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Halex 3/8-in Die Cast Zinc Set Screw Connector Conduit Fittings (100-Pack) Use the 3/8 in. Twin Screw Clamp Connectors (100-Pack) to connect non-metallic sheathed cable to steel outlet boxes. The connectors are designed for indoor use only and fit standard 1/2 in. They are made of zinc and are corrosion resistant. Equipped with our patented Speed Safety Valve for fast and easy inflating and deflating & Kwik-Connects to hook the SIDEWINDERS together. 63' x 50' (each tube, deflated) 1-3 rider tube for boating & watersports. Kwik-Connect - Airhead's patented Kwik-Connect for quick and easy rope connection. Universal Push-Pull Tube Output. Designed for general purpose or replacement use in push-pull tube output circuits. Frequency response: 150 Hz. 15 Khz at full rated power (+/- 1db max. 1 Khz) Open style with minimum 5' long primary leads. Secondary solder lugs for convenient secondary connections (except 125B - uses minimum. I haven’t opened this game since 2 months ago ?.
The thoughts below are all the evolving opinion of one person (me). These are opinions, not facts, and in many cases I'm making generalizations, so take this advice for what it is. Anymp4 dvd converter 8 2 12 download. Your ears, your room, your system..are all yours. So in short, your mileage may vary.
Single Ended vs. Push Pull
In general, I’ve found that single ended amplifiers produce a more detailed, more realistic soundscape than push pull amplifiers do. They can make a good recording sound so very real and in the room, pulsating with life and vibrancy and lit from within. The human voice reproduced through a single ended amplifier can be spooky realistic, but it requires a specific quality of speaker to truly appreciate.
![Pull Pull](https://m.media-amazon.com/images/I/715fF9+BAWL._AC_SX425_.jpg)
The two biggest disadvantages that many single ended amps have are bass and power; some of them do not make much deep bass and many circuits put out less than 2 watts per channel. However, there are a lot of factors at work here beyond the circuit, the tube, and its limitations: the type and quality of the transformers, the type and efficiency of the speakers, etc, all have a big role to play. So poor bass performance is not always the case, and low power does not have to equate to low output. Some single ended amplifiers produce very low and very well controlled bass that rival the best push pull designs, and with the right speakers, 2 watts can fill a room with sound loud enough to bother the neighbors.
Push pull amplifiers generally have one big advantage over single ended amps. Power. Most push pull designs produce more power than single ended amps do, and this can be a big factor for inefficient speakers. If you have 82 db/wm multi driver monsters, you’ll have a hard time finding a single ended amp that will drive them to acceptable room-filling and realistic sounding levels. In that case, push pull amps will almost always sound better. In addition, I've found that some hi efficiency speakers (Lowther, I’m looking at you) actually sound better with a bit of power, and 12 or so watts of PP 6V6 can be a great thing! Push pull will fit most situations better than single ended amps will simply because of speaker compatiility, but they usually give up a touch of the palpability and “air” that single ended does so well.
This is a good excuse to have both.
Speaker efficiency Audulus 3 4 1 – minimalist modular audio processor.
So this brings us to speaker efficiency, and its importance in matching your amplifier. If you want to play with the tiny flea-watt single ended amplifiers (think the 45, 1626 or the 71a) you’ll need speakers with the highest efficiency possible. With amps of under 2 watts, its my feeling that you should be aiming for speakers in the 97 db/wm range or above. More is better. That's not to say a 45 wont work with a less efficient speaker, it certainly will. But it likely won’t have the grunt to make the most satisfying reproduction of the program material. It probably wont “breathe” in the way that showcases what the little tube can really do.
Once you get into the 3-5 watt range, things open up a bit. 92 db/wm is a good minimum recommendation for amps in this spectrum. Of course, more efficiency is almost always better. It’s like having more horsepower under the hood. Sometimes you need a bit extra to pass on a hill, and having that power at your disposal opens things up.
So why aren’t all speakers efficient?
It seems that back in the day they were. When tubes were the standard, and small amps were common, necessity dictated that speakers were built to be very efficient. Then, in the mid-1960’s, things changed. The transistor came along, and suddenly amplifier power was no longer an issue. Making a hundred watts per channel became possible and affordable, and huge and powerful transistor amps became the norm in the marketplace, quickly pushing the tube amplifiers out of mainstream production. This opened the way for less efficient speaker designs, and we began to see some really inefficient designs in the speaker world, with massive and complicated muti-drivers and huge crossovers that burned up more wattage themselves than many single ended amps could produce in total. But the audio marketing folks loved it (think megapixels in today’s digital camera world, each year upping the ante with questionable results but compelling marketing copy) and each year newer, “better” and even less efficient speakers came into the market powered by the newest “improved” transistor designs. The tube amplifier was an antique and nearly obsolete in just a decade or less.
If not for some hobbyists in Japan and on the West coast, hifi tube audio and single ended designs in particular might have disappeared forever. Now we find ourselves in a kind of renaissance of tube amplification, with new and innovative designs being developed in DIY basements and small scale production houses, picking up where engineers left off 50, 60 and 70 years ago. In 1985 it would have seemed very unlikely that new production 300B tubes would be common in 2017, much less the real antique outliers like the 45 or the PX25. But here we are (thank God!).
Side note: Its worth noting that tube amplification was never in danger from the music industry side of things. Tube guitar amps have been the mainstay of many, many musicians since the very beginning, and that is still true today. While the hifi world may have become finicky about tubes, the people who actually make the music never wavered.
Why full range drivers?
A good full range driver will make music sound real. The ideal (dream) full range driver would faithfully reproduce all of the critical frequencies by itself, so there would be no need for separate low frequency and high frequency drivers, and therefore no need for a crossover. Because the entire spectrum is being produced by one driver, the full range driver is a point source, and our very sensitive ears don't hear that critical midrange being broken up from multiple points and timings as a multi-driver speaker design does. This is tough to do with one driver in the real world, and of course there are compromises at both frequency extremes, but namely bass energy. Not many full range drivers can make really low bass, say sub 60hz. But the midrange can be so wonderful that the lowest bit of bass often matters less.
The crude graphic below illustrates just how low in the spectrum the vast majority of music and voice fall. As you can see, almost all of the really critical information is below 4khz, (although what you really care about hearing is likely below 2khz) and that is well within the ability of even a modest full range driver to reproduce with startling accuracy. Having all of that midrange information coming from a point source is what makes full range drivers sound the way they do. I’ve certainly found it addictive.
DIY Vacuum Tube Amplifier Projects Do-It-Yourself (DIY) vacuum tube (valve) amplifier and tube preamplifier projects. Please be aware that most of these vacuum tube projects use potentially lethal voltages that can kill you so do not attempt them if you are not familiar with high voltage safety! Some of the projects use low voltage and if you are new to tubes and high voltage safety you should start with these. For books on the subject of vacuum tubes, see our DIY Audio Book recommendations. Questions and discussion about tubes and hi-fi audio is always welcome in the DIY Vacuum Tubes forum. Last update: 10 November 2019 | Follow DIY Audio Projects |
DIY Vacuum Tube Amplifier Projects
Chronological list of our DIY vacuum tube Hi-Fi audio projects.
High Fidelity Tube Junk Box Audio Amplifier - 10 November 2019 NEW Bruce Heran outlines the design and construction of a High Fidelity Tube Junk Box Audio Amplifier (JBAA). The schematic is similar to the PoddWatt design and able to use a huge variety of tubes. The JBAA tube amplifier can use a 12AX7, 12AU7, ECC82, ECC83, 5751, 12SL7 or 6SL7 in the driver position while 6V6, 6AQ5, 6005, 6Y6G, EL84, 6BQ5, 6F5P, 6P15P-EB, 6Y6GA, 6K6, 6W6, 6GV8, 6BM8, ECL82 or ECL85 can be used for the output tubes. The circuit is biased into Class-A, ultra-linear operation and output power will be dependent on the tubes utilized. |
6CY7 Single-Ended Triode (SET) Amplifier - 30 July 2016 This inexpensive Single-Ended Triode (SET) amp is built around a pair of 6CY7 vertical deflection dual triodes built for TVs. At full output the amp produces a clean 1.3 Watts output per channel into 8Ω. The Edcor XSE output transformers are rated from 70Hz to 18kHz. This amplifier did a little better than this having a -3dB bandwidth from about 46Hz to about 30kHz. The 6CY7 stereo amp uses a 6CA4 tube rectified power supply with excellent channel separation. Matt reports: This is quickly becoming my favorite amp. I currently have a set of NOS Sylvania tubes in it, but I have also used a set of old used GE tubes which sound just as good. I highly recommend that anyone looking for a little iPod or computer amp give this one a try. |
6EM7 Single-Ended Triode (SET) Amplifier - 29 June 2015 Matt describes the design and construction of a Single-Ended Triode (SET) amplifier built around a pair of 6EM7 double triode tubes. The clean output power from the 6EM7 SET amplifier is about 2.2 Watts per channel with a frequency response that matches the audio output transformers. The single-ended 6EM7 amplifier is housed in a vertical wooden chassis that has been styled after early vacuum tube equipment of the 1920s. The 6EM7 SET amplifier uses a 6CA4 tube rectified power supply with excellent channel separation and which is very quiet. Matt reports that The 6EM7 amplifier sounds wonderful! The bass is well articulated without being boomy, mid-tones are clear and even, and the highs are crystal clear. |
DIY 300B Single-Ended-Triode (SET) Hi-Fi Amplifier - 24 March 2014 This DIY 300B triode amplifier project was completed by Stamou Tasos who is from Greece. As a thank you for the 300B amplifier schematics, Stamou has shared his implementation of the 300B single-ended tube amplifier schematic by J.C. Morrison. The 300B SET amp uses a 6SN7 direct coupled driver stage and an all low mu triode array. The power supply filtering sections have been duplicated for each channel for this 300B triode amplifier and premium parts are used throughout. The audio output transformers are Lundahl LL1623. This is a great sounding 300B triode amplifier that I am sure DIYers will find very rewarding. |
4S Universal Preamplifier for 12A*7 Tubes - 15 December 2013 The 4S Universal preamp is a Super Simple Single Stage (4S) line level Hi-Fi preamplifier that works well with the entire range of 12A*7 tubes - 12AU7, 12AV7, 12AY7, 12AT7, 12AZ7, and 12AX7. You can change the tube type to vary the sound and gain considerably. The preamp uses a 6CA4 tube rectified power supply which is very quiet. The Universal preamp is fun as it allows tube rolling to compare various tubes in your stash. This is a great simple preamplifier unit to bring out the most in your power amps. |
DIY 6DJ8 (ECC88) Tube Headphone Amplifier - 24 November 2012 This low power tube headphone amplifier project comes from Bruce Heran. The simple tube headamp uses one 6DJ8 (ECC88) tube per channel. The amplifier circuit is push-pull and biased into class-A operation with a CCS. Gain is sufficient that no driver stage is required for the tube amp. The 6DJ8 tube headphone amplifier is suitable for use with many Hi-Fi headphones. Output power is over 100 mW between 32 ohms to 300 ohms. The response is 20 Hz to 28 kHz within 0.5 dB and the wide band signal-to-noise is -84 dB. |
DIY EL84 Push-Pull (Class-A, Ultra-Linear) Amplifier - 30 September 2012 Bruce Heran of OddWatt Audio outlines the design and construction of monoblock Push-Pull EL84 (6BQ5) valve amplifiers. The Mini Block tube amps use a 5751 twin triode to drive the EL84 push-pull output stage which is biased into class-A operation, ultra-linear mode. Output power is 5.8 W @ 2% (0.25% @ 1 W) and the response is 10 Hz to 44 kHz within 0.2 dB. Bruce reports that the Mini Blocks are more powerful than the Poddwatts and seem to have more detail while retaining all the good characteristics of the Poddwatt amps. |
DIY (12AX7 / 12AT7) Tube RIAA Phono Preamplifier - 1 November 2011 UPDATED The latest project from Bruce's workbench is the Groovewatt, a tube RIAA phonograph preamplifier design. The preamp uses a solid state HT power supply and DC for the heaters. Gain is 45 dB, sufficient for use with a high output MC cartridge. The design uses two 12AX7 SRPP gain stages, passive RIAA equalization and a 12AT7 cathode follower. |
Parallel Push-Pull 300B Tube Monoblock Amps - 29 September 2010 - [External Link] Rudolf Moers shares with us his parallel push-pull 300B tube amplifier design. The large 25 kg (55 lbs) monoblock amplifiers were built over a period of 14 months and cost about 1300 Euro. The input stage of the amplifiers consist of a preamplifier and cathode phase splitter using a ECC82, a driver stage using a ECC99 and cathode followers using a ECC82 tubes. The output stage uses four 300B directly heated power triodes in a parallel push-pull configuration. The output power is about 25W. An AX50 tube rectifier is used for the HT supply and all heaters are operated using DC. |
DIY ECC802S (12AU7 / ECC82) Vacuum Tube SRPP Preamplifier - 23 August 2010 Bruce of OddWatt Audio shares with us his ECC802S tube SRPP preamplifier design. The preamplifier uses a solid state power supply and DC is used for the heaters. The gain of the preamp can be set at 7 or 11. 12AU7 and ECC82 tubes can also be used. The tube preamplifier measures well performance wise and Bruce reports very clean and detailed sound with that typical warm lush tube sound. |
![Amp Amp](https://i5.walmartimages.com/asr/c3b464d5-82ab-4b0a-81ab-23164d70a971_1.d42a4a249470193fe3ff86280eaa77a4.jpeg?odnHeight=2000&odnWidth=2000&odnBg=ffffff)
DIY 12AU7 (ECC82) / IRF510 Headphone Amplifier - 12 April 2010 Low Voltage Rogers has built an improved version of his popular and simple low voltage 12AU7 / IRF612 Headphone Amplifier (5 Aug 2008). The new version allows novice builders to experience assembling and listening to their own headamp. The headphone amplifier is similar to the previous version in that a single 12AU7 (ECC82) vacuum tube is used for voltage gain and an IRF510 MOSFET follower stage is used to provide current to drive demanding headphones. The hybrid tube and MOSFET amplifier operates off a 12V SLA battery so there are no high voltage concerns. The main difference from the original version is that a LM317 regulator is used as a CCS to bias the MOSFET into class-A operation instead of a load resistor. The project includes PCB image files and can also be built on a protoboard. This simple headphone amp can be built for about $40-50. |
Pull Tube 1 3 45 X
DIY 6L6 / 5881 Single-Ended (SE) Tube Amplifier - 9 February 2010 This fantastic looking tube amplifier was put together by Mr. Chey in Thailand. The DIY enclosure is constructed from aluminum sections and the audio output transformer covers are built using copper clad board. The circuit is very simple, a single-ended output stage using 6L6 or 5881 tubes, driven by 6SJ7 or 6SD7 cutoff pentodes. Mr. Chey is very pleased with the results and has replaced his solid state amp with this beauty. Nice work! |
DIY KT88 Push-Pull Monoblock Tube Amp Kit - 30 November 2009 KIT A build and review of the Odd Block KT88 Series 1 Tube Amp Kits. The monoblock tube amp kit uses an SRPP input stage with 5751 driver tubes and a push-pull output stage with KT88 power tubes. A constant current source (LM317HVT voltage regulator) is used to force the output stage into class-A operation. A solid state power supply is used. The tube amp kit comes with a nice steel enclosure and the power output is about 25 watts. The amplifier circuit is very simple with minimal parts in the signal path. The result is a very nice sounding tube amplifier kit that performs well. |
5751 SRPP / EL84 (6BQ5) Push-Pull Tube Amp - 19 Oct 2009 UPDATED (8 Oct 2012) Bruce has constructed another one of his great sounding OddWatt tube amplifier designs, the PoddWatt. This one is very similar to the first Push-Pull EL84 (6BQ5) Oddwatt project from nearly two years ago. The tube amp uses EL84 / 6BQ5 valves in a self-inverting push-pull (SIPP) topology with a 5751 SRPP driver stage. The amplifier measures well and Bruce has reported that the sound is very good with clean detailed mids and highs and a great sound stage. |
KT88 Push-Pull Mono Block Tube Amplifier Project - 29 October 2008 UPDATED (9 Oct 2012) Bruce's second follow up to his original 'OddWatt' project are the 'Odd Blocks', a pair of KT88 Push-Pull Mono Block Tube Amplifiers. Like the Oddwatt 225, the mono block tube amplifiers will work with a number of octal tubes (KT77, 6CA7, EL34, 6L6GC, KT88, 6550, KT90). Like the previous projects the driver stage is an SRPP but this time with the 12SL7 tube and the output stage is a Class A UL SIPP with KT88 tubes. LM317HV Regulators are used for the cathode CCS. |
Pull Tube 1 3 450
KT88 Single Ended (SE) Tube Amp - 11 June 2007 Alex has pulled together a single ended tube amp based around the popular KT88 valve. EL34 tubes can be used in place of the KT88 tubes. The preamplifier tube is a inexpensive 6N1P, but the 6DJ8 / ECC88 / E88CC family of tubes can also be used. The power supply uses a 5U4 dual rectifier. |
5687 LED Biased Tube Preamplifier - 1 March 2007 Vincent has pulled together a fine looking preamplifier that is based around the 5687 twin triode. Each channel uses both sections of a 5687 vacuum tube with LED biasing used on each section. To keep potential hum at a minimum, the heater filaments are supplies with DC. To further minimize the potential for unwanted noise, the power supply is external to the preamp section and consists of a RCA-83 mercury rectifier and two 50H chokes. Very nice work Vincent. |
More Modifications for the K-12M Tube Amp Kit - 25 January 2007 KIT Another S-5 Electronics K-12M Tube Amplifier Kit! This is Bruce's build of the popular and inexpensive Tube Amplifier Kit. Bruce has completed several modifications which include many of VoltSecond's mods, new input and coupling caps, a beefed up power supply and upgraded output transformers wired in Ultra Linear (UL) Mode. |
A Case for the K-12M Tube Amplifier Kit - 9 November 2006 KIT This is Mark's build of the S-5 Electronics K-12M Tube Amplifier Kit. In fact, Mark has built three of these fantastic kits! His modifications include snubbers, a beefed up power supply and upgraded power and output transformers. |
K-12M Tube Amplifier Kit - 2 January 2005 KIT This inexpensive Tube Amplifier kit has been available for a number of years now and makes for a nice little tube amp. Don't let the inexpensive price tag fool you, as this tube amp can go head to head with amps that cost $800. With its very modest price tag, this kit is an affordable step into the wonderful world of vacuum tube audio. I have provided information about my experiences with the K-12M kit as well as several modifications and upgrades that I have tried out. |
Discontinued Tube Amplifier Kits and Superseded Tube Projects
The following projects pages are of diy vacuum tube amplifier kits that are now discontinued or tube projects that have been superseded by a more up to date project.
- Oatley K282 Valve (Tube) RIAA Phono Preamplifier Kit - 3 May 2010 - Discontinued.
- Oatley DIY 6418 Tube Preamplifier / Headphone Amplifier Kit - 24 August 2009 - Discontinued.
- Push-Pull 6T9 Tube Stereo Amplifier - 8 November 2008 - Rare Tubes.
- 12AU7 Tube Preamplifier - 24 November 2008 - Superseded, see DIY 12AU7 Tube SRPP Preamp.
- 12AU7 / IRF612 Headphone Amp - 5 August 2008 - Superseded, see DIY 12AU7 / IRF510 Headphone Amp.
- 6T9 Tube Amplifier Project (PCB Kit) - 28 July 2008 - Discontinued, Rare Tubes.
- Oddwatt 225: KT77 Push-Pull Tube Amp - 19 May 2008 - Superseded, see OddBlock Class-A Push-Pull Tube Amplifiers.
- OddWatt 212: Push-Pull EL84 (6BQ5) Tube Stereo Amplifier - 22 October 2007 - Superseded, see Update.
- The 'Beauty' - 12AX7 Tube Preamp Kit - 1 May 2007 - Discontinued, see 4S Universal Preamplifier for 12A*7 Tubes.
- 12AX7 Tube Preamplifier Kit - 12 February 2007 - Discontinued, see 4S Universal Preamplifier for 12A*7 Tubes.
- Single-Ended (SE) 50EH5 Tube Amplifier - 14 May 2005