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MD Attempt to improve the Amstrad MegaPC md sound output, comparison inside

keropi

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Hello!
Some time ago I managed to find an Amstrad MegaPC setup - I was looking years for one and finally got it :)
After sourcing the "mandatory" 486slc motherboard upgrade to make it more usable in DOS I started messing with ways to improve the md experience.
I reached out to Tiido (the original CCAM author) and with the help of the low-quality service manual that is available he advised on some changes and the end result is this:



The output went from flat and muffled to more clear , more bass and improved stereo desperation. Keep in mind the changes include removing/replacing smd caps and resistors on the existing pcb - there is no extra output pcb like the mega-amp or triple-bypass , I am not that keen on starting to mess that much with this piece of hardware so it's definitely a restriction. These are the kind of changes I mention - sadly there was no way to not use these 10uf THT caps in the place of the original smd ones :



So what do you guys think? Was it worth it? Anything else you think it's missing and really needs tuning?
The output does have system noise in it but keep in mind it's basically a md2 console on an ISA card inside a pc and it's audio/video output goes through a switch along with the pc-side audio/video.

Any feedback/input will be greatly appreciated!
Thanks for looking!
 

Mr. Sound-About

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I could hear the difference instantly. And, when one does a very close "play by play" comparison of the two, it quickly becomes clear just how much more alive the "after" version sounds. So I'd say it was definitely worth it. Thanks for sharing the info.

I always enjoy reading about projects like this. The Mega PC is a cool piece of kit. To me, the 60hz mod was essential. And your sound mod is tempting. The thing I'm waiting for now, is for someone to figure out the video pinout. I'd like to have an adaptor built so I can use the Mega PC ISA card in a different machine.
 

keropi

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thanks for the input!
I do plan to release the info on how to improve the sound with an easy to understand format like the 60hz mod pic I made some time ago:



I predict that soon enough we will have a better quality service manual available, there is an amstrad group on fb and the admin has an original copy of the manual that he will share. I will post it here as well, it will be easy then to see the pinout.
How do you plan to use the card in another system? the main issue is that you need to modify the case to support the cartridge/ports pcb ... looking forward to see what you have thought :)
 

Mr. Sound-About

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I predict that soon enough we will have a better quality service manual available, there is an amstrad group on fb and the admin has an original copy of the manual that he will share. I will post it here as well, it will be easy then to see the pinout.


Fantastic. I find the "MD in a PC" option convenient, but the Mega PC is too underpowered and severely lacking in ISA slots for it to be a suitable "several-in-one" machine for my needs.

How do you plan to use the card in another system? the main issue is that you need to modify the case to support the cartridge/ports pcb ... looking forward to see what you have thought :)


I have a Tandy 1000 TX that I ripped open to install a PK-X486/87SL5-1 CPU upgrade into (netting it a 50 TOPBENCH score!), and full-length ISA cards. The Mega PC card would go in there. The whole thing will look like a mess, but be very useful (& fun!) for me.
 

keropi

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Yes the stock 386sx mobo doesn't cut it unless you stick to older pc games... still a little boost is needed IMHO. With the 486slc mobo you still can't play DOOM for example but you do get 30fps in Wolfenstein3D and Jazz Jackrabbit runs super smooth with no frame delays , for me this is all I wanted this system to do.

I actually plan to make an addon card specifically for the megapc , it will have a SoundBlaster2 compatible part based on the BlasterBoard design by LABS, no OPL2/OPL3 (megapc has it already) and it will also have onboard the PCMIDI mpu interface that I produce with a friend .
I will also try for it to have a 10mbps network controller so it will basically be 3in1 :)
I have big plans :D
 

Mr. Sound-About

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Yes the stock 386sx mobo doesn't cut it unless you stick to older pc games... still a little boost is needed IMHO.


I installed the "snap-in" 50MHz Cyrix 486 SRx2. It helped a little.

I actually plan to make an addon card specifically for the megapc , it will have a SoundBlaster2 compatible part based on the BlasterBoard design by LABS, no OPL2/OPL3 (megapc has it already) and it will also have onboard the PCMIDI mpu interface that I produce with a friend .
I will also try for it to have a 10mbps network controller so it will basically be 3in1 :)
I have big plans :D


Righteous idea. No question some people would find that kind of thing useful not only in a Mega PC but in other systems with few slots.
 

keropi

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I had the same upgrade I think, it had 8kb internal L1 cache that really made a difference. But in my system I had to use the "slow" caching scheme so the boost was not enormous. With fast scheme it was great but you could see video errors in games, I guess the onboard gfx or something else could not keep up.
 
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