without making sure I was sending the proper voltage baffles me now.
good luck and I hope this helps.

 

[Moonwalker]

Just a heads up I used this setup and it’s far superior to anything else ive seen. This setup has the ability to use the jamma by unplugging the 4 pin and making it stock. I also used a line level converter to convert the powered positive and negative to line level rca. This is an old trick we used in the 90s for car audio. You can add a filter to completely eliminate nose but I’m not really getting any whatsoeve. This is the proper way to do it. You have to manually unplug rca cords or switch plugs to go back to stock but it works really well.

Thank you very much jimmyjames. I am thinking of enhancing my 3 NACs with a stereo amp and maybe get better speakers as well and would like to ask some questions.
I will update after trying it out

 

[Moonwalker]

I confirm the stereo mod works like a charm in a New Astro City and would like to give some help to others who would like to mod their NAC this way. The speaker part does not work for a NAC since they do not fit. I do not see any urge to change the NAC stock speakers though since they are great when amplified.

Except the amp and line converter you need the following for a NAC:

- Cables for crimps etc. (I used a cinch cable)
- AMP UP connector 4 pin male and female with the fitting crimp contacts
- AMP UP connector 12 pin male with the fitting crimps (2 crimps are enough for the setup, I take a 5V out of it for a Jamma MiSTer setup though)
- Cinch cable for connecting

If anyone has questions feel free to contact me.
Thanks again to @jimmyjames for this great mod!

 

[jimmyjames]

Thanks man
appreciate it.
line level was the missing key.

 

[Onizuka]

Hi Moonwalker & jimmyjames

Thanks for all the info! I’m currently waiting on delivery of a NAC. However, due to my limited apartment space, I’m shipping the cab directly to a friend’s vacation house about 2hrs away. Not ideal, but it’s going to good hands. When it arrives I plan to setup a Mistercade and this Amp/Speaker upgrade. I’ve purchased the speakers (Logitech z5500), line leveler and audio amp. I’m hoping you might be able to link to the exact additional parts (amp up, cables, crimps, etc) that I’ll need to complete the project. I’m a total newbie to Arcade wiring. Goal is to have RCA stereo out of the Mistercade with the ability to easily switch back to stock. Attached is a pic of inside of cab. Thanks!

 

[Moonwalker]

Hi Moonwalker & jimmyjames

Thanks for all the info! I’m currently waiting on delivery of a NAC. However, due to my limited apartment space, I’m shipping the cab directly to a friend’s vacation house about 2hrs away. Not ideal, but it’s going to good hands. When it arrives I plan to setup a Mistercade and this Amp/Speaker upgrade. I’ve purchased the speakers (Logitech z5500), line leveler and audio amp. I’m hoping you might be able to link to the exact additional parts (amp up, cables, crimps, etc) that I’ll need to complete the project. I’m a total newbie to Arcade wiring. Goal is to have RCA stereo out of the Mistercade with the ability to easily switch back to stock. Attached is a pic of inside of cab. Thanks!

Are you sure the speakers fit? The NAC speakers are measured so that they fit exactly into their place. Those seem they will not fit there. I do not feel the urge to replace them anyway, after amplifying them even the mono signal from the Jamma bar sounds great.

Just check m y post above there is explained what you need additionally to JimmyJames explanation. Keep in mind he is giving the tutorial for an Astro not New Astro.

 

[Onizuka]

Thanks or getting back.
They sort of fit. It was used in this thread:

https://www.arcade-projects.com/threads/new-astro-city-speaker-change-to-new-product-question.22187/

I guess I’m asking what cables did you use for crimping (cinch cable?) What is a crimp? Similar to crimping a cat6 cable? I’ve looked up what AMP UP connectors are and their different pinout sizes, but are misunderstanding exact details: “e.g. male with 2 crimps, “fitting crimps” on your NAC specific parts list. Sorry for my ignorance!

 

[Moonwalker]

I see, when they fit it is fine.
You can take any cable you can work with, I just used a Cinch cable and cut it open. Crimps are the contacts for the amp up connectors and you need to crimp them on the cable with a fitting tool. You need exactly what I wrote up there regarding the connectors and crimps. Order some more crimps an maybe double the connectors just in case when you mess up.

Good luck!

 

[Onizuka]

While watching MrAddons Mistercade assembly video I just realized that it natively has a line level audio out with amp and RCA outputs. Is going this route now redundant? If so, what would be the best option to move forward? Convert RCA to the AMP up connection going to the speakers?

 

[Thomas]

While watching MrAddons Mistercade assembly video I just realized that it natively has a line level audio out with amp and RCA outputs. Is going this route now redundant? If so, what would be the best option to move forward? Convert RCA to the AMP up connection going to the speakers?

I didn't read all of the previous posts thoroughly but it looks like all the details are there. I would follow what is written above. If the Mistercade has RCA stereo out, connect that to your amplifier. Connect the speaker output of your amplifier to the AMP UP connector under the control panel. Assuming Astro/New Astro use the same connector, you need AMP UP part# 176284 and for 16-20AWG wire, contact pins part# 175150. You need a special crimping tool like this: https://www.amazon.com/IWISS-Barrel-Terminal-Crimper-Terminals/dp/B07476C1LD
My wiring looks like this: https://www.arcade-projects.com/threads/sega-astro-city-restored.18550/post-347273

 

[Onizuka]

Thomas, what an amazing restore! Congrats! I'm going to emulate your model (will stick with the tinny Logitechs speakers though!) as I think it's really optimal and removes the need to leverage the 5V and 12V from my power supply. I purchased the Acoustic Audio PSW250-6 off Ebay and will using it along with a Kinter 2020A+ amp and Logitech speakers. A couple of questions if possible:

1. Did you go with the 2 outlet splitter specifically because that's all you needed? Would a 4 or even 5 outlet work all the same?

These are from Cable Matters - 4 outlet is 16awg and the multi colored 5 outlet/with switch is 14awg. I'm guessing the switch on the 5 outlet is redundant with the switch on the cab? Would connect the Mistercade, Amp, Subwoofer, and any possible future needs.

2. For the sub, I saw that on your Astro you did not leverage the speaker Hi-level output and just the Input. If I connected the Hi- Level output to the AMP UP connector going to the Logitechs, is that any different from stacking the wires to the amp in your setup?
I was also going to leverage the line level as shown on the diagram:

Would this be no longer necessary if I were to route through the subwoofer?
Should I also pickup of the inline capacitors for the speaker wire? If so, can you reference what you used?

Thank you very much!

 

[Thomas]

1. Did you go with the 2 outlet splitter specifically because that's all you needed? Would a 4 or even 5 outlet work all the same?

You can use a 4 or 5 outlet splitter. The only thing to pay attention to is the current rating. 16 gauge should be plenty good enough. I wouldn't use the colorful one with a switch.

2. For the sub, I saw that on your Astro you did not leverage the speaker Hi-level output and just the Input. If I connected the Hi- Level output to the AMP UP connector going to the Logitechs, is that any different from stacking the wires to the amp in your setup?
I was also going to leverage the line level as shown on the diagram:


Would this be no longer necessary if I were to route through the subwoofer?
Should I also pickup of the inline capacitors for the speaker wire? If so, can you reference what you used?

Thank you very much!

I'm trying to think of why I wired it that way but can't remember. Since I added the subwoofer later after the amplifier was already installed, maybe I didn't want to extend the speaker wiring to connect to the subwoofer high level output. You can connect the subwoofer speaker output to the AMP UP connector and it might sound better that way since the subwoofer applies a crossover filter. Your diagram looks like a line output converter and you only need that for converting JAMMA amplified audio to line level audio. If the Mistercade has line level RCA audio output then you don't need a converter. Inline capacitors are optional and you may not hear any difference with them. And if you use the subwoofer speaker output then you definitley don't need capacitors since the low frequencies are already filtered out. The capacitors I used are 125uF 100v electrolytic bipolar (non polarized) from Parts Express.

 

[Onizuka]

Thanks Thomas! I think I know the answer based on reading your Astro restore, but am I safe to assume you've had no CRT related issues with the subwoofer being a 1-2ft away? I know there are some old magnetically shielded subs in the wild, but I'm hoping to not have to rethink Acoustic Audio.

BuddyC's addition of the Behringer EQ sounds interesting to help with the Logitech's. Do you think it's worth it in my scenario? Sorry for the serious lack in Audio/Arcade knowledge! My cab will be 2 hours away and I'll be super limited to make ongoing improvements. Thanks again!

 

[Thomas]

Thanks Thomas! I think I know the answer based on reading your Astro restore, but am I safe to assume you've had no CRT related issues with the subwoofer being a 1-2ft away? I know there are some old magnetically shielded subs in the wild, but I'm hoping to not have to rethink Acoustic Audio.

BuddyC's addition of the Behringer EQ sounds interesting to help with the Logitech's. Do you think it's worth it in my scenario? Sorry for the serious lack in Audio/Arcade knowledge! My cab will be 2 hours away and I'll be super limited to make ongoing improvements. Thanks again!

No issues with the CRT. That subwoofer is only a 6" driver and too far away for the magnet to affect the monitor. Adding an equalizer will allow you to reduce the 2k-6k frequency range to hopefully eliminate any harshness. If you really want the best sound you can try to build a ported enclosure for the logitech speakers. You would need to modify the speaker mounts and there's not much space in there so it would be challenging.