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#1
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Sacd tube sony modified!
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#2
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On Mon, 04 Apr 2005 08:03:48 +0200, Pippo wrote:
http://www.audiocostruzioni.com/a_d/...d-modifica.htm is it stereo outputs only in valve or 5.1 outputs in valve? |
#3
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For non-Italian speaking RATs:
it is a VERY interesting tweak of a SACD, where the operational amplifiers treating the differential output from the converters and providing the analog output are replaced with tubes. An ECC82 is used as differential amplifier and one half of a ECC88, in cathode follower, provides the low impedance output (per channel). Filaments are run on stabilised DC, B+ comes from a dedicated CLC filter per each channel. It is really unbelievable how this guy managed to fit all that stuff under the hood of the original Sony SACD. There are only 3 tubes therefore I suppose that only plain stereo output has tweaked, not 5.1 (which is generally not used by RATs and similar). Ciao Fabio ha scritto nel messaggio ... On Mon, 04 Apr 2005 08:03:48 +0200, Pippo wrote: http://www.audiocostruzioni.com/a_d/...d-modifica.htm is it stereo outputs only in valve or 5.1 outputs in valve? |
#4
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Il Mon, 04 Apr 2005 08:51:16 +0000, Fabio Berutti ha scritto:
For non-Italian speaking RATs: it is a VERY interesting tweak of a SACD, where the operational amplifiers treating the differential output from the converters and providing the analog output are replaced with tubes. An ECC82 is used as differential amplifier and one half of a ECC88, in cathode follower, provides the low impedance output (per channel). Filaments are run on stabilised DC, B+ comes from a dedicated CLC filter per each channel. It is really unbelievable how this guy managed to fit all that stuff under the hood of the original Sony SACD. There are only 3 tubes therefore I suppose that only plain stereo output has tweaked, not 5.1 (which is generally not used by RATs and similar). Ciao Fabio ha scritto nel messaggio ... On Mon, 04 Apr 2005 08:03:48 +0200, Pippo wrote: http://www.audiocostruzioni.com/a_d/...d-modifica.htm is it stereo outputs only in valve or 5.1 outputs in valve? Only stereo output front. |
#5
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Fabio Berutti wrote:
For non-Italian speaking RATs: it is a VERY interesting tweak of a SACD, where the operational amplifiers treating the differential output from the converters and providing the analog output are replaced with tubes. An ECC82 is used as differential amplifier and one half of a ECC88, in cathode follower, provides the low impedance output (per channel). Filaments are run on stabilised DC, B+ comes from a dedicated CLC filter per each channel. It is really unbelievable how this guy managed to fit all that stuff under the hood of the original Sony SACD. Having the tubes right up against the ribbon cables would concern me. Usually those ribbon cables have digital signals on them, and I had noise coupling problems with tubes right near the digital stuff (microcontroller circuits for sensing button presses and commands to the CD transport, etc). Sub-mini tubes, aside from looking "cute", reduces the space issue. But any tube will produce heat (mostly from the heater) so one has to select a spot away from digital circuits and select a spot near everything that won't mind the heat. Unless you use filament signal tubes, but that limits what you can do with cathodes. |
#6
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In fact I'd be concerned, too, but there are only a few volts to be swung:
the tubes can be fed only 80-90V and work at 1/10 of their rated anode dissipation. I have a tubed phono preamp using EF86s and ECC88s @ about 1/4W per anode or less: the glass gets barely lukewarm, and the screening metal can remains as cold as the rest of the unit. I suppose that using a similar approach (low dissipation + screening cans) there shouldn't be any problem. By the way: in this case the flat cables convey high frequency signals, while the tubes handle LF. This probably eases the noise issue, but don't shoot me, I'm not an electronic professional. Ciao Fabio "robert casey" ha scritto nel messaggio k.net... Fabio Berutti wrote: For non-Italian speaking RATs: it is a VERY interesting tweak of a SACD, where the operational amplifiers treating the differential output from the converters and providing the analog output are replaced with tubes. An ECC82 is used as differential amplifier and one half of a ECC88, in cathode follower, provides the low impedance output (per channel). Filaments are run on stabilised DC, B+ comes from a dedicated CLC filter per each channel. It is really unbelievable how this guy managed to fit all that stuff under the hood of the original Sony SACD. Having the tubes right up against the ribbon cables would concern me. Usually those ribbon cables have digital signals on them, and I had noise coupling problems with tubes right near the digital stuff (microcontroller circuits for sensing button presses and commands to the CD transport, etc). Sub-mini tubes, aside from looking "cute", reduces the space issue. But any tube will produce heat (mostly from the heater) so one has to select a spot away from digital circuits and select a spot near everything that won't mind the heat. Unless you use filament signal tubes, but that limits what you can do with cathodes. |
#7
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Fabio Berutti wrote:
In fact I'd be concerned, too, but there are only a few volts to be swung: the tubes can be fed only 80-90V and work at 1/10 of their rated anode dissipation. I have a tubed phono preamp using EF86s and ECC88s @ about 1/4W per anode or less: the glass gets barely lukewarm, and the screening metal can remains as cold as the rest of the unit. I suppose that using a similar approach (low dissipation + screening cans) there shouldn't be any problem. By the way: in this case the flat cables convey high frequency signals, while the tubes handle LF. This probably eases the noise issue, but don't shoot me, I'm not an electronic professional. If the tubes normally have tube shields over them, then the ribbon cable issue goes away. Take a look at my web page http://pw2.netcom.com/~wa2ise/radios/tubedac.htm where I describe a few tube related mods to CD players. |
#8
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WOW! This is a contribute! Sub-miniature tubes fit anywhere and are even
easy to find (see Russian 6N16B-V which is +/- a 6211..) If I hadn't done something similar with an ECC88 I'd clone Your project. Thanks Fabio "robert casey" ha scritto nel messaggio nk.net... Fabio Berutti wrote: In fact I'd be concerned, too, but there are only a few volts to be swung: the tubes can be fed only 80-90V and work at 1/10 of their rated anode dissipation. I have a tubed phono preamp using EF86s and ECC88s @ about 1/4W per anode or less: the glass gets barely lukewarm, and the screening metal can remains as cold as the rest of the unit. I suppose that using a similar approach (low dissipation + screening cans) there shouldn't be any problem. By the way: in this case the flat cables convey high frequency signals, while the tubes handle LF. This probably eases the noise issue, but don't shoot me, I'm not an electronic professional. If the tubes normally have tube shields over them, then the ribbon cable issue goes away. Take a look at my web page http://pw2.netcom.com/~wa2ise/radios/tubedac.htm where I describe a few tube related mods to CD players. |
#9
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Fabio Berutti wrote:
WOW! This is a contribute! Sub-miniature tubes fit anywhere and are even easy to find (see Russian 6N16B-V which is +/- a 6211..) If I hadn't done something similar with an ECC88 I'd clone Your project. Thanks, happy you like it. A new idea (at least to me, it's probably been done somewhere) is a differential pair-SRPP circuit. See at AudioKarma: http://audiokarma.org/forums/showthread.php?t=36116 http://audiokarma.org/forums/attachm...id=31022&stc=1 If you want differential outputs use a tube and circuit like V6 in place of R10. I've only run simulations, haven't built it yet... |
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