The Last Laugh
Yup, Cowan told us that once "equipment is NOT effected by movement, let alone small tiny vibrations. think about it, how could that possibly change anything?"
Chris8 too "Spikes on electronics? Improving sound? No evidence to support this. Speculation."
Peter, yeah I couldn't resist it either - don't be sorry.
There are a couple of other current threads where I'm finding it hard to resist the same temptation.
Eric.
Yup, Cowan told us that once "equipment is NOT effected by movement, let alone small tiny vibrations. think about it, how could that possibly change anything?"
Chris8 too "Spikes on electronics? Improving sound? No evidence to support this. Speculation."
Peter, yeah I couldn't resist it either - don't be sorry.
There are a couple of other current threads where I'm finding it hard to resist the same temptation.
Eric.
Space Age Materials
Bob, yes sorbothane is weird stuff.
So is the kids toy 'Silly Putty'.
If you roll it into a ball and throw it at the floor, it will bounce just like a 'Superball', and when it stops bouncing will ooze into a puddle - don't let it come to rest on carpet !.
It will also shatter if hit with a hammer.
I have thought of dropping a car valve spring into a 35mm film canister and filling at least partially with silly putty.
Three or four of these under equipment or speakers might make an interesting change.
Eric.
Bob, yes sorbothane is weird stuff.
So is the kids toy 'Silly Putty'.
If you roll it into a ball and throw it at the floor, it will bounce just like a 'Superball', and when it stops bouncing will ooze into a puddle - don't let it come to rest on carpet !.
It will also shatter if hit with a hammer.
I have thought of dropping a car valve spring into a 35mm film canister and filling at least partially with silly putty.
Three or four of these under equipment or speakers might make an interesting change.
Eric.
I've read a couple of snippetts about cryoing engine parts, but not enough to be conclusive. However I will say, having been around a lot of racers in the past, they will often disseminate bad information or distort it to confuse other teams and competitiors about what they're up to.mrfeedback said:
One of the best 'bush' mechanics I know, goes and finds old engines with lots of miles on them, but not worn out, and builds his race motors from them, because all the thermal stresses in the grain structure will have 'settled' by the time he gets it. He will strip them, measure and then have everything precision machined true. His cars were damn fast, and there were few name parts in them, but a lot of time. I don't think his van ever ran at Castlereagh or Eastern Creek, but he won a LOT of money at Homebush Bay drags. For Aussies: HT Holden van, 253 V8, quadrajet, dual-plane, 2 speed pwerglide, 3.55 rear end, and easily into the 11s for a day to day work van.
Silicon rings have been recommended to me often by tubeheads who's opinions I respect. They're only a few cents each, so why not try.
Neutron Bob mentions using Sorbothane. That's interesting as I thought it would be ideal, but the envelope of most of the tube I run, get real hot, and I thought the sorbo would melt, or melt onto the glass. The silicon O rings certainly wouldn't have the ability to dissipate vibration like sorbo, but they may work in a different mannet, if placed at the vibrational node on the envelope, and shift the major resonance to a different frequency out of band, or spread it, lowering Q, and make it less audible in some instances.
The best experience I have had with eliminating environmental structure-borne/acoustic vibrations from my equiptment, is to
- build the case as rigid as possible, and then suspend it from the equiptment cabinet/table in some way. Sorbothane pucks or half-spheres, hanging on nylon monfilaments, or sometimes even timber blocks, such as maple. I like the nylon monos best, esp with lead fishing weights crimped to them at 1/3 and 1/5 of the length. I think in the next version, mono mounts might also use sorbo to further reduce structural transmission.
Of course, ensure there are no vibration sources <i>inside</i> such as power transformers, or PSU input chokes. Remote supply and umbilical works best here.
BTW, a tape accelerometer or microphone, and an HP spec-an were very helpful in developing this. As I've seen the significance of the vibration on a piece of instrumentation, does that mean I'm allowed to <i>hear</i> it now?
Cheers
"the thermal stresses in the grain structure will have 'settled' by the time he gets it." - I understand this to be the Rolls Royce reasoning. .... allows them to machine the block once and precisely and it to remain stable and true in usage.
"HT Holden van, ........" - misspent youth Brett ?
"Silicone rings ....." - where from ?
"tape accelerometer " - what's that ?
Eric.
"HT Holden van, ........" - misspent youth Brett ?
"Silicone rings ....." - where from ?
"tape accelerometer " - what's that ?
Eric.
Hi everyone,
*First on dampers: -rule number one : don't use dampers that choke the tube.Types such as sorbothane rings dampen very effectively but enclose so much of the glass that :
1/ the tube gets too hot, hence shortening its lifespan.
2/ the dampening material gets too hot,hence shortening its lifespan.
3/Instead of dampening the tube, try suspending the circuit board or if that's not viable put the unit on an isalotion base such as the Mission Isoplat (don't know if their still on sale)
4/Lead is also a very good dampening material with a very low Q.
> don't forget it is an electrical conductor.
*The cryo stuff sounds interesting,would be great if the factories would do that before sealing the tubes...
Sigh...
*First on dampers: -rule number one : don't use dampers that choke the tube.Types such as sorbothane rings dampen very effectively but enclose so much of the glass that :
1/ the tube gets too hot, hence shortening its lifespan.
2/ the dampening material gets too hot,hence shortening its lifespan.
3/Instead of dampening the tube, try suspending the circuit board or if that's not viable put the unit on an isalotion base such as the Mission Isoplat (don't know if their still on sale)
4/Lead is also a very good dampening material with a very low Q.
> don't forget it is an electrical conductor.
*The cryo stuff sounds interesting,would be great if the factories would do that before sealing the tubes...
Sigh...
Hola Eric-san,
I thought I'd replied to yer message, but these days I seem to have no short term memory left. Wonder why?
Cheerio
I thought I'd replied to yer message, but these days I seem to have no short term memory left. Wonder why?
If this van's a-rockin'.....mrfeedback said:
Silicon rubber O rings, same types as used in industrial equiptment. Last lot I got were fom a bearing supplier.
These were some small accelerometers I got from a friend in the aerospace biz. They looked like the Countryman mics you stick to the body of acoustic instruments, and weighed almost nothing. I think John Atkinson of Stereophile uses them to test loudspeaker enclosures with LibInst or whatever he uses.
Cheerio
changes in metal structure
Before getting my degree in EE, I did half a degree in Metallurgical engineering (and switched when I "saw the light")...
I can tell you with certainty that cooling a metal off with liquid nitrogen will do basically nothing to change it's atomic structure... unless you're cooling it from a high temperature. Cooling down from room temp, the only thing you might do is induce small stress fractures when the metal becomes brittle at low temp. You might even make a tube gassy by reducing the effectiveness of the seal between the metal and glass parts, since the two materials will have different thermal coefficients. All round, immersing tubes in liquid N2 just sounds like a really BAD idea.
In fact, the way to change the structure of a metal is to use carefully controlled high temperature cycles. When any substance is cold, the atoms move around less, and the material becomes more rigid (as everyone here knows from everyday experience). You can cool most materials as much as you want, and atomically speaking, precisely <i>nothing</i> happens. OTOH, when you heat a substance, the particles gain enough kinetic energy that they can break atomic bonds and move around to a certain extent. If you do it right, and control the heating and cooling process carefully, a metal's structure can be altered to acheive various objectives. Heat treatment is commonly used to remove the internal stresses in metal parts caused by machining and forming processes. Heat treatment can be used to change the strength and maleability properties of a metal, it's hardness, and a host of other parameters. Believe me, it's a <i>very</i> complicated topic, especially when you start talking about grain structures and alloy compositions. There's an unbelievable number of things you can do with iron (including the important category of steels) just by heating and cooling it right, and changing it's chemical composition tiny fractions.
As for Rolls-Royce leaving engine blocks in the yard for a long time... sounds like someone spouting hot air. The first time you fire up a new engine, it's going to get good 'n hot, and that will have loads more effect than sitting cold for 10 years. Why do you think they tell you to keep the revs low on a new car engine till it's broken in? During that whole break-in period, new parts are deforming with thermal stress cycles, and wearing against each other to achieve a good fit. If Rolls is really leaving engine blocks in the yard for 10 years, it probably has more to do with their astronomical sales volume.
...just my 2 cents
Before getting my degree in EE, I did half a degree in Metallurgical engineering (and switched when I "saw the light")...
I can tell you with certainty that cooling a metal off with liquid nitrogen will do basically nothing to change it's atomic structure... unless you're cooling it from a high temperature. Cooling down from room temp, the only thing you might do is induce small stress fractures when the metal becomes brittle at low temp. You might even make a tube gassy by reducing the effectiveness of the seal between the metal and glass parts, since the two materials will have different thermal coefficients. All round, immersing tubes in liquid N2 just sounds like a really BAD idea.
In fact, the way to change the structure of a metal is to use carefully controlled high temperature cycles. When any substance is cold, the atoms move around less, and the material becomes more rigid (as everyone here knows from everyday experience). You can cool most materials as much as you want, and atomically speaking, precisely <i>nothing</i> happens. OTOH, when you heat a substance, the particles gain enough kinetic energy that they can break atomic bonds and move around to a certain extent. If you do it right, and control the heating and cooling process carefully, a metal's structure can be altered to acheive various objectives. Heat treatment is commonly used to remove the internal stresses in metal parts caused by machining and forming processes. Heat treatment can be used to change the strength and maleability properties of a metal, it's hardness, and a host of other parameters. Believe me, it's a <i>very</i> complicated topic, especially when you start talking about grain structures and alloy compositions. There's an unbelievable number of things you can do with iron (including the important category of steels) just by heating and cooling it right, and changing it's chemical composition tiny fractions.
As for Rolls-Royce leaving engine blocks in the yard for a long time... sounds like someone spouting hot air. The first time you fire up a new engine, it's going to get good 'n hot, and that will have loads more effect than sitting cold for 10 years. Why do you think they tell you to keep the revs low on a new car engine till it's broken in? During that whole break-in period, new parts are deforming with thermal stress cycles, and wearing against each other to achieve a good fit. If Rolls is really leaving engine blocks in the yard for 10 years, it probably has more to do with their astronomical sales volume.
...just my 2 cents
Cryogenics
Cryo treatment is very effective; however it is not nearly as simple as most of the casual vendors would have you believe. Proper cryotreatment has a material specific series of cool down and warm up cycles that are carefully engineered to refine material grain structures for a specific purpose.
Throwing something in LN, plucking it out and calling it good is usually a serious misapplication of a darn usefull process.
Done right it ain't quick and it ain't cheap. Unless you are in a research enviornment it usually only pays when you have a batch large enough to fill the entire computer driven enviornmental chamber.
Just my two cents worth!
Cyclotronguy
Cryo treatment is very effective; however it is not nearly as simple as most of the casual vendors would have you believe. Proper cryotreatment has a material specific series of cool down and warm up cycles that are carefully engineered to refine material grain structures for a specific purpose.
Throwing something in LN, plucking it out and calling it good is usually a serious misapplication of a darn usefull process.
Done right it ain't quick and it ain't cheap. Unless you are in a research enviornment it usually only pays when you have a batch large enough to fill the entire computer driven enviornmental chamber.
Just my two cents worth!
Cyclotronguy
Well, perhaps I was a bit premature in dismissing cryogenic treatment... I did some reading, and it appears that some structural changes can be effected with deep cryogenic treatment, primarily in steels, though some physical changes may be acheived with other metals. It does not appear to be a mainstream technique however, as attested to by the fact that in my entire time studying metallurgical engineering I was never exposed to anything related to the cryogenic treatment of metals, but was exposed to a very wide variety of other heat treatment methods...
From my understanding, cryogenic treatment can reduce voids in metals, as well as force some realignment of the atomic matrix near atomic dislocations. The net result is a hardening and strengthening of the metal (the extent of this is of course highly dependent on the specific material composition involved, it's prior heat treatment history, as well as the specifics of the cryogenic treatment used). However, I believe the effect of cryogenic treatment is significantly less dramatic than what can be achieved with heat treatment methods. Also, I am uncertain of the effect of cryogenic treatment on a vacuum tube's glass envelope - there is a potential safety concern here if the envelope is appreciably weakened.
The practical utility of cryogenic treatment as it pertains to vacuum tubes reamins very doubtful in my mind. The metal changes indroduced would seem to have little bearing on the operation of the tube, exept perhaps with respect to it's microphonic characteristics. And, at that, this influence is not necessarily a positive one.
Given the variety of different metals used in the construction of a single tube, and the precision temperature profile control required during treatment, I find it unlikely that one particular cryo process could be optimal for treatment of a tube. The mechanical construction of a tube is also rather complex, and the changes introduced in it's microphonic characteristics will be very difficult to determine... especially if one does not know the metallic alloy composition and heat treatment history of the internal parts, and hence how each part will be affected by the cryo treatment. If anything, I would be very concerned about introducing nitrogen gas into the tube by leakage past the pins, since the thermal expansion coefficients of the metal pins and the glass envelope will be different.
Also, from Mr. Perkins' description in the CryoVac paper, it looks like he does a lot more than just cryo cycle the tubes... in fact, he not only puts them through a high-temperature annealing process after cryo treatment (this will tend to reverse some of the effects of the cryo process!), but he also etches oxides off the pins, and bright tins them. I can certainly see how his tubes might sound different after all of this! I mean, your contacts are going to be better for one...
I still maintain that the cryo treatment sounds like a dodgy idea. If there are genuine benefits to specially treating the metal parts in tubes, I think the right place for this sort of treatment is during their manufacture, not after they're fully assembled.
I did some reading, and it appears that some structural changes can be effected with deep cryogenic treatment, primarily in steels, though some physical changes may be acheived with other metals. It does not appear to be a mainstream technique however, as attested to by the fact that in my entire time studying metallurgical engineering I was never exposed to anything related to the cryogenic treatment of metals, but was exposed to a very wide variety of other heat treatment methods...From my understanding, cryogenic treatment can reduce voids in metals, as well as force some realignment of the atomic matrix near atomic dislocations. The net result is a hardening and strengthening of the metal (the extent of this is of course highly dependent on the specific material composition involved, it's prior heat treatment history, as well as the specifics of the cryogenic treatment used). However, I believe the effect of cryogenic treatment is significantly less dramatic than what can be achieved with heat treatment methods. Also, I am uncertain of the effect of cryogenic treatment on a vacuum tube's glass envelope - there is a potential safety concern here if the envelope is appreciably weakened.
The practical utility of cryogenic treatment as it pertains to vacuum tubes reamins very doubtful in my mind. The metal changes indroduced would seem to have little bearing on the operation of the tube, exept perhaps with respect to it's microphonic characteristics. And, at that, this influence is not necessarily a positive one.
Given the variety of different metals used in the construction of a single tube, and the precision temperature profile control required during treatment, I find it unlikely that one particular cryo process could be optimal for treatment of a tube. The mechanical construction of a tube is also rather complex, and the changes introduced in it's microphonic characteristics will be very difficult to determine... especially if one does not know the metallic alloy composition and heat treatment history of the internal parts, and hence how each part will be affected by the cryo treatment. If anything, I would be very concerned about introducing nitrogen gas into the tube by leakage past the pins, since the thermal expansion coefficients of the metal pins and the glass envelope will be different.
Also, from Mr. Perkins' description in the CryoVac paper, it looks like he does a lot more than just cryo cycle the tubes... in fact, he not only puts them through a high-temperature annealing process after cryo treatment (this will tend to reverse some of the effects of the cryo process!), but he also etches oxides off the pins, and bright tins them. I can certainly see how his tubes might sound different after all of this! I mean, your contacts are going to be better for one...
I still maintain that the cryo treatment sounds like a dodgy idea. If there are genuine benefits to specially treating the metal parts in tubes, I think the right place for this sort of treatment is during their manufacture, not after they're fully assembled.
Chad,
I'm with you!
Having spent many hours rebuilding vacuum tubes for particle accelerators and radio telescopes, I can attest to the fragile nature of vacuum seals between dissimilar substances.
My first pumpdown on a tube used to be around 10 ee-6 torr, giving a mean free path between gas molecules of about 10 meters. Final pumpdown before firing the getter was 10 ee-12 torr, which is a whole lot of nuthin!
When the tubes were put in service great care was taken to bring them up to temperature slowly..... and they were kept at temperature 24/7 untill they failed. This level of care usually resulted in a tube life in excess of 10k hours before performance started to fall off.
Hundreds of thousands of operational hours with careful historical documentation on each tube as well as records of rebuild procedures for each tube are hard to ignore.
The message here being..... the folks who make tubes go to great trouble to get the gas burden inside a tube "just so". Frankly I would be very cautious about doing anything that might compromise the mechanical seals in a glo-FET.
If a tube doesn't meet your needs as it comes from the box, trying to improve it after the fact seems to me a dubious pastime.
Cyclotronguy
I'm with you!
Having spent many hours rebuilding vacuum tubes for particle accelerators and radio telescopes, I can attest to the fragile nature of vacuum seals between dissimilar substances.
My first pumpdown on a tube used to be around 10 ee-6 torr, giving a mean free path between gas molecules of about 10 meters. Final pumpdown before firing the getter was 10 ee-12 torr, which is a whole lot of nuthin!
When the tubes were put in service great care was taken to bring them up to temperature slowly..... and they were kept at temperature 24/7 untill they failed. This level of care usually resulted in a tube life in excess of 10k hours before performance started to fall off.
Hundreds of thousands of operational hours with careful historical documentation on each tube as well as records of rebuild procedures for each tube are hard to ignore.
The message here being..... the folks who make tubes go to great trouble to get the gas burden inside a tube "just so". Frankly I would be very cautious about doing anything that might compromise the mechanical seals in a glo-FET.
If a tube doesn't meet your needs as it comes from the box, trying to improve it after the fact seems to me a dubious pastime.
Cyclotronguy
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