Hello Terry
Regarding you caps, I think you should use 100V caps for a supply of 1.41*55 – 1.2 = 75V.
Generally you should never apply more than about 80% of the rated voltage to electrolytic capacitors.
\Jens
Regarding you caps, I think you should use 100V caps for a supply of 1.41*55 – 1.2 = 75V.
Generally you should never apply more than about 80% of the rated voltage to electrolytic capacitors.
\Jens
Hi Jens
I was afraid you were going to say that.
😀
Aw, what's another $50 anyway?😉 It's only money.
Blessings, Terry
I was afraid you were going to say that.
😀
Aw, what's another $50 anyway?😉 It's only money.
Blessings, Terry
WorkingAtHome,
"What am I missing?"
Seems you have trouble recognizing balderdash when you read it.
There are no downsides to sockets that are demonstrable.
I betcha if I remove the hubcaps from my wheels, that will get the backpressure off the lugbolts.
Prosit
"What am I missing?"
Seems you have trouble recognizing balderdash when you read it.
There are no downsides to sockets that are demonstrable.
I betcha if I remove the hubcaps from my wheels, that will get the backpressure off the lugbolts.
Prosit
I hope you can recognize sarcasm when you read it.
Stillwater- Dr. Leach refers to these in his docs. They replace the mica/grease combo:
http://dkc3.digikey.com/PDF/T051/0640.pdf
Stillwater- Dr. Leach refers to these in his docs. They replace the mica/grease combo:
http://dkc3.digikey.com/PDF/T051/0640.pdf
WorkingAtHome,
Hmmm, yup sarcasm is pretty easy to recognize. Pseudo-scientific explainations of Micro-somethings, thermal performance radials and torque adjustments just seem to slip by most folks though. The mil-spec isolators available over here in the local surplus store are just called "teflon" style. Turns out they are indeed teflon. Isn't that the stuff they put on cooking pans? And then there's the folks who swear by Kapton tape. A pin head of thermal grease will spread all the way up the wall if dropped on the floor.
The point of an "isolator" is to electrically isolate the the TO-3 from the heatsink and provide some assistance in transferring the heat from the transistor to the heatsink.
Seems like common sense isn't all that common..
Prosit
Hmmm, yup sarcasm is pretty easy to recognize. Pseudo-scientific explainations of Micro-somethings, thermal performance radials and torque adjustments just seem to slip by most folks though. The mil-spec isolators available over here in the local surplus store are just called "teflon" style. Turns out they are indeed teflon. Isn't that the stuff they put on cooking pans? And then there's the folks who swear by Kapton tape. A pin head of thermal grease will spread all the way up the wall if dropped on the floor.
The point of an "isolator" is to electrically isolate the the TO-3 from the heatsink and provide some assistance in transferring the heat from the transistor to the heatsink.
Seems like common sense isn't all that common..
Prosit
OK, ask a question and get five different answers from five different people. 😀
This hobby is nuts. 😀
The sockets and sil pads cost more than the transistors. 😱
I can see why folks strip old amps for parts. 🙂
Hey I tried the PnP yesterday. It didn't stick to the whole board. How hot do you need to get this? I was afraid of overheating it. Good thing I bought 20 sheets. 😀
Thanks, Terry
This hobby is nuts. 😀
The sockets and sil pads cost more than the transistors. 😱
I can see why folks strip old amps for parts. 🙂
Hey I tried the PnP yesterday. It didn't stick to the whole board. How hot do you need to get this? I was afraid of overheating it. Good thing I bought 20 sheets. 😀
Thanks, Terry
acenovelty said:
I just use the word "nonsense" instead.
A specialist in aerodynamics can tell you the difference of laminated flow and turbulent flow.
He can explain that using hubcaps on the wheels of your car reduces fuel consumption and may increase driveability.
Whether you regard it as "balderdash" is your choice.
Mica is a lot better than Silicon, by the way.
Mica is a great deal cheaper, less vulnerable, and gives better cooling.
To top it off Mica is used by the majority of the industry.
In my opinion a difference of 0.10 C/W for the connection between output device and heatsink is important.
With one output device the difference of a 0.30 C/W heatsink and a 0.40 C/W heatsink is significant.
You may calculate what the cummulative effect for multiple output devices will be yourself.
Silicon is used by folks who think it is all balderdash anyway, the best thing is to hold the thermal grease totally.
Some regard the primary function of an isolator to be the transfer of heat.
That is what the connection between output device and heatsink is there for.
Some regard the negative thermal effect of isolator materials of such importance that they skip the isolator completely.
I can name at least 5 manufacturers who bolt the transistors straight on the heatsinks and accept having a potential on the heatsink because they find the thermal resistance of isolators having too great an influence on the thermal condition.
Quite a number of Class A people on the Pass forum use thick anodised heatsinks to get rid of the isolator, just ask Kilowattski.
Sockets and Silicon isolators were invented by the industry to save time, thus save money.
They were certainly not thought of to raise quality.
Anyone who has mounted a TO3 on a heatsink with a mica isolator, thermal grease and isolator rings, knows that it is filthy time consuming labor.
Using a silpad and a socket is much easier.
The major difference between low power and high power amplifiers often is the number of output devices, the Leach amplifier is a good example.
It is not the higher voltage that calls for the need of a higher number, often the same output devices are used.
It is not the higher current that depicts an array of transistors, often 2 transistor in parallel can handle 30 amps or more.
Take a look at the ZapPulse amps, huge power and low output device number.
THE major factor is heat dissipation, more power means higher heat dissipation.
Heat dissipation is completely controlled by total thermal resistance, the division between the number of output devices and the heatsink factor is influenced by the optimal amount of money spent and heatsink dimensions.
Putting few outputs on a very large heatsink is not economical and uses space.
Placing a very large number of outputs on a small heatsink may not be the cheapest solution either.
The required thermal condition can be obtained by an optimal number of output devices and type of heatsink,leading to the lowest amount of money spent.
The optimum is influenced by the ratio of the thermal resistance of transistor, isolator and heatsink.
For many the goals of DIY audio are:
1 saving money
2 obtaining the highest quality
3 enjoying to build yourself
4 doing it better.
Using silpads and sockets is more expensive and sacrifices quality for time saved.
Where is the diy advantage ?
The main reason for output transistor breakdown is overheating.
A major cause for overheated output devices is bad thermal connection between device and heatsink.
In many cases of a bad thermal connection the reasons were insufficient thermal grease and/or a bad torque division on the device leading to bad pressure distribution.
Spending time and interest on isolator issues leads to better thermal connection between output transistor and heatsink.
This in turn leads to an amplifier with a higher performance level.
Some may call that common sense.
That is what the connection between output device and heatsink is there for.
Some regard the negative thermal effect of isolator materials of such importance that they skip the isolator completely.
I can name at least 5 manufacturers who bolt the transistors straight on the heatsinks and accept having a potential on the heatsink because they find the thermal resistance of isolators having too great an influence on the thermal condition.
Quite a number of Class A people on the Pass forum use thick anodised heatsinks to get rid of the isolator, just ask Kilowattski.
Sockets and Silicon isolators were invented by the industry to save time, thus save money.
They were certainly not thought of to raise quality.
Anyone who has mounted a TO3 on a heatsink with a mica isolator, thermal grease and isolator rings, knows that it is filthy time consuming labor.
Using a silpad and a socket is much easier.
The major difference between low power and high power amplifiers often is the number of output devices, the Leach amplifier is a good example.
It is not the higher voltage that calls for the need of a higher number, often the same output devices are used.
It is not the higher current that depicts an array of transistors, often 2 transistor in parallel can handle 30 amps or more.
Take a look at the ZapPulse amps, huge power and low output device number.
THE major factor is heat dissipation, more power means higher heat dissipation.
Heat dissipation is completely controlled by total thermal resistance, the division between the number of output devices and the heatsink factor is influenced by the optimal amount of money spent and heatsink dimensions.
Putting few outputs on a very large heatsink is not economical and uses space.
Placing a very large number of outputs on a small heatsink may not be the cheapest solution either.
The required thermal condition can be obtained by an optimal number of output devices and type of heatsink,leading to the lowest amount of money spent.
The optimum is influenced by the ratio of the thermal resistance of transistor, isolator and heatsink.
For many the goals of DIY audio are:
1 saving money
2 obtaining the highest quality
3 enjoying to build yourself
4 doing it better.
Using silpads and sockets is more expensive and sacrifices quality for time saved.
Where is the diy advantage ?
The main reason for output transistor breakdown is overheating.
A major cause for overheated output devices is bad thermal connection between device and heatsink.
In many cases of a bad thermal connection the reasons were insufficient thermal grease and/or a bad torque division on the device leading to bad pressure distribution.
Spending time and interest on isolator issues leads to better thermal connection between output transistor and heatsink.
This in turn leads to an amplifier with a higher performance level.
Some may call that common sense.
acenovelty said:
Now that is what i call Balderdash and it is not even pseudo-scientific.
No one with any knowledge on thermo-dynamics would make such a statement.
Isolators do not only isolate potentials, they isolate heat.
Thus, thermally speaking, isolators are certainly not a helper, they are an obstruction.
The exact reason why the term used in thermo-dynamics is thermal resistance.
Air has a very high thermal resistance, so air is a very good thermal isolator.
Meaning, air does not provide any assistance in transferring heat at all, it is an obstruction for heat transfer.
OK, question. On my P101 I used Kapton tape and grease. Different type of transistors though. Will kapton tape work with TO-3 transistors? It's got to me less thermal insulating that mica or sil pads.
What do you think?
Thanks, Terry
What do you think?
Thanks, Terry
Wow. I had no idea *this* would be such a hot topic. Not like we are talking speaker wire (!) (me use zip cord, btw).
I am going to use silpads on the amp I'm building now, mainly because they won't kill my son if he gets into them (which he will). I figure the Leach is generally a conserv. amp. If I have a heat problem in testing, I can switch to grease/mica to see if it improves anything (you know, DIY style). Just need to shackle the kid for a bit.
As for the main purpose of isolators, it is to isolate electrically. That they isolate thermally is a drawback that is compensated with thermal grease. Not ideal, but it works.
So, other than the "torque" issue, what would be the drawback of sockets if I solder the TO3 pins to the socket (from the back side) after the amp is tested and working? If anything, the socket pins give a better solder point for my wires.
One more point, I would say that the number one cause of transistor failure (in DIY anyway) is not heat. It is accidental shorts.
Okay. everyone smile for a minute, then breath. Now let's build.
-b
I am going to use silpads on the amp I'm building now, mainly because they won't kill my son if he gets into them (which he will). I figure the Leach is generally a conserv. amp. If I have a heat problem in testing, I can switch to grease/mica to see if it improves anything (you know, DIY style). Just need to shackle the kid for a bit.
As for the main purpose of isolators, it is to isolate electrically. That they isolate thermally is a drawback that is compensated with thermal grease. Not ideal, but it works.
So, other than the "torque" issue, what would be the drawback of sockets if I solder the TO3 pins to the socket (from the back side) after the amp is tested and working? If anything, the socket pins give a better solder point for my wires.
One more point, I would say that the number one cause of transistor failure (in DIY anyway) is not heat. It is accidental shorts.
Okay. everyone smile for a minute, then breath. Now let's build.
-b
For me it is not such a hot issue, adding another connecting is so thats what i mentioned as the main thing.
When i started with amplifiers i used sockets too for, transistors and opamps.
Because they were available i thought it would be wise to spend money on them.
On top of that i thought it wise to use because it would be safer for the expensive devices, think of static sensitive op-amps.
Later i was told it was better to solder them in the socket for better contact, later still i learned that quality may suffer from any added connection.
So, less is actually more.
I too used silicon isolators, thinking it was better and cleaner.
At the time i had to travel 150 miles to buy the stuff by the sheet in Germany, and it came expensive.
Thermal grease is awfull stuff, i never learned how to handle it and not smear it all over everything and me.
Mr Pass wrote on the F1 thread that he is covered too at the end of the day when he has been building his amplifiers.
I dont think using silicon sheets or silpads instead of mica is a major crime if you are not fighting for every watt, like with class A amplifiers.
Not using thermal grease is not a good choice, not so long ago i checked with Nelson Pass and others, he stated that thermal paste is still the best to use.
Of course bad thermal connection is not the number 1 amp killer but it is a reason for amplifier failure quite often, you can check with professional amplifier technicians on the web.
I agree too that the discussions on cables is a heap of hogwash, i un-subscribed from the thread here because of it.
Terry stated that he would like to learn and he wants to do it right.
In my view his choice of spending money on Kapton and thermal grease on his amplifier from Mr Elliot is money spent wiser than spending it on sockets.
Kapton can be bought on a role or ready made to size for any device, also in TO3 shape.
The Leach Superamp is a big one, it delivers next to 300 watts in 8 Ohms, more than 500 in 4 Ohms, with an adequate powersupply it could be near to 750 watts in 2 Ohms.
It needs adequate cooling ability even if it is class AB.
If you do a thermal calculation and add up the costs you may conclude that money spent on low thermal isolators is good economy, not humpty-dumpty science.
Even Kapton is relatively cheap compared to the thermal costs of high power transistors and heat sinks.
I'd say if sockets are already paid for and are essential for getting a son enthousiastic for building amplifiers then thats the ticket.
My friend and audio tutor worked in the electronics field all his active life, back then he told me that a lot of trouble originates from bad connections, he gave me the advice to solder the legs.
I am still very gratefull to have had someone then who gave me such a lot of professional insight when i knew next to nothing and solid information was hard to come by.
If you make sure the soldered connections are good, an added contact may be relative.
I prefer class A amplifiers, the number of devices i burnt because of failing isolation at biasing time i dread to mention.
Good isolation is very important, i do not have the guts to put them on heatsinks isolated and trust that the anodising layer will do the job.
I use industrial silver stranded coaxial cables as speakerwire,
1/2 an inch thick, bi-wired.
Cheap, and saves me the headache of esoteric talk. I'd rather listen to music instead.
When i started with amplifiers i used sockets too for, transistors and opamps.
Because they were available i thought it would be wise to spend money on them.
On top of that i thought it wise to use because it would be safer for the expensive devices, think of static sensitive op-amps.
Later i was told it was better to solder them in the socket for better contact, later still i learned that quality may suffer from any added connection.
So, less is actually more.
I too used silicon isolators, thinking it was better and cleaner.
At the time i had to travel 150 miles to buy the stuff by the sheet in Germany, and it came expensive.
Thermal grease is awfull stuff, i never learned how to handle it and not smear it all over everything and me.
Mr Pass wrote on the F1 thread that he is covered too at the end of the day when he has been building his amplifiers.
I dont think using silicon sheets or silpads instead of mica is a major crime if you are not fighting for every watt, like with class A amplifiers.
Not using thermal grease is not a good choice, not so long ago i checked with Nelson Pass and others, he stated that thermal paste is still the best to use.
Of course bad thermal connection is not the number 1 amp killer but it is a reason for amplifier failure quite often, you can check with professional amplifier technicians on the web.
I agree too that the discussions on cables is a heap of hogwash, i un-subscribed from the thread here because of it.
Terry stated that he would like to learn and he wants to do it right.
In my view his choice of spending money on Kapton and thermal grease on his amplifier from Mr Elliot is money spent wiser than spending it on sockets.
Kapton can be bought on a role or ready made to size for any device, also in TO3 shape.
The Leach Superamp is a big one, it delivers next to 300 watts in 8 Ohms, more than 500 in 4 Ohms, with an adequate powersupply it could be near to 750 watts in 2 Ohms.
It needs adequate cooling ability even if it is class AB.
If you do a thermal calculation and add up the costs you may conclude that money spent on low thermal isolators is good economy, not humpty-dumpty science.
Even Kapton is relatively cheap compared to the thermal costs of high power transistors and heat sinks.
I'd say if sockets are already paid for and are essential for getting a son enthousiastic for building amplifiers then thats the ticket.
My friend and audio tutor worked in the electronics field all his active life, back then he told me that a lot of trouble originates from bad connections, he gave me the advice to solder the legs.
I am still very gratefull to have had someone then who gave me such a lot of professional insight when i knew next to nothing and solid information was hard to come by.
If you make sure the soldered connections are good, an added contact may be relative.
I prefer class A amplifiers, the number of devices i burnt because of failing isolation at biasing time i dread to mention.
Good isolation is very important, i do not have the guts to put them on heatsinks isolated and trust that the anodising layer will do the job.
I use industrial silver stranded coaxial cables as speakerwire,
1/2 an inch thick, bi-wired.
Cheap, and saves me the headache of esoteric talk. I'd rather listen to music instead.
Hi,
I thought the sockets were in contact with the TO3, but I may be wrong. Someone else said they are on the other side of the heatsink. Can an expert confirm where the TO3 sockets are located?
If the sockets are between the TO3 and the heatsink then I recommend you omit them and use conventional thermal jointing.
Still4given, what thickness Kapton did you use? 0.001 inch(1 thou) is good, 0.006 inch is not so good but ok. Both are better with thermal grease to each contact face.
regards Andrew T.
I thought the sockets were in contact with the TO3, but I may be wrong. Someone else said they are on the other side of the heatsink. Can an expert confirm where the TO3 sockets are located?
If the sockets are between the TO3 and the heatsink then I recommend you omit them and use conventional thermal jointing.
Still4given, what thickness Kapton did you use? 0.001 inch(1 thou) is good, 0.006 inch is not so good but ok. Both are better with thermal grease to each contact face.
regards Andrew T.
Hi jacco-
I agree with everything you just said.
My comment about my son: he is 22months old. Everything goes in his mouth. I found him playing with one of my old t220 heatsinks a few weeks ago - luckily the paste was on the inside, and he hadn't (yet) touched it. It's hard to keep him out of thw workshop, so it's silpads for the near term. Also, I am experimenting a bit with the heatsinks, and it would be much easier to move the TO3s around if I wasn;t always playing with the grease.
Perhaps I will ditch the sockets after I get everything working well. Who knows. I can never leave well-enough alone. ("But if a just tweak that one little thing..." bang!).
Maybe I will have my brother machine some Al covers to go over my TO3's (with grease) to act as both an additional heatsink as well as a strong flange for machine screws. Hmm...
There must be something like that out there..
-b
I agree with everything you just said.
My comment about my son: he is 22months old. Everything goes in his mouth. I found him playing with one of my old t220 heatsinks a few weeks ago - luckily the paste was on the inside, and he hadn't (yet) touched it. It's hard to keep him out of thw workshop, so it's silpads for the near term. Also, I am experimenting a bit with the heatsinks, and it would be much easier to move the TO3s around if I wasn;t always playing with the grease.
Perhaps I will ditch the sockets after I get everything working well. Who knows. I can never leave well-enough alone. ("But if a just tweak that one little thing..." bang!).
Maybe I will have my brother machine some Al covers to go over my TO3's (with grease) to act as both an additional heatsink as well as a strong flange for machine screws. Hmm...
There must be something like that out there..
-b
TO3's have two legs, and 1 connection to the casing.
As they are mounted on a heatsink, both legs need to go through the heatsink plus two bolts to tighten the TO3 to the heatsink.
Without a socket you will need to isolate both the bolts and the two legs with isolating washers/nipples with varying diameter.
TO3 is something like 0.160 " for the bolt holes , TO3 legs
are 0.063 " thick.
The socket combines all washers/nipples on one plate and is mounted from the other side of the heatsink.
The sockets come in two models ; with or without soldering extensions.
The first mentioned can be thin, the latter has up to 0.2 " thickness.
If you want the experts and a view on a socket, take a look :
www.fischerelectronics.de
For a story on different cooling material, their merits and downsides, and some info on un-even pressure effects read the man himself : Rod Elliot.
He had a tech article on his ESP site about transistor mounting.
Those that like to see a TO3 AluminiumOxide(Al2O3) isolator have a peak at the pic below.
If anyone desires to know what i used them for, and how much heat you would be looking at, he can always ask me.
As they are mounted on a heatsink, both legs need to go through the heatsink plus two bolts to tighten the TO3 to the heatsink.
Without a socket you will need to isolate both the bolts and the two legs with isolating washers/nipples with varying diameter.
TO3 is something like 0.160 " for the bolt holes , TO3 legs
are 0.063 " thick.
The socket combines all washers/nipples on one plate and is mounted from the other side of the heatsink.
The sockets come in two models ; with or without soldering extensions.
The first mentioned can be thin, the latter has up to 0.2 " thickness.
If you want the experts and a view on a socket, take a look :
www.fischerelectronics.de
For a story on different cooling material, their merits and downsides, and some info on un-even pressure effects read the man himself : Rod Elliot.
He had a tech article on his ESP site about transistor mounting.
Those that like to see a TO3 AluminiumOxide(Al2O3) isolator have a peak at the pic below.
If anyone desires to know what i used them for, and how much heat you would be looking at, he can always ask me.
Attachments
He should have a talk with my kid.
Rafael loved to hit the Vifa domes on my DIY speakers as a baby, daddy was sweating with a needle to get the dome shape back out the speaker again every time.
I had to store the dynamic speakers, the Quad ESL's, and my amps for over two years in my hobby room.
I can show you a pic of the class A headphone amp i had to suffer with all that time.
Rafael is 7 now, 3 weeks ago he ran off with a plastic bag containing 100 IRF's. Daddy had a near heart attach again.
On the TO3's, there are bolt-on heatsinks for them, undoubtebly Fischer has pics of them on their site.
Musical Fidelity used them on their B200 power amplifier, a derivitive of the A1 integrated.
That one had a bunch of 2N3055 output devices with only a heatsink mounted on top of them, something like a dozen per channel.
Think they are called finger-coolers, with two small holes for the bolts holding the TO3 , and a large one in the middle for the TO3 body to go through.
Rafael loved to hit the Vifa domes on my DIY speakers as a baby, daddy was sweating with a needle to get the dome shape back out the speaker again every time.
I had to store the dynamic speakers, the Quad ESL's, and my amps for over two years in my hobby room.
I can show you a pic of the class A headphone amp i had to suffer with all that time.
Rafael is 7 now, 3 weeks ago he ran off with a plastic bag containing 100 IRF's. Daddy had a near heart attach again.
On the TO3's, there are bolt-on heatsinks for them, undoubtebly Fischer has pics of them on their site.
Musical Fidelity used them on their B200 power amplifier, a derivitive of the A1 integrated.
That one had a bunch of 2N3055 output devices with only a heatsink mounted on top of them, something like a dozen per channel.
Think they are called finger-coolers, with two small holes for the bolts holding the TO3 , and a large one in the middle for the TO3 body to go through.
Oh please, if you must quote me, at least keep all the quote and in context.
"The point of an "isolator" is to electrically isolate the the TO-3 from the heatsink and provide some assistance in transferring the heat from the transistor to the heatsink. "
Go ahead and solder the wires to the sockets if you must. Then when it is necessary to remove a socket soldered transistor, tell us how much fun it was to desolder your fine work.
Yes the Superamp puts out lots of power and a good electrical connection is required.
Maybe I'll consider soldering the wires to the battery in my car instead of using a connector.
Manufacturers commonly use as few parts as possible to reduce build cost and improve profit. If there is any benefit to you or the amp is debateable. My goodness, what a firestorm.
Prosit
"The point of an "isolator" is to electrically isolate the the TO-3 from the heatsink and provide some assistance in transferring the heat from the transistor to the heatsink. "
Go ahead and solder the wires to the sockets if you must. Then when it is necessary to remove a socket soldered transistor, tell us how much fun it was to desolder your fine work.
Yes the Superamp puts out lots of power and a good electrical connection is required.
Maybe I'll consider soldering the wires to the battery in my car instead of using a connector.
Manufacturers commonly use as few parts as possible to reduce build cost and improve profit. If there is any benefit to you or the amp is debateable. My goodness, what a firestorm.
Prosit
Terry,
I use the PnP material with a slightly modified "pouch Laminator". Really slick. Just run the board with the PnP on it thru the laminator and out comes perfectly applied PnP. Resolution is great and works as well as photo processing for me. The laminator is about $130 at office supply stores.
Visit www.pulsar.gs for details on how to do this. Pulsar also sells another material system similar to PnP, but I find that PnP is easier to use and works as well or better. With the laminator it works every time (including the very first time I tried it) and is VERY easy.
Bill
I use the PnP material with a slightly modified "pouch Laminator". Really slick. Just run the board with the PnP on it thru the laminator and out comes perfectly applied PnP. Resolution is great and works as well as photo processing for me. The laminator is about $130 at office supply stores.
Visit www.pulsar.gs for details on how to do this. Pulsar also sells another material system similar to PnP, but I find that PnP is easier to use and works as well or better. With the laminator it works every time (including the very first time I tried it) and is VERY easy.
Bill
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