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Thread: Are you kidding me!? Really!?

  1. #1
    Senior Member Wilder Amplification's Avatar
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    Are you kidding me!? Really!?

    This just in from the Eurotubes site -

    "10/21/10 - A little over a year ago we asked our good friends at JJ Electronic to build us a low power EL84 and they agreed to do it! It's not an easy task to build a tube that has never been built, but JJ has proven they are the people to do it. We have been testing different revisions of the brand new JJ EL844 since January of 2010 and it is ready!

    We talked about several tubes that would be welcome additions and we have to tell you, JJ has been VERY busy! We are really happy with the way the EL844 has turned out! It's a wonderful sounding tube and will dissipate right at 9 watts rather than 12 watts which will be a great option for players who want to get to the sweet spot at a little lower volume.
    Really!? Since when does the rated plate dissipation of a tube govern the output power it's capable of achieving in a given amp circuit? Last I checked, P = V^2 / Load Impedance (nothing in that equation about the "rated plate dissipation of a tube") and plate dissipation governs the minimum safe load impedance you can run at a given B+ voltage. Yes these parameters do affect output power but...he's basically saying that by simply dropping the rated dissipation of the tube itself that that's somehow going to drop the amp's output power and give breakup at a lower volume???

    For the record all that's gonna do is cause some BIG overheating issues in EL84 amps...NOT "drop the amp's output power" like he's thinking. Just goes to show how much he DOESN'T know about tube amps...I swear this guy is like the Aspen Pittman of JJ. After all the misinformation in his marketing tactics, why would anyone want to buy from this guy?
    Jon Wilder
    Wilder Amplification

    Quote Originally Posted by m-fine
    I don't know about you, but I find it a LOT easier to change a capacitor than to actually learn how to play well
    Quote Originally Posted by JoeM
    I doubt if any of my favorite players even own a soldering iron.

  2. #2
    Noodle of Reality Steve Conner's Avatar
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    Gimme that sucker, I'll "test" it
    68810_487826291583_745931583_7024262_1568493_n.jpg
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  3. #3
    Supporting Member Alex R's Avatar
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    "All valves burned in on our special rig" ;-)

    I'm finding it a bit hard to imagine how Eurotubes instigated this new manufacturing venture on the part of their suppliers. Maybe it was like...

    "Hey Vaclav, we're thinking we need a new type of EL84, kind of less powerful than the ones you make now, like weaker and punier and just sort of generally not so good."

    "You mean, from the reject bin you want them?"

    "Well, not exactly..."

    "Or like an EL83 you want?"

    - and so on.

    Hey it looks like some German supplier has a direct line to JJ product development also:

    Tube-Town Online-Store - NEU ! JJ EL844 jjel844

  4. #4
    Supporting Member Alex R's Avatar
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    4601_0.jpgtesla_el83.jpg

    Getters look different, plates similar. Ah well, who know, not me that's for sure.

  5. #5
    Noodle of Reality Steve Conner's Avatar
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    All valves burned OUT on our special rig here
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  6. #6
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    Quote Originally Posted by Steve Conner View Post
    Gimme that sucker, I'll "test" it
    Click image for larger version. 

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    Hi Steve!
    Did you mean "Test" or "toast"?

    Cheers

    Bob
    Hoc unum scio: me nihil scire.

  7. #7
    Noodle of Reality Steve Conner's Avatar
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    Test, toast, same thing... I guess the B+ is a bit too high since I changed to a solid-state rectifier.

    The screen voltage on this amp is variable. I turned it all the way up for the photo, but I usually run it just about two-thirds. So don't worry, the plate doesn't glow like that in normal use

    To me it seems that power scaling techniques like that make more sense than swapping in a weaker tube. But Eurotubes sells tubes, and a tube replacement is an easy, convenient plug-in mod.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  8. #8
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    Jon Wilder wrote: "Since when does the rated plate dissipation of a tube govern the output power it's capable of achieving in a given amp circuit?"...is this a joke, are you teasing us? ;-)

    It may not follow to the last % but that is probably in line with manufacturing tolerances, but in fixed bias, class AB (with adequate plate voltage & transformers, circuit allowing) it is generally the "rule of thumb", at least at the higher end of the scale. Many designers don't seem to feel that amps sound their best at max power output however. So I would expect the 9W JJEL844 to have lower ceiling of clean headroom that the regular 12W tube.

    Yes power (measured, rather than potential) is V^2/load impedance...but it only tallies with max output if the amp is designed that way in the first place.

    However, as you say Jon, I don't actually know of many amps (if any) that allow a EL84 type tube to idle at less than 10W (without plate voltage rising, defeating the object somewhat in the process)...so the application for this tube would seem limited? That said, many EL84 amps already run their tubes well over max idle dissipation, even in fixed bias and a tube's longevity is in part determined by how hard it is driven, so it's possible that even the 9W tube run at over max dissipation could be useful to home pickers/apartment dwellers who aren't going to drive it intro redplating all the time? I guess the situation is similar to owners of 50W+ amps who want to run vintage 23W 5881, you might bias cooler & accept a slight drop in headroom compared to true 30W 6L6GC or 7581A?

    Admittedly, I think the message can be easily misconstrued by the layman and amp owners should have their amp/application evaluated to see if the tube is a good match. Nevertheless, I don't think that Bob Plekta is clueless, I'm sure he has done some homework on this & he does have a lot of practical experience with JJ tubes. Even if this tube was "created/sorted/reclaimed from the reject bin" at his instigation, JJ will ultimately make it available through all their outlets, so I wouldn't be surprised if dealers in other countries are stocking the tube.
    Last edited by MWJB; 10-25-2010 at 02:16 PM.

  9. #9
    Noodle of Reality Steve Conner's Avatar
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    Quote Originally Posted by MWJB View Post
    you might bias cooler & accept a slight drop in headroom compared to true 30W 6L6GC or 7581A
    That's what Jon is trying to get at. Biasing cooler gives you MORE headroom, all other factors being constant.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    Yes, but "all other factors being constant" really means using the same tube in both scenarios, if the EL844 can't supply the sonic headroom, but it can still take the voltage, it is still making less clean power. Likewise, if you have a 6L6 amp that runs late 400's but can take 6V6, the 6V6s will be biased cooler & run at higher B+ due to lower current draws, the 6L6 will run at lower voltage (assuming both biased to a similar % disipation) but as long as that drop isn't too dramatic, the 6L6 will still have better headroom & more clean WRMS.

  11. #11
    Senior Member Wilder Amplification's Avatar
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    Quote Originally Posted by Steve Conner View Post
    That's what Jon is trying to get at. Biasing cooler gives you MORE headroom, all other factors being constant.
    Exactly! Biasing cooler reduces the power amp's input sensitivity (i.e. "gain") which makes it so that you have to push the preamp/phase inverter (where applicable) harder to drive the power amp to full output. This means the power amp will have MORE headroom...not less.

    According to Eurotubes's literature they're made to get earlier POWER TUBE breakup. However, if you're having to bias them colder which increases the headroom of the amp, then how are you supposed to get the power tubes to break up "earlier" if you're having to push the preamp harder to even get the power amp to the onset of clipping?

    Furthermore, with the lower dissipation rating, how is it gonna be able to safely operate into the same load that was spec'ed for a tube with a higher dissipation rating? Of course like MWJB stated this would probably require a trip to the tech to find out what your load impedance actually is to see if it's too low for the lower dissipation tube....

    But in no way will changing JUST the tube's rated dissipation change the output power that the amp is capable of putting out. It will only change the environment in which that tube can safely operate.

    My original point was to state that it's been a long held myth that "power is in the tubes" when tubes are just a "voltage actuated current control valve" that controls current to the load. How much actual average power they dissipate when performing this task is governed by the B+/load impedance combination (i.e. the "load line") and the dissipation must be rated for at least this average power to safely operate in that environment.
    Last edited by Wilder Amplification; 10-25-2010 at 06:37 PM.
    Jon Wilder
    Wilder Amplification

    Quote Originally Posted by m-fine
    I don't know about you, but I find it a LOT easier to change a capacitor than to actually learn how to play well
    Quote Originally Posted by JoeM
    I doubt if any of my favorite players even own a soldering iron.

  12. #12
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    Power is universally rated as clean W RMS, so if you fit a significantly less powerful tube to a circuit, even if the plate voltage rises by a few volts due to reduced current draw, the amp will make less clean W RMS (maybe only a little less). However, few EL84 amps are designed to exploit maximum clean W RMS & I have very little interest in W RMS, other than as a diagnostic reference point...as long as your amp sounds good at the power output you run it at, and is at least ball-park in terms of output, anyone should be happy.

    If we're talking about existing amps primary-Z is already decided & is really a moot point, unless alternative taps can be utilised.

  13. #13
    Senior Member Wilder Amplification's Avatar
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    Quote Originally Posted by MWJB View Post
    Power is universally rated as clean W RMS, so if you fit a significantly less powerful tube to a circuit, even if the plate voltage rises by a few volts due to reduced current draw, the amp will make less clean W RMS (maybe only a little less).
    Yes but this has to do more with the plate characteristic curves than it does the plate dissipation. In the marketing literature, it specifically states that these new tubes will be a "9 watt dissipation tube instead of a 12 watt dissipation tube". That directly refers to the plate dissipation itself, which has little to nothing to do with the plate characteristic curves. He makes no mention of the curves at all...only the dissipation itself.

    For the record...the screen voltage controls where those curves are anyway so why not just lower the voltage to the screens like lots do with power scaling?
    Jon Wilder
    Wilder Amplification

    Quote Originally Posted by m-fine
    I don't know about you, but I find it a LOT easier to change a capacitor than to actually learn how to play well
    Quote Originally Posted by JoeM
    I doubt if any of my favorite players even own a soldering iron.

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    If it is a 9W tube, then it can't make 12W clean, irrespective of curves. A 12W tube can make 9W clean but not the other way round. A pint pot can hold half a pint, 3/4 of a pint, but not a gallon.

    The load lines point to ideals, but graphs & data sheets are bits of paper and the amps that these tubes will be used in already exist, they don't know about load lines & data sheets, the vast majority of amps using a given tube use more, or less the same primary Z, irrespective of B+...they probably won't realise the full potential of either tube due to shortfalls in design (as regards power, guitarists buy amps because of what they sound like)...looks like someone is going to have to buy some EL844 and A/B against EL84...

  15. #15
    Senior Member Wilder Amplification's Avatar
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    Quote Originally Posted by MWJB View Post
    If it is a 9W tube, then it can't make 12W clean, irrespective of curves.
    OK then...explain how a pair of 35 watt dissipation tubes can make 100 watts clean power.
    Jon Wilder
    Wilder Amplification

    Quote Originally Posted by m-fine
    I don't know about you, but I find it a LOT easier to change a capacitor than to actually learn how to play well
    Quote Originally Posted by JoeM
    I doubt if any of my favorite players even own a soldering iron.

  16. #16
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    Class AB guitar amp is this?

  17. #17
    Senior Member Wilder Amplification's Avatar
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    Quote Originally Posted by MWJB View Post
    Class AB guitar amp is this?
    Yes.
    Jon Wilder
    Wilder Amplification

    Quote Originally Posted by m-fine
    I don't know about you, but I find it a LOT easier to change a capacitor than to actually learn how to play well
    Quote Originally Posted by JoeM
    I doubt if any of my favorite players even own a soldering iron.

  18. #18
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    Come on then, put me out of my misery...:-)

  19. #19
    Supporting Member Jazz P Bass's Avatar
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    What are the limiting factors to a vacuum tubes current rating?
    There are the mechanical aspects, heat dissipation & such.
    And then there are the electrical aspects.
    The cathode, when heated, "boils off" electrons creating a space charge.
    When a steadily increasing positive voltage is applied to the plate, the voltage field reaches into the space charge & pulls electrons to it.
    Think diode.
    Wallah. Measurable current.
    The negative grid voltage is what controls how far into the space charge the positive field can reach.
    The amount of electrons available from the cathode, at a constant temperature, does not change even if the plate voltage is changed.
    So maybe JJ is using a smaller cathode?
    Last edited by Jazz P Bass; 10-26-2010 at 03:41 AM. Reason: Spelling

  20. #20
    Member ivey's Avatar
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    No.

    They are using a different material for the plate.

    Maybe a low grade Monel metal. Good for about 3300 deg. f
    Tungsten (element #74) is good to 4500 deg. f or greater.
    Heating elements in space heaters is make of nickel/copper (Monel)
    and it comes in different grades. Submarines in the US use Monel 60. Which is very hard and non-flexible.
    So they have to de-rate the tubes using the new material.
    Once it glows red..., its dead.

    Some sweet spot.., yeah vow.

    Take Care

    Ivey
    Last edited by ivey; 10-26-2010 at 04:30 AM.

  21. #21
    Old Timer defaced's Avatar
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    What's your source for this info?
    -Mike

  22. #22
    Member ivey's Avatar
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    100 watts from 35 watts..., it is very simple in the radio world

    Just add the input power needed to drive your linear rf power amp to full output.

    By adding the wattage used to drive the unit to the power need to produce the output, you get total power wattage of the complete system.

    Even thou total input power does not mean total output power.

    Numbers game.


    Ivey

  23. #23
    Member ivey's Avatar
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    It only make sense.

    If the tube enters are all the same. Then it has to be the materials. Something have to change.

    To reduce the speed and power in a car with the same engine, you reduce the carbs or the gas amount being fed into the engine.

    The materials have to change. Just check with the development of tubes through the 1930's to the 1950's. The type of materials used and the size were the factors. If everything is the same size inside and out of the tube. The materials are the only remaining factor left.

    Even if they change the cathode heaters, they reduce the current on the tube heaters; in order to get it to reduce its space cloud.

    What would cause the heater to require less current. The material it is made of is reduce in size or length, requiring less filament current.

    Yes or No

    Take Care

    Ivey
    Last edited by ivey; 10-26-2010 at 06:32 AM.

  24. #24
    Member ivey's Avatar
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    They change something in the tube.

    The 6SN7 and 12AU7 are the same tube. But power wise, the latter is much smaller and produce less wattage/power output. Size and materials made the difference. They do the same thing, but the 6SN7 has a larger output.


    Take Care

    Ivey

    They are claiming..., what? Same size, same materials. No way.

    Take Care

  25. #25
    Noodle of Reality Steve Conner's Avatar
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    Ivey, I'll have some of what you're on!

    Here is the straight dope once and for all on power ratings.

    In a Class-B linear amp with ideal output devices, operated just on the edge of clipping, the efficiency is 70%. That comes from the math behind making a sine wave out of DC.
    (reference: Amplifier Efficiency)

    Therefore, an amp rated at 100 watts will have to draw 140W from the HT supply, and dissipate the 40W difference in its output devices. So, two tubes with 20W plate dissipation would do. Philips' maximum rating for their EL34 came close: EL34s have a plate dissipation rating of 25W, and they claimed 100W from a pair running on 800V B+. That's only 10 watts of "non-ideality", pretty good for vacuum tubes.

    Biasing into Class-AB so that the devices are already hot before any signal even hits them, using non-ideal output devices such as vacuum tubes that drop 50 or 100V even when turned fully on, all eat into this figure: you get less output for a given plate dissipation. Many people think that the idle power dissipation in a Class-AB amp is equal to the output power: it's not. It's a waste that takes away from the output power, but we tolerate it because it decreases distortion. A Class-B tube amp is too distorted even for guitar.
    Last edited by Steve Conner; 10-26-2010 at 09:22 AM.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    Power output in AB, in excess of the tube's rated plate dissipation is easily accessible...it's the "clean W RMS" that's the sticking point. You can get 100W from 2xReflector 5881WXT, but it's not clean. Fender get 55-58W "clean W RMS" from the same tubes, which is pretty close to extracting power that matches plate dissipation...that's if anyone really knows what that tube's plate dissipation is, we can assume it's at least a 27.5W to 29W tube?

  27. #27
    Old Timer defaced's Avatar
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    Quote Originally Posted by ivey View Post
    If the tube enters are all the same. Then it has to be the materials. Something have to change.

    To reduce the speed and power in a car with the same engine, you reduce the carbs or the gas amount being fed into the engine.

    The materials have to change. Just check with the development of tubes through the 1930's to the 1950's. The type of materials used and the size were the factors. If everything is the same size inside and out of the tube. The materials are the only remaining factor left.

    Even if they change the cathode heaters, they reduce the current on the tube heaters; in order to get it to reduce its space cloud.

    What would cause the heater to require less current. The material it is made of is reduce in size or length, requiring less filament current.

    Yes or No

    Take Care

    Ivey
    I agree, changing the materials makes sense, I was just wondering where you got Monel from. I couldn't think of why a nickel/copper alloy would be used for the anode. Monel alloys are usually used for corrosion resistant and high temp strength applications.
    -Mike

  28. #28
    Noodle of Reality Steve Conner's Avatar
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    I heard that the plates were made of molybdenum, or iron, or some combination of metals laminated together, maybe to stop it warping under extreme heat.

    This is the first I've heard of monel being used.

    Also I thought space heater elements were made of Nichrome.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

  29. #29
    Old Timer defaced's Avatar
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    NiChrome is very common for heating/resistive elements in general (stove, hair dryer, industrial load banks, etc). The typical compositions are resistant to oxidization at elevated temperatures which keeps them from scaling in service. If you've ever seen a video of steel making, you'll notice the large chunks of stuff flaking off, that's the iron oxide scale. That said, assuming the vacuum inside a tube is relatively void of oxygen (<10ppm or there abouts), oxidization and scaling wouldn't be an issue.

    As for lamination, I'd think it'd be more like a coatings/thermal spray of a super duper secret electron catching whizbang composition. As to what's in the coating, assuming it's coated, who knows.
    -Mike

  30. #30
    Member ivey's Avatar
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    Yes my brothers:

    That is what they do.


    We get screwed by these manufactures into thinking we are getting our monies worth. It is not until you get into the game that you discover that it is fake.

    I finish U of Penn, in 1952, as a electronics engineer. My god, before I knew it, I was paddling the same lie. I had to pay bills and feed myself. And marriage only made it bearable.

    Take Marshall. He copied the Fender Bass man Amp. By all rights he violated Fender's rights. But he was smart enough to change the preamp tube from a 12AY7 to a 12AX7, plus change the mixing resistor from 270k to 470k. And then charge a small fortune for it. Claiming 45 watts of power. Yes it is, RMS, not brute power.

    Take a look at the Heathkit TA-16, it claims ungodly music power, yea right. Not out of those transistors.

    Engineering shows that, in order to get up to a power level, you must burn power, in the form of heat. Lots of heat. Like a car, it is economical when cold, once it is hot, you lose power. Because the engine must turn the tranny and the tranny must turn the wheels and the wheels get hotter as it meets the road surface, creating more heat, causing wear. Which increases drag. More drag, more fuel, more heat, less power. And we all try to meet in the middle. Harmony.

    So the engine on a dynamo, its power is static power, not dynamic power. And we all know that auto makers love to use dynamo power specs. Hell, there's no car body, drag, weight, or transmission issues to worry about. Great engine!!!!!!!!!!!!

    So if JJ sells these tubes, it will be 9 watts SE or 18 watts PP. Which is really only 5 watts and 12.5 watts respectively. Remember wasted heat.

    You see my brothers, they are going to give a little and take a lot. A lot of our money that is.

    I just love the "Industrial Revolution".


    Take Care

    Ivey

  31. #31
    Noodle of Reality Steve Conner's Avatar
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    Quote Originally Posted by ivey View Post
    Take Marshall. He copied the Fender Bass man Amp. By all rights he violated Fender's rights. But he was smart enough to change the preamp tube from a 12AY7 to a 12AX7, plus change the mixing resistor from 270k to 470k. And then charge a small fortune for it. Claiming 45 watts of power. Yes it is, RMS, not brute power.
    It was still cheaper to buy in the UK than an imported Fender: the only reason he started making them. He also changed the power tubes to KT66s and added two honking big speaker cabinets with closed backs. The rest is history.

    they are going to give a little and take a lot...
    before I knew it, I was paddling the same lie.
    You mean, WE are going to give a little and take a lot. I work in the industry too and have bills to pay. If you want to bitch about something, take it to the Parking Lot/Soap Box forums on this site.
    "Enzo, I see that you replied parasitic oscillations. Is that a hypothesis? Or is that your amazing metal band I should check out?"

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    AFAIK, the very earliest were 6L6, and the 270k were retained for a while (270k is seen in some of the 100 watters). Also, it was a couple of guys Jim M. knew who decided to clone the Fender (one worked for him). They were the ones who had the electronics background (ham radio) and not Jim M.(he was the one with the capitol and the music stores).

  33. #33
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    "We get screwed by these manufactures into thinking we are getting our monies worth. It is not until you get into the game that you discover that it is fake."

    Ivey, I think you got the wrong end of the stick...my point was that the Fenders in question use 2x 25-29W tubes (never seen exact specs for the 5881WXT, but going by typical current production 6L6GC ratings) and the amps DO deliver that power as clean usable wattage.

    There are amps that get more than 18W out of 2xEL84 but they tend to be on the overly clean/sterile side for many players. Just because popular amps don't realise their full power potential doesn't necessarily mean that the tubes can't, in an amp designed to do so....whether anyone would buy the said amp is another matter. This is true for most tube types, the majority of guitar amp designers run them below practical max in the interests of what they perceive to be "tone". So, as long as your particular amp is deemed not to be overstressing the tubes in it, a lower W rated tube isn't necessarily a bad thing, if you like the sound of it & it is reliable. Getting back to the original post, Eurotubes have a lot of hands on experience and like other vendors, sell pre selected/graded tubes for certain amps/applications.

    EL84s are pretty cheap anyway.

    Ditto what Steve says, Marshall was seeking a more affordable option for the UK, not seeking to push up the price due to any perceived sense of provenance. I'm sure it would have been Western Electric AT&T that would have felt their rights were violated...it was their design, licenced to & honed by Leo.

  34. #34
    Member ivey's Avatar
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    Monel is cheap, not like before. The Russians have been flooding the market with monel from their decommission submarine fleet. And we will be following their lead.

    We built this huge atomic waste dump in Nevada, I install the security system in it, in 1991 and again on the final level in 1998. We can not allow those nuclear vessels to rust away in salt water and spill toxic nuclear waste into our food chain. We will remove the nuclear sections of those vessels and store them in that dump. Seal them and fill them with water to reduce the neutron and gamma radiation and weld seal it again. They will stay there forever or until we figure out a way to neturalize the radiation or rocket it into space towards the sun.

    Monel have good properties, but it is hard, very hard. High temp, high strength, and almost no corrosion. Outside of sea water.

    I like the idea of using Monel, because building bigger tubes means more power, which last a lot longer.

    Coating was used in the old days and still used today, but it is a costly action, with tube sells no where near what it was in the 1950's, 1960,s or even in the 1980's. Besides the coating breaks down with heat and destroys the vacuum.

    People have move on into the smt phases of their lives. Cell phones are king, with yuppies, kids, teenagers, cheating spouses, you name it. "If I can not record it on my DVR, it is not worth watching". That's my wife talking.

    Take Care

    Ivey

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    That is very exciting! I love the back story Ivey!

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