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John C to continue HiFi System Components |
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Ash
Senior Member Joined: 18 Mar 2013 Location: Dorset Status: Offline Points: 4334 |
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It's all down to component supply chains. If you can no longer purchase the parts you need and the designer can't find a workaround, the product suddenly becomes limited edition.
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We do not see things as they are. We see things as we are.
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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There was a number of things I did before I decided to quit. I think the world might end before John C runs out of Majestic parts. (I'd best update his website )
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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ICL1P
Senior Member Joined: 04 Aug 2012 Location: Faringdon, Oxon Status: Offline Points: 2341 |
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That’s good to hear.
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Ifor
===== Reflex M & ACCESSION M, CuSat50, Majestic DAC, a Proprius pair. |
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Lucabeer
Senior Member Joined: 24 Jan 2009 Location: Torino, Italy Status: Offline Points: 703 |
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Happy retirement, Graham! My only regret is that you are retiring before you ever had the chance of designing an updated Reflex M/Accession M with variable gain (41/45/48 dB)! But I will enjoy what I have for many years to come!
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Designing a phono stage that has up to 48dB of gain isn't all that hard. The hard part is the restrictions. It's a bit like changing a plug socket. You'll be better-off keeping the cracked and dangerous one than buying a new one and fitting it. Because, if you do, your home insurance is void. You see now, the regulations state that only a qualified part P electrician can do it. It's just the same with power supplies. You spend ten thousand for the privilege of being able to legally sell a power supply - which all electronics have - because, if you don't legally sell a power supply, your trading insurance is void. So, to do 48dB gain, which is 250 times, and a cartridge might be 10mV out, the output needs to swing 2.5V, but then there's the headroom. They press records such that the stylus isn't easily thrown out of the groove, which is taken to be +14dB 500Hz to 2000Hz, but the frequency doesn't matter as it's all equalised in the end. So +14dB is 5 times, so the max out is 12.5 volts r.m.s. and that's nearly 18 volts peak, and in both directions, 36 volts, so the power supply needs to be 36 volts DC, and regulated at that. But, you spent all your money for 24 volts DC regulated. Because the normally required gain leads to an output easily accommodated by that. They can't get at you if you're DIY though. I expect that one day they might restrict your every move... So now, as they can't get at me anymore, I suppose I could give you a design that does just what you want, but it will be at a much more casual pace, and you'd have to build it for yourself. I have given John permission to make anything I design in retirement too, but not for my financial gain, and at his risk. |
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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Lucabeer
Senior Member Joined: 24 Jan 2009 Location: Torino, Italy Status: Offline Points: 703 |
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Wow, I didn't think that regulations on power supplies were so strict as to allow such little design freedom... It must have become a nightmare to design good sounding products with all these restrictions! My question arose from the curiosity to try some weird cartridges which are HOMC... but not that "high output". There are some that are around 1.5 mV output, which is a bit low-ish for a standard 41-42 dB MM phono stage (and viceversa, too high for a MC phono stage). I guess it could be done with a 24V supply only by accepting less "overload margin", which I know it is NOT a good design move since I have read all your informative posts on the subject. My idea was that a variable gain MM phono stage could actually be done with a 24V supply, but with a HUGE warning to the user saying "absolutely DO NOT use the 48 dB setting with normal MM cartridges, use it - and only at your peril - with VERY low output HOMC cartridges". But yes, I don't know how many units such a phono stage would sell and if it would be economically viable.
Edited by Lucabeer - 08 Jan 2023 at 10:36am |
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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A really great idea would be for as many members to be DIY as possible, and have some circuits to have a go at, designed by ?, and if any good, the non-DIY members paid the DIY members to make them one. The designer, having no further commitments, can work for nothing and spend his pension... ...how about a donate button? I'm quite happy to share what I know because it would keep my grey matter active. But without pressure please. The way to make a high gain phono stage is to give it a high enough supply voltage, and introduce the variability at its output. Once you start messing about with voltage gain per se, it mucks about the EQ, so you wouldn't want it there (though so many do). |
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That none should be able to buy or sell without a smartphone and the knowledge in how to use apps
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