Cathodyne Phase Inverter

Maybe Tubenit could draw a schematic and layout for that?. 090 Aluminum Powder-Coated Chassis; Highest Quality Chassis Mount Tube Sockets; GR-10 FR-4 Circuit Boards; 3 Spring Reverb Tank; Uniquely Shaped Solid Ply Cabinet (no rectangles here) Crushed Glass Faceplates with Industrial Silkscreen; Made by Hand in Raleigh, NC USA; One 8-ohm 3 Monkeys Speaker. The changes to the circuit are highlighted in pink. Having said that, the Rambler's power section is much more like a Tweed Pro and its phase inverter is based on a Princeton. Our single to three phase converters will supply a number and variety of loads at full performance. Blackbird Vacuum Tube Preamp. But this amp is its own beast. I wish to address a common misconception about the output impedance of the cathodyne phase inverter with a couple of screen captures from LTspice. Many amps like Audioromy FU29 have already used Cathodyne Phase Inverter. The Brat is a 14 Watt 6V6 powered amp inspired by the tweed era of Fender amps. Super simple for a push-pull amp. Our comprehensive range comprises rotary converters from 1. To take advantage of its wide bandwidth ability, I removed the input coupling cap. I think I will keep the cathodyne phase inverter. Cathodyne Phase Inverter. A 6N6P Based Amp April 27, 2015 admin 0. It used a 6N6P triode based push pull. This is shown in the lower photograph, and it is usually this which causes the ugly 'blatting', 'swirling' or 'grainy' sounds sometimes heard in amps using this kind of phase inverter. The phase inverter has been modified to reduce double frequency distortion. Then it goes to the volume control and a simple treble bleed tone control. The split load inverter was one of the "features" of this long lasting Williamson design. The Tucson Micro Inverter Series is a single-phase, standby, solid-state Lighting (SSL) inverter system. It has a 6C4 cathodyne phase invertor. Showing all 13 results Sale! Read More. the power tubes, which increased power in comparison to the earlier cathode bias design, and a cathodyne phase inverter, using half of the 12AX7 tube Epiphone Valve Junior (757 words) [view diff] case mismatch in snippet view article find links to article. Draw the Load Line. Preamp-two 12AX7 phono stage-one 12AU7 gain stage-three inputs including phono. Cathodyne setting has more bass and a looser response. The low freq. Many very good sounding amplifiers have used this topology. The phase invertor uses the most common circuit (the Cathodyne), which when properly built can have a very good balance and can often be used in a Hi-Fi application. 6L6 – KT88 PP TUBE AMPLIFIER Designer: Nanook. Result is higher output for stage use. The meaning of PPIMV abbreviation is "Post Phase Inverter Master Volume". The precision of the phase splitting are determined by the match of the plate and cathode resistance. It uses the 12AY7 and 12AX7 preamp tube but with a cathodyne phase inverter. With a few changed, jumpered and removed parts the Windsor preamp can be used as a JCM800 pre. catholic synonyms, catholic pronunciation, catholic translation, English dictionary definition of catholic. I just finished and amp I had been working on for a while. Power Amp: Three phase inverter designs show up in tweed amps. The big issue with doing so is that you need to feed the amp with a differential signal to drive both channels. guitar amps) is that it doesn't generate any gain, so all your voltage swing has to come from the preamp. One 12AX7 gain stage followed by a volume control and one-knob tone stack. 01uF into 470k) and a 1000pF mica capacitor into the bootstrapped 6SN7 cathodyne phase inverter. The two 12AX7s not only allow you to compensate the gain-loss of the tone stack and to use a PI but also provide you with an overall different sound and overdrive behavior than an amp with just one. Then I have 142V across the tube. Think of them as two sine waves with one turned upside down. We have pre-amp, power and rectifier vacuum tubes among other types in New Old Stock from the golden era of American & European manufacturing as well as current production tubes from today. Amplifier No. In a push-pull amp, the output tubes’ inputs arrive 180 degrees out of phase. From: Vermont. Despite its extreme simplicity, the split load phase inverter is. Then I have 142V across the tube. Ray Moth, that it is again available here. The VOICE switch changes both the gain structure and the tone as you rotate it clockwise. This sort of phase inverter only uses one of the two triodes in the tube, so balancing them is pointless. This time, we push on to the output stage. One side of the tube works at unity - so something with the gain and current capacity of a 12AU7 would work great and the other side is a gain stage where a 12AX7 would be desirable. The special 6 and ultra forums have useful information. Cathodyne / LTP switch- Two common tube amp phase inverters. The Marshall/Fender phase inverter is commonly known as a "long-tail pair", or "Schmitt" type phase inverter, or phase splitter (actually, the original Schmitt inverter was a differential pair with a large "tail" resistor; the "standard" guitar amplifier phase inverter is a self-biased version of this circuit that works better with positive-only power supplies and ground-referenced inputs). Please use well-matched pairs of power tubes for maximum performance and minimum hum in triode mode. I just finished a 5e7 and also added a grid stopper resistor to the phase inverter (pin 7 i believe) WOW what a difference! I originally saw an article on the valve wizard website and decided to try it. The third gain stage is directly coupled to the cathodyne phase inverter. Interstage transformer type. The cathodyne phase inverter is a cross between a gain stage and a cathode follower, because the total load resistance is divided into two parts and shared between the anode and cathode. The amount of clean headroom you'll get from the power section is somewhat dictated by the grade of power tube used. What I want to discern is where that compresion is actually happening. However by the Brownface years the Princeton was the only Fender amp that used the cathodyne phase inverter circuit. The inverter is fed by a dc source and the current is injected into the grid as per the reference command. The VOICE switch changes both the gain structure and the tone as you rotate it clockwise. Thus these two electrodes automatically provide the two anti-phase signals required, and all that is then necessary to do is to design the circuit so that these. All parameters are adjusted for minimum distortion. The PT really calls for a voltage doubler and that hasn't been unreasonable to work with. JP, if you have time, can you model all 3? I haven't thought about p-p amp design in so many years my memory may be a bit foggy as to some of the methods I had success with (old age you know!). Williamson: cathodyne + differential amp (also known as a "long tailed pair) 6. Any change to a twin triode like a 12AX7 would change the gain structure of the amp considerably, especially if you stayed with the gain stage + cathodyne inverter setup like the Sunn has. NASTY, but vintage-y. I’m going to suggest a mod to enhance the amp’s clean aspects by keeping the output signal more symmetrical at higher volumes. Other amps using a cathodyne phase inverter: all Fender tweeds EXCEPT last-generation Bassman (5F6) and Twin (5F8). 5k cathode bias resistor (mf 1%), probably a switch for a 1. Caps say 1975. Cathodyne Phase Inverter. This is in current terminology a differential amplifier. Then it goes to the volume control and a simple treble bleed tone control. The optical tremolo on the Deluxe Reverb leaves a lot to be desired, but so does the half tube bias tremolo on the princeton. The amount of clean headroom you'll get from the power section is somewhat dictated by the grade of power tube used. cathodyne phase inverter 82a triode (anode signal) partially bypassed 81b triode (anode signal continued) cold biased 82b +HPF (cathode signal) fully bypassed 81a +LPF; cathode follower 82a; bandaxall tone stack; nubypassed 81b; cathodyne phase inverter 82b triode; double 81 driver stage; 6 el34 power stage. A negatively charged electrode, as of an electrolytic cell, storage battery, diode, or electron tube. Phase Inverter: Cathodyne type: 1/2 x 12ax7 The F. OK everybody which phase inverter design is the best, as in best balance and equal output. But first, let us do a quick recap on the circuit. Cathodyne / LTP switch- Two common tube amp phase inverters. Williamsons used the cathodyne phase splitter, aka: split load phase inverter. The special 6 and ultra forums have useful information. RL is the phase inverter plate load resistor value. PPI Master Volume. Phase Inverters D. The Harvard was a fixed bias amplifier, using a basic cathodyne phase inverter, but did include a selenium rectifier in the bias circuit. The main characteristic of this topology is "no Gain",thus giving the Princeton less clean gain, earlier breakup, and a smooth distortion. It's about the only slot in the pre-amp section. Try sticking a large value grid stopper resistor at the input of the cathodyne phase inverter (at least 100k. That's generally called a "split-load" or "cathodyne" phase inverter. Cathodyne Phase Inverter listed as CPI. LTP (long tail pair) for tightening up the low end and a more focused sound. For the 5F6 Bassman of 1957, Fender scrapped the cathodyne (a. Showing all 13 results Sale! Read More. NASTY, but vintage-y. I will choose to use a split-load (cathodyne) phase splitter, just like the SB12. They also can be used as a type of cathodyne Phase inverter, typical on Orange amps and some of the Peavey Classic 50 designs. The cathodyne is cleaner than the phase inverters used in other early Deluxe models and has it's own nasally kind of snarl with the amp turned up. Oddly the Hiwatt uses a cathode follower to set the bias voltage on the phase inverter, but not to pass signal, which seems a waste and wouldn't require much in the way rewiring to effect in a Hiwatt, although I've never done this as I don't like hacking around vintage amps, especially Hiwatts which are so beautifully wired. In a world where technological progress for the sake of “the product” seems to outstrip genuine cultural and social advancement, it’s refreshing to still be able to fire up a chunk of archaic technology and make some rock ‘n’ roll. Some models have phono amplifiers and some do not. When it comes to running vacuum tubes we have a slight challenge on our hands: they need very high voltages to run efficiently, and pretty much no one in. Two low and one high sensitivity input. 20 Billy D Light 3 years ago very cool! 5E6, is that still cathodyne phase inverter? I kinda liked the black tolex look too, but that is a beautiful restoration indeed. I was just reading up on that circuit and I am dialing in the values for the this Cathodyne as well. Cathodyne Phase Inverter: CPI: Center for Public Initiatives (University of Scranton) CPI: Colibria Philippines, Inc. Next, let’s look at the phase inverter stage. the magic of the Princeton Reverb is the cathodyne phase inverter. Taking a look at the GA40 power amplifier: The triode section of the 6BL8 is being used as a split load ( or cathodyne ) phase inverter. Chapter 7 is titled "The Cathodyne Phase Inverter". Unlike the Firefly, which uses a self-split power stage, the Lummerland drives the output tubes with a cathodyne phase inverter. Examples are nearly everywhere on this site. Not so much for a long tailed pair, which is the most common phase inverter, or for a floating paraphase. Quote:On 09/11/2018 @ 00:25, John Smart wrote : I'm brewing an amp with a 6SN7 cathodyne PI and am curious about how to implement a master volume. Many very good sounding amplifiers have used this topology. ORANGE OR112M Overdrive Series Two 1979 EX+ Input - F. The 5E3 uses a cathodyne phase inverter, so half of V2 is the PI and the other used as an extra gain stage to make up for losses in the tone control or tone-stack. On top of that, the PR36’s tube-driven reverb produces gorgeous ambience without washing out your playing. With a PRE Phase Inverter Master Volume you can easily dial in how much phase inverter distortion gets through to the power tubes. I used 83 meters long longwire antenna at height of approximately 20 meters. On top of that, the PR36's tube-driven reverb produces gorgeous ambience without washing out your playing. That simplicity is a big advantage in smaller amps when there are only so many tubes to go around and tight bass response is often deemed of negligible importance. Our single to three phase converters will supply a number and variety of loads at full performance. Yes, it goes by many names. In addition to the four output pentodes, the Cary uses four small-signal tubes—two 6922s, two 6SN7s—and splits the signal phase with a cathodyne ("split-load") phase inverter, for which HR expressed preference when compared with the more common long-tailed pair/dual-differential stages. When it comes to running vacuum tubes we have a slight challenge on our hands: they need very high voltages to run efficiently, and pretty much no one in. split-load) phase inverter design shared by its medium and larger amps at the time in favor of the long-tail-pair topology developed by Mullard, a feature that helped define the biggest and most-powerful amps in the lineup. To take advantage of its wide bandwidth ability, I removed the input coupling cap. Therefore, the phase inverter must supply two voltages of equal magnitude and 180° phase difference. Phase Inverters D. I’m curious how the 2/50/2 and 2/90/2 compare to the CL/CLX and Ultralead power amps, respectively. Next comes a second 12AX7 gain stage with global negative feedback, followed by a cathodyne phase inverter. Later (1955 and on) were cathodyne circuits, which do draw more current and will wear a tube out. Quote:On 09/11/2018 @ 00:25, John Smart wrote : I'm brewing an amp with a 6SN7 cathodyne PI and am curious about how to implement a master volume. Hence changing the 'phase inverter' tube in an OR120 to a lower gain type will lower the overall gain of the preamp stage, but this is primarily because you are reducing the gain of the gain stage immediately before the PI. A cathodyne phase inverter maintains a slightly squishy feel that's sure to put a smile on your face. Click here to download layout in PDF format. The Silvertone is not really a 5E3 but it has two 6V6s and a Cathodyne Phase Inverter (I think) so it is probably in the same ball park. It seems that a common feature of the bone stock Tweed 5E3 Deluxe is compression when turned up fully to 12. Chapter 12: The Cathodyne Phase Inverter The cathodyne * is the quintessential phase inverter -beautifully simple and absolutely balanced when used properly. It makes an amazing difference on cathodyne phase inverters. On top of that, the PR36’s tube-driven reverb produces gorgeous ambience without washing out your playing. This switch has more influence with more pentodes gain. This type of phase inverter has a gain of less than unity, so it is standard practice to have a gain stage immediately preceding the PI. So, the Rambler shares heritage with a few Fender classics. I'd say go ahead and try it. the power tubes, which increased power in comparison to the earlier cathode bias design, and a cathodyne phase inverter, using half of the 12AX7 tube Epiphone Valve Junior (757 words) [view diff] case mismatch in snippet view article find links to article. 6J5 weird phase inverter I came across this old GE J-805 radio at a local goodwill and am in the process of restoring it. The original incarnations of the tweed bandmaster were cathode biased 15" combo amps with a primitive paraphase phase inverter as opposed to the iconic 3x10" combo which utilized a cathodyne (AKA concertina) phase inverter in fixed bias. The Harvard was a fixed bias amplifier, using a basic cathodyne phase inverter, but did include a selenium rectifier in the bias circuit. Add the rest of the components. Long tailed, differential pair Mullard type. Also known as inverter. Tone Shaping Circuits. In strategizing the project, I'm noticing some high-pass filters, one at the input (0. The 5F10 was discontinued in 1961. V2A is DC coupled to a cathodyne phase inverter and then 4xEL34 in the output. The split load phase inverter takes advantage of the circumstance that the signal voltage at the junction of the plate and plate load resistor is out of phase with the grid of a tube, while the signal at the cathode is in phase. When it comes to running vacuum tubes we have a slight challenge on our hands: they need very high voltages to run efficiently, and pretty much no one in. I just finished and amp I had been working on for a while. Very simple circuit, the 7247 is essentially a twin triode wherein the first section is like a 12Ax7 direct coupled to a 12AU7 cathodyne phase inverter. The power supply is pretty poorly regulated and combined with the valve rectification isn't exactly what amp designers would call "Stiff". A huge voice from a very small box. A cathodyne phase inverter maintains a slightly squishy feel that’s sure to put a smile on your face. Killer amp!! 21 JazzBoxJunky 3 years ago. The mod converts the phase inverter from cathode bias to fixed bias to balance output and increase clean headroom. Does a tube amp's phase inverter tube have any effect on its tone? I notice most amps seem to call for a 12AX7 in this slot. The Compass is a very different design comprised of a Voight Style tone stack with a passive mid control and frequency sweep in an all tube signal path. - Bass - Treble - Presence - Gain - Master - Echo Send - Echo Return - Pilot Light - Power. I looked in my Dave Funk book and looked up the split load inverter, which is what is in the Music Man or the Cathodyne inverter. Cathodyne inverters split the signal out of one side of the final preamp tube to drive both main tubes, rather than using one side per main tube, so the 12DW7 mu difference. Haven't seen a mod forum for this amp. split-load) phase inverter design shared by its medium and larger amps at the time in favor of the long-tail-pair topology developed by Mullard, a feature that helped define the biggest and most-powerful amps in the lineup. Cathodyne Phase Inverter G. The 5F10 was discontinued in 1961. 8’s preamp section is quite unique. 21 shows the circuit with actual measured voltages, and by measuring the voltage across Rg2 it was. The push-pull output stage uses a pair of 6CA7/EL34s in ultralinear connection. The two 12AX7s not only allow you to compensate the gain-loss of the tone stack and to use a PI but also provide you with an overall different sound and overdrive behavior than an amp with just one. Phase inverter. The pentode section provides plenty of voltage gain while the triode is deployed as a cathodyne phase-inverter. Think of them as two sine waves with one turned upside down. On top of that, the PR36's tube-driven reverb produces gorgeous ambience without washing out your playing. US$699 AMP! CAB!. It is unique and throaty. for the 180 degree split to feed the two tubes. You want an octal front end and a paraphase phase inverter and cathode biased power tubes. The push/pull phase inverter is vastly superior to the Cathodyne splitter. the later "split-load" phase inverter (also known as the "Cathodyne") type which eliminated the AC balance adjustment. From a design standpoint, it made sense that Thomas designed the V-2 Pacemaker with a "cathodyne" inverter. 5D3 5E3 5F6A 5F11 6F4P Tube 6K6GT Tube 6L6GC Tube 6N2P Tube 6N6P Tube 6P1P Tube 6v6 Tube 18 Watt 5725 pentode AC15 Bassman Blackface boost switch Bridged-T Cathodyne Phase Inverter Crate EL34 Tube EL84 Tube Fender Gibson High Gain JCM800 Line 6 low watt Marshall Mods Park Plexi Push-Pull Output Reverb Rockhead single ended SRPP Supro switch. The common configurations are the cathodyne (AKA concertina), long tail phase splitter, and paraphase. The triode produces two phases of up about 26Vrms to drive output EL34 grids. Blackbird Vacuum Tube Preamp. This switch has more influence with more pentodes gain. One side of the tube works at unity - so something with the gain and current capacity of a 12AU7 would work great and the other side is a gain stage where a 12AX7 would be desirable. Two 6V6 power tubes with fixed bias. extruded styling, wide "C" case/chassis: 11 tubes: (4) 12AX7 (2) 6U8 or 7199 (Split-load phase inverter) (4) 7591 (1) 5AR4: 272: Stereo 88-watt Integrated Amplifier with "DYNAURAL" Rumble Supressor 37-wpc (RMS) 1960. Hence changing the 'phase inverter' tube in an OR120 to a lower gain type will lower the overall gain of the preamp stage, but this is primarily because you are reducing the gain of the gain stage immediately before the PI. The Harvard was a fixed bias amplifier, using a basic cathodyne phase inverter, but did include a selenium rectifier in the bias circuit. Got mine about a week. I'm sure a certain person will come in and try to disprove me on this but the 222C/D are biased further to the class B side of Push Pull AB1 than a 299A/B in all actuality the 299A is the biased the deapest into Class A of the 7189 based Scott amps. To save costs, Scott eliminated the 299-C's Phase Reversal, Rumble Filter switches, and "Christmas Tree, tri-function indicators. 12AT7 section is about equal to the 6AN8 triode section as used for the cathodyne phase inverter in the Dynaco amp. 5E6 has indeed a cathodyne inverter, the best phase inverter. Over the life of the Deluxe, Fender used three types of phase splitter. Haven't seen a mod forum for this amp. It uses the 12AY7 and 12AX7 preamp tube but with a cathodyne phase inverter. split load inverter: also known as P/K or "cathodyne" phase splitter. The Marshall/Fender phase inverter is commonly known as a "long-tail pair", or "Schmitt" type phase inverter, or phase splitter (actually, the original Schmitt inverter was a differential pair with a large "tail" resistor; the "standard" guitar amplifier phase inverter is a self-biased version of this circuit that works better with positive-only power supplies and. The PR36 employs a cathodyne phase inverter to keep that slightly squishy round feel to the tone. Larger amps like the Bassman and the Twin use the long-tailed-pair inverter. It does NOT like to be overdriven, which causes it to produce some odd artefacts. LTP (long tail pair) for tightening up the low end and a more focused sound. This is in current terminology a differential amplifier. 5 HP) all built to high quality standards and backed by a comprehensive pre and post sales service and our guarantees. The usual trick is to bias things so that you end up with thirds - 1/3 across the plate resistor, 1/3 across the tube, and 1/3 across the cathode resistor. The LTD can be pushed to the limit without clamping and still has the same feel and drive like the original models. A value of 100k to 1Meg is usually necessary. 22-47k will fit most triodes. Williamson: cathodyne + differential amp (also known as a "long tailed pair) 6. This time, we push on to the output stage. I use a 6SN7GTB for this position. The Fender Bassman is a bass amplifier introduced by Fender during 1952. PPI Master Volume. Hence changing the 'phase inverter' tube in an OR120 to a lower gain type will lower the overall gain of the preamp stage, but this is primarily because you are reducing the gain of the gain stage immediately before the PI. Which Orange model is the most Dual Rectifier-ish sounding? RV MkIII? Thunderverb? [MEDIA] [MEDIA] [MEDIA] TH series is the 'closest'. Maybe Tubenit could draw a schematic and layout for that?. The amplifier had a very simple circuit and used only a single channel with a two-stage preamp, with just a volume and (treble-cut) tone control. 12 watt EL84 Class A cathode biased power amp JJ ECC83s single triode 1st gain stage JJ ECC83s 2nd gain stage and cathodyne phase inverter. rolloff thru the earlier stages is good down to about 3 Hz at the phase inverter grid. As modulator I used an amplifier with two EL84 (6BQ5) in a push-pull connection, ECC83 (12AX7) as cathodyne phase inverter, EF86 (6267) as line preamp and ECC81 (12AT7) as microphone preamp in connection with amplitude limiter. Diagram of phase inverter and power tubes is like Dynaco MK 3 amp, but using 6L6 in your case vs KT88. All parameters are adjusted for minimum distortion. Paraphase Inverter E. A negatively charged electrode, as of an electrolytic cell, storage battery, diode, or electron tube. But because this amplifier is for headphones, I’d like to keep the overall size and power supply requirements low. The Lead & Rhythm Professional (LR-Pro) is an original circuit design from Sanford Magnetics. The concertina response is only valid when the power amp is not overdriven. Stuart Yaniger. the Cathodyne phase splitter; the Split Load Inverter; This type of phase splitter (and there are several alternative topologies), is cheep, easy to implement, and capable of good signal voltage balance between the two anti-phase outputs. Probably close to 99% of tube guitar amps use long-tailed pair phase inverters. There is much debate about the validity of this subject, but you might want to try a 12AX7 with balanced triodes. What I want to discern is where that compresion is actually happening. 022uF 630v 2 0 + + 2 2 u F Hi-Low Inputs. Each of these use half of a 12AY7, and have their own volume control. Very simple circuit, the 7247 is essentially a twin triode wherein the first section is like a 12Ax7 direct coupled to a 12AU7 cathodyne phase inverter. I will use spade plugs and pins as needed but, plan on removing the 9 pin header and direct. This amp is the most. The circuit had two innovations: a fixed bias for the power tubes, which increased power in comparison to the earlier cathode bias design, and a cathodyne phase inverter, using half of the 12AX7 tube and allowing a third gain stage on the other half. A cathodyne Phase inverter as stated above also has high voltages on the cathodes similar to cathode followers. The cathodyne phase inverter is similar to the cathode follower in design, but the total load resistance is divided in two and shared between the anode and cathode. Hi amp gurus, I recently acquired a Merrell MA-12 monoblock hi-fi amplifier off e-bay. Cathodyne Phase Inverter. The so called Cathodyne Phase Inverter circuitry has been updated to prevent coupling capacitor clamping, a phenomenon that occurs in most cathodyne circuits. The phase inverter tube is critical in a 5E3, ½ of the tube is used for the cathodyne phase splitter while the other half is a gain stage used before the cathodyne. The inverter drives the output tubes which are operated with fixed bias. 2 – Self-bias phase inverter or cathode follower; 3 – Fixed-bias cathode follower; 4 – Fixed-bias cathodyne phase inverter; Dual triode. The Variac Overdrive is an expressive overdrive pedal with the articulation and touch sensitivity of a tube amplifier. The two ouput tubes are Sylvania J. Total harmonic distortion: 0. The rectifier was a 5Y3 and the oscillator was a 12AU7 or a 12AX7. That simplicity is a big advantage in smaller amps when there are only so many tubes to go around and tight bass response is often deemed of negligible importance. cathodyne is an old standby, you can drive kt88/kt90/6550 into distortion with one. At 28 watts the Rambler makes more power and is cleaner than a Deluxe, and their pre-amp sections are similar. We have pre-amp, power and rectifier vacuum tubes among other types in New Old Stock from the golden era of American & European manufacturing as well as current production tubes from today. This design is very simple and brings good audio quality if properly built. The transition theme continues in the '62 Princeton's classic 6G2 circuit, which you could say sits halfway between a Tweed amp and the later 'Blackface' models - it has a fixed bias output stage, a cathodyne phase inverter and the famous 'harmonic tremolo' effect, using one half of a 12AX7 along with a few other components to. Chapter 12: The Cathodyne Phase Inverter The cathodyne * is the quintessential phase inverter –beautifully simple and absolutely balanced when used properly. V2A is DC coupled to a cathodyne phase inverter and then 4xEL34 in the output. It does NOT like to be overdriven, which causes it to produce some odd artefacts. The final stage grid drive rolls off (6dbV down) at 18 Hz, which means phase shift will start to show up below 180 Hz. Around 26-28 watts. I've read that the cathodyne aka split load aka concertina phase inverter suffers from inability to adequately drive the output stage. The mod converts the phase inverter from cathode bias to fixed bias to balance output and increase clean headroom. The push/pull phase inverter is vastly superior to the Cathodyne splitter. I wish to address a common misconception about the output impedance of the cathodyne phase inverter with a couple of screen captures from LTspice. Replace the Phase Inverter/Vibrato tube with a special tube having half a 12AX7 for the vibrato and half a 12AU7 for the Phase Inverter. The bottom point of the line is the B+3 supply voltage of 250 volts. The first phase inverter was the "Paraphase PI". The inverter is fed by a dc source and the current is injected into the grid as per the reference command. Hence changing the 'phase inverter' tube in an OR120 to a lower gain type will lower the overall gain of the preamp stage, but this is primarily because you are reducing the gain of the gain stage immediately before the PI. V2B (upper center) is the cathodyne phase inverter circuit. When it comes to running vacuum tubes we have a slight challenge on our hands: they need very high voltages to run efficiently, and pretty much no one in. These amps use a cathodyne phase inverter so no need for a balanced PI tube. This thing has 2 6V6 power tubes, 1 5Y3 rectifier, 1 12AT7 used in the phase splitter, and 1 12AX7 for the preamp section. The power supply is pretty poorly regulated and combined with the valve rectification isn't exactly what amp designers would call "Stiff". 090 Aluminum Powder-Coated Chassis; Highest Quality Chassis Mount Tube Sockets; GR-10 FR-4 Circuit Boards; 3 Spring Reverb Tank; Uniquely Shaped Solid Ply Cabinet (no rectangles here) Crushed Glass Faceplates with Industrial Silkscreen; Made by Hand in Raleigh, NC USA; One 8-ohm 3 Monkeys Speaker. 29 Responses to "3W Tube Power Amp". If you went with a long tail pair arrangement or a floating paraphase inverter arrangement then some of the gain could be brought back but I still think. 66: Mark III with Cathodyne Phase Inverter (5. Put the two together and connect a speaker and voila! You’ve got a guitar amplifier. A phase inverter circuit often used in high fi and guitar amplifiers in the 1950s and 1960s is the long tail pair. The Variac Overdrive emulates both a hot-rodded tube preamp and a power amp with two phase inverter options. Thus in amps that use a cathodyne PI such as the OR120 the other triode in the 'phase inverter' tube is used as another gain stage prior to the phase inverter. Phase inverter double frequency blocking distortion is the reason why high gain modifications to cathodyne phase inverter amps are not popular. Later I removed the. The topology is very common in most PP amps, input stage driving a cathodyne phase inverter that feeds the output tubes. Both the 2/50/2 and 2/90/2 use a 12ax7 for the input stage and cathodyne phase inverter, then a 12au7 post-phase inverter as a voltage amp and driver. one is input amp, the second is phase splitter/inverter Assume you mean V2/V3 are the matched ones, as they are the ones that can use the matching. I wish to address a common misconception about the output impedance of the cathodyne phase inverter with a couple of screen captures from LTspice. I will use spade plugs and pins as needed but, plan on removing the 9 pin header and direct. Here, using Polypropylene in place of Mylar yields subtle variations. Diagram of phase inverter and power tubes is like Dynaco MK 3 amp, but using 6L6 in your case vs KT88. The phase invertor uses the most common circuit (the Cathodyne), which when properly built can have a very good balance and can often be used in a Hi-Fi application. The concertina response is only valid when the power amp is not overdriven. But because this amplifier is for headphones, I’d like to keep the overall size and power supply requirements low. A pentode voltage amplifier, with parameters adjusted for minimum distortion, is directly coupled to a cathodyne phase inverter. The Marshall/Fender phase inverter is commonly known as a "long-tail pair", or "Schmitt" type phase inverter, or phase splitter (actually, the original Schmitt inverter was a differential pair with a large "tail" resistor; the "standard" guitar amplifier phase inverter is a self-biased version of this circuit that works better with positive-only power supplies and. 1/2 x 12AX7 Cathodyne. I'm going to suggest a mod to enhance the amp's clean aspects by keeping the output signal more symmetrical at higher volumes. A 6N6P Based Amp April 27, 2015 admin 0. From the input to the phase inverter this book discusses in detail the inner workings and practical design of every part. CPI: Cost Plus Incentives (contract) CPI: Center for Public Initiatives (University of Scranton) CPI: Cross Program Integration: CPI: Civilian Personnel Integration: CPI: Conditional Priority Inheritance: CPI: Command Performance Indicator: CPI: Client Program Interface (computing. 022uF 630v 2 0 + + 2 2 u F Hi-Low Inputs. Our single to three phase converters will supply a number and variety of loads at full performance. Cathodyne Phase Inverter. This amp features a 6SL7 Octal Pre-amp tube, a 12AX7 Cathodyne Phase Inverter, 2x 6v6 Class A, Cathode Bias power section and a 5AR4 tube rectifier. On top of that, the PR36's tube-driven reverb produces gorgeous ambience without washing out your playing. balanced input signal, which should mean exhibiting equal impedances, but means instead having two output phases and ground:. These amps use a cathodyne phase inverter so no need for a balanced PI tube. I just finished and amp I had been working on for a while. My amps supply to the Cathodyne plate resistor is 340V, I have a 100K plate and it drops 100V. In a push-pull amp, the output tubes’ inputs arrive 180 degrees out of phase. catholic synonyms, catholic pronunciation, catholic translation, English dictionary definition of catholic. There are two designs that dominate guitar amps. I'd say go ahead and try it. The push-pull output stage uses a pair of 6CA7/EL34s in ultralinear connection. This type of phase inverter has the unique advantage that its operation is independent of tube ageing so that no adjustments are required in maintaining optimum performance. The phase inverter was changed from a cathode biased cathodyne phase inverter to a fixed biased cathodyne phase inverter. Some models have phono amplifiers and some do not. To take advantage of its wide bandwidth ability, I removed the input coupling cap. Fender's late-1950s 4x10 tweed Bassman combo is among the most celebrated guitar amps. This is in current terminology a differential amplifier. But this amp is its own beast. A 9JW8 valve is used in this position as it was designed to have low microphony and hum – ideal for the preamp. Q: A: What is PPIMV abbreviation? One of the definitions of PPIMV is "Post Phase Inverter Master Volume". The Mullard and some McIntosh amps, as well as other vintage and historically important amps did use the long tailed pair arrangements. The main characteristic of this topology is "no Gain",thus giving the Princeton less clean gain, earlier breakup, and a smooth distortion. They should also be less than 10% of R6, which we have set at 220k. Solar Inverter-Single Phase Inverter Omniksol-2k-TL series inverters use world class technologies, the maximum convert efficiency could reach 97. It has a 6C4 cathodyne phase invertor. control stands for Frequency Analysing Control. [DIY Fever] 3W Tube Power Amp - 6AK6 power amp with 6021 submini tube and LND150 stage Cathodyne phase inverter using one spare 6021 triode. On T1, a single 5 volt winding is. A 6N6P Based Amp April 27, 2015 admin 0. The FireBelly Tweed Deluxe, 1955 Classic is the ultimate mid wattage tone machine. RL is the phase inverter plate load resistor value. This amp is LOUD though you will never have an issue with clean headroom with the PR36. Yes, nothing but a generic "cathodyne" phase inverter there. "paraphase" inverter 4. I'll do a more complete write up on this amp at some point in the near. The 6G2 Princeton's fixed-bias output stage takes it out of the nominal-class-A camp of the cathode-biased tweed Deluxe and the like, but its cathodyne inverter (a. So that leaves an extra triode and we can’t have that going to waste!. a cathodyne phase inverter is a fancy name for a phase-splitter where the plate R is divided between the cathode and the plate, and cathode and plate signals are used to drive a push-pull AF power stage without need for a interstage transformer. Extremely loud, powerful, deep lows, and overall a bit cleaner than you would expect. I’m going to suggest a mod to enhance the amp’s clean aspects by keeping the output signal more symmetrical at higher volumes. Think of them as two sine waves with one turned upside down. On top of that, the PR36's tube-driven reverb produces gorgeous ambience without washing out your playing. The Cambridge Reverb uses a both triodes of an ECC83 in a "long tailed pair" phase inverter. On top of that, the PR36's tube-driven reverb produces gorgeous ambience without washing out your playing. Q: A: What does PPIMV mean? PPIMV as abbreviation means "Post Phase Inverter Master Volume". Long-Tailed Pair Phase Inverter Lesson 12. ORANGE OR112M Overdrive Series Two 1979 EX+. Extremely loud, powerful, deep lows, and overall a bit cleaner than you would expect. Williamson: cathodyne + differential amp (also known as a "long tailed pair) 6. A typical style element of these amps was the front that had only pictures to describe the. To draw a cathodyne phase inverter's load lines we have to consider the tail load resistance and how the tail load resistor affects the cathode and grid voltages. cathodyne is an old standby, you can drive kt88/kt90/6550 into distortion with one. One half of a 12AX7 provides bias modulated tremolo with Speed and Depth controls. I always try to get the best possible parts for any device I'm building. Not in a Princeton Reverb or any other amp which uses a "cathodyne" phase inverter. Handwired on turret boards, custom made, welded 16 gauge steel chassis, custom Heyboer transformers. The later Scott models (299-C, LK-72, 222-C, LK-48) used a different phase inverter topology (cathodyne), which is lower impedance. Which Orange model is the most Dual Rectifier-ish sounding? RV MkIII? Thunderverb? [MEDIA] [MEDIA] [MEDIA] TH series is the 'closest'. Long-Tailed Pair Phase Inverter Lesson 12. And yes, while that cathodyne phase inverter may be "a bit wonky" it certainly contributes a fair amount of the overall character of the 5E3 Tweed Deluxe. The cathodyne type phase inverter has some good points, one being that it is better balanced than a long tail pair, though it has less output. Probably close to 99% of tube guitar amps use long-tailed pair phase inverters. On top of that, the PR36's tube-driven reverb produces gorgeous ambience without washing out your playing. The preamp feeds into the tried and true split load cathodyne phase inverter, which also includes one extra gain stage like a 70’s Orange/Matamp design. One side of the tube works at unity - so something with the gain and current capacity of a 12AU7 would work great and the other side is a gain stage where a 12AX7 would be desirable. Examples are nearly everywhere on this site. The split load inverter was one of the "features" of this long lasting Williamson design. The perfect head for running. You could convert a Quickie to do duty in this position, which would involve using the hardware and tubes, but setting up the second half of a cathodyne phase inverter and sending that to the Quicksand. It has a cathode follower preamp with volume, treble, middle and bass controls, a poweramp with a cathodyne phase inverter, a pair of 6V6 power tubes and a 5AR4 rectifier. Okay, now its time for the phase splitter. High pass Filters D. Unlike the V-3 Cambridge Reverb, which used a "Long-Tail" or "Schmitt" phase inverter circuit, the V-2 Pacemaker incorporated a "cathodyne" or "split load" phase inverter. The cathodyne, a simplified explanation of how it works. When it comes to running vacuum tubes we have a slight challenge on our hands: they need very high voltages to run efficiently, and pretty much no one in. The cab has a great-sounding speaker in it, too. Two low and one high sensitivity input. schematic, but if that amp's got a cathodyne phase inverter, then it's also the wrong kind of amp to expect much result from a 12DW7. SYLVANIA ELECTRONIC. Add the 82K and 100K resistors, and connect their common end to the 18K 1watt resistor at the top left of the fiber board. To take advantage of its wide bandwidth ability, I removed the input coupling cap. Princeton guys, this won't work, the Princeton uses a single triode cathodyne type phase inverter (the other triode is used to drive the vibrato effect) and using a 12DW7 in this position would just alter the vibrato effect. VR1 is the gain control, the tone controls are VR2 for bass and VR3 for treble. The Cambridge Reverb uses a both triodes of an ECC83 in a "long tailed pair" phase inverter. These amps are cathode biased, there is no bias adjustment to be made. 2 – Self-bias phase inverter or cathode follower; 3 – Fixed-bias cathode follower; 4 – Fixed-bias cathodyne phase inverter; Dual triode. Here am yet again with a simple push pull amplifier circuit using Vacuum tubes. Ideally I would use a cathodyne design but, from what I understand, this might not be possible because there is no seperate cathode and thus no cathode resistor (R k). 01uF into 470k) and a 1000pF mica capacitor into the bootstrapped 6SN7 cathodyne phase inverter. "paraphase" inverter 4. CPI: Cost Plus Incentives (contract) CPI: Center for Public Initiatives (University of Scranton) CPI: Cross Program Integration: CPI: Civilian Personnel Integration: CPI: Conditional Priority Inheritance: CPI: Command Performance Indicator: CPI: Client Program Interface (computing. So that leaves an extra triode and we can’t have that going to waste!. 6L6s in push pull, cathode biased, cathodyne phase inverter and no negative feedback. The Lar-Mar is a post phase inverter MV that in my opinion retains as much tone as an external attenuator, with 20 bucks worth of parts at most. The phase inverter is most commonly employed as the input stage for a push-pull amplifier. The same stage also receives negative voltage feedback from the output. The tube complement is one 12SL7 (phono version only), one 12SQ7 utilized as a tone control amplifier, a 12SN7 as a voltage amplifier, and cathodyne phase inverter, and a pair of cathode biased 12A6/VT134A beam power pentodes in an ultra-linear connection. Phase splitters are like religions, you belong to one or another and discussions between fans are often emotional. However, Hafler confided many years later that he selected the 7199 and 6AN8 combination tubes for cost and space-saving reasons,. This came out in 1953 in the 5E3 Deluxe and almost all Orange and Hiwatt amps have it as well. Phase Splitter Ideas Okay, it's time to give circlotron a rest, but not time to forget it entirely. V2A is DC coupled to a cathodyne phase inverter and then 4xEL34 in the output. Extremely loud, powerful, deep lows, and overall a bit cleaner than you would expect. the triode grid which is a concertina phase inverter ( aka "cathodyne" phase inverter. What does this calculator do? If the output from an inverting amplifier is used as a phase inverter output, it can be sent to a second inverting amplifier to invert the phase again for the second output. But this amp is its own beast. 150 /300 Ma Heater-Cathode , applications requiring a high gain voltage amplifier and S. Hi amp gurus, I recently acquired a Merrell MA-12 monoblock hi-fi amplifier off e-bay. Thus in amps that use a cathodyne PI such as the OR120 the other triode in the 'phase inverter' tube is used as another gain stage prior to the phase inverter. Fender's late-1950s 4x10 tweed Bassman combo is among the most celebrated guitar amps. Stuart Yaniger. Ready to convert on any scale you need. A pentode voltage amplifier, with parameters adjusted for minimum distortion, is directly coupled to a cathodyne phase inverter. This sort of phase inverter only uses one of the two triodes in the tube, so balancing them is pointless. control stands for Frequency Analysing Control. It has been used in many popular guitar amps including the Fender (push-pull) Princeton, most Orange amps and several Ampegs. To take advantage of its wide bandwidth ability, I removed the input coupling cap. A notable article on this is Notes on the Cathodyne Phase-Splitter, Albert Preisman, Audio, April 1960, pp22~23. The Lead & Rhythm Professional (LR-Pro) is an original circuit design from Sanford Magnetics. Components not included. It does NOT like to be overdriven, which causes it to produce some odd artefacts. Abstract: 6gu7 tube TWIN TRIODE rs tube. It's a unique mashup of Fender circuits. On top of that, the PR36's tube-driven reverb produces gorgeous ambience without washing out your playing. Best fit is the AC coupled long tailed pair phase inverter. -12AU7 driver/phase inverter-5U4 rectifier tube w/filter choke-30 watts/channel. I'm building an audio amplifier using Raytheon 6418 valves and I'm struggling with the phase splitter. manufacturers, along with a small number of European manufacturers and are tested. CPIの他の意味 Cathodyne 相インバーター 以外にもCPI には意味があります。これらは、以下の左側にリストされています。下にスクロールしてクリックすると、それぞれが表示されます。. These schematics are reproduced from a book of schematics provided by Gibson. The phase inverter is used when you have a push-pull output stage, like in the imp amp, it inverts the signal that goes to the second output tube. It has a 6C4 cathodyne phase invertor. The phase inverter was changed from a cathode biased cathodyne phase inverter to a fixed biased cathodyne phase inverter. If you went with a long tail pair arrangement or a floating paraphase inverter arrangement then some of the gain could be brought back but I still think. At 28 watts the Rambler makes more power and is cleaner than a Deluxe, and their pre-amp sections are similar. 12 watt EL84 Class A cathode biased power amp JJ ECC83s single triode 1st gain stage JJ ECC83s 2nd gain stage and cathodyne phase inverter. [4] The 120 has a paraphase inverter, so the gain stage is technically part of the phase inverter. With a PRE Phase Inverter Master Volume you can easily dial in how much phase inverter distortion gets through to the power tubes. This design used a cathodyne phase inverter which is circuit that was found in 5E3 Tweed Deluxe and many other amps of day. As can be seen from the above illustration, the cathodyne resembles both a classic gain stage,. Designing Long-Tail Pairs - The Load Line Approach. 022uF 630v 2 0 + + 2 2 u F Hi-Low Inputs. Then I have 142V across the tube. Each of these use half of a 12AY7, and have their own volume control. CF / EQ / Cathodyne PCB Universal Amp PCBs This PCB can be configured as a gain stage plus cathode follower, or gain stage plus cathodyne phase inverter. A cathodyne phase inverter maintains a slightly squishy feel that's sure to put a smile on your face. Basically the amp starts with one triode of a 6N2P set up like the first triode of an AC30. Power output: 40 watts per channel into 8Ω (stereo) Frequency response: 20Hz to 20kHz. The cathodyne phase inverter is common in small push pull tube amplifier designs. The split load phase inverter takes advantage of the circumstance that the signal voltage at the junction of the plate and plate load resistor is out of phase with the grid of a tube, while the signal at the cathode is in phase. The 'shape'. The VOLUME control interacts with the VOICE switch to produce shimmering cleans and smooth overdriven tones. 1 – Gain and DC-coupled cathode follower; 2 – Cascode gain stage; 3 – Cascode SRPP; 4 – Phase inverter; 5 – Phase inverter with current source; PC application; Links. A similar arrangement using one 6SN7 as a push-pull output pair is seen here on ax84. Got mine about a week. Okay, now its time for the phase splitter. The phase inverter is what is known as a “Bootstrapped Cathodyne” circuit that swings an unbelievable (90 db of gain) amount of power to the Eight 6L6 power tubes. 5E6 has indeed a cathodyne inverter, the best phase inverter. split-phase inverter) puts it in sort of two-steps-forward, one-step-back situation. Haven't seen a mod forum for this amp. Der erste Phase Inverter war der "Paraphase PI", dem bisweilen magische EIgenschaften aufgrund seiner leicht asymetrischen Aufbereitung zugesagt werden. NASTY, but vintage-y. It seems to me that the ECC832 or 823 would be suited for use in a cathodyne circuit as phase splitter & final gain. I too was diggin the blackface look. Jim Marshall liked it so much that he pilfered Fender's schematic to create the JTM45 and the early-to-mid- 1960s Plexi. As you raise Drive, the bottom end tightens up as gain increases. Each inverter has its own flavor, and plays with feed back in different ways. Abstract: 6gu7 tube TWIN TRIODE rs tube. Other amps using a cathodyne phase inverter: all Fender tweeds EXCEPT last-generation Bassman (5F6) and Twin (5F8). V3 (which is a 6CG7 cathodyne PI). Output tubes are EL34, 30W output. This video describes the purpose and design of three different common phase inverter circuits: Split Load or Cathodyne, Paraphase, and Long-Tailed Pair. The one shown below is a direct coupled version and is a variation of one used in a commercial amplifier that had cathode loaded output stages. The Long-Tail Pair. The 829b needs to be driven by low impedance output and this LTP using 12AU7 is a good candidate. A negatively charged electrode, as of an electrolytic cell, storage battery, diode, or electron tube. But I don't have a schematic of the Ultra to see whether or not it has a cathodyne PI. I wish to address a common misconception about the output impedance of the cathodyne phase inverter with a couple of screen captures from LTspice. The ’72 Orange has a bandaxall tone stack, cathodyne phase inverter & EL34 tubes, the Bassman has a fender tone stack, long tail pair phase inverter & 6L6 tubes, the Hiwatt has a hiwatt tone stack, long tail pair phase inverter & EL34 tubes, and the AC30 has a Vox tone stack, long tail pair phase inverter & EL84 tubes. However, we will design it as a cathode biased version. Phase splitters are like religions, you belong to one or another and discussions between fans are often emotional. Initially intended to amplify bass guitars, the 5B6 Bassman was used by musicians for other instrument amplification, including the electric guitar, harmonica, and pedal steel guitars. This may consist of one or two triodes and prepares the signal for the PP power amp. The coupling capacitors CG block the high DC voltage from the phase inverter while allowing the inverted and non-inverted audio signals to pass. I covered the metal PA case in tweed, and call the amp the Jazz Tank. The changes to the circuit are highlighted in pink. Thus in amps that use a cathodyne PI such as the OR120 the other triode in the 'phase inverter' tube is used as another gain stage prior to the phase inverter. The bottom point of the line is the B+3 supply voltage of 250 volts. The Fender Bassman is a bass amplifier introduced by Fender during 1952. Just a 12AX7 for V1 driving the tone stack and FAC selector then a 12Ax7 in V2. Therefore, the phase inverter must supply two voltages of equal magnitude and 180° phase difference. control stands for Frequency Analysing Control. Cathodyne phase inverter and power section carry straight over. The Split-Load is the simplest arrangement. Grid of the phase inverter is galvanically coupled to the anode of proceeding triode, in which the cathode circuit is connected with negative feedback loop. PI stands for "Phase Inverter". Cathodyne Phase Inverter listed as CPI. This type of phase inverter has the unique advantage that its operation is independent of tube aging so that no adjustments are required in maintaining optimum performance. I just finished and amp I had been working on for a while. Cathodyne Phase Inverter. 7K) up to decrease or down to increase NFB External Tube Connections Heater 6. Would it be worth changing the PI to a higher gain single triode? Maybe in the sense that 6C4s are notoriously microphonic and a huge pain in the ass. Components not included. Synonyms for Catholic in Free Thesaurus. The phase inverter gets its plate voltage from a previously unused filter stage. Stuart Yaniger Despite its extreme simplicity, the split load phase inverter is capable of stellar. The G12Q is supposed to be good from 5E3 type circuits. This is in current terminology a differential amplifier. The inverter drives the output tubes which are operated with fixed bias. Actually, only 1/2 of the 12AX7 is used for the tremolo, with the other triode serving the usual duty as the first stage of the preamp. Output measures 13. Then it goes to the volume control and a simple treble bleed tone control. Equally important, the phase inverter (driver) was changed to a cathodyne phase inverter (driving the output tube) and output was now raised to 20-watts with a duet of matched JJ-6V6's. Hi, the triode V2b is wired as a cathodyne phase inverter. A similar arrangement using one 6SN7 as a push-pull output pair is seen here on ax84. A typical style element of these amps was the front that had only pictures to describe the. The phase invertor uses the most common circuit (the Cathodyne), which when properly built can have a very good balance and can often be used in a Hi-Fi application. Lafayette • 12 watt EL84 Class A cathode biased power amp • JJ ECC83s single triode 1st gain stage • JJ ECC83s 2nd gain stage and cathodyne phase inverter • Volume and Tone controls • 4 position Schizo tone stack gain control • 3 position standby switch for 6 or 12 watt operation • Single 8 ohm speaker out. This type of phase inverter has the unique advantage that its operation is independent of tube aging so that no adjustments are required in maintaining optimum performance. Regarding the cathodyne phase inverter, it is self balancing so concerns about the AC balance of the amp are eliminated. While not common, and a little odd, this is legit. Quote:On 09/11/2018 @ 00:25, John Smart wrote : I'm brewing an amp with a 6SN7 cathodyne PI and am curious about how to implement a master volume. The amount of clean headroom you'll get from the power section is somewhat dictated by the grade of power tube used. To draw a cathodyne phase inverter's load lines we have to consider the tail load resistance and how the tail load resistor affects the cathode and grid voltages. At the time of writing my link to the on-line source of this article had evaporated, but I'm subsequently (3/03) helpfully advised by fellow enthusiast, Mr. amplifier directly coupled to a cathodyne phase inverter. Very simple circuit, the 7247 is essentially a twin triode wherein the first section is like a 12Ax7 direct coupled to a 12AU7 cathodyne phase inverter. This video describes the purpose and design of three different common phase inverter circuits: Split Load or Cathodyne, Paraphase, and Long-Tailed Pair. A value of 100k to 1Meg is usually necessary. 6L6 – KT88 PP TUBE AMPLIFIER Designer: Nanook. plifier directly coupled to a cathodyne phase inverter.