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Sonnet Doubler/Allegro SE/30 accelerator: pics

Posted by: Byrd on 2021-11-04 04:50:58

Hi all,

I've been tearing down my SE/30 and thought I'd put up pics of the accelerator, a 33Mhz '030 Sonnet Doubler/Allegro designed for the SE/30 and IIx.

This would have been the poor man's SE/30 upgrade, very simple in design and has timing issues being unable to boot from a HD floppy at startup, and reportedly either reduces the CPU speed or floppy read speed on the desktop to read from a drive (once the driver has been installed). Some earlier B&W game sounds are too fast, but most are OK. However, it's reliable, never gets warm and is snappy in use. I'm running a IIfx ROM in mine and must try later OS releases to see if later versions of Sound Manager make any difference.

Years ago, I posted about some issues with the card 🙂

SE/30 + Sonnet Allegro Doubler = wonky system sounds

Hi, I treated my SE/30 to a Sonnet Allegro "doubler" accelerator, boosting it to 33Mhz '030 off the socketed board. It installed easily bar having to lengthen the legs on a replacement capacitor nearby to make it fit. It has 80MB RAM, 1GB HD, with a PDS network card, so fairly stock apart...

68kmla.org

Enjoy,

JB

Posted by: Byrd on 2021-11-21 00:43:59

This upgrade has been causing no end of problems in multiple SE/30s; I thought it was a bad CPU socket, bad ROM socket, RAM, etc - it's this upgrade. Any SE/30 I installed it to would maybe chime 1/10 attempts, maybe boot 1/5 out of that, and usually crash pretty quickly. I've deep cleaned, reflowed pads with the same issues. Remove this upgrade, chuck in the stock 16Mhz 030 and all is fine.

Amusingly, I pulled off the heatsink - a tiny little piece of crap - and underneath is an MC68030FE16B - a 50% overclocked part! Clutching at straws I've purchased a MC68030FE33B QFP CPU and will attempt a CPU transplant when it arrives.

It was a nice little fast upgrade when running - the IIfx ROM made it behave much better (normal speed chime).

Posted by: Franklinstein on 2021-11-26 13:09:07

MC68030FE16B - a 50% overclocked part!

Yikes. Well Sonnet sometimes does have a disclaimer about stuff like that, at least with some of their later upgrades, saying 'sometimes parts are speed-binned for an order but the order is cancelled so the chips are re-qualified and sold at higher ratings even though the badging may be for the original order.' That could also be total garbage.

Otherwise yeah maybe I'd try checking thermals to see if it's actually clocked that high? A part OC'd to that degree should run really hot in addition to being glitchy. For best results my personal guideline is to keep an OC to about 20% maximum only if also vastly improving cooling, with 10% being ideal for maintaining low-stress mostly-stock systems.

Posted by: croissantking on 2023-12-08 11:58:37

Hi @Byrd, do you still have this accelerator? And did you get it working?
I find it quite interesting and would like to reverse engineer one. How are they, performance-wise?

Posted by: Byrd on 2023-12-09 00:32:50

I've still got it, some time back I put in my socketed SE/30 and it worked fine. However, I recall with continued use it became unstable. As you say it's not a complex part so perhaps mine has a minor trace issue somewhere I'll look into.

Performance wise it certainly made my SE/30 much snappier, note sound and floppy drive issues however.

JB

Posted by: Phipli on 2023-12-09 01:35:25

Performance wise it certainly made my SE/30 much snappier, note sound and floppy drive issues however.

Did you install the driver? This sounds like what happens when you run something like this without the manufacture's patches.

Posted by: ymk on 2023-12-09 02:05:10

Amusingly, I pulled off the heatsink - a tiny little piece of crap - and underneath is an MC68030FE16B - a 50% overclocked part!

16Mhz to 32MHz is 100% overclocked.

50% overclocked would be 24MHz.

Posted by: Byrd on 2023-12-09 04:02:44

Did you install the driver? This sounds like what happens when you run something like this without the manufacture's patches.

Yep, with sound and floppy caveats as Sonnet notes.

Posted by: croissantking on 2023-12-09 06:04:36

Those are some pretty serious caveats for a commercially sold product.

Posted by: joshc on 2023-12-09 18:52:28

Those are some pretty serious caveats for a commercially sold product.

It was a much cheaper option than alternatives from Daystar etc.

Posted by: Byrd on 2023-12-09 19:55:08

When it worked - it was great but took quite a few dumb moments when you realised you couldn’t boot from a floppy, including floppy emu - made installing an OS a bit tedious, basically needing a second Mac to do then install.

Posted by: ymk on 2023-12-09 20:48:38

When it worked - it was great but took quite a few dumb moments when you realised you couldn’t boot from a floppy, including floppy emu - made installing an OS a bit tedious, basically needing a second Mac to do then install.

Would you have MacBench 3 benchmarks, by chance?

Posted by: Byrd on 2023-12-10 03:10:38

No, it’s benched out of my SE/30 but will put back in and trial again soon.