Works for fender champ, tweed champ, blackface champ and tweed princeton 5f2a. There are several things that are important in getting an output transformer made. A discussion had been ongoing on the diyaudio forums about these transformers, and questions were raised concerning the few impedance selections that were available. Professionals with experience in transformer assemblies use the computer program to calculate the number of coils and wire thickness. Excellent magnetic properties of r core as well as precisely wound construction of the coil by the computerized.
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. Tube amp power transformer current draw calculator javascript must be enabled in order for the calculations to work. Calculating output transformer impedance sarris custom. It has two types, single phase and three phase transformer. The following guidelines should be taken into account. Information about tube audio, transformers ohs audio. All we need to do is determine the turns ratio of the transformer, and with that information we can calculate what impedance will be reflected back to the primary with a given load on the secondary. Audio engineering society, october 1987, ukpdfgavs. Transformer calculation software electronic circuits. Optional rload in ohms typically the output transformer primary impedance only considered when pp pushpull is selected number of tubes power tubes pre amp tubes. But i think the transformers always work with ac current and the formula above has already been constructed with ac current. Transformers, diy tube amplifiers majestic transformer co. Artists later took advantage of this saturation for that tube sound along with higher than normal plate voltages pushing the maximums for more power from a small container.
Youre right, the 5f1 output transformer is under rated mostly for cost saving. F where flux max for the particular core is in webers. Get a low voltage ac transformer about 10v or less and place it across the speaker taps of the output transformer ot. It was suggested that you could put an 8 ohm load on a 16 ohm 5k primary transformer to. 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 ht is applied to the centre tap and either end of the primary winding is connected to the anode of a power valve.
An ot reflects the impedance load the speaker on the secondary back onto the primary winding. When current passes through the primary coil, it creates a magnetic field which then. The right on the photo is the r core output transformer in bare condition. The disadvantage is that the a2 triode requires the cost of an extra tube, and the output tube grid can overheat, so a2 is in. Choice of core material also affects the performance of the transformer. It is important to note, however, that these solutions are best only for those experts who have knowledge and experience with assembly transformers. Secrets of output transformers dali technical sales. Most core material saturates at a flux density a bit less than 1wbm2, so you need to find that value for the material you have. The cost of a tube amplifier mostly consists of the cost of an output transformer and tubes that is usually a factor limiting the sound quality. Calculation of output transformers 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.
A tube manual or tube manufacturers technical data sheets should be consulted first, before making a decision on a proper output transformer. Enter the parameters in the yellow coloured fields, and then click the calculate buttons. 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. Are you looking for the best transformer calculator software for your next project. World tube audio portal category output transformers pp. So i want to know, how to calculate turns, impedance and watts. Enclosed shielded, 4 slot, above chassis type x mounting. You know you would like to match this impedance to loads of 8 and 4 ohms, and this will be used for. Impedance matching calculator learning about electronics. If we put 5 ohms on the secondary, the tube would only see 20 ohms 5 22.
Ive made a simple automatic calculation spreadsheet along with a short pdf tutorial to help. By using the above formula, we can calculate the turn number of windings required. A 3 phase transformer has three magnetic circuits that are interlaced to give a uniform distribution of the. There are a few abbreviations i am going to use for the purpose of this explanation. The objective of this project is to develop an output transformer for singleended tube amplifiers with. Universal output transformer wiring antique radio forums.
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. So we apply an ac voltage to the primary of the transformer and we measure the output voltage to the secondary. Tube amplifiers, tube amplifiers kits, forum, parts olimpiaaudio. 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.
From the tube data books, you determine that a pair of 6l6s will put 4050w in class ab push pull into a 4400 ohm plate to plate impedance. An output transformer designed for pushpull operation has a centre tap. If you have an output transformer with unknown values and want to find the intended speaker impedance for a given tube type there are several things to consider. For any type of transformer the rms voltage from a winding is 4.
This is necessary to get an efficient transfer of the audio signal to the speaker. There are more output transformers for tube amplifier, you can get your wanted from them. Transformer capacity calculator three phase transformer. The output transformer is the heart of a valve amplifier. Results of his output transformer research were published at aes conventions in 1994 and 1998. 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. Building a tube amp, how to calculate output transformer. 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. As an example, you might want to design an output transformer for a single pair of 6l6 output tubes. We have been producing tube output transformers continuously for over 75 years, constantly improving and tweaking their performance. This impedance matching calculator can calculate the impedance of the primary or secondary circuit so that the necessary impedance value can be determined for optimum performance of a circuit.
The wattage output in an amplifier may vary from application to application due to many variables such as tube types, solid state vs. There are more tube amplifiers such as singleended, pullpush, high power, and wireless bluetooth tube amplifier. It is a regen radio, and the article specifies using a 10k ohm to 8. Output transformers made in usa triode usa tube amp. Understanding your output transformer part one by mark. To separate the high voltage and match the speaker impendance with the tube impendance we need audio grade output transformer. Audio transformer is the primary part of a tube amplifier which generates an electromagnetic field. To increasedecrease the alternating volts in electric power, transformers are used. Javascript must be enabled in order for the calculations to work. Transformer calculating output voltage ac input voltage. For homebrew projects, the best option is to construct those transformers by ourselves and this script helps to calculate winding parameters for those. Transformer winding turns and voltage ratio calculatorv1, n1, v2, n2. Designed for general purpose or replacement use not hifi, in single ended, tube output circuits. Brainstock video production our diy amp, studio, gear blog.
The forty ohms in this example is the impedance that a tube would see at the primary with a 2. This action is performed by winding different amounts of turns on the incoming primary and outgoing secondary side of the opt. In electronics, there are many instances where circuits require a specific load impedance for optimum performance. Turns ratio v in to the primary v out measured in the secondary e. Use the following instructions to determine the load resistance of an unknown audio output transformer. In tube amplifiers you need an opt because the voltages in the tube. Transformer output, 8 w, single ended amplified parts. Grand stack version with more iron, thus more power, more bass and finally more tone. A transformer is essentially a pair of coils wrapped around iron cores, which are called primary windings and secondary windings for input and output, respectively. He wrote over 360 articles for various dutch high end audio magazines and is the author of the book transformers and tubes.
Next, measure the voltage across the speaker taps with a. The capacitor that couples the output transformer to the triodes plate must be large enough to allow lowfrequency bandwidth down to 20hz or so. How you operate the tubes ultralinear, bias, plate voltage, operating points, etc. An online three phase transformer calculator to find the current in different power units. Designed specially for mot microwave oven transformers but this calculator will work for any transformer. I want to make an audio output transformer for tube amplifier. The output transformer as an impedance matching device, works on the principal of reflected load. The product is enclosed in the square case on the left.
I wonder if i have to double the value of the output voltage to get the final answer the peaktopeak output voltage. Checking an unknown output transformer we can now use this knowledge to determine the impedance of any unknown output transformer. It is proportional to the ratio of input and output impedances. In this way, current flows in opposite directions through the output transformer. The free shipping option allows tubedepot to choose the most appropriate carrier and service. Output transformerless amplifier designs otl but most tube amps use output transformers. High permeability materials make it possible to design high bandwidth transformers but such a transformer is also very sensitive to dc magnetisation. With this coil calculator you can design and calculate the properties of a coil or transformer. We have been producing tube output transformers continuously for over 75 years. Output transformers transformers passive components. Rw20 is r core audio output transformer for singleended amplifier.
The function of an opt is to lower the high voltage to safe values and to multiply the weak tube currents into larger values. Now that we know how a parafeed amplifier works, we can look into how it is implemented. 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. How to calculate electrical transformer output sciencing. Output trannys contribute most of the distortion in a valve amp and have a limited bandwidth.
Classic tube output audio transformer overview hammond mfg. How to calculate audio output transformer load resistance. Tube amp power transformer current draw calculator. 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. To design an output transformer, it is necessary to determine the output power according to the tubess characteristics. My ios calculator app for power and output transformers. Ttgcfb5000pp tube output cfb transformer 5kohm cathode feedback pushpull 474,00 zl threephase transformer t3s 2500va 3x400v 3x230v 1 890,00 zl shop is in view mode.