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Steve Ford's Junk

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From wiredstate audio community:

 

 

 

actually the "ode" came from the term electrode so a diode is a vacuum tube device (wala pa SS when they coined the term in the turn of the last century) with two electrodes or di-electrode or simply diode same with tri-electrode for triode, tetra-electrode (4) for tetrodes and penta-electrodes for pentodes.

 

Huge difference between the two, triodes and other multigrid amplifying device (barest amplifying device is a triode, a diode do not amplify) like tetrodes and pentodes have non linear characteristics but can handle more gain, very efficient and more power the triode on the other hand triode is inefficient, small gain but highly linear.

 

Linearity dictates amount of distortion, a pentode without feedback will generate 15% distortion (because of it's non-linear response), with feedback will go as low as 8% distortion pero panget tunog even with low distortion (due to phase shift, which is an imaging killer).

 

Triode naman usually have 5% distortion but only 10 to 15% efficient so a 30 Watt triode tube can only spew 2 to 8 watts the rest is converted to heat. But can reproduce near exact tones and thousandfold better than pentodes.

 

and

 

 

 

Q: What is "ultralinear" operation?

 

A: In ultralinear operation, the screen grid is connected to a tap on the output transformer primary such that the screen voltage varies in proportion to the plate signal voltage. The constant of proportion- ality typically ranges from 30-50%, although other ratios will also work. The resulting tube characteristic has properties intermediate between those of the triode and the pentode. In essence, the ultra- linear connection forms a local negative feedback loop around the output stage. This may be advantageous depending on circuit topology and gain distribution. Advocates of ultralinear operation claim this connection combines the best features of triode and pentode mode, while detractors claim it lack the virtues of either.

 

Q: Compare the general properties of triode, pentode, and ultralinear power amplifiers.

 

A: It is probably misleading to characterize the various types of output stage connections in terms of sound quality. Many factors contribute to the sound of an amplifier, and a good designer will blend these elements in order to achieve a particular goal. On the other hand, certain sonic qualities are associated with each type of output stage frequently enough that they deserve repeating here. In addition, there are objective differences that are worth mentioning.

 

The triode amplifier is characterized by low efficiency and low power output. This is because a smaller voltage swing is available from the triode for a given DC plate voltage. Consequently, the triode amplifier burns up more power at idle relative to its peak output. The sound of the triode amplifier is often described as "rich" or "sweet", conveying in a natural and realistic way the harmonic structure of musical instruments and voices.

 

The pentode amplifier is often described as having a more analytical sound than comparable triode units. Others may accuse it of sounding harsh. Objectively, the pentode output stage tends to produce more high-order distortion products than a comparable triode. In addition, the pentode is more sensitive to load impedance variations and may clip more sharply than the triode.

 

The ultralinear amplifier combines the benefits (or flaws, depending on your point of view) of the triode and pentode connections. The ultralinear characteristic curves resemble those of the triode in some ways, those of the pentode in others, and have unique characteristics as well (regretably, they are hard to render in ASCII). While the general concensus favors triode mode above all, there seems to be no strong trend supporting ultralinear over pentode mode, or vice-versa. Perusing the high-end magazines, one can find examples of well-regarded amplifiers ueing either type of output connection.

 

The one certainty is that the ultralinear connection is the cheapest way to get good performance and high power out of a pentode. Whereas a quality pentode design requires a stiffly regulated screen grid supply, all that is needed to implement an ultralinear output stage is a pair of transformer primary taps. Perhaps the economic argument leads the sound quality argument in this case.

 

Q: Can I convert my amplifier back and forth between pentode, triode and ultralinear modes in order to hear the difference for myself?

 

A: In general, the answer to this question is "No." Under some circumstances, it may be possible to perform such experiments, but subject to limitations.

 

If the amplifier is an ultralinear design, it is possible to convert it to pentode operation by connecting the screens to a fixed voltage source. The correct screen voltage depends on the type of output tube, the B+ supply voltage, and the output transformer primary impedance. For audiophile performance, a regulated screen supply may be required. This makes the pentode conversion a major modification.

 

The most common conversion is to modify an ultralinear or pentode mode amplifier for triode operation. In many cases, this modification can be made successfuly and with little effort, but some caveats apply. One would like to be sure that the maximum triode-connected plate potential is not exceeded. For many EL-34/6L6/KT-66/5881 amplifiers running B+ supplies on the order of 400V, there is no problem converting to triode operation. On the other hand, a 6550 amplifier with 550V on the plates is probably not a candidate for triode conversion without a reduction in B+ voltage. When the conversion is made, a 100 Ohm non-inductive resistor is usually specified, connected directly between the screen and plate pins on the tube socket, to suppress RF instability.

 

Changing the output stage connection from pentode to triode mode typically lowers the open-loop gain of the amplifier. As a result, the closed-loop global feedback factor also goes down. The output impedance of the amplifier, its sensitivity, the total harmonic distortion and the distortion spectrum will all change. Overload behavior and stability will likely be improved. Typical comments are that the triode-connected amplifier sounds "more relaxed", "warmer", and "sweeter" after the conversion. Whether this is due to an inherent quality of triode-strapped pentodes, or is a consequence of modifying a topology that was not designed with triode output in mind, is open for debate.

 

Q: What about "pure-triode" amplifiers?

 

A: The vintage triode power tubes, such as the 845, 2A3, and 300B, are classic devices from the earlier days of vacuum tube technology. They are still available in limited supply and at high cost (although there are now Chinese copies on the market that offer a reasonable, lower- price alternative). A significant structural difference between these tubes and more modern units is the use of a directly-heated cathode. In this design, the cathode heater also serves as the emissive element. In contrast, newer tubes employ a separate heater that is electrically and mechanically isolated from the cathode.

 

These tubes are "pure triodes", meaning that there is no screen grid to be strapped to the plate in order to achieve triode operation. The classic triodes have very low plate resistance and low voltage gain. Many require significantly higher plate supply voltages than ordinary pentodes. In exchange for these limitations, these tubes offer very linear characteristic curves, making possible the design of low- distortion amplifiers that use little or no local or global feedback. The sound of a pure-triode amplifier is reputed to be exceedingly musical, with a natural harmonic structure, very low grain or noise, and a realistic, inviting nature. Triode adherents claim that the pure-triode output stage is sonically superior to one constructed with strapped screen grid pentodes. Other listeners will find the pure-triode amplifier to be colored, restricted in bandwidth, inefficient, and overpriced.

 

Single-ended triode amplifiers have been very popular in Japan for some time, and are making a limited comeback in North America.

 

Q: What is the difference between a single-ended and push-pull amplifier?

 

A: A push-pull output stage uses one or more pairs of output devices connected in a symmetrical arrangement such that output current flows to the load first through one half of the circuit and then through the other half. The advantages of the push-pull topology are higher efficiency, higher power output, much lower even-order distortions, immunity from power supply ripple, and zero DC current in the output transformer primary.

 

In contrast, the single-ended output stage employs only one set of output devices which conduct continuously throughout the output current cycle. This forces the stage to be operated in class A mode, limiting the available power output and greatly lowering efficiency. Total harmonic distortion is higher because there is no cancellation of even-order harmonics. Power supply ripple is not rejected by the single-ended output.

 

The most significant difficulty of the single-ended output stage is that the output transformer is required to carry a large DC current in its primary. Due to magnetic saturation and nonlinearity effects, a very special output transformer design is required. Such a transformer is large, heavy, expensive, and has a low power rating. The resulting amplifier is restricted in bandwidth at both extremes of the audio spectrum and produces a great deal of distortion. To minimize distortion (and to add to the single-ended mystique), it has become fashionable to design single-ended amplifiers with pure-triode output stages.

 

While no one claims the pure-triode, single-ended amplifier is "neutral" or "accurate", devotees of the genre describe in almost mystical terms the sonic attributes of these amplifiers. The word "magic" is often used. Listeners will have to judge for themselves.

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Thanks Rich,

 

I have had my tube amp for a while, but have only had it hooked up

for the last 4-5 days. It is triode/ultralinear switchable, the above post gives me a starting

point for understanding the differences....for a newb like me stuff like this is perfect.

I need to do more reading........or should I say more comprehending.

 

Steve......those look awesome, would love to hear your "junk"

 

Perry

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The nematode option is reserved for my monitor lizards. Little parasite joke.

 

I was talking to Snarffy about how I always thought people were crazy to buy tube amps because of the price but now I understand why they do it.

Speaking of buying stuff, I'd better get my butt to work!

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Sometime back I spoke with a fellow at Jolida regarding the infamous $800 power cord debate. His take was that a power cord might be a good addition but I'd get a lot more mileage out of a power conditioner.

That was on the back burner until I got the VTLs and I suspected that they were sucking up a LOT of power.

So, I finally broke down and bought a power conditioner.

I went with a new silver APC H15 and not surprising, voltage was 119 with everything off, 113V with everything turned on.

It's now running at a steady 121V.

How did it work? Everything certainly got a LOT sharper (or perhaps clearer) sounding! Kind of got rid of some of the mud which I didn't even realize was there.

Well worth doing.

I guess that's what I like best about audio gear - you can always do something to improve what you've got.

Did rebias the tubes once I had the proper voltage, by the way.

Here's some factory photos; silver ones are on blow out sale so mine's silver powder coat. Not the most attractive finish but it works.

 

P.S.

My mistake, the VTLs are triode according to the reviews from way back when (1997).

apc.jpg.9db58e50f11bfb87550d6153566c1cd0.jpg

apcrear.jpg.ae6b75bf09003a1515b4eb91a09bdacd.jpg

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I won a set of PS Audio Extreme Speaker Cables from James over at carveraudio.

These replaced some 12 gauge Tributaries speaker wire and quite a difference.

Mo' betta bass and a much deeper soundstage.

For instance, I sat down to listen to Zappa's Apostrophe' and for the first time, I could tell that there are 3 female vocalists and they were staggered 1-2-3 to the left/front of the band. Pretty neat.

These are hooked up to the downstairs system. Once I can afford a real cabinet for the upstairs, I'll have to get either get another set of these or transfer these cables to the upstairs.

Thanks, James/ClassClown, that was really nice of you.

P.S.

I'm going to take James' advice and put heatshrink or electrical tape over the spades and metal connectors where they connect to the Stax headphone box. I had to use Belleville washers to get them snug but even so, that is a real good idea.

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Quote from Steve;

"For instance, I sat down to listen to Zappa's Apostrophe' and for the first time, I could tell that there are 3 female vocalists and they were staggered 1-2-3 to the left/front of the band. Pretty neat."

 

Hey Steve, you are bang on about upgrades. I love being able to hear separate voices that had always sounded "blended" before. Getting closer to reality, one step at a time.

 

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Went with heat shrink AND spiral wrap. That should do the trick.

I also replaced the stock ElectroHarmonix tubes in the Jolida Phono Stage with Sovtek 12AX7 LPS' and the sound is greatly improved. Recommended if anyone else goes this route.

Swapped the Ei tubes in the Jolida CD player for some Sovteks just for the heck of it. Sound pretty much stayed the same, maybe a little different but nothing night and day.

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Six hours later I've finally got the upstairs crap in a cabinet and have moved the PS Audio Extreme speaker "hoses" upstairs. The improvement in sound is kind of astonishing.

It's all done except for running up on the roof and moving the coax cable to the other side of the house and then hooking up the tuner which will be a nightmare. Coax to power conditioner, coax to tuner and there's just no room whatsoever to work with.

Will post pics tomorrow, right now it looks like a bomb hit.

Oh yeah, reinstalled the original Ei tubes in the Jolida.

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Talk about cramped working quarters; the amps are eventually going behind the speakers but that will have to wait until I have longer interconnects and power cords.

The whole idea was to lose those ugly shelves, use those monster speaker cables (large diameter, not the manufacturer) and be able to access the screws for the amp cover for tube biasing. Two out of three so far.

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Busy weekend - my two week old stereo cabinet decided to sag like Yoko Ono's bosoms SO I ran out and snagged a much higher quality one off of Craig's List and then hooked all of the crap back up.

This is how it's going to have to stay due to the weird room configuration. Only snag is I need to order longer power cords for the amps. It's always something.

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Really nice, I'd love having that attic room. What a Man Cave you could make out of that, Lucky "B"

 

Oh, and really nice gear!!

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Thank you. 

I'd love to keep it (the house) but doesn't look like that's in the cards.  Medical problems with the little woman who was just horribly overextended financially to begin with. 

Need to retreat and regroup, I'm afraid. 

 

I'm really sorry to hear that Steve and that was the first thing to go through my mind when I heard of Lynda's problem.  That is why this whole universal medical insurance debate in the US os so important so good people don't lose everything if you get sick.  Our Canadian system may have its problems, but at least we don't have to suffer the financial hardships you Americans can have to go through if we have the bad luck to have a medical emergency.

 

Good luck with the decisions you will have to make in the coming days Steve.

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......at least we don't have to suffer the financial hardships you Americans can have to go through if we have the bad luck to have a medical emergency.

 

Tell me about it; my surgery came to over $300,000.  Hope things work out for you Steve

 

In talking with my brother tonight (he's had a couple of expensive surgeries in the last two years) I brought up 'my' version/recollection of my surgery expense (a bit over $300,000) and was told by my wife that the bills surpassed 3/4 of a million, so I guess I was confabulating again.

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......at least we don't have to suffer the financial hardships you Americans can have to go through if we have the bad luck to have a medical emergency.

 

Tell me about it; my surgery came to over $300,000.  Hope things work out for you Steve

 

In talking with my brother tonight (he's had a couple of expensive surgeries in the last two years) I brought up 'my' version/recollection of my surgery expense (a bit over $300,000) and was told by my wife that the bills surpassed 3/4 of a million, so I guess I was confabulating again.

 

3/4 of a million dollars sounds more like it.  I don't know how you Americans can survive without universal healthcare.

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We suffer stoically. 

Shit, mister, I pulled my own tooth last year.  Wasn't so bad.

Guess we're rugged frontier types - I remember this one Pennsylvania Dutchie, a tree fell on him and he was trapped.  He got out a knife, made a tourniquet out of his belt, hacked his own leg off and dragged himself to a telephone.  Nothing tougher than an old Dutchie!

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I remember when that happened....here's the news story:

 

Cut or Die

 

By Pam Lambert

Trapped by a Fallen Tree, Donald Wyman Amputates His Own Leg to Save His Life

August 09, 1993

 

IN THE STILL OF THE EVENING THE ONLY sound was the lowing of the cows—and then came the screams. Outside his barn, dairy farmer John Huber Jr. saw a mud-spattered pickup. Behind the wheel was a man who appeared to be stark, raving mad. "I cut my leg off!," the man was bellowing. "I cut my leg off!" Cautiously approaching the Chevy $-10, Huber watched the frantic driver struggle to raise his left leg into the air. Huber gasped. The leg was a bloody mess—and below the knee it was gone. "Help me!," the man shouted. "I'm bleeding to death!"

 

For the stunned Huber, 43, it was the start of a desperate race to save the life of 37-year-old Donald Wyman. But Wyman, a burly bulldozer operator, had already waged his own herculean struggle for survival. Minutes earlier, alone in the western Pennsylvania woods, he had been forced to amputate part of his own leg with a three-inch pocket knife. It was his only hope of escaping the huge oak tree that had crushed the leg and pinned him to the ground. Leaving a bloody trail, he crawled 135 feet uphill to his bulldozer, hoisted himself into it and rumbled 1,500 feet to his pickup. Then, using a metal file to depress the clutch when he shifted, he drove his manual-transmission truck a mile and a half to Huber's place. "I told myself it's too early to go out like this," Wyman told PEOPLE days after his July 20 ordeal. "I thought, I gotta get out of this for my family.' "

 

At the farm, Huber raced inside to call for help. But when he got back, Wyman said, "That's not fast enough." With remarkable clearheadedness, the hemorrhaging man, who lives with his wife and teenage son 15 miles from Huber's Oliver Township spread, urged the farmer to tell the dispatcher that the pair would meet the rescue squad at a crossroads.

 

"I never saw a man so sharp under those conditions," says Huber, who did the driving. "He kept thinking and planning. Not me. I was praying." Huber says his passenger was so levelheaded that he actually asked Huber to slow down. Explains Huber: "He didn't want to die in a car wreck."

 

Minutes later, Wyman calmly told the ambulance crew, "Go get my leg," then sketched a map that would lead them to the accident site. Wyman lifted himself onto the gurney, declining both oxygen and painkillers.

 

"He has more stamina than anyone I know on the whole earth," says David Osikowicz, president of Original Fuels Inc., the local surface-coal-mining company for which Wyman has worked the past three years. "If anyone could have gutted it out like that, it was him." Wyman, a steelworker's son, is more modest. "I guess I just like to do things on my own," he says. "I've always been pretty determined."

 

The road to Wyman's hell was paved with the best of intentions—building a house for his wife, Janet, 35, and son, Brian, 17, so that they could move out of their two-bedroom mobile home in New Bethlehem, Pa. After finishing his shift clearing trees at the mouth of a strip mine, Wyman wanted to gather some logs to barter at a local sawmill for lumber for his house. Everyone else was leaving as he sharpened his chain saw. Around 4 p.m. he began slicing into a massive oak lying on a hillside. Then it happened.

 

Suddenly the trunk snapped back at him and fell, pinning his leg underneath. Because the top of the tree had been wedged between others it was slightly bowed; the cut released the tension like an enormous spring. "As many trees as I've cut, I should have known better," Wyman says. "It drove me right into the ground. I didn't, know what had hit me." Seconds later, he knew. The trunk had rolled over his left shin about seven inches below" the knee, cutting flesh, shattering bone and burying his lower leg under an immovable weight of oak.

 

For the next hour, Wyman dug feverishly to free his broken leg; every so often he stopped "to bellow for help." Unable to reach much of the log with his saw, he used it instead to chop the hard ground beneath his leg, then scooped the soil away with his hands. "I felt some fear, but not too much," he says. "Mostly I just tried to assess the situation and not panic."

 

But then Wyman ran into a huge rock—one he couldn't dig around to free his foot. He weighed his odds of rescue—it would be several hours before his wife started to worry about him and, by then, he might bleed to death. "I had my knife," Wyman recalls. "I just realized that if I was gonna get outta here, this [amputation] might be the only way."

 

First, Wyman grabbed a rock to sharpen the dull blade of the $3 flea-market knife. Next he sliced away his jeans. Then he pulled the starter cord out of his chain saw and made a tourniquet to stanch the bleeding.

 

After a first quick cut, Wyman, who remembers fainting at the sight of blood in a high school biology class, thought, "I can't do this. I'm not gonna be able to cut my leg off because of the pain." So he sat there for three or four minutes, realizing it was his only choice. Reliving the ordeal, Wyman has increasing difficulty getting out the words. Finally he pauses, squeezing his wife's hand for support.

 

"I was praying," he says. "When I got ready to cut, I said, 'God, help me to get out of here'—and He did. But once I started culling, I didn't pray—I was so concentrated on that." After a minute of agony as he cut through the splintered bone, Wyman felt a surge of joy. "My leg was free now!" he says. "At that moment, I thought I was starting down the road to being saved."

 

Thanks largely to his own courageous efforts, Wyman made it. But the rest of his leg didn't. Although the rescue crew easily found the limb—still wrapped in blue jeans and wearing a laced-up, steel-toed boot—by the time they were able to saw it free and rush it to the hospital, more than two hours held elapsed and tissue damage was too severe for reattachment. But despite his sacrifice, many are convinced that Wyman made the right choice. "If he wanted to live, he had to gel out of there," says assistant fire chief Christopher Lento. "And that was his only way out."

 

The warmest praise for Wyman comes from his family. 'I think he's the greatest man alive, that he could do something like this," says Brian, a high school senior who hopes to become a lawyer. "Don would do anything for us," adds Janet. "He did what he did because he knew he was coming back to his family."

 

After less than a week in the hospital, Wyman was ready to go home. It will be a while before he'll be back bass fishing or tracking deer—or at work, which Original Fuels has promised he'll have for life. But according to his physical therapist, Wyman can expect eventually to regain up to 95 percent of his leg function with an artificial limb. (Meanwhile a Don Wyman Fund—c/o Harmarville Rehabilitation Center, Box 11460, Pittsburgh, Pa. 15238—has been established to raise money for his medical bills and Brian's education.)

 

Looking back now at his narrow escape, Wyman says simply, "I had a life-and-death situation. I have so much to live for that I did the only thing I could—I chose life."

 

PAM LAMBERT

TOM NUGENT in Punxsutawney

------------------------------------------------------------------------
 
here's some more similar stories:
 
  • In 2007, 66-year-old Al Hill amputated his leg below the knee using his pocketknife after the leg got stuck beneath a fallen tree he was cutting in California.
  • In 2003, 27-year-old Aron Ralston amputated his forearm using his pocketknife and breaking and tearing the two bones, after the arm got stuck under a boulder when hiking in Utah.[
  • Also in 2003, an Australian coal miner amputated his own arm with a Stanley knife after it became trapped when the front-end loader he was driving overturned three kilometers underground.
  • In the 1990s, a crab fisherman got his arm caught in the winch during a storm and had to amputate it at the shoulder, as reported in The New Englander.

 

 

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