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  1. G

    Spectral factory contact - help

    Website back online...
  2. G

    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...
  6. G

    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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    Spectral DMC-30 SV

    ack, SemiSouth is long gone. The link you posted is from 2011 and the "made for audio" claim was an effort to keep the company alive by covering applications the SiC technology was never meant for. Try the company website and you'll find a weight loss company now. SiC, as well as GaN, are made...
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    Spectral DMC-30 SV

    Hi ack, thermal tails used to be a problem for wide bandwidth circuits made with discrete components, back when ICs where not yet available. Wide bandwidth and high speed are synonymous. No difference. Both self heating (linear) and thermal tails (non-linear) distortions have been eliminated by...
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    Spectral DMC-30 SV

    Thanks for posting the link to the 30SV bulletin. A lot of marketing hype. Too bad for a company that is truly state of the art. That is probably how you survive so long in the high end arena. The "thermal tails" stuff is old news. It used to be new when the world switched from hollow state...
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    Sibilance with Spectral gear

    Hello, the new speakers may have affected the stability of your amplifier and caused excessive distortion that may be perceived on high pitched tones. It is a matter of interaction between the amplifier output stage (at frequency well beyond the audio band) with cable and loudspeaker...

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