Royal Navy Dido class Light Crusiers

[Foeth]

Typical distortion of a well-built amplifier is in the 0.01-0.03 % range and the preamplification stage <0.01% . Really, expert listing boards cannot distinguish one well-built amplifier from another in ABX testing enviroments. At 0.05% distortion, you have a distortion-to-signal ratio of -66 db, or the difference in sound level of standing below a landing jet airplane and listening to normal conversation

Plus, this distortion occurs when you are overloading the tubes. You shouldn't ever overload your audio amplification gear.

One of the true advantages of the tube is that it is (more?) resistant to EMP shockwaves. Should that matter when listening to music?

[bengtsson]

I'll bite a little on the off topic and then leave it at that. I enjoy the audio debate. My electronics training began in 1969, and at that time the tube was still king. On it's way out, but only just.
I think an understanding of the physics involved are necessary to the debate. But there is no room for that here. It is just in the different physics of semi conductors and tubes that the difference in sound reproduction lies. After all, we are talking about reproduction. Perfect harmonic reproduction was a doubtful quantity in the early solid state amplifier during my education. The field of harmonics is central to that debate and also way above our time to go into. I'm open to both sides, reproducing what is on the record or CD is only part of audio. It's how you got that original music recorded. Tubes, solid state.
When we studied digital music. Changing the sign waves of music into 1 and 0s that alot of us began to question modern music reproduction. Where do complex harmonic interactions go when they are stripped out and turned into 1s and 0s. Thus early on digital music was less rich and very sharp and had a tin sound to it. It has gotten better. But to a kid of the late 60s with a passion for music, 2007 CDs of Pink Floyd or the Moody Blues seem to my ear at least to lack harmonics that existed in original recordings. 1s and 0s can be converted back to sound, and averaged out to produce the sign waves of music, but where do the very fine harmonics that are created by interactions of multiple sound waves. Do they make it through the digital processing. I think alot does, but some doesn't and that which is stripped out may be why I still hear the difference when a CD of my favorite music is played.
Solid state amplification would seem to me to be able to handle harmonics very well. Tubes would handle them prefectly. Noise and distortion should be worse with a tube. My problem is with the digital reproduction, not the final amplification.

On topic. I want to see the tube used in that VT fuse! How it was packed. For my money, just use heavy wires and lots of solder on connection pack a little rubber around it and Fire Away . Only the tube itself would be your problem.

Bob B.

[Timmy C]

Would this pic be good for the VT Fuse shell innards?


Link to the USN's article on VT fuses: http://www.history.navy.mil/faqs/faq96-1.htm

[bengtsson]

Bravo! Timmy C.

Bob B.

[Timmy C]

It was the first image to come up when you Google "VT Fuse"

[Foeth]

Solid state amplification would seem to me to be able to handle harmonics very well.

I just want to continue off topic, of course Perhaps we should have a small topic split as the Dido class thread is quite interesting. Note that it doesn't matter one iota if you're amplifying harmonics, blocks, pulses or whatever. The voltage going in is amplified and that's that! Audiophiles somethings say that music is a complex pattern, unlike a sine, and is therefore "different". But it is not.

Digital reproduction isn't the problem. The quality of digital production is far superior to analogue reproduction. But the analogue master tapes can still sound every bit as good as a digital one. Take a photograph, for example. You can shoot a 8 Mpixel picture with such a color range that it is visually indistinguishable from a normal analogue picture. That is, unless you zoom in on that digital picture. But there is no such thing as zooming in on sound. I refer again to the ten biggest lies in audio. It's a pleasant read

BTW, that link to decware even has a page declaring superiority to their audio cables and power cords. Anyone doing that is a fraud. Period. So, that reference isn't worth anything as it is completely untrustworthy. Not that audio cables have absolutely no effect on the sound, but power cords... it's similar to painting a blue ring around your water tap and claiming the taste of the water has improved.

[bengtsson]

I can't leave it alone It's too interesting a topic.

An amplifier is simply a variable resistor, the input voltage is the control.
On harmonics, I admit, in our program as USN Submarine Sonar Technicians, harmonics was important stuff. Yet we did an introduction to it for a few days and then let it go. Being told, just accept the theory and don't worry about the physics behind it all. Thank god for that much
The idea being that mechanical motion produces sound waves, once the waves are created, they can intereact and produce whole new sounds independent of the means of their production. Music is the classic example. Russian submarines as well. Also, we all know about harmonic vibrations that can tear a building a bridge or a glass to bits.
With digital recording, one wonders if these independent harmonics can survive being turned into 1s and 0s. I swear I don't know, but my gut tells me that analog , which is the signal itself with all it's harmonics, just might lose something in the conversion.
Naval Passive Sonars were just making the switch over to solid state systems when I went through sonar school. For the simple act of passive listening, solid state was perhaps even better than tubes, with their noise generation. No digital conversion came into it in those days. Analog was king. We did also use huge tape recorders for both recording Russian warship sound profiles and also these multi head recorders were used for running training simulations. With something like 38 or more heads, each one carried an input signal to the sonar set. So it could play a full active or passive sonar scenario for us.
Tube sonars had alot of voltage. Solid state sonars had very high currents for the active elements. You could fry a wrecking ball in the final stages of ampification of the active pulse. Or so they said Could be they were kidding.

Bob B.

[Foeth]

I swear I don't know, but my gut tells me that analog , which is the signal itself with all it's harmonics, just might lose something in the conversion.

Well, of course you loose something. But the question is: is that what you are loosing in any way important? If you are listening to a 20 Hz signal and you sample it at 50,000Hz, you get a pretty good impression of that 20Hz signal, even if you do loose something. Note that for proper signal acquisition, you must condition the signal, so you filter out everything above a certain frequency (or band passes or low passes or high passes etcetera). So, that information is lost before you do the conversion. For human hearing, it doesn't matter if you include or exclude signals that cannot be detected by our ears. Unlike what the audiophile wil tell you, a human ear isn't the best sensor around!

I don't know much about sonar amplification, but I guess that's some distance from home audio. Perhaps not. But if you need more power tubes might do a bit better.

[bengtsson]

I don't know much about sonar amplification, but I guess that's some distance from home audio. Perhaps not. But if you need more power tubes might do a bit better.

Passive sonar doesn't need alot of power, as you are only listening and boosting a weak signal. That signal needs little boosting for the human ear.
Active sonar is where the Massive Power Amplifier Tubes came into play. Six cabinets lined up down in the equipment spaces. All containing one huge tube for each branch of the transmitter. Big, like bigger than a large man's forearm. Of course active sonar needs massive power for the pulse. Shorting tubes when the pulse hit was a major problem. Everything looked good till the pulse hit then you lost that one channel and had to cut out that whole bank of tubes till you found the bad one. Good luck!
Passive sonar made alot of use of filters to try and get at a frequency the target seemed to produce alot of. Without the background noise you could key in on alot of different sounds a particular ship might happen to be making at the time.

Bob B.

[phil gollin]

Link to the USN's article on VT fuses: http://www.history.navy.mil/faqs/faq96-1.htm

Very good, just a couple of errors.

The British had a working proximity fuze for rockets in 1940 - this design was one of the secrets given to the US in the Tizard mission. It was this design that was patented for radio frequency proximity fuzes and formed the basis for US research.

The US tried to develop its own firing circuit design but failed and ended up using the British design.

But the article's emphasise on the problems of ruggedisation is very true.

[Werner]

The British had a working proximity fuze for rockets in 1940 - this design was one of the secrets given to the US in the Tizard mission. It was this design that was patented for radio frequency proximity fuzes and formed the basis for US research.

The US tried to develop its own firing circuit design but failed and ended up using the British design.

I'm sure we would all like a reference supporting this.

[RNfanDan]

But the article's emphasise on the problems of ruggedisation is very true.

Oddly enough, the solution to the battery problem was nothing more than a refinement of the German Hertz horn mine trigger--used in WW1!

I wonder how a VT fuze would adapt to large-caliber shells; the Japanese fired main-battery barrages at US planes, purportedly with some success. Radar-directed main guns using VT-equipped HE shells would have been an interesting concept--provided, of course, the enemy had planes close enough to fire at!

[Werner]

the Japanese fired main-battery barrages at US planes, purportedly with some success.

The Japanese san-shiki main-caliber AA shells were a spectacular failure. Essentially they were a bundle of rubberized explosive rods and steel pellets, shot out of the barrel and which ignited after a fixed delay.

In action they were said to resemble Roman Candles, and had no effect other than to generate an extraordinary amount of radio chatter.

They were used by Musashi during her failed transit of the Sibuyan Sea, October 24, 1944, and by Yamato on the final sortie.

[Guest]

the Japanese fired main-battery barrages at US planes, purportedly with some success.

The Japanese san-shiki main-caliber AA shells were a spectacular failure. Essentially they were a bundle of rubberized explosive rods and steel pellets, shot out of the barrel and which ignited after a fixed delay.

Quite a misleading description. Far from being giant shot gun shells or roman candles, they were actually cluster weapons that leaves the barrel as an intact shell and release their incendiary sub munition upon reaching the predetermined barrage zone. When they release the sub munition ignites and creates a very distinctive fan shaped pattern of smoke trails that continue down range. This burst pattern is clearly seen on a number of photos taken from US aircraft during the late 1944 campaign.

[Guest]

I wonder how a VT fuze would adapt to large-caliber shells; the Japanese fired main-battery barrages at US planes, purportedly with some success. Radar-directed main guns using VT-equipped HE shells would have been an interesting concept--provided, of course, the enemy had planes close enough to fire at!

So did the Germans. The Tirpitz had 15" AA shells. There would be no technical problem whatsoever with adapting it to a large caliber shell. The condition in the large caliber shell would actually be much more mild than in a 5"/38 gun. Look how much distance an 18"/45 shell covers to reach its muzzle velocity, and how much distance it takes a 5" shell to do the same. Clearly a 18" shell is experiencing a lot less Gs than a 5" shell. The problem is the Japanese and Germans didn't have one to adapt.

Also, the idea of a proximity fuse probably defeats the concept of Japanese San Shiki shell. The shell was intended to really be an barrage weapon that has a leathality cone of about 1000 yards long and 300-400 yards wide. The idea was to explode 1000 yards ahead of the enemy formation and take out an significant number of planes all at once. The cone of smoke trails from the sub munition also presents a psychological deterrent to the enemy flyers.

If you trigger an San Shiki shell with a proximity fuse, it would trigger too late, and most of the enemy flight would be to the sides of the cone rather than be inside it.

Incidentally, I am not aware of any automatic fuse setting arrangement in Japanese main caliber turrets for the San Shiki shell. Does anyone have any information on how the fuse on San Shiki shells are set?

[phil gollin]

The British had a working proximity fuze for rockets in 1940 - this design was one of the secrets given to the US in the Tizard mission. It was this design that was patented for radio frequency proximity fuzes and formed the basis for US research.

The US tried to develop its own firing circuit design but failed and ended up using the British design.

I'm sure we would all like a reference supporting this.

Oh dear - yet again.

"The Deadly" Fuze" (previously recommended) will give you the details of the transfer of info and especially the problems regarding circuitry.

The Patent "problems" are held in the PRO files - the US scientists claiming the patent "forgot" about the British information until provcen wrong in 1952 and the US government accepted the British patent.

Lots of stuff got "forgotten" in those days.

[bengtsson]

Back to the Didos and RN main armament AA fire. When did the Royal Navy get the VT fuse and how did it work out in practice? Did the VT go into all the major RN AA shells? 4in etc. etc. ??

Didn't the British bring over to the USA about the single most important development in radar history, the one thing that made allied radar superior. the Cavity Magnetron? The US was no better off than the axis nations till this little baby was handed over. Or so I understand.

Bob B.

[ar]

Back to the Didos and RN main armament AA fire. When did the Royal Navy get the VT fuse and how did it work out in practice? Did the VT go into all the major RN AA shells? 4in etc. etc. ??

Didn't the British bring over to the USA about the single most important development in radar history, the one thing that made allied radar superior. the Cavity Magnetron? The US was no better off than the axis nations till this little baby was handed over. Or so I understand.

Bob B.

I believe that the fuse was deleivered to the Fleet sometime in late 1944 bit cannot be certain.
There are files waiting to be looked at in the PRO that tell the entire story.
The problem with the British, is that almost nobody will get off their fat lazy bums. Unlike the US archives, the UK stuff is laid out with indexes and available on demand.

Read the book, Menlo Park, this gives in amazing detail the story of the transfer of the cavity magnetron and subsequent US development.
It recounts (in detail) when the thing was unveiled to the Americans in a Manhatten apartment in the summer of 1940 and the reaction that it drew. It was a revelation to them. THat night, the group of Americans while still in the apartment, began to plan out the future of the wartiome US radar programme.
Buy, borrow, or steal the book.

[Foeth]

Do you have an author with that book? Searching for Menlo Park at amazon gives 17350 hits

[ar]

Do you have an author with that book? Searching for Menlo Park at amazon gives 17350 hits

Regret I cannot remember. The book is really a biography, have forgotten who. Written by an American woman. Published about two years ago.
According to the book, that night the British laid out in detail the operational use of radar in the Battle of Britain, along with other things. A treasure trove of secrets, nothing was held back. There are little tit bits like how the journey was made from London to the US, how the train compartment was kept clear of other passengers, telephone calls etc. A description of the first time that one of the very first microwave sets using the British Cavity magnetron made by the Americans was placed on a aircraft, (a B18 I think) and tested aginst ships up and down Long Island Sound. Details that make the story come to life.
Try your local library, they will know. The book MAY, have been on the NY Times best seller list.