Dec 25, 2011 a 60 watt push pull audio transformer for a pair of 6l6gc tubes is rated 5000 ohms plate to plate with 4, 8, 16 ohms on the secondary. If you need to more easily switch between different speaker impedances on our output transformers ll1620, ll1623 and ll1627, this sheet suggests two different wiring alternatives where the opt secondary is reconnected using only three jumpers. He wrote over 360 articles for various dutch high end audio magazines and is the author of the book transformers and tubes. To separate the high voltage and match the speaker impendance with the tube impendance we need audio grade output transformer. For the frequencies prominent in most music 100 hz to 1 khz this transformer will make to 14 watts at or below 5% the 1628se will only do 10 watts. Audio transformers tube output transformers lundahl. They also often have a graph showing power output vs load resistance, and percent distortion vs load. The secret of selecting a good output transformer audiotalk. Since a transformer does not create power, the power output from the secondary of an ideal transformer can only equal and in a real transformer only be less than the power input to the primary. Heres how audio transformers work for impedance matching, as discussed in my book teach yourself electricity and electronics.
For homebrew projects, the best option is to construct those transformers by ourselves and this script helps to calculate winding parameters for those. Amplifier circuit details are available in chapters 54, 66 or 67, 69 and 95. Cathode feedback helps this transformer quite a bit. Build vanderveen 70 and 100 watt single channel amplifiers. The plitron patpcb1 is designed for use with the pat4004 or pat4006 output transformers. Tube amplifier circuit board plitron manufacturing. Hammond transformers for tube audio amplifiers tube amp kits.
Results of his output transformer research were published at aes conventions in 1994 and 1998. The halfprimaries of the output transformer should have identical voltages on them. Use the ac wall wart below to power this transformer. Building a tube amp, how to calculate output transformer. The output transformer as an impedance matching device, works on the principal of reflected load. Vacuum tube audio audio projects 25 w stereo amplifier. Audio transformer tube, audio transformer tube suppliers. The output transformer is probably the most expensive part in the amplifier and something you have to live with if you like classic tube amplification. An amplifier with directly heated output tube and the same power rating would require to spend at least 3 times as much on parts to surpass the sound level. Hammond puts a century of experience into manufacturing high quality magnetics for tube applications like hifi audio and guitar amplifiers. Shown on the right is the secondgeneration 20 w stereo amplifier described below.
This blog is dedicated solely to the if transformers used in vintage radios that employ electron tubes and not transistor designs. Audio transformers line output transformers lundahl. Mcintosh circuit independent of the plate supply voltage. Mercury quite literally evolved a new science of guitar amp transformer design for tubebased guitar amps from there, and has continued to innovate and revolutionize it since. Pat pcb 1, tube amplifier circuit board the patpcb1 simplifies construction of proven tube amplifiers designs, using plitron pat audio transformers, and matching power transformers. Tube output transformers, which ones are really good.
There are tabs on the case that attach if to the radios chassis through slots. Tube amp transformers tube amp parts, guitar amp parts. To design an output transformer, it is necessary to determine the output power according to the tubess characteristics, most. If an output valve can deliver 10 watts into a load of 3000. You can also choose from single, three tube output transformer there are 460 suppliers who sells tube output transformer on, mainly located in asia. Hammond manufactures direct replacement transformers for popular tube amps from fender, marshall, vox, ampeg, orange, and yorkville traynor. Perhaps few people realize the significance of these discoveries and the resultant developments. In particular the mixed feedback drive circuits for line output transformers are analyzed in great detail. The sound of the amp is ultimately determined by the tube, the output transformer and the ultrapath cap. Most of my rca tube handbooks have, for each audio output tube, an entry in typical operations and characteristics called load resistance. A singleended power amplifier is created by removing the lower tube and the lower. If theres an example of pushpull operation they will show load resistance platetoplate.
An if transformer is typically enclosed in an aluminum case. Audio transformers tube output transformers lundahl transformers. The if transformers tabs are sometimes soldered to the chassis. How to safely test the output transformer on tube radio or. Aug 06, 20 heres how audio transformers work for impedance matching, as discussed in my book teach yourself electricity and electronics. We have been producing tube output transformers continuously for over 75 years, constantly improving and tweaking their performance. A discussion had been ongoing on the diyaudio forums about these transformers, and questions were raised concerning the few impedance selections that were available. Designing tube amplifiers is his vocationcombined with playing the. Then i cover the different speaker combinations and. This page includes supporting information for the 25 w stereo amplifier project described chapters 10 and 12 in the tab guide to vacuum tube audio, along with commentary from the author. Since the birth of audio electronics, the audio transformer has played an. The energy is transferred to an alternating magnetic field and back to electric power again. The ac impedance of an output transformer, seen by the anode of a vacuum tube when a load a speaker in our case is connected to the secondary, depends on the ratio between the number of turns, of the primary and the secondary. Understanding audio transformer technology for tube amps.
The best introduction to tube hifi ive seen, the first volume starts with the nature of sound, and covers the basics of speakers and microphones. Looking through all of my scavenged transformers i cant find a single one in the thousands of ohms, most are a few hundred and lower. It works together with the ac negative feedback from the output of the audio transformer to the cathode of ef86. Yesterdays post covered output transformers on tube power amplifiers and why they were needed. The tabs are bent so as to prevent them from coming out of the chassis slot. The views expressed herein regarding the former philco corporation are the opinions of the philco radio historical society. The if transformers used in transistor radio designs are typically too small to service and there is still a ready supply available, making it more cost and time effective to just replace. The right on the photo is the r core output transformer in bare condition. Regardless, the if transformer case tabs must be freed. Power transformer is 6000600 plate to plate 150 ma. The society shall not be held liable for their accuracy, nor shall they be held responsible for any damages caused to others by the expression of these opinions. It is a regen radio, and the article specifies using a 10k ohm to 8 ohm audio output transformer. Information on lloyd swackhammers book radios of canada.
The output transformers being compared were sansui h155 19581965 and hashimoto h205. Winding the output transformer for vaccum tube audio. The function of the audio output transformer is to transform the high impedance of the output tube to match the much lower impedance of the speaker. Output audio transformer design the output transformer in a singleended tube amplifier is the device which matches the high output impedance of the tube to the low input impedance of the speaker load 4, 8 or 16 ohm. Audiophile tube output transformers whether you are into the clean, free spirited single ended tube output or high efficiency, high power, pushpull audio, we have the output transformer for you. This is a suitable value for the screen grid potential of ef86 via r9, but the most important feature of this strange and clever dccoupling is a dc negative feedback nfb system from cathode of el84 to screen grid of ef86. A wide variety of tube output transformer options are available to you, such as power, audio, and high frequency. Inspire a love of reading with prime book box for kids. Hammond classic tube amp a classic tube audio amplifier example using all hammond. The circuit is designed by menno vanderveen, and the published in his book modern highend valve amplifiers based on toroidal output transformers. The wattage output in an amplifier may vary from application to application due to many variables such as tube types, solid state vs.
It also covered the fact that imho transformers are the last thing i would add to the output stage of a solid state power amplifier because output transformers like this contribute so much to the sound quality of an amp and not in a way that would make better sound, again imho. All opts are built in our dual coil single ccore style and can be ordered with a choice of core airgap for. Audio output transformers are heavily used in a vacuum tube and some older transistor base audio power amplifiers, but these days output transformer are quite hard to find and expensive item. Whether you are into the clean, free spirited single ended tube output or high efficiency, high power, pushpull audio, we have the output transformer for you. There is really one circuit this thing was made for that is a cathode follower. I volunteered to put a 4 ohm load on my amplifier and re run the tests. The product is enclosed in the square case on the left. The one thing im stuck on is the output transformer, according to the datasheet i need to get a 35004000 ohm transformer with a 4 ohm output to power a car speaker i have. Understanding your output transformer part one by mark. Nov 18, 20 amps that use this smaller 28watt transformer are always going to have that certain compression and dynamic that defines an output transformer going into saturation. The output transformer on a tube radio or amp is a crucial part of the design of the circuit, so a restorations viability may depend on whether it is functioning or not. Amps that use this smaller 28watt transformer are always going to have that certain compression and dynamic that defines an output transformer going into saturation. Order quick and save via our webshop toroidal all our items are immediately available from stock.
Sep 09, 2017 200 watts output transformer wiring tza 4000 power amplifier output transformer wiring. This is necessary to get an efficient transfer of the audio signal to the speaker. This is a 3volume set on, as the title implies, basic audio. Wide band output transformers with third winding for nfb exclusive use, which can make stabilized nfb circuit, eliminating unstable oscillation through the changes of secondary load. I cover how to calculate the reflected impedance of the output transformer secondary onto the primary. This tranny has pc style mounting pins but you can also solder wires to the pins for non pc hookups.
The output transformer is the heart of a valve amplifier. Due to the low part count excellent results can be achieved with a moderate budget. We have standardized the listings to make transformer selection and amp design application simpler. Rw405 is r core audio output transformer for single ended type amplifier. Mar 02, 20 yesterdays post covered output transformers on tube power amplifiers and why they were needed. In contrast, the larger bassmansuper reverb trannies will relate the vacuum tube and circuits clipping before the tranny hits the ceiling, which accounts for the fast, grainy. For the primaries of output tubes, this can be up to a couple of hundred volts, so dont think that you can relax your safety precautions it can still kill you, even driven with 3vac on the secondary of the output transformer. I need an audio output transformer for a single 50l6 tube. Basic audio, norman crowhurst, 1959 thanks to keith carlsen.
A 60 watt push pull audio transformer for a pair of 6l6gc tubes is rated 5000 ohms plate to plate with 4, 8, 16 ohms on the secondary. I want to make an audio output transformer for tube amplifier. Understanding your output transformer part one by mark baier. Audio transformers for tube amp tamura corporation. Annoying loud sound before and after updating the latest firmware november 20, the only fast workaround is restarting the os. This graph shows what cathode feedback does for this transformer at two. Circuit of tube amplifier device the output transformer is an important part of the amplifier requiring a thorough parameter determination. A schematic and the design details of this amplifier are available in mullard circuits for audio amplifiers book and in the national valve museum article. Impedance for nfb winding is 16 sg taps are provided for the models excepting f781, 782, 783, so that ul circuits can be constructed.
It was suggested that you could put an 8 ohm load on a 16 ohm 5k primary transformer to get a 2. Audio transformer is the primary part of a tube amplifier which. In section two we explored filter topologies and actually designed three which were suitable. Classic tube output audio transformer overview hammond mfg. Building an amplifier is an important step in the experimental part of the project. Designing tube amplifiers is his vocationcombined with playing the jazz guitar. Output audio transformer design the output transformer in a singleended tube amplifier is the device which matches the highoutput impedance of the tube to the low input impedance of the speaker load 4, 8 or 16 ohm. By considering the time period in which the h155 was produced, this transformer must be a little brother of those on the most popular sansui tube amplifiers and receivers, such as sansui model au70, au111, 500, 500a, and a.
Mercury quite literally evolved a new science of guitar amp transformer design for tube based guitar amps from there, and has continued to innovate and revolutionize it since. Output trannys contribute most of the distortion in a valve amp and have a limited bandwidth. In the book op amp applications analog devices, edited by walt jung the use of op amps and audio transformers in line input and output applications are discussed in depth. This transformer information appears in print form in our book. Apr 30, 2010 the output transformer is the heart of a valve amplifier. A mcintosh audio amplifier incorporating a trifilar. The two output trannys are rotated 90deg to the power mains tranny to avoid picking up induced hum from the mains tranny external magnetic field.
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