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"Green" Reflex Tweak |
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Posted: 15 Jan 2008 at 4:23pm |
This is a tweak for the few owners of the pre-release "green" Reflex who bought via the Rockgrotto offer, and applies to those phono preamps shipped before today's date (15th Jan 2008).
It requires a simple value change to a resistor in the discrete voltage regulator section. There is a bank of 5 resistors and a diode above one of the op-amps. The resistor furthest away next to the diode is currently 470R. It should be changed to 1k. It's a good idea to use a Welwyn TI MFR4 type which is the type used throughout the design. After modifying the board it is wise to check the voltage across the series zeners (located in the centre of the pcb) which should be 18.2V plus or minus 5%. I'd detected a very slight "sizzle" on some vocals and instruments like saxophone and decided it must be an artefact of the switched-mode power supply. The tweak reduces the zener current sufficiently to curtail this subtle distortion. If owners can't detect anything like I've described, not to worry, the unit will carry on working without this mod. |
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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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Sol
New Member Joined: 14 Jan 2008 Status: Offline Points: 28 |
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Blimey .. give me a chance Graham - I haven't even plugged the thing in - it having just arrived today
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Semper in excretum, nil profundum variat.
Non illigitimum carburundum! Cuius testiculos habes, habeas cardia et cerebellum |
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John C
Admin Group gspaudio moderator Joined: 13 Jan 2008 Location: Sheffield Status: Offline Points: 197 |
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Don't worry Sol, he does it to me all the time....
Oh!! hello Graham, didn,t see you there....
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hooograa
New Member Joined: 19 Jan 2008 Location: Australia Status: Offline Points: 3 |
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Being the holistic person you are Graham what kind of solder do you use? I've got some plain lead and some silver/lead types. As I can vaguely remember electrical differences and interference being a bugbear that you had to fight in development. Thanks David
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Graham Slee
Admin Group Retired Joined: 11 Jan 2008 Location: South Yorkshire Status: Offline Points: 16298 |
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Hi David,
We use Multicore 99C which is mainly Tin with a trace of Copper. Lead is a banned substance in European Community and Californian consumer electronics manufacture. 99C was the best of the Lead-free solders I could find - the rest gave "dry-looking" joints. Even after using Lead-free since 2004, I miss the Lead based solders for their ability to flow out properly and desolder when required with great ease. Visit most European assemblers or repair shops and you should hear numerous exclamations of "solder you bas****!" from extremely frustrated staff...
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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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John C
Admin Group gspaudio moderator Joined: 13 Jan 2008 Location: Sheffield Status: Offline Points: 197 |
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I'll second that one. I know Leo will agree too
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ServerBaboon
Senior Member Joined: 16 Jan 2008 Location: NW England Status: Offline Points: 968 |
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Have noticed what seems to be a bit of distortion on a couple of old 60s tracks (repressing/reissues not originals) especially with some Saxaphone which I took to be a bit of overload in the studio does it manifest in loud parts or climaxes or is noticable in quieter passages? To be honest I am sorting out getting a new cartridge as mine is quite old and so I have also wondered if its this. I will compare with my Gram amp 2SE. Edited by ServerBaboon - 28 Jan 2008 at 11:23pm |
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