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ALO The Continental - Page 7

post #91 of 456
Quote:
Originally Posted by Uncle Erik View Post

Maybe I'll contact the seller tomorrow. Today is busy.

I need to get my ears candled, spend some time exercising my pet unicorn and attend a séance after dinner.


If you run across Jimi Hendrix at the seance tell him I said hi and I love his music biggrin.gif

post #92 of 456
In fairness to ALO, they are far from the only people who are using the 6111 in a mini tube headphone amp. I'm not sure who first came up with the idea, but there is a design frm a board in Korea that surfaced late 2005 (or sooner, hard to tell ):

http://www.headphoneamp.co.kr/bbs/zboard.php?id=diy_sijosae&page=1&sn1=&divpage=1&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=239
post #93 of 456
Quote:
Originally Posted by Skylab View Post

In fairness to ALO, they are far from the only people who are using the 6111 in a mini tube headphone amp. I'm not sure who first came up with the idea, but there is a design frm a board in Korea that surfaced late 2005 (or sooner, hard to tell ):

http://www.headphoneamp.co.kr/bbs/zboard.php?id=diy_sijosae&page=1&sn1=&divpage=1&sn=off&ss=on&sc=on&select_arrange=headnum&desc=asc&no=239


 


That little amp looks mega cool bigsmile_face.gif Mr Skylab would you be so kind as to give out some reviews in the near future of little tube amps of that calibre and form factor please biggrin.gif

 

post #94 of 456
Quote:
Originally Posted by Uncle Erik View Post

True, logwed. You could also have a circuit that puts 1 Kilowatt into 300 Ohms.

Of course, you need a circuit and components capable of generating 1 Kilowatt in the first place.

All that is offered here is a rating that works out to 6.25mW. Clarification and explanation were asked for weeks ago. The only response was a third-hand testimonial that it "works."

As for a lay explanation, I chose to go after this in terms of heat for a reason.

Eyes glaze over when you talk electricity and use numbers. There is also a widespread perception that "numbers don't matter" and science isn't worthwhile.

Fine. But everyone understands heat. Everyone knows what boiling water is like. Everyone knows the blast of hot air from getting something out of the oven. You do not need an engineering course to remember what it is like to touch a hot oven.

Electricity and heat are deeply intertwined. Generate electricity and you get heat. Heat can generate electricity. The engine in your car generates heat when it creates power. Your body generates heat the harder you work. And I'm sure everyone understands why there's a fan on a CPU. I like to think people understand the relationship between heat and energy on a fundamental, intuitive level.

This is physics. There is a deep amount of research going back a good 140 years on the relationship between heat and electricity.

The 6111 tube generates heat when it generates power. A lot of heat. Fully driven, it will create heat on a level between boiling water and cooking a potato. If it were generating that kind of heat:

1. It would destroy the internal components;
2. It would give the user serious burns;
3. The battery would run out of power in minutes; and
4. The tube (per manufacturer's specs) would burn out in about 1,000 hours, not 100,000 hours.

The only possible conclusion is that the tube isn't really being run at all. It is mostly being lit up for show.

The only way there could be a slight amount of amplification is if other solid state devices (I only see one tube) are creating it.

Now, if someone contends that an an ordinary tube can be driven for 100,000 hours, create loads of power and be cool enough to hold in your hands, I am absolutely astounded. That violates the known laws of physics. It would change not only amps, but the way electric motors are designed, computers, the lightbulbs in your house, and, well, pretty much anything that runs on electricity.

So you can understand why I find this especially interesting.

On the other hand, it could just be an aluminum box with a paltry amount of power generated by some little chips and a lit tube as decoration.

By the way, if anyone wants a decorative tube, I have a box of tubes that sadly had their identifying marks rubbed off. I'll send you a decorative tube for the cost of postage - about $4 in the US. I'll tell you how to make it light up, too, free of charge. For another $25 or so, you could build a CMoy around it. Heck, a CMoy will give you about 35mW of power. You could have an amp with five times the power and a decorative tube for about $30.
 


Is it possible however that a smaller tube of this kind, which I'm assumed was built as such with portability in mind, is designed to run differently? Perhaps this particular tube does not run as hot? It certainly isn't any where near as big as a regular tube. is it even possible the power delivery is different to that of a full size tube? This is Ken's description of the tube.

 

The Raytheon 6111 vacuum tube is a sub-miniature low gain, ultra-low micro-phonics, dual triode with a characteristic open sound stage and smooth delivery.  It can deliver a 25VAC audio frequency signal into a 100K ohm load.

The 6111 vacuum tube, with its ultra-low micro-phonics, low power consumption and rugged build is ideal for portable amplification which is why it is at the heart of the Continental. The 6111 is built for rugged use, an ultra long life and low power consumption requirements. The estimated life of a 6111 tube is approximately 100,000 hours. 

Certainly doesn't sound like it would be as powerful or hot as a regular sized tube. You talk about the correlation between heat and electricity, and cpu fans etc. You realise diodes and nm process chips get smaller and run cooler as they do? There's a reason why for example, lower end smaller performance generating GPU's can often be cooled by heatsink alone, whilst other higher end or larger chipsets or parts require high rpm fans and behemoth heatsinks. You have to appreciate that as you scale down, so does the level of heat output and power consumed.

 

I think one of the problems I'm having with your assessment is it's very black and white. You're suggesting that it would be boiling hot if run at maximum power (how much truth is there to this anyway?), and if it's not, it must not be being used at all, only being lit. There is literally nothing in-between. It's either on and super hot, or not being used at all. I think this method of thinking is potentially flawed and even then, is full of a lot of assumption or conjecture.

 

 


Edited by Naim.F.C - 8/21/11 at 5:04pm
post #95 of 456
Ha! Not likely, sorry to say. I'm not really into portable amps anymore, and as I mentioned, as much as I like tube amps for home use, I really don't see the logic in using a tube in a portable amp. Tubes have some really excellent amplification qualities, almost all of which would have to be significantly compromised in a small portable amp. Even the data sheet for the 6111 says that maintaining heater voltage is critical to reliable to good performance. I don't think that's likely in the tiny battery power supply that a small portable amp has.

Let's face it, there are applications where little solid state op amps are ideal. A portable headphone amp is one of those.
post #96 of 456
Quote:
Originally Posted by Uncle Erik View Post

True, logwed. You could also have a circuit that puts 1 Kilowatt into 300 Ohms.

Of course, you need a circuit and components capable of generating 1 Kilowatt in the first place.

All that is offered here is a rating that works out to 6.25mW. Clarification and explanation were asked for weeks ago. The only response was a third-hand testimonial that it "works."

As for a lay explanation, I chose to go after this in terms of heat for a reason.

Eyes glaze over when you talk electricity and use numbers. There is also a widespread perception that "numbers don't matter" and science isn't worthwhile.

Fine. But everyone understands heat. Everyone knows what boiling water is like. Everyone knows the blast of hot air from getting something out of the oven. You do not need an engineering course to remember what it is like to touch a hot oven.

Electricity and heat are deeply intertwined. Generate electricity and you get heat. Heat can generate electricity. The engine in your car generates heat when it creates power. Your body generates heat the harder you work. And I'm sure everyone understands why there's a fan on a CPU. I like to think people understand the relationship between heat and energy on a fundamental, intuitive level.

This is physics. There is a deep amount of research going back a good 140 years on the relationship between heat and electricity.

The 6111 tube generates heat when it generates power. A lot of heat. Fully driven, it will create heat on a level between boiling water and cooking a potato. If it were generating that kind of heat:

1. It would destroy the internal components;
2. It would give the user serious burns;
3. The battery would run out of power in minutes; and
4. The tube (per manufacturer's specs) would burn out in about 1,000 hours, not 100,000 hours.
 


 

I said that it put 2.08W into 300ohms assuming that it can put out 25V into that impedance, I have no idea what you're getting at with this 1kW other than random hyperbole... I'm an engineering undergrad, so please don't lump me into those who are science ignoramuses. My calculation was meaningless because I don't know how many volts the amplifier can actually put into 300 ohms, it is undoubtedly much less. Your calculation is meaningless because 100,000 ohms is not a realistic load in any way, it doesn't tell us anything about how much power and current it can put out into a normal load.

 

I was simply pointing out how you are clearly extrapolating meaningless data into condemning a product that you have never tried. 

 

The 25V into 100K ohms is certainly a marketing bit meant to make the amp look impressive by people who will only look at the voltage swing. I don't disagree that an amplifier will create waste heat, but I haven't seen you put together any set of numbers that indicates that the heat created by the tube is dangerous. The fact that the tube is 220C at the hottest point doesn't indicate all that much if we don't know how effective the case is at radiating/venting  said heat, or really how much heat is released by the tube at all, temperature is not the same as heat.

 

The 100,000 hour assertion is definitely the most suspect statement, since it is a radically unrealistic number, and the 'explanation' that it uses a unique design is vaporous and snake-oily at best.

post #97 of 456
READ THE DATASHEETS.

I'm citing temperatures listed by the manufacturers of the tubes.

Not my opinion.

This is data from 50 years ago.

Again, not my opinion.

From what I gather, the tube was meant for subminiature assemblies in aircraft. Much is made of how it does well at 60,000 feet.

Yes, chips can get more efficient and use less power as they are scaled down.

But this is a tube from the late 1950s. It generates a lot of heat when run. Again, go read where Raytheon tested it at 200° C/425° F.

Now look at the curves, also in the datasheet. To get the tube linear, you will generate heat that is well above the boiling point of water.

Yes, that is a black and white proposition. Some things in life simply are.

You are more than welcome to use a bench power supply to raise the tube to operating temperatures and use a thermometer to find out for yourself. Personally, I'll take the word of the lab engineers who ran the tests back in the 1950s. They certainly weren't trying to game stats for an amplifier made in 2011.

There are simply too many contradictions here.

Claims of huge bass, while the amp cuts off at 40Hz, missing the entire lower octave. How can that be?

Claims of huge power output, while listing 6.25mV of power. How can that be?

Claims of running a tube without actually running a tube. If it were run, it would be extremely hot (as per manufacturer's description), hot enough to destroy its caps and resistors (or force them to run at very different values), the battery would last for a few minutes, and the tube would burn out in 1,000 hours, not 100,000 hours. How can that be?

I would welcome explanation from the manufacturer. That is why it was asked for several weeks ago.

There was no response.

If you are going to claim a 100,000 tube life from a 1,000 tube, people are going to ask questions.

If you are going to claim huge power from what is listed as a 6.25mW output, people are going to ask questions.
post #98 of 456

I have no idea why you keep harping on this 6.25 mW output, it doesn't mean anything.

 

The temperature of a tube itself doesn't mean much unless we also know how well the case can ventilate the heat.

 

I agree with you on the 40hz cutoff, there are playable notes that are missed there, that does not make sense.

 

I agree with you on the 100,000 hour life, that doesn't make sense when compared with the data sheet numbers or conventional knowledge at all.

 

Do you know how much current the tube draws during normal operation from that data sheet? If so, we could compare that to how much current is drawn in normal operation by the amplifier on the whole to see if it is greater than the power draw of the tube, which would indicate that the tube is being used. If it is much/significantly less than the sheet value for the tube, then we could probably assume that the tube is not being powered/used.

post #99 of 456
They draw 300 mA.
post #100 of 456
Quote:
Originally Posted by Skylab View Post

They draw 300 mA.


Ok, so all we need is to determine how many mAH the battery is rated to, and find out how long it takes for it to run all the way down. 

post #101 of 456
Dunno about the ALO, but in the Miu amp that is 6111 based, they use a 2500 mAh battery. However, the solid state devices are also drawing from the battery, so that would have to be factored in too.
post #102 of 456
Quote:
Originally Posted by Skylab View Post

Dunno about the ALO, but in the Miu amp that is 6111 based, they use a 2500 mAh battery. However, the solid state devices are also drawing from the battery, so that would have to be factored in too.


Mhm, but would it be fair to say that the other circuitry would likely cause less than 300 mA to be dissipated, correct? I'm only saying this based on the current drawn from a Mini3 (25 mA), so I may be wrong. If we were to get a value for the current draw of <300 mA, so less than 8.3 hours of battery life (assuming that they use a battery of the same size), we could definitively say that the tube is not being utilized because that's not even enough to power the tube, regardless of how much the other components draw.

post #103 of 456
Quote:
Originally Posted by logwed View Post

The temperature of a tube itself doesn't mean much unless we also know how well the case can ventilate the heat.


You're grasping a bit there.  The principles of Thermodynamics are pretty darned linear.   I'm not an EE but I build my own PC's and blueprint race engines and do aero/cooling mods for the track as a hobby.  You don't need to lose a multi-million dollar payload destined for Mars to know how efficient passive ambient cooling is.  I don't care how many holes or vents you have.  If there isn't a fan or Peltier cooler the temperature the amp is running at is absolutely indicative of performance and output.  Even gas exchange tubes will only get so far w/o active cooling.  Of course this wouldn't be a problem operating above 60,000 feet as was intended.

 

In such case the tube is not functioning as the primary output stage.  If you can offer a better explanation for how a tube runs relatively cool as an output I'm happy to listen.  Ambient cooling is a no go.

 


Edited by Anaxilus - 8/21/11 at 7:08pm
post #104 of 456
Tubes are designed to run hot. The bigger issue is whether the components around them can handle the heat they generate.
post #105 of 456

If you don't think that ambient cooling will cut it, I'm glad to believe you. 

I was just thinking that the combination of the small size of this specific tube in combination with the venting holes and ability of the metal case to radiate heat effectively could be enough to deal with the waste heat from the amplifier. Obviously if you have experience with this sort of thing, you would understand it more deeply than I.

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