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Finished~0.JPGOPA2134 Opamp Preamp - Big Brass Knob3976 viewsMy third Burr-Brown OPA2134 based preamp sees a sleek red die-cast aluminum case of two coats of epoxy paint and a sexy 4 oz brass knob. This build is based around the 1uf Jupiter Bees Wax and Paper caps. See other photos for more info. The first thing I notice when playing this preamp through my valve monoblocks was a dramatic increase in bass. The other obvious audio advantage is an increase in stereo focus. Not only is bass deeper (and louder) but there appears to be more layers to it. Voice sounds earthier and more immediate. A 26V 3.5A computer PS powers the unit but each channel has its own and separate virtual PS. Five 220uF low ESR caps store power directly on the cct. brds. A suspended wooden floor in the case provides a base to suspend the cct. brds on. Silver wire and silver solder is used throughout with an Alps blue velvet attenuator. Very impressive sound. The very best one I have made to date.
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ECL86_SE.JPGECL86 Single-Ended Amplifier3968 viewsSingle-Ended monoblock amplifier using ECL86 / 6GW8 tube.
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6C33C-SE-Amp-Don.jpgSingle-Ended 6C33CC Tube Amp with 6SL7 driver3965 viewsTake a look at Don’s new single-ended 6C33C amp. The top plate is ABS plastic, the wood base is Australian Spotted Gum. There is a power transformer for the HT supply and a toroid for the 6C33C heaters. Two chokes are used to split the HT into two seperate PS channels. This is a three stage amp with 6SL7 driver tubes. The two 6SL7 triodes are linked with a cap but the second triode drives the power tube direct. Each power tube will run up to 220mA but even at 150mA the power tranni gets real hot. Don’s work is ultra neat but I had to correct all the wiring around the 6SL7 for him to get the amp to go. It sounds absolutely fabulous. Has to be Don’s best tube amp build to date.
Mark Houston – retro-thermionic
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6V6_PP_1_S.jpg6V6 PP, 6SL7 LTP Driver - Phase Splitter3956 viewsAnother try to small power PP AMPS. 6SL7 in frint in LTP configuration, using IXYS 10M45s as current sink at 1.2mA.
Output tubes are set with a fixed bias, using a separate and negative voltage power supply.
A nice sounding amplifier which provides about 10.5 Watts at 1.5 % THD. This amp uses Hammond OPT's and a PSU choke.
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Dynaco-MKIII-Copper-Steam-Deux.jpgDynaco MKIII - DEUX3953 viewsHere is a photo of my latest build. I call it the DEUX.
These are Dynaco MKIII's with the VTA octal Driver upgrade. I hardwired the driver circuit to avoid using the PC boards under the hood. The bases are made from walnut, and the top plate is 1/8" copper. The bolts are 3/4" brass.
More photos and construction shots here: http://blog.coppersteam.com/steampunk-art/deux-final/
Mike Cochran
Key West, Florida. USA
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LM3875-amplifier.jpgLM3875 Gainclone Chipamp on Protoboard3952 viewsEach LM3875 amplifier module (board) has its own DC rectifier that is made from high speed switching diodes. The supply capacitors are on the board. See the Point to Point LM3875 Non-Inverting Gainclone Chipamp Instructions for ideas on how to construct an amplifier like this on a protoboard or veroboard.
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6N7-Tube-Preamp-Heavy-Metal.jpg6N7 tube preamp (Heavy Metal)3952 viewsConstruction is in a timber box. There are three switchable RCA inputs and power is supplied by an external 18V 2.2A AC power pack. Internally 255V is developed with a linear PS and regulated 12VDC for the heaters which are wired in series.
An Alps blue velvet potentiometer is fitted at the output for attenuation control with a fine solid brass knob to compliment the gold right-angle RCA jacks, name plate and ventilation holes. Wire wrap wire is used in the signal path. The power supply and amplifier are on separate circuit boards. Bitumanised heavy aluminum foil is used to line sections of the timber box for resonance control.
For more info, see the 6N7 metal tube preamp thread on the discussion forum.
Mark Houston – retro-thermionic
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MerlotJJSGallery.jpgretro-thermionic Merlot Amp with JJ KT88 Blue Glass3948 viewsNot meaning to hog the Gallery at the moment but lots of development underway with my Merlot KT88 SE UL valve amps. I'll make it short: This is the Merlot amp with matched a pair of JJ KT88 Blue Glass. Sound: weightier bass and sharper mids but the JJs are only hours old.
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00118.jpgLM3886's and heatsink3944 viewsThe thin cables are for the grounds that (i suppose) don't carry high current. The chips have silicone grease for better thermal conduction.
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Claravox-Dogma.jpgClaraVox Dogma Loudspeakers3940 viewsVery modern looking setup. If you think it looks expensive, they are $59,000 a pair for the speakers only! I wonder how well they image with the tweeter so far away from the mid?
Website: http://www.dgfdesign.it
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Nelson-Pass-B1-Buffer-Preamp.jpg3910 viewsThe Pass B1 Buffer Preamp complete in Hammond Aluminum case. The B1 is a very transparent and PS tolerant preamp/ driver. Because it is a source follower some signal is lost (about 15%). But it is an excellent attenuator and offers a high impedance input and low output and is dead quiet. This build shares the same components as the DIY JFET BoZ preamp but sounds quite different.
For more information about this build see the Russian Pass B1 FET Preamp/Buffer thread on the forum.
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EF86-EL84-Parafeed-Tube-Amplifier.jpgEF86 / EL84 Parafeed Tube Amplifier3908 viewsEF86 driver and EL84 output Parafeed Tube Amplifier. Uses a 230V primary, 9V secondary Talema 30VA mains toroidal transformer as the audio output transformer (OPT). For more details and a schematic, see the EF86 / EL84 Parafeed amp thread.
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chipamp-gainclone-amplifier.jpgDIY Chipamp / Gainclone Amplifier3906 viewsThis is the diy enclosure for my 5 channel gainclone project. The five channels are powered by an external transformer that was borrowed from an old Fisher receiver. The amplifier is It is driven directly from an external SoundBlaster Live audio card. The cost of the whole setup, was under $100.
See the gainclone page for more amplifier ideas.
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BillsSetUp.JPGBills beautiful gear3889 viewsBill, an audio club member, held an afternoon of beautiful and varied music compliments of his valve based equipment. Valve Cymer monoblocks (bottom), passive preamp, Hydra power conditioner and separate DAC and transport. The speakers are local made but have been heavily modified with external Xovers. Truly magnificent sound.
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6E5P_SE_6n1p_driver-_maze_OPTS.jpg6E5P SE, 6n1p driver, MAZE OPT's in a scrappy chassis for testings3882 viewsThis is one of my latest audio tube DIY projects made in a scrappy chassis for breadboard use and measurements. I 'll transfer it to a nice wooden chassis now for sure.
The tube in output is the russian HF tetrode 6E5P, with max anode dissipation 8.5 Watts. It's a hell of a driver together with a CCS or Choke loaded solution. The driver is a classic ground cathode with the 6n1p for both channels. The 6n1p cathodes are not cap bypassed so the gain in this operating point is ~ 8. This is what exactly needed to drive the 6E5P in full output without the use of a preamp. The PSU is a tube type one using the Sovtek 5AR4. All the PSU caps are MKP (Mcap by Mundorf 100μF/400v.
By the way there is no Electrolytic cap in this Frankie amp. The cathode bypass cap on the 6E5P stage (output) is also MKP by Solen 82μF/250V. The coupling cap from driver to 6E5P grids is RC type using the marvelous 0.22/1000V PIO K40Y Russian caps. The OPTS are a bit over sized with 5K primary impedance made by mazeboutique.com.
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00126.jpgFinished, rear view (Ipod not included)3875 viewsCheck out the DIY heatsink.
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OPA2134-opamp-Headphone-Amplifier.jpgOPA2134 CMoy Style Portable Headphone Amplifier3859 viewsThis simple headphone amplifier is based on the high performance OPA2134 opamp chip. This headphone amp\driver is good sounding and portable. The schematic is based on the very popular CMoy headphone amp design with some changes in passive parts values. For the power supply I elected to power the amp from two 9V batteries (18V) which provides longer playback time and greater dynamics.
There is only 100 mm of hookup wire in the signal path and all connections are component-2-component on the protoboard. Low ESR 200uF caps and a resistive network provide the differential voltages required to operate the chip without an output capacitor. The brd. is silver soldered with Mil. spec machined chip socket and Russian PIO caps on the input. Power only comes on when both phone jacks have plugs in them and the power switch (at the back) is on. The enclosure is impact resistant and lined with heavy aluminum foil for shielding and enclosure resonance control. The sound is clean and bright with good volume and dynamics. The amp is dead quiet with no signal.
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5687-Tube-CD-Linestage.jpg5687 Tube Linestage3839 viewsHere I am using a diy 5687 tube preamp as a line stage for a Sony CD player.
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6P15-EL84-SV83-Tube-Amp.jpgEL84 / SV83 / 6P15 Single-Ended (SE) Tube Amp3831 viewsSingle-Ended Tube Amp using 6P15 output tubes (similar to the EL84 or SV83). 5963 signal tube and 5Y3 rectifier tube. The output transformers are inside the chassis.
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6N1P-5881-SE-UL-Tube-Amp.jpgSingle-Ended 5881 Tube Amp with 6N1P driver3829 viewsSingle-Ended (SE) 5881 Tube Amp operating in Ultra-Linear (UL) mode with a 6N1P driver. The amplifier is based on this KT88 SE UL Tube Amp. I constructed my own and used a couple of 5881 tubes which I got for free. I did use the 6N1P though. I over specked the power tranni which originally produce over 600V with no load and diode rectification. I eventually used the secondary centre tap, limiting resistors and a standby switch and brought B+ to 405V. The base is made of Asian Merbeau and the top plate epoxy enamel paint. Edcor XSE15-8-5K OPTs, and ceramic sockets add to the overall quality finish. The sound is clean and airy and the amp is dead quiet between tracks. It will play quite loud with efficient speakers and has no audible distortion. The sound stage fills the room and stereo image is very accurate.
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