In such a setup, the following selector swith can come in handy, as it only switches right and left chanel hots. Moreover, the Select-4 allows up to six input signal sources to be used Select-Phase Switch The following item has been available, but I haven't made a big deal about it, so many do not know that it exists.
I get a lot of e-mail asking if I believe in phase. In other words, do I believe that we can hear the difference that phase reversal makes? The 1-ohm resistor is a 4W device, so the maximum current output is 2A Mono Position Balanced Stepped Attenuator Good news for the those audiophiles who run balanced systems. The BM-1 is a new stepped attenuator that I have designed.
It uses 24 resistors and two rotary switches: one position, 1-pole, shorting switch; one 6-position, 2-pole, shorting switch. The configuration is interesting, as it consists of a shunt stepped attenuator cascading into two series stepped attenuators, one for each phase The M1 stepped attenuator combines both series and ladder stepped attenuators into a single functional attenuator.
The ladder attenuator's job is to provide six fine steps of attenuation, each step being -1dB; the series attenuator, eleven coarse steps of attenuation, each step being -6dB.
The result is that 66 attenuation settings are possible. In other words, we can set the attenuation to any value from 0dB to dB in -1dB decrements PS-9 New Heater Power Supply Over the years, I have hard-wired together the following circuit many times, as I often have used solid-state rectification in my own tube power amplifiers and I didn't want the 5Vac rectifier winding to go to waste.
The circuit is a simple voltage doubler that converts the 5Vac into 12Vdc for the power amplifier's frontend circuitry New Balanced Step Attenuator Like its unbalanced predecessor, this stepped attenuator offers 36 steps of attenuation for two channels of signal. The center rotary switch controls both channels and presents coarse decrements, while the two flanking switches afford fine volume decrements for each channel I then made a few improvements to the PCB, so it is now in Rev.
I tested the new board by building a tube-based headphone amplifier, this time with 6N1P and 6H30 tubes. It sounds impressive. The bass is rock solid and it slams.
I swear I can feel the bass notes in my chest. The music comes out alive and forceful. On the other hand, my octal equivalent sounds more mellow, in a radiant, glowing way, which is altogether beguiling. It isn't sloppy by any means; it's just more yang than yin. I sold many PCBs and kits and I have gotten great comments from users. I still listen to headphones with it and it sounds amazingly good as a line-stage amplifier.
Moreover, when a supply of a trendy tube grows small, two things happen: obviously, the price goes up and, all too often, the quality goes down. Diminished quality? One thing that I love about OpAmp circuits is being able to hook up two 9-volt batteries and run, with just a single bypass capacitor across the positive and negative power supply pins—no lethal voltages and no heater power supply to worry about. Low-voltage power supplies are a breeze The low-voltage regulator is meant to power the tube heaters; the high-voltage power supply, the rest of the tube circuit But I decided that since octal tubes seem more retro than 9-pin tubes and the Janus regulator is a pure-tube design that even uses a tube rectifier, why not wed a Janus regulator to the Aikido stage instead?
Tube Clock Tube clock? Is it a piece of artwork, worthy of window display in exclusive art galleries?
Or is it the long-awaited analog replacement to the famed Tice digital clock? Or is it a chronometer of exceptional precision? Or is a timepiece of uncanny beauty, suitable for adorning walls of Beverly Hills mansions and Manhattan penthouses? Or is it something like a badge of affiliation to an almost cult-like adoration of vacuum tubes?
It is also my latest kit offering Now for something completely different I have created small, 4 by 6 inch PCB that holds a low-voltage bipolar regulated power supply for solid-state use.
I have been experimenting with OpAmp circuits lately and I needed a killer low-voltage, bipolar power supply I made the PCB half an inch taller, which allowed a fatter heatsink to be used. In general, a fat, short heatsink is better than a tall, skinny heatsink. The intrinsic thermal resistance of the metal is effectively placed in parallel in a fat heatsink; in series, a tall heatsink.
This chubby heatsink boasts a thermal resistance of only 3. The selector switch assembly accepts three stereo inputs, with both the hot and grounds of each signal source to be selected. So if a signal source, say a CD player, is not selected, neither its outputs or grounds make any connection to the line-stage amplifier Each voltage regulator also finds its own raw power supply, holding the all the rectifiers and power-supply reservoir capacitors required for feeding each regulator its raw DC voltage.
In other words, except for the power transformer s , the PS-1 PCB holds all that is needed to make a superb regulated power supply for tube-circuits At long last: the Aikido Phono Preamp This Aikido phono preamp uses passive equalization, rather than active, feedback-based equalization.
The passive equalization network sits in between two Aikido gain stages Now the attenuator will fit within a 1U rack-mount enclosure. Second, the TCJ stepped attenuator now offers many more positions, a total of 66 steps with 1dB resolution, as the center switch now presents 11 positions, rather than the old 6 positions.
Third, and most importantly, the old open-frame rotary switches have been replaced by Elma switches. Swiss-made, gold-heavy, precisely-designed and exquisitely-made, Elma rotary switches are justly famous as the gold-standard in switches. And like all things golden, they are obscenely expensive. But when only the best will do…. Janus Shunt Regulator The feedforward shunt regulator only looks forward, creating a counter noise signal to null the original power-supply-induced noise.
Unfortunately, it is blind to what develops on the other side of the series resistor. In contrast, the feedback-based shunt regulator sees only the disturbance on the output side of the series resistor.
Now, what would happen if we wed the two approaches together? The attenuator is a hybrid design that uses both series and ladder attenuators and three rotary switches to yield 36 positions of attenuation in -2dB decrements. In the first six positions, the attenuator is just a ladder attenuator, with no more than two resistors in the signal path; thereafter, the attenuator uses both a ladder and series attenuator configurations, with never more than eight resistors in the signal path.
With -2dB decrements, a maximum of dB of attenuation is accomplished. First the good news: the rumored Aikido printed circuit boards do exist, and they are beautiful. They look fabulous and feel solid in the hand. They are extra thick, 0. Sneaking Aikido Mojo Into a Regulator Sometimes a small modification to an existing circuit can produce a large improvement.
Let's take a look at a simple series high-voltage regulator that uses a single tube, a 12DW7 dissimilar-triode tube. Hybrid Janus Regulator My original Janus regulator was an all-tube affair. Like the Roman god, Janus, the regulator looks at both the raw DC power-supply voltage and the regulated output voltage. Actually, the regulator didn't regulate the output DC voltage, only the AC component of the output voltage. Back when I was a young lad in the previous century, my favorite English teacher only allowed one exclamation point per essay.
Well while typing this section heading, I was sorely tempted to use two. First, some background history: for the longest time I have wanted to build a current-output headphone amplifier. In fact, seven years ago I started building one, which I displayed in post Well, I was going through the articles and I saw one by Fabio Barberini, which details how he implemented regulated fixed-bias for his tube-based push-pull power amplifier.
Each output tube gets its own negative three-pin voltage regulator an LM and adjustment potentiometer Music Recommendation: Composition Transcriptions A transcription is a new arrangement of an existing musical composition for some other instrument or voice than that for which it was originally written.
We can transcribe from small to large or large to small. Back when most middle-class homes held a piano, transcriptions of orchestral works to piano were common; but we can go from piano to orchestral, which brings us to Mussorgsky Happy Halloween Is your perception the same as mine?
When I was a child, Halloween lasted about two to four hours at the very end of October. Today, it's a many-day event My thanks to Davide Bucciarelli, who wrote an interesting article that details his construction of a based class-A, push-pull power amplifier, which happens to use my Aikido split-load phase splitter I didn't bother to make a SPICE circuit based on this circuit to evaluate it, as I had plenty of hands-on experience with similar circuits.
But as I looked over the circuit recently, I wondered if the KT88 was the best choice and just how low an output impedance the regulator might achieve Patent US 8,, Bipolar Speaker with Improved Clarity While searching for something else, I found on my hard-drive an interesting patent, which I have no memory of seeing before.
How did it get there? No doubt, I ran across it during a Google-Patent search and I downloaded it for future perusal, which means that I forgot about it.
The patent, by Definitive Technology, covers a bipole loudspeaker, with a slight—but patentable—twist His album, Kaleidoscope, impressed me even more More Shunt Regulators The shunt regulator stands out due to its relative rarity.
If it were the primary regulator topology, I would be writing about the series regulator instead. The contrast between the two is interesting. The series regulator operates in current phase with the load. If the audio circuit draws more current, the regulator sees the same current increase. In contrast, the shunt regulator conducts in anti-current phase Bastode Series Regulators As far as I can tell, I haven't covered bastode-based voltage regulators here before.
Time to make amends. The name "Bastode" is Rene Jaeger's inspiration, the circuit being like a cascode, but not really. The bastode is simply a differential amplifier that is arranged vertically, rather than horizontally or laterally More Series Regulators A big fat book could be written on the topic of voltage regulators; the subject is near infinite.
For example, I start with one circuit, then I see a variation, which then gives rise to another variation…on and on it goes I wouldn't have to make the long drive to Denver, deal with hotel arrangements, fight to find a parking spot near the event, acquire my press pass, lug my tote-bag from room to room, wait for elevators, endure sales rep's endless prattle, squeeze into tiny rooms filled with huge loudspeakers, subject my ears and soul to relentless and oppressive bass thumps, take brochures that I knew I would never read, mourn the want of vitality from the attendees and sanity from the exhibitors, miss connections with friends… Damn.
My delight now transforms into depression First of all, their music sounds to my ears far more American than European. RMAF is closing its doors. Vacuum Tubes Coming to Your Street? There are many types of vacuum tubes. Most audiophiles have heard of rectifiers diodes , triodes and pentodes.
In contrast, few have heard of carcinotron, klystron, and gyrotron tubes Two-Triode Aikido Amplifiers Building upon the last post, which showed a two-triode line stage that was imbued with Aikido Mojo, let's look at some other two-triode designs. In Post eleven years ago, the Broskie split-load phase splitter appeared. This variation on the simple split-load phase splitter aka, cathodyne was to use two triodes to improve vastly the circuit's PSRR One of the best was made by Philips for O'Neill, the surfer gear company.
The blue earbuds didn't sound better, but they were robust enough to last the longest Combining Series and Shunt Regulators Series regulators dominate, as they are far more efficient—in general—than shunt regulators.
The analogy I like to make is that series and shunt regulators are, respectively, similar to class-B and class-A amplifiers Randall Jarrell I am a huge fan of the American poet, literary critic, essayist, and novelist, Randall Jarrell, although I have only read his literary criticisms and essays.
He died in ; he was only As I read the first few paragraphs, I was struck by how one could easily substitute the words "poetry" with "high-end audio gear," "reading public" with "audiophiles," "publishers" with "audio manufacturers," and the same conclusions remained intact. Here is my altered version for your evaluation Originally, there was the Penguin Cafe Orchestra, which ended in Penguin Cafe resurrected the band in in From their website we learn The Noval MFB PCB is configured for 2nd-order filters, but we can create a 3rd-order Butterworth low-pass and high-pass filters by adding two external sets of capacitors and resistors.
This dawned on my while creating the user guide for the PCB In the twenty steps I took to return to its brothers, I flipped through its pages. Two circuits instantly caught my eye. The first was a huge schematic typo; in other words, a mis-drawn schematic. Here is the original Kreskovsky Transient Perfect 2nd-Order Crossover Everyone knows that 2nd-order crossovers introduce a shifting phase that starts at zero, reaches 90 degrees at the crossover frequency, and ends in a degree shift; moreover, that the two drivers must be wired in anti-phase to avoid a deep suck-out at the crossover frequency.
So, how is a phase-flat 2nd-order crossover possible? The punch line is that John Kreskovsky's crossover is not really a speaker crossover but a speaker over-lapper. Nonetheless, it delivers a phase-flat output. In other words, square waves go in and square waves come out Broskie Phase-Flat 2nd-Order Crossover Working on the assumption that a picture is worth a thousand words, while a schematic is only worth five hundred, here is a picture of what is possible It was fun revisiting these female singers as they have matured.
For example, Suzanne Vega now sounds as if she has been smoking for years. In addition, we cannot be constantly foraging for something new, as there are times when retrenchment and consolidation are advised. If for no other reason than it make future forages more fun They were for me and friends, but not for sale. I feared headaches, endless email exchanges. The math was too complicated and sourcing the needed tight-tolerance capacitors too difficult for too many potential customers.
Mental self-preservation, in short, explains all. Well, since posting on the MFB filter in post , I have had a change of mind. I fired up MS Excel and created the following tables that list the filter values for a Linkwitz-Riley 2nd-order filter crossover Solid-state Power Buffer About half a decade ago, I had a fun correspondence with an electric engineer, after he had read post , which detailed an IC I would love to see being made, the TS The idea behind my fanciful IC was that a complete totem-pole OTL frontend input stage, driver stage, and auto-bias circuitry could be housed inside an eight-pin IC package.
My correspondent disagreed, as he thought the heat dissipation would prove excessive for such a small device; he recommended the 7-pin TO package instead Bipolar Power Supply from 12Vac The triangle buffer shown above needs a bipolar power supply.
We could go the fancy route, with fully regulated positive and negative power-supply rails. On the other hand, we could use a 12Vac wallwart.
My reasoning is that since the triangle buffer shown runs a heavy idle current to maintain class-A amplifier push-pull operation, we could get away with something simpler Hybrid Phono Preamps Our goal is simple: use each technology where its strengths shine through. With hybrid power amplifiers, the usual setup uses tube up front for signal gain, with the solid-state output devices following, delivering current gain.
With a hybrid phono preamp, we reverse the order. Solid-state offers low-noise amplification; tube-based circuits, lush sound and huge voltage swings. With a hybrid phono preamp, we don't want the tubes leading in front and the OpAmp following behind, as the tube's high noise will only get amplified Bi-Amped Phono Preamps In the previous hybrid designs, the OpAmp receives the signal from the phono cartridge and pass along the amplified signal to the tube-based circuit.
This is the obvious way to proceed. What if, on the other hand, we feed cartridge's signal to triode and the OpAmp at once, in parallel, so both can deliver amplified output signals?
Okay, that is crazy enough an idea, but I can make it even crazier. What if we let the triode handle frequencies above Hz and the OpAmp handle frequencies below Hz, then we sum the two output signals into one?
Of the four, I would say that Natalie Merchant is the best singer, but that has not precluded my listening to the other three. Last week I realized that many years have passed since I last checked in on them. Streaming-music sources, such as Amazon Music and Tidal, however, make this an easy task. Better Facemask Since it appears that, much like the poor, facemasks will always be with us, why not design a better mask? I love asking such questions in front of some of my friends, as the gasps of near-lethal incredulity are delightful to behold.
Am I a doctor? How dare I dare to presume to dare disturb the universe…? I dare. If nothing else, why has no enterprising company sold facemasks with the bottom-half of our faces printed on the front?
You send in a photo of your face and the masks arrive displaying your smile High-End Loudness Control Let us think back to happier times. When your father or grandfather wanted to play his new stereo-demo LP at a moderate sound level, he switched on the loudness switch on his receiver, filling the room with balanced sound, albeit at a lower volume level.
Today, we turn down the volume and resulting sound falls short, sounding thin and eviscerated. Why so? We do not have a loudness control. Somewhere around , audio puritans denounced the loudness control as being audio-impure, along with all other tone controls, which only mid-fi listeners would desire and use.
A big mistake this was, as a high-quality loudness control would make for much more enjoyable listening. Too-Loud Loudness Compensation Not just Wallace Simpson aka Duchess of Windsor , but many hold to the belief that one can never be too thin or too rich.
Well, for many audiophiles, music playback can never be too loud. Indeed, for non-audiophiles, an audiophile is someone who is hard of hearing that happens to be also rich Music Recommendation: Estonian Incantations 1 I have listened to many albums with the Estonian Philharmonic Chamber Choir, but I have never sought out their albums in particular.
Recently, I did seek their albums out at Amazon Music. Plenty albums showed up for my sampling. I choose the album, Estonian Incantations 1. This is not your father's classical album, unless he listened to Leonard Bernstein's MASS —many did, in the early 70s, although it generally received bad reviews.
What am I getting at? Speaker Diffraction Loss While writing my last post, and while looking at the first of the two passive RIAA equalization networks, the shelving network that boost the lows below 50Hz by 20dB and then fell off at 50Hz before flattening at Hz, I noticed an exact ratio between the two resistors in the shelving network This was not the case five years ago, when it seemed that all everyone was interested in was building a better DAC, usually with post tube sweetening Music Recommendation: Crime Of The Century While waiting in a local sandwich shop, I listen to music hits from the s pour from the ceiling speakers.
My pleasure restrained by my fear that the under-twenty workers must feel oppressed by this music, preferring as they must something more modern, something trendier. As I collect my roast-beef sandwich, I mention the music to the young man. He loves it; the radio station is his choice. Amazingly enough, he revels in s music. Mind-boggling—well at least my mind boggled At the time, I owned bi-amped, home-built loudspeakers that held a Hz crossover frequency.
The speaker was a two-way design with an Audex 6-inch polypropylene woofer with a cast frame in an insanely over-built sealed enclosure, whose walls were 2. The motive is to exclude the resistor cathode from the AC signal path, which now includes only the output transformer, the output tube, and the bypass capacitor that completes the circle Music Recommendation: The Naxos classical-music label should be far better known and appreciated than it is. Many, if not most, of their efforts are beautifully recorded and their CDs cost less than other more famous labels.
Over the years, I have bought many of their box sets and have loved the music and the price. Well, when I saw that Naxos had released a collection of hitherto unrecorded music by one of the composers that interests me greatly—Villa-Lobos, the Brazilian composer, conductor, cellist, and classical guitarist—I had to listen to it Loudspeakers Loudspeakers constantly come to mind—well, to my mind.
Loudspeakers need the most help. With just cause, loudspeakers are identified as a stereo system's weakest link, not amplifiers or cables or DACs or equipment stands or power AC filters Crossover Thoughts If a loudspeaker holds more than one driver, it will need a passive crossover to divide the audio band of frequencies between the drivers.
As soon as I finished writing the previous sentence, I thought of exceptions; for example, we could use two fullrange drivers, one facing forward and one facing rearward for bi-pole design. Even this design, however, would need a shared Zobel network. Three-Way Crossover Woes Textbooks inform us that three-way crossovers do not work—not even 1st-order three-way crossovers. Neither the parallel nor the series 1st-order crossover yields a flat impedance or a flat frequency response Often, I am the sole source, which seems to trouble them, as a common viewpoint is that no new tube topology is possible, all topological development ending about 70 years ago The album bridges American jazz with African music, with a healthy dollop of church music mixed in.
All the tracks are varied, some with singer accompaniment, including his own wife on the first track Thus, I set about making a SPICE curve tracer and I took the resulting plate curves and overlaid them upon a set of curves from an actual curve tracer Another Split-Load Phase Splitter Version After making my last post, I had this haunting feeling that I forgot to include another version of the split-load phase splitter that delivered equal and in-phase PSRR from both outputs.
I went hunting. If we include the SPICE circuits living on USB sticks and my main computer and the few hundred that I have lost due to hard-drive deaths, the total must be well over 5, Well, I found a more complicated version of what I sought. Since the circuit is somewhat complicated, we will work our way up to it AnTec output Transformers Over the last two decades, I have bought many toroidal power transformers from AnTek ; and over the last three decades, I have bought many aluminum enclosures from AnTec's sister company, Metal.
Fairly recently, AnTek has offered output transformers for tube-based power amplifiers, with push-pull output transformers that range from 10W to W and a 30W single-ended output transformer.
All are flat toroidal designs and the prices are more than reasonable. The transformers that interested me most are the 10W and 15W, as they offer the most extended high-frequency output I believe that this album was mention in a review of another album that was deemed to fall short of it; thus, my efforts to seek out the better album.
Domador de Huellas literally means "the tamer of the footprints. It worked. As far as I know, I had made all the solder joints. It certainly played loud enough. There was too much resistor noise for my taste, but the white-noise hiss is fairly easy to ignore.
Next week, the preamp will meet another system with an equally low-output moving coil phono cartridge This is a tad unfortunate, as the design is a very clever two-switch combination of stepped shunt and series attenuators that delivered 66 steps of attenuation, the result of using 6-position and position rotary switches.
What it didn't produce, however, was a flat input impedance, the result of using the shunt portion of the attenuator. Well, a potential customer asked when it would be back in stock.
My answer was possibly never, as the new gold-contact Attn-2 stereo stepped attenuator works perfectly as a mono balanced stepped attenuator with 66 steps of attenuation A high CMRR ensures that signals shared in common are ignored; noise is usually a common-mode signal. The two easy ways to achieve a high CMRR is to use either an input signal transformer or a constant-current source with a differential amplifier input stage Conclusion So, is this last circuit the best design?
Remember, something is only best in relation to some goal or task. For example, an antiaircraft gun will kill a housefly, but it is not the best means of doing so. Using only two tubes per channel is a huge feature and offering a low differential output impedance is also a huge feature when it comes to driving high-impedance headphones Lateef was an amazing American jazz musician, composer, novelist, businessman, college professor, and purveyor of "World Music" before it had the name.
His Ph. D dissertation was a comparative study of Western and Islamic music education. He played too many instruments to list, but was best known for his saxophone and flute playing. The first was a silkscreen error on the bottom of the PCB where the positive and negative sign on the heater pads are reversed.
This typo can cause a blown capacitor, as the heaters are shunted with a large, low-ESR capacitor. Fortunately, the fix was easy enough: just use a Q-tip dipped in acetone to remove the polarity signs Cynosure Resistor and Aikido Cascode The best way to achieve power-supply noise nulls is not with tight-tolerance capacitors, but with tight-tolerance resistors, as tight-tolerance resistors are both plentiful and cheap, whereas tight-tolerance capacitors are neither.
In addition, we can use a potentiometer, but not a variable capacitor. Here is an example of a 6DJ8-based Aikido cascode that uses two tight-tolerance capacitors Cynosure Split-Load Phase Splitter I am building a push-pull, tube-based, stereo integrated power amplifier, so phase splitters have been on my mind. Unless a balanced input signal is provided, push-pull power tube-based amplifiers require a phase splitter to drive their output stages.
This is true for both OTL and transformer-coupled push-pull tube-based power amplifiers My goal was to reduce the voltage differential between the input grounded-cathode amplifier's heater and the phase splitter's cathode, while still maintaining an equal and in-phase PSRR from both phase splitter outputs Cynosure Paraphase Phase Splitter The paraphase phase splitter is the pairing of a grounded-cathode amplifier and an anode follower, the latter of which is setup for unity-gain inverted output.
In England, it is known as the paraphrase phase splitter. It has made several appearances in previous posts, such as post and Last year during the pandemic, American female singer Morgan James created two albums with only her husband, Doug Wamble, playing acoustic guitar for accompaniment he sings with her on the Islands in the Stream track ; do not worry, as he is a gifted jazz guitarist MC Phono Preamp—Tube-Based After a month of thinking about tube-based moving-coil pre-preamps, I began to wonder if this trip was really necessary.
No, I wasn't thinking about step-up transformers or higher-output phono cartridges. Why not just build a phono preamp with enough gain to run a low-output MC cartridge, say, one with a gain of 60dB? This task would be easy enough with solid-state devices, but tubes require much more care and consideration If we pause to think about it, we soon realize that we ask an awful lot of the simple SRPP circuit, as it is expected to provide signal gain and phase splitting, and push-pull operation capable of delivering close to twice the idle current into an external load resistance.
Music Recommendation: High-Res Singers I was searching Amazon Music streaming service for high-resolution albums, when it hit me: I was doing it backwards. I should have been searching high-resolution music websites and finding the overlap between the website's catalog and Amazon Music's catalog.
I listened to a friend's MC cartridge with 40dB tube-based phono stage of mine. With the line-stage amplifier at full gain, the music played—played amazing well, in fact—but was too noisy. Either a step-up transformer or an active pre-preamp with a 20dB would have made all the difference. Later that day, I filled out two pages in my sketchpad with circuits More Electrostatic Loudspeaker Ideas Post mentioned Harold Beveridge's amazing electrostatic loudspeaker design, which is unique in that he drove both the stators and the diaphragm, using two OTL amplifiers.
In the overwhelming majority of electrostatic speakers, the diaphragm passively sits between two driven stators, biased to a high-voltage through a many mega-ohm resistor, pushed forward and backward by the developing electrostatic forces Electrostatic Speakers with Wire Stators Be prepared to be mightily impressed. Mercy, doe she have amazing woodworking skills. Not only is Charlie a big advocate for wire stators, he has developed some truly interesting designs that use a segmented stators to tailor the high-frequency radiation, concentrating at the center of the tall diaphragm I don't, sadly.
The Balancer design offer gain and balanced outputs. This question, however, brought back memories from 30 years ago. A high-end audio company had major problems with a no-gain phase splitter that a genius tube guru had designed for them. My first question was why would anyone need a unity-gain phase splitter? More Crazy Speaker Ideas In the last post , we saw an electrodynamic planar loudspeaker that held no magnets, just a large solenoid.
Well, how about using electromagnets instead? The dynamic loudspeaker is almost years old invented in and most speakers back then held a field-coil to create an electromagnet—up until WWII, when lighter, powerful magnets were developed.
The field-coil often doubled as the choke in the power amplifier's power supply. In other words, speakers with electromagnets are nothing new. What I am proposing is that planar speaker be built Bipole Electrostatic Speaker First, some electrostatic basics: electrostatic loudspeakers sandwich three key parts, the diaphragm in the center, and a stator on each side of the diaphragm.
The stators are electrically conductive and are acoustically porous due to holes or gaps in their surface: for example, perforated-sheet-metal or wire screen or many sheathed wires in parallel. Each stator receives a high-voltage audio signal, with the stators driven in anti-phase to each other Magnetostatic Electromagnetic Loudspeakers I hate the word, "magnetostatic," as it just confuses things.
I prefer the adjectives, "electromagnetic" or "electro-dynamic," when describing planar loudspeakers such as the famous Magnepan speakers, which hold many bar magnets and a low-resistance diaphragm More on MC Pre-preamp I have been giving some more thought to the idea of a tube-based moving-coil cartridge pre-preamp. For example, here is a variation with three 6DJ8 tubes per channel Music Recommendation: Offertorium The path I took to find this album was circuitous in the extreme, which is so typical of any music hunt at either Tidal or Amazon Music.
Just the other day, I asked my son if he knew the word, "divagate. Cummings poetry. Reading his poetry is difficult; listening to it being read, a delight. The results were tiny, sadly. I did, however, find quite a bit of T. Eliot's poetry In addition, it allowed me to try out the new Attn-2 in an actual piece of audio gear.
Hard Constant-Current Sources A constant-current source is a current limiter or current regulator that freely allows the flow of current, but only up to a set limit. It is a practicable version of an ideal constant-current source, which would be something like a special battery that delivered a fixed current flow, not a fixed voltage; in other words, it would deliver a steady current flow regardless of the voltage-drop required.
For example, an ideal 1mA constant-current source would develop 1kV across a 1M resistor and 1V across a 1k resistor and 1mV across a 1-ohm resistor. In contrast, a battery strives to deliver a fixed DC voltage regardless of the current flow, be it only 1mA or 1A or 1kA He is not alone.
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