Recent content by geppo

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    Spectral factory contact - help

    Website back online...
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    Spectral factory contact - help

    Website seems to be down, at least from here (Italy). Are they still in business? Regards G.
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    Spectral DMA-500AR board pictures

    Hi, It seems to me the big metal can dual FET comes from Interfet process N0132L, see: https://www.interfet.com/jfet-datasheets/jfet-n0132l-geometry-interfet.r00.pdf The four digit number is probably the date code, i.e. manufactured in the 43rd week of 2017. 307 might be a customer code as...
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    Spectral Voltage conversion

    The issue with the input fuse is not the current rating but the safety certification of the product. One thing is to make the preamp work with the other mains voltage, another thing is to maintain its safety certification valid in a different market than the intended one. Some component may be...
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    Spectral Voltage conversion

    Just noticed that nobody mentioned the AC mains fuse...
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    Spectral DMC-30 SV

    ack, Enjoy the Thanksgiving holiday with your loved ones and a lot of great music from a great preamp and system. After all, that is what really matters. ;)
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    Spectral DMC-30 SV

    ack, Thank you for the pictures and the P/N for the custom dual J-FET. And, yes, it is a custom part. Well, maybe not. Anybody, willing to shell out some 25€ can buy the same chip, in the modern SMD package I've been advocating for a while, from a catalogue distributor like Mouser...
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    Spectral DMC-30 SV

    If harsh environment and wide bandwidths are both a requirement, modern ceramic packages are available for the task, see this Semelab webpage for some examples. Worth to note that the TO71 selected by Spectral is listed as a traditional package here (TO71 has the same overall size of a TO18 and...
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    Spectral DMC-30 SV

    Yes, I think they found older parts - but newer than the original NPD5566 - re-packaged in a metal can that are a better alternative in their circuit. My only complaint is about how long it took to replace an obsolete part. Hermetically sealed - metal cans and side brazed ceramic - parts used...
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    Spectral DMC-30 SV

    Forgot to mention, and for completeness, there might be some differences between semiconductors that are simply not evident because markings of small parts are not readable. I'd be curious to know what the marking is on the new "custom" dual J-FET...
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    Spectral DMC-30 SV

    Hi ack, Thanks for the great pictures. Spectral layout is a work of art and a pleasure to look at. I had a look at the many pictures of the SHHA module I've saved over the years and this is what I've found: The SMA-1 marking has nothing to do with revision levels. The P/N along with REV is...
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    Spectral DMC-30 SV

    Hi, I went through the video and I think Mr. Fryer misrepresents the current state of the art of discrete dual j-FETs, which is what I'm debating here. Some facts: The NPD5566 was first designed-in into a Spectral product by Demian Martin in the early 80s. I have a DMC10 rev. 2 schematic...
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    Spectral DMC-30 SV

    Seen the video. Well, it was a marketing presentation after all. Not a tech conference. I tend to be skeptical about most of the info about semis. You can be personal friend with the CEO of Fairchild but having custom made dies because of that is simply not going to happen. Not for a limited...
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    Spectral DMC-30 SV

    ack, I'd like to provide some answers to your questions and convey more information about semis. First off, you made a very good point about designer-design-sound priorities, I will elaborate on this later. Going back to SemiSouth SITs, the fundamental theory goes back to the mid '70s and...
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    Spectral DMC-30 SV

    ack, I wish I had more time to elaborate but I'm leaving for my summer holidays so please don't think I'm being rude if I tend to summarize things. SemiSouth going south is not irrelevant. You need to know the full story to understand what happened and the nature of semiconductor business...
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