There are two things I dislike about choke input: 1. good chokes are expensive. 2. some means of preventing over-voltage at start-up while amplifier valve heaters warm up is necessary.
But, assuming you know what you are doing, it is easy enough to minimise the resonant effects, particularly since high value capacitors are easily available and thus the resonant peak can be held at a low frequency and the Q kept low, maybe only needing a small series resistance.
But, assuming you know what you are doing, it is easy enough to minimise the resonant effects, particularly since high value capacitors are easily available and thus the resonant peak can be held at a low frequency and the Q kept low, maybe only needing a small series resistance.
Im the kind of guy who likes to put a 25A bridge rectifier in a CRC supply, clean up the junk with a 25 cents inductor, or just move the entire supply to a different box. Most people struggle with tube regulators, if you want to have a GZ34 in there why not make it a 6080? and drive it with a insane EF184 cascode CCS loaded. You get approx the same voltage drop, and the added benefit of slow start on the DHT's that warm up. Plus you can get the noise down to under 1-2mV with EASE. And you get lower impedance out of the supply than 25 lead acid starter batteries in series. 😀
Tektronix for example used about 10R of series resistance per 100V in their diode rectified oscilloscopes and good low ESR capacitors to dampen the junk.
Too many scare stories about capacitor charging current spikes in here. If you just load it with a good low ESR industrial type it will knock out any junk.Those have flat impedance curves out to 200Khz or so, that is.
But people want choke supplies in there because of vintage sentiments. Or so they can burn up all the rectifier tubes, glorified light bulbs IMHO. I thought it was funny people wanted to pay good money for my stash of AZ1 mesh.
The militairy didnt give a flying f, once semiconductors where invented and became reliable, tube rectifiers where done for. And stabilised supplies where the name of the game, why do you think the Russians made 10Thousands of 6C33? Thats not because they where big on OTL in their fighter jets. 😀
Just a bit of a low quality troll on my part. Sorry about that.
I mean, there is some surplus industrial stuff out there, you and i know Kwakkelstein for example. That is industrial and military surplus and cheap as chips. I get my coupling capacitors from there, put in a small inexpensive inductor in series, and it sounds like one of those boutique coupling capacitors. Because all the important parameters of the old capacitors you can simulate with cheap passives. I think that if you take apart a black gate capacitor, inside are the same materials as a industrial capacitor. Too many people selling snake oil in audio and companies sometimes just go along with it to make a profit.
Attached a piece from the black gate capacitor series data sheet, its utter and complete bull. I actually could NOT find a datasheet with the most basic of parameters like ESR and ESL, cause if that exists, people can figure out how to make a 7 dollar industrial capacitor sound like a 75 dollar black gate with a 25 cent inductor.
But claiming that your capacitor leads are made out of "Quote pure copper" Is COMPLETE AND UTTER BULL. as ALL capacitor leads except for Aliexpress stuff is made out of PURE COPPER.
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300B amplifiers deserve the best, so yes, a good choke might be expensive.
When using tube rectification, over-voltage (especially when using indirect heated tubes) should not be an issue; the minimal (and specified) minimum high voltage winding dc resistance should be respected.
@vlve lover:
Hey, I respect your personal, subjective opinion about the vintage sentiments.
Others might have other, equally valuable opinions though...
I think that the main reason that the Sovjets made the large number of 6C33's is their limited life expectancy (rated max. 500 hrs for the particular application) and the heavy mechanical stress that these tubes face in their fighter jet duty.
Hey, I respect your personal, subjective opinion about the vintage sentiments.
Others might have other, equally valuable opinions though...
I think that the main reason that the Sovjets made the large number of 6C33's is their limited life expectancy (rated max. 500 hrs for the particular application) and the heavy mechanical stress that these tubes face in their fighter jet duty.
Yes Kwakkelstein! Long gone.
I remember wandering through his warehouses, gathering loads of fine carbon film resistors among other things.
Agree on the snake oil thing 😉
I actually know a fair bit about Russian Military aviation, its one of my interests. These are some of the things i have picked up over the years.
What happend that lead to these massive stocks of tubes is this: fighter jets in the soviet air force/naval air force and PVO where scheduled for depot level maintenance every 500 Flying hours or so. They did this to keep the factories and repair depots busy, and to always have everything in perfect working order. So when excrements hit the fan, they would never be caught with their pants down.
Soviet MIG engines have lifetimes between overhaul specified in 100s of hours for that very reason, not because the Soviets could not make stuff better, but it was cheaper and better to keep everyone employed to build low quality stuff.
On the other hand: people that ran these factories got bonuses for production quota, so they would deliberately understate the lifetime of tubes so they could ramp up production. And if they had bad raw materials for tubes for a while, they would still meet the very low bar of 500 hours, without the head tube designer going to Siberia to get some air.😉
The soviets where stockpiling everything they need for another "great patriotic war" The Soviet political and military leadership was still DEEPLY traumatized by the events of 1941. But then how could they not 75 percent of boys born in 1928 did not live to see 1946.*
I am personally of the opinion that -E and -EV tubes are just as good as Philips made gold pin stuff, 5000 hours was the design life for most, and those figures are very conservative because the head engineer could get in serious trouble if they didn't meet the specification.
*Sorry this borders on the political. And i likely have the year wrong, more likely 1922.
What happend that lead to these massive stocks of tubes is this: fighter jets in the soviet air force/naval air force and PVO where scheduled for depot level maintenance every 500 Flying hours or so. They did this to keep the factories and repair depots busy, and to always have everything in perfect working order. So when excrements hit the fan, they would never be caught with their pants down.
Soviet MIG engines have lifetimes between overhaul specified in 100s of hours for that very reason, not because the Soviets could not make stuff better, but it was cheaper and better to keep everyone employed to build low quality stuff.
On the other hand: people that ran these factories got bonuses for production quota, so they would deliberately understate the lifetime of tubes so they could ramp up production. And if they had bad raw materials for tubes for a while, they would still meet the very low bar of 500 hours, without the head tube designer going to Siberia to get some air.😉
The soviets where stockpiling everything they need for another "great patriotic war" The Soviet political and military leadership was still DEEPLY traumatized by the events of 1941. But then how could they not 75 percent of boys born in 1928 did not live to see 1946.*
I am personally of the opinion that -E and -EV tubes are just as good as Philips made gold pin stuff, 5000 hours was the design life for most, and those figures are very conservative because the head engineer could get in serious trouble if they didn't meet the specification.
*Sorry this borders on the political. And i likely have the year wrong, more likely 1922.
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I disagree with mostly everything you said and especially this. There are reputable capacitors, such as Rubycon ZL that have steel leads.
And while you're mentioning an industrial cap filters out mostly everything to 200kHz, what about the EMF radiated into open space from the capacitor charging pulses and the transformer potentially being noisier due to instantaneous higher current draw?
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v4lve, I absolutely agree with you on Soviet tubes. Have you noticed how the stocks seem to be disappearing though, compared with 10 years ago. Also, I don't think the horrifying statistic you quote is political at all; it is a fact that every single member of the human race needs to remember.
I also gave you a simple solution: instead of mono blocks, put the noisy stuff in Box A and the sensitive stuff in Box B. Then you go on Aliexpress and get some militairy style "Aviation connectors" for 5 euro per set.
EMI is indeed a problem, but not what it is made out to be. Charging peaks with 10R/100V are modest, and most capacitors are faraday cage shielded because the negative is the outer shell. Using that same logic i could lam bast everyone without proper metalworking skills that they have not shielded their amplifier properly. Some of these doofuses try silver wiring with teflon on the outside. And then complain when they have a hum problem.
There is a French expression that says: the exception confirms the rule, that the Rubycons have tin plated steel leads likely indicated an engineering decision to increase mechanical strength at the expense of slightly worse conductivity. Or to save on copper.
People use PSUD and don't realize the transformer inductance itself is left out of the equation, PSUD-II is a .EXE file that runs a spice simulation. However the inductance of the secondary winding is hard to measure and therefore left out. As most of the approximations can be done by using a sinewave voltage source for the calculations and the DCR measurements the person has done with a 12 euro multimeter.
You can run a spectrum analyser on the noise coming out of a diode rectified supply, and indeed you get a nice plot, but half of the folks here interpet that plot without realizing that its on a LOG scale.😡 So the next harmonic over may be -20Db allready.. So just looking at the plot you can be excused for thinking : WOW thats a lot of junk. Yeah but 100Hz is your fundamental, and the next harmonic is not even visible on a linear scale.
🙂 Im not mad or anything, but im also on EEVBLOG. And those guys visit Diyaudio when they need a good laugh..
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I have. A capacitor mitigates the mechanical vibration, and the bigger the capacitor, the quieter it gets. Unfortunately, getting it silent requires a capacitor that is too big for it to be a choke input supply.
Yes, people tend to attack the soviet political and economic system, but don't realize the tremendous cost bore by the soviets and the deep psychological and cultural scars this has left in their mind. The Russians deserve far more credit for their accomplishments.
Yes stocks are dissapearing, because the warehouses are running empty. I remember back in the day 2014 or so, people had 100PC factory boxes on ebay for less than 50 quid for some tubes. Nowadays entire types are gone from ebay.
History repeats itself over, and over. Back in the 90's before Tesla became JJ, they made some ultra high quality KT88 but all the audio guys where cheap at the times and didn't want to spend 25 quid on a tube. Now you can't get these tubes at ALL.
Appearantly tesla focussed on transmitter tubes, and when that marked came crashing down they had another go at audio tubes but that failed because the experienced tube builders (The engineers) where let go or had left. This eventually resulted in EAT, who make high end tubes for the bespoke product line. Source: Jacmusic
EML makes some really fine DHT's that are far in advance quality wise of anything else. If you read between the lines on the Jacmusic website, that company is run by a former Tesla QC engineer.
AVVT split up, into a multitude of different companies. KR for example also makes 300B but they use a carbonized anode process, that may be superior dissipation wise, but carries the risk of contaminants.
Tube building comes down to this: Clean materials: attention to detail and trying to reduce contamination wherever possible. There is a story about Philips in the war on the Ronald dekker website (muTracer) that said they could sabotage tubes with a simple bottle of Chlorine.
Elrog tubes in my mind are overpriced, and stupid sometimes, they have some really good German tube builders behind the Wheel, but Thomas seems to be interested in nonsense products like : Hard metal anodes normally seen in transmitter tubes where they glow red hot. But they dont glow red hot in a 300B (The fillament is incapable of that) and are thus a big fat purple crocodile in my mind. Their tubes are unique in that they use a pressed glass base with tungsten lead-in wires (and thus have way lower inductance), i bet you could make a nice AM transmitter out of their 300B's if you wanted to.
If i had to spend my money on a DHT from Europe, EML would be far ahead of anything else price/performance/quality wise. Western electric is just a plaything for people that want a hype brand.
One of the half a dozen or so tube manufacturers from the Soviet era is still in business as a specialist metallurgy company they can supply MOST of the materials Aluminium clad nickel for anodes for example. Or even some of the explosion welded triple layer stuff that went into the Tung-Sol 5881. But the big problem with tubes nowadays is the cathode nickel.
Attached you will find the material datasheet for cathode nickel alloys used back in the day
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I also visit EEVBLOG when I need everything else of electronics explained EXCEPT audio. And it makes me laugh too when these folks talk about audio 😀
I intentionally mentioned the Rubycons to counter your style of absolution in your opinion.
You are giving absolute opinions of categories where there's a lot of headroom of diverse thinking.
And on top of that you start mentioning other categories which weren't even discussed.
Of course, a first capacitor, depending of its value, will take away some of the AC flux density burden the choke has to withstand, so less mechanical hum in result.
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Point taken, however i try to de-mystify some of the audio stuff, and people only respond to absolutism at times. If someone spends 50 euro's on a rather overpriced low quality capacitor that makes me upset because in my mind they have been had. Now people are free to do with their money as they please, i can only recommend but sometimes people are sold a bag of goods. I approach everything from a quality and value for money point of view.
Absolutism is bound to turn-off a large portion of well-informed people. I'm sorry if i offended in the slightest.
ELROG makes some nice tubes, but due to low production numbers and high wages/margins these are sadly out of my reach. One suggestion i could make to them is to pull appart a GU50 and learn from the anode materials used in those. Big fat nickel alloy anodes coated with sintered-on zirconium makes a insanely built tube. And gets rid of those nasty screws they use for joining to halves of the molybdenum plate.
JJ could make very high quality tubes, if they use ultra pure nickel for their cathodes. But this means you may have to activate the tube for 72 hours in a rack before you get the tubes up to emission (in literature this means a passive cathode). This uses up a lot of electricity and room in your burn-in racks so production figures are likely to be way lower.
Absolutism is bound to turn-off a large portion of well-informed people. I'm sorry if i offended in the slightest.
ELROG makes some nice tubes, but due to low production numbers and high wages/margins these are sadly out of my reach. One suggestion i could make to them is to pull appart a GU50 and learn from the anode materials used in those. Big fat nickel alloy anodes coated with sintered-on zirconium makes a insanely built tube. And gets rid of those nasty screws they use for joining to halves of the molybdenum plate.
JJ could make very high quality tubes, if they use ultra pure nickel for their cathodes. But this means you may have to activate the tube for 72 hours in a rack before you get the tubes up to emission (in literature this means a passive cathode). This uses up a lot of electricity and room in your burn-in racks so production figures are likely to be way lower.
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I'm with you on the de-mystification, always trying building stuff with the cheapest parts possible, beaten up a lot of claimed hi-end stuff for small bucks, hating most proclaimed high-end on the market, but...
There are tricks to model your sound that aren't related to electricity, despite audio systems depending on it. Not necessarily wishing to make a point, just adding food for thought. I guess mechanics and acoustics come to play and IMHO every passive components play a role in this.
There are tricks to model your sound that aren't related to electricity, despite audio systems depending on it. Not necessarily wishing to make a point, just adding food for thought. I guess mechanics and acoustics come to play and IMHO every passive components play a role in this.
v4lve lover,
Could you please explain the sentence that begins with “But this means .....”
It is a bit off-topic, but I’m enjoying your information about Soviet tubes and tube making in general. Thanks!
Perhaps you should start a thread on this interesting topic.
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Well, indirectly heated tubes use a nickel cathode as you may be aware of. The composition of this nickel is the dominant factor behind vacuum tube lifetime. And without it you cannot make long life tubes. Behind that is the quality of the heater and the efforts put into outgassing everything before the evacuation straw is molten off and the tube is nearly finished.
Now during manufacture, these cathodes are coated with a spray gun to get an uniform layer of barium strontium and calcium carbonates on the cathode. This is emission liquid made by Heatwave labs in the states. Or by any chemist that can mix up the carbonate powders and make a solution that has the right viscosity. The binder seems to some organic compound that will turn into vapour at room temperature like paint thinner.
Once the tube is sealed and put upside down on the evacuaton carrousel, this carrousel uses vacuum pumps to draw out the air. And simultanoiously the heater is powered on at 150% of rated voltage. This carrousel then has induction heaters that glow all the tube parts red hot to get rid of all the gas into the pumps.
The industry dirty little secret is that they don't draw out all the air to an ultra-hard vacuum, but rely on the Barium getter to get rid of the remaining gas. Its been that way since tube time began, and some notable exceptions are the getter-less tubes made in the 20s for the postal service.
Getting simple things right like the mechanical tollerances of your grids, anode stampings and everything like that is not very hard at all. Its a question of maintaining and rebuilding your machines from time to time to replace worn-out bearings ect. Its a mechanical tolerance question. But getting the cathodes right is far more complicated.
Anyway, what i was getting at is that during some of the last steps of receiver tube manufacture the outgassing part, the cathode paste is reduced to oxides that can only exist in a vacuum. But simply having an oxide on the cathode doesn't give you emission. For that these oxides need to be reduced to a thin layer of metalic barium on the surface of a cathode.
Now it was discovered that trace metals in the nickel speed up this process, this means: less time and electricity wasted in the final step. But this is bad for lifetime. Therefore very high quality tubes back in the day used cathode nickel that was nearly 100% pure nickel, with a few trace elements to get the rigidity and flexibility required for the particular tube. (If its too hard to bend in your stamping machines its useless)
If you get nickel 200 billets from a supplier and send them off for for some other company to roll into strips you can use in your machines, you run the risk that your nickel has impurities that KILL the emission in a few 100 hours.
Judging from the Jacmusic site, Jac bought a batch of JJ tubes that had this problem, or were not activated to the correct schedule, and therefore he concluded that JJ had bad quality control.
In conclusion: using purified nickel for the cathodes is a sledgehammer approach to getting very long lifetime out of a particular tube, but it is expensive in production and takes up a lot of time on the machines.
Audio people tend to be very cheap, and there is only a niche marked of people that will pay for something very nice. Therefore most of the stuff JJ makes is built to a price. Furthermore its in their best interest to have the Guitar people come back every year or so for a replacement set of tubes.
Svetlana St-Petersburg made the best tubes in the world before they stopped glass tube production in 2010 or so. They got into bed with EHX but got the ****** part of the stick and management apparently called it quits. Their factory price was higher than the List price for most EHX tubes, Quality comes at a price.
BTB is the larges tube supplier in Europe by far that i know of, they have the clout to tell JJ to take back bad batches of tubes. Then JJ takes them back, but i have no clue what happens to them after that.
Now during manufacture, these cathodes are coated with a spray gun to get an uniform layer of barium strontium and calcium carbonates on the cathode. This is emission liquid made by Heatwave labs in the states. Or by any chemist that can mix up the carbonate powders and make a solution that has the right viscosity. The binder seems to some organic compound that will turn into vapour at room temperature like paint thinner.
Once the tube is sealed and put upside down on the evacuaton carrousel, this carrousel uses vacuum pumps to draw out the air. And simultanoiously the heater is powered on at 150% of rated voltage. This carrousel then has induction heaters that glow all the tube parts red hot to get rid of all the gas into the pumps.
The industry dirty little secret is that they don't draw out all the air to an ultra-hard vacuum, but rely on the Barium getter to get rid of the remaining gas. Its been that way since tube time began, and some notable exceptions are the getter-less tubes made in the 20s for the postal service.
Getting simple things right like the mechanical tollerances of your grids, anode stampings and everything like that is not very hard at all. Its a question of maintaining and rebuilding your machines from time to time to replace worn-out bearings ect. Its a mechanical tolerance question. But getting the cathodes right is far more complicated.
Anyway, what i was getting at is that during some of the last steps of receiver tube manufacture the outgassing part, the cathode paste is reduced to oxides that can only exist in a vacuum. But simply having an oxide on the cathode doesn't give you emission. For that these oxides need to be reduced to a thin layer of metalic barium on the surface of a cathode.
Now it was discovered that trace metals in the nickel speed up this process, this means: less time and electricity wasted in the final step. But this is bad for lifetime. Therefore very high quality tubes back in the day used cathode nickel that was nearly 100% pure nickel, with a few trace elements to get the rigidity and flexibility required for the particular tube. (If its too hard to bend in your stamping machines its useless)
If you get nickel 200 billets from a supplier and send them off for for some other company to roll into strips you can use in your machines, you run the risk that your nickel has impurities that KILL the emission in a few 100 hours.
Judging from the Jacmusic site, Jac bought a batch of JJ tubes that had this problem, or were not activated to the correct schedule, and therefore he concluded that JJ had bad quality control.
In conclusion: using purified nickel for the cathodes is a sledgehammer approach to getting very long lifetime out of a particular tube, but it is expensive in production and takes up a lot of time on the machines.
Audio people tend to be very cheap, and there is only a niche marked of people that will pay for something very nice. Therefore most of the stuff JJ makes is built to a price. Furthermore its in their best interest to have the Guitar people come back every year or so for a replacement set of tubes.
Svetlana St-Petersburg made the best tubes in the world before they stopped glass tube production in 2010 or so. They got into bed with EHX but got the ****** part of the stick and management apparently called it quits. Their factory price was higher than the List price for most EHX tubes, Quality comes at a price.
BTB is the larges tube supplier in Europe by far that i know of, they have the clout to tell JJ to take back bad batches of tubes. Then JJ takes them back, but i have no clue what happens to them after that.