Vacuum Tube (Valve) Audio Projects
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12AX7-Golden-Dragon-Valve-PreAmp.jpgTube Preamp with Golden Dragon 12AX73125 viewsThis is a 12AX7 Tube preamp kit with many upgraded components. The tube is a Golden Dragon 12AX7. The capacitors are Sprague "Orange Drops".
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Push-Pull-KT88-Tube-Amp.jpgMillett UniAmp: Push Pull KT88 Tube Amplifier2876 viewsPete Millett UniAmp with KT88
Transformer input (phase splitter) 6SN7 driver / 6SN7 voltage gain. Push-Pull KT88 Amplifier section. 5AR4 power supply into 47uF then 10 H (draws about 165mA from 620V CT transformer) then 2700uF @ 400VDC.
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Workshop_Heater.JPG2nd DIY OTL monoblock being built3556 viewsFreezing cold in the workshop , it was a pleasure to be right next to the first monoblock that was pre heating and breaking in the output stage.
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Mill_2.JPGRear View of the DIY OTL Tube Amps 2453 viewsThe chassis of my amps were machined in this German Milling machine - a real beast . It had to be repaired at a few stages just to complete the build. You can see the torodials that are used for the Driver stage ( smallest ) ..The Heaters ( next largest 6.3vac @ 32A ) and the Output Power supply ( the largest toroid - 1KVA @ 100 VAC )
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Mill_1.JPGFront View of the DIY OTL Tube monoblocks3212 viewsWeighing in at 18.5kg's each , these chassis are milled out of Aluminum plate and form part of the main heat sink for the tube sockets that are a precision fit . 6mm thick plate was used through out . The feet are solid with machined slots using cap screws to capture from the inside ( so no holes can be seen )
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2nd_monoblock.JPGUnderbelly shot of the DIY OTL Tube monoblock2356 viewsStrangely enough , the second was made intentionally Mirror Image , but I had neglected the fact that the Toroids had the same winding tail positions , so the build wasn't perfectly mirror image after all . This actually was a bit of a headache , since the first was more ideally layed out in electrical design & visual eye candy
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Underside.JPGPartial Wiring Close up2503 viewsPoint to point wiring is a must in my opinion to achieve what you owe yourself , when it comes to turning the piece of art on . I just wish I could of shown my grandfathers what I have built. This shot shows some of the input stage power supply , Hexfreds , Precision resistors from PRP , and a snippet of the output power supply cap banks for the + / - DC rails that make up the 140 VDC supply.
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9pin-to-octal-adapter.jpg9 pin to octal tube adapter2060 viewsI wanted to verify that a 12AT7 was equal to a 6SL7 in the OD2.5. So this is an adapter made from an old octal tube base and a 9 pin socket. It worked and yes the tubes are interchangeable. I will check the frequency response and distortion and see if there is any difference, but sound wise they seem the same.
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6SN7-6L6-Tube-Amp-4.jpg6SN7-6L6 Tube Amp Top View2463 viewsTop view 6SN7, 6L6 Tube Amp.
Link to the schematics for this tube amp: Williamson 6SN7 - 6L6 (KT66) Tube Amplifier
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6SN7-6L6-Tube-Amp-3.jpg6SN7 / 6L6 Tube Amp2942 viewsWilliamson front end and phase splitter, with ultralinear output stage. 6SN7, followed by another 6SN7 driving a pair of 6L6.
Tube Amp Schematics: Williamson 6SN7 - 6L6 (KT66) Tube Amplifier
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6SN7-6L6-Tube-Amp-2.jpg6SN7-6L6 DIY Tube Amplifier2627 viewsThis amplifier uses a Williamson front end and phase splitter, with an ultralinear output stage. The valve lineup for each channel is a 6SN7 as first amplifier and phase splitter, followed by another 6SN7 driving a pair of 6L6s. Bias is set by active semiconductor current sinks. The 400V HT is generated by a double anode diode (5R4) driving a choke input filter. The audio output transformers are Hammond Manufacturing 1620s. Conservative rating of 20W per channel.
Schematic: Williamson 6SN7 - 6L6 (KT66) Tube Amplifier
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6SN7-6L6-Tube-Amp-1.jpg6SN7 / 6L6 DIY Tube Amp2946 viewsThe valve lineup for each channel is a 6SN7 as first amplifier and phase splitter, followed by another 6SN7 driving a pair of 6L6s. Bias is set by active semiconductor current sinks. The 400V HT is generated by a double anode diode (5R4) driving a choke input filter. The audio output transformers are Hammond Manufacturing 1620s. With a conservative rating of 20W per channel, measured frequency response is 10Hz to 40KHz with minimal square wave overshoot. I'm very pleased with how this unit sounds and looks.
Schematic Drawing: Williamson 6SN7 - 6L6 (KT66) Tube Amplifier
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Wooden-5687-Valve-Preamp-Rear.jpg5687 Valve Preamp - Rear View2087 viewsMy second DIY 5687 Valve Preamp project. This one is housed in a wooden box.
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Wooden-5687-Valve-Preamplifier.jpg5687 Valve Line Preamplifier1700 viewsThis is the second DIY 5687 Valve Preamplifier that I built. The enclosure is a DIY wooden box and painted black.
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DIY-5687-Tube-Preamp-Rear.jpgDIY 5687 Tube Preamp - Rear View1701 viewsRear view of my first 5687 tube preamp project. It sounds great for such a simple preamp.
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DIY-5687-Tube-Preamplifier.jpgDIY 5687 Tube Preamplifier1551 viewsThis is my first DIY 5687 tube preamplifier. Sounds great for such a simple preamp. Front view.
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DIY-6NS7-KT88-Tube-Monoblocks.jpgDIY 6NS7-KT88 Monoblock Tube Amps1823 viewsI purchased these extreme valve monoblocks from Dan in Australia, who built them from the ground up, for a song. They are based on the uni-amp cct. brd. You can plug and play KT88(s), 6L6(s) and EL34(s) output valves and switch between pentode and triode mode. The transformers are oversized and were special wound for Dan. Each block weighs over 22kg. The input and driver tubes are Golden Dragon 6SN7(s) with tube rectification. It uses tranni input coupling. Power is 27W.
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50EH5-DIY-Tube-Amplifier.jpgDIY 50EH5 Single Ended Tube Amplifier1508 viewsThis is my build of Giovanni's DIY 50EH5 Single Ended Tube Amplifier. The enclosure is a metal cookie box that has been painted black. The transformers were custom wound by a local guy.
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50EH5-DIY-Tube-Amp-Rear.jpgDIY 50EH5 SE Tube Amp - Rear View1507 viewsThis tube amp is based on Giovanni's DIY 50EH5 SE Tube Amplifier. The enclosure is a black painted metal cookie tin.
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12AX7-Tube-Preamp-Kit.jpgDIY 12AX7 Tube Preamplifier Kit1796 viewsThis is my build of the Silicon Chip Magazine 12AX7 DIY Tube Preamplifier Kit. All of the coupling capacitors were upgraded to Auricaps. The volume control is an ALPS pot from Radio Shack
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