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6N1P-5881-SE-UL-Tube-Amp.jpgSingle-Ended 5881 Tube Amp with 6N1P driver3961 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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retro-EL34-SE-UL.jpg3944 viewsThe enclosure base is made using Australian Spotted Gum and the power transformers and choke are from Hammond. The audio output transformers (OPT) are from Edcor (15W XSE open frame type series) and reside in the base and are shock mounted. The feet are filled with lead sinkers for resonance control. A CLCRC filter network ensures the amp performs dead quietly and has an extremely high head room. Frequency response is to 40kHz and power is 5W RMS into 8ohms. Russian paper in oil caps are used in the inter-stage and bipolar caps and low ESR caps are used in the cathode bypass. Silver plated wire-wrap wire hooks up the gold plated RCAs to the nearby 6N1P and connects the secondary of the OPTs to the binding post. The paint work is epoxy enamel on 2mm high grade Al plate and component-2-component wiring. This is a fast amp with a huge sound stage and a rich lush EL34 sound.
For more info, see the Pimp my tube amp thread on the discussion forum.
Mark Houston – retro-thermionic
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6T9-Vacuum-Tube-Amplifier-Kit.jpg6T9 Tube Amplifier in Ultra Linear Mode3934 viewsMy second 6T9 vacuum tube amp with Edcor transformers. This time the screen grid resistor was cut away and the UL tap was used. I believe it sounds better using the UL tap. Detail in voice appears to be much richer and the sound stage more detailed than with the previous amp. The tubes once more are NOS GE and are the taller variety. For full details, see the Ultra-Linear 6T9 DIY Tube Amplifier page. Also, here is my first DIY 6T9 Vacuum Tube Amplifier Project.
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IMG_1419.JPGDissipator3930 viewsThe dissipater is homemade.
Note the shape and size of the inter-connecting metal between sheets... i don know if the shape was necessary but... it was a aesthetic choice.
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DIY-EL84-Push-Pull-Tube-Amp.jpgDIY EL84 / 6BQ5 Push Pull Tube Amp3926 viewsThe first "OddWatt" project. This is an DIY EL84 / 6BQ5 Push-Pull Tube Amplifier. The input stage is a SRPP using ECC802S tubes, while the output stage is ultra linear. LM317 Regulators are used as constant current sources (CCS) for the output stages. DC is used for the tube heaters.
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IMG_1420.JPGDIY Heat Sink3913 viewsAfter polishing... beautiful, no?
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6T9-SE-Tube-Amp-Kit.jpg6T9 Tube Amp with Edcor Output Transformers3909 viewsThe addition of the Edcor OPTs (XSE15-8-5K) has allowed this little amp to perform to its full potential. -3dB points are 30Hz and 20kHz and though the 1kHz square wave is a little wobbly, the amp plays well with good bass and lots of treble. See the 6T9 Tube Amp Project page for full details.
Also, here is a Ultra-Linear 6T9 Tube Amplifier that I built.
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DIY-50EH5-SE-Tube-Amp.jpgSingle Ended 50EH5 Tube Amplifier3894 viewsA DIY SE Tube amp from Japan using 50EH5 vacuum tubes. Similar in design to this DIY 50EH5 Single Ended Tube Amplifier project.
diyAudioProjects.com Comments: While we have seen similar projects built without the use of an isolation transformer, we always recommend that one is used for safety reasons.
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parallel-push-pull-300B-tube-monoblock-amplifier.jpgParallel push-pull 300B tube monoblock amplifiers3885 viewsParallel push-pull 300B vacuum tube monoblock amplifiers build by Rudolf Moers.
More information including schematics for this amplifier build are available here: Parallel push-pull 300B tube monoblock amplifiers.
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IMG_2675.JPG50EH5 / 25EH5 Tube Amplifier Internals3882 viewsFinally, the internals of the 50EH5 tube amp. I think I went a bit extreme on the fancy parts as I used 100uF Black Gate's and 62 ohm Riken's on the cathode bias of the tubes. As for the preamp I used more Riken's and a couple of 0.1 Mundorf plate caps. I also used a 12AT7 rather than the 12AX7, although they are interchangeable to what ever you decide. I then re-used a 500K pot as the volume control instead of the 100K (because that is what I had) and added a switch between preamp and line in.
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4SUTea_I_retro.jpg4SUTea - Super Simple Single Stage (4S) Tube preamp3882 views4SUTea is another Super Simple Single Stage (4S) Tube preamp that I have built. This one features single board construction with PS and amplifier together and no PCB. All housed in a Twinings timber Tea Box: Bitumanised aluminum foil controls enclosure resonance and Russian paper in oil caps link the modulated HT to the real world. Silver solder is used throughout. Heavy duty high grade gold plated RCAs grace the back and all is powered by a 24V 1A plug pack. There are two switchable inputs, Alps blue velvet pot and black chromed solid brass knob.
See the project page 4S Universal Preamp for 12A?7 Valves.
Mark Houston (Australia)
retro-thermionic
mwhouston: retro-thermionic
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SV101672.JPGBurr-Brown OpAmp Preamp II3881 viewsThis is the second of my preamps based on the high performance Burr-Brown OPA2134PA. This one has been custom built for a fellow in the US. This build has additional and switchable inputs-as you can see. The bottom and center row of inputs are selectable by the switch, the top row of connections is the output. See the DIY OP Amp Based Preamplifier page for more details.
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IMG_3498.jpgFinal active crossover + gainclone setup3879 viewsBurning the 4-channel DIY Gainclone and active crossover. I think this is the greatest sound quality improvement, especially for $50 active crossover. There is still hum from the new pair which I need to troubleshoot.
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00139.jpgFinished, front view3874 viewsNow you know why it is named Blackbox, right?
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6P15-Tube-Amp.jpg6P15 Tube Amplifier (also EL84 or SV83)3874 viewsThe tubes I'm using are a 5Y3 rectifier, Soviet military 6P15 output tubes (similar to the EL84 or SV83 either will work) and a 5963 signal tube The output transformers are inside the chassis and are vintage ones salvaged from a 1960's console amp. The power transformer and power supply choke are also salvaged.
The two volume controls are the 100K Single Series Single Shunt Stepped Attenuator (S5 Attenuator). They are the -20 to -50 dB versions which is fine with my Loth-X speakers but would be too restrictive with less efficient speakers.
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DIY-12AU7-Cathode-Follower-Preamp.JPGDIY 12AU7 Cathode Follower Tube Preamp3873 viewsA Foreplay inspired 12AU7 vacuum tube preamplifier. This is an all tube build, rectified with a 6X5GT, and regulated using an 0D3.
More details about my DIY 12AU7 Tube preamp.
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Sony-CDP-315-Modifications-and-Upgrades.jpgSony CDP-315 Modifications and Upgrades3857 viewsOK, so I also got a Sony CDP-315 single disc player and decided to try modding it. This one was much harder as It had a pair of SMD opamps and replacing them with a pair of 8 pin DIP sockets wasn't easy, but I managed to do it just fine.
So, here are the mods:
1. Installed 0.15uF X2 power filter cap
2. Intsalled a pair of ferrite chokes (on on power cord and another on the line out flat cable)
3. Replaced original opamps with NE5532 and later with Burr-Brown OPA2134 (2134s do sound better).
4. Replaced electrolytic coupling caps with a pair of Jantzens 4.7uF/630V.
5. Replaced RCAs connectors with gold plated ones.
The increase in performance was great too, but nos as good as my ONKYO DX-C380 CDP. I plan on replacing all supply and decoupling caps with Rubycon ZLs to improve it further.
Bernardo
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ONKYO-DX-C380-CDP-Modifications.jpgONKYO DX-C380 CDP Modifications3856 viewsOk, so I got this Onkyo CD Player and noticed that it was really worth modding.
Its a 6 CD player and its well constructed. It also uses the very common Sony KSS-213 pickup (the same one the Marantz 5001 and 5003 uses).
Since I had just got some Elna Cerafine caps, I decided to try them in. Here's what I did:
1- Replaced all coupling caps with 100uF/50V Elna Cerafines
2- Replaced all PS and decoupling caps with Ultra-Low ESR Rubycon ZLs.
3- Added a line supply Cap (1uF X2 Rated)
4- Added a power input choke.
5- Bypassed supply caps with smaller (1/10th capacitance) caps
6- Replaced JRC2968 OPAMP with Burr-Brown OPA2134
The end result was amazing. This is now a truly Hi-End player. It just amazing how good those Elna Cerafines sound int this kind of application. I was willing to try some Black Gates in place, but these Cerafines sound so good in there that I just gave up.
Bernardo
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furniture_014_YMax_red.jpgSET Tube Amo with 6BX7 twin triode3818 views6BX7 Single Ended Triode tube amplifier, 3 watts per channel, Transcendar audio Output Transformers, a 12 LED Watt Level "Meter", built with Poplar and Brass
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OatleyPhonoPreInsideS.jpgMongrel Dog Audio JAN6 418 valve phono preamp3814 viewsThis is the new tube phono preamp kit for MM cartridges from Oatley Electronics. The small tube preamp kit comes with all components required, including NOS JAN 6418 sub-miniature tubes and a wall wart for the switch mode power supply. The wall wart PS has multi-outlet adapters to fit most mains power outlets worldwide. The PS auto-switches to the correct mains voltage to provide 5V DC to the kit. There are two tube stages with each stage supporting a FET buffer to the next. The PCB is plated through and screen printed.
See the 6418 Tube RIAA Stereo Phono Preamplifier Kit project page for more details and a review of this kit.
Mark Houston
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