cpt_paranoia
Addicted Member
Okay, I confess; my 'as stated in the datasheet' was a deliberate red rag...
Thanks for the history.
Thanks for the history.
Looking for a budget DAC that can upsample... not finding much.
- Thread starter jmanusa6
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- dac upsampling
restorer-john
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cpt_paranoia
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Just looking at the photo of that Philips prototype. You'd hope someone would be taking better care of it, or at least giving it a bit of a dusting before taking photos of it...
cpt_paranoia
Addicted Member
I just stumbled across this, as the thread bubbled to the top on ASR... ;-)
https://www.audiosciencereview.com/...s-of-cambridge-dacmagic-plus.6887/post-153281
My guess is that that data sheet page is a revision; there may be a revision list somewhere. Or it's the first production data sheet, and there's a preliminary version somewhere; ceramic packages very much suggest early engineering samples, or pre-production run, given the bulk of the production was (I think) in plastic. Most of our engineering samples were in ceramic packages, and revisions/production versions then moved to plastic (depending on requirements). Admittedly, my first ASIC went straight to 68PLCC, but then it was right first time... I was just a two-year graduate in the mobile comms research department, not part of the 'ASIC department'. Looking back, it's amazing they gave that much responsibility to such a junior engineer; it was the basis of Vodafone's initial GSM base station and mobile development, admittedly, just one part, even if a fairly vital part (the RF synthesis/modulation).
https://www.audiosciencereview.com/...s-of-cambridge-dacmagic-plus.6887/post-153281
My guess is that that data sheet page is a revision; there may be a revision list somewhere. Or it's the first production data sheet, and there's a preliminary version somewhere; ceramic packages very much suggest early engineering samples, or pre-production run, given the bulk of the production was (I think) in plastic. Most of our engineering samples were in ceramic packages, and revisions/production versions then moved to plastic (depending on requirements). Admittedly, my first ASIC went straight to 68PLCC, but then it was right first time... I was just a two-year graduate in the mobile comms research department, not part of the 'ASIC department'. Looking back, it's amazing they gave that much responsibility to such a junior engineer; it was the basis of Vodafone's initial GSM base station and mobile development, admittedly, just one part, even if a fairly vital part (the RF synthesis/modulation).
restorer-john
Addicted Member
They could clearly see the potential..
Tell me about dual vs single ceramic packages- to my knowledge they were either ceramic or plastic (thermo). Is it a separate sandwich style process? I really don't know myself. I've seen/used ceramic substrates with silicon and then microwave? cured epoxy on top, but they weren't production. Otherwise it was ceramic and capped over the die AFAIK. Like early EEPROMs- remember them? The ceramic process back then is a mystery to me. Didn't the die go in afterwards and then get capped?
My goodness, it was the 1980s, UV eraseable eeproms. 16Kx1bit RAM (4116), Apple IIs and Z80s. CD was absolute bleeding edge...
Those early TDA 1540s are dual layer ceramic (just like the prototype but without the Al die-cap). I have some inside a few 1st generation CD players (Akai CD-D1- Kyocera built). There's a very early CDM-0 based Philips here I can take a few pics of just for fun.
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cpt_paranoia
Addicted Member
Dual-layer ceramics? Like Bourbon biscuits? Hmmm... I think it was a low temperature glass frit, rather than epoxy.
https://en.m.wikipedia.org/wiki/Glass_frit_bonding
We only ever used capped cavity ceramics, with, essentially, a soldered lid. We often received them with the lids sellotaped in place, allowing us to examine or probe them. Feature size was somewhat larger 30 years ago...
https://en.m.wikipedia.org/wiki/Glass_frit_bonding
We only ever used capped cavity ceramics, with, essentially, a soldered lid. We often received them with the lids sellotaped in place, allowing us to examine or probe them. Feature size was somewhat larger 30 years ago...