I've been doing appliance service. The new GE fridges all fail within three years. Total junk and the parts are expensive. DC evaporator fans, motherboards, thermistor control instead of old-fashioned thermostats. You name it and it fails. I questioned the energy savings even before they started to fail. And they've been nothing but trouble.
To me doing it the old fashioned way is far better. Less is better.
I've built well over 150 mid to full size computers over the last 10 years, some for fun but most as custom builds for clients. I have found ebmPapst fans formerly just Papst, to be of excellent quality in terms of longevity and quietude. Some have a thermistor which would automatically change the fan speed as temperature increases. If cleaned on a regular schedule (every 3-6 months) they may last 5+ years of 8hour/day duty. Bearings are the weak link in most fans, unbalanced blades are the killer of case fans. Blowing the dust out and wiping down the blades will increase MTBF.
Ron
Ron
HP used Papst fans in the HP5328 -- probably other test stuff as well. I've built stuff with the dead carcases of the '5328 and the fans don't seem to have failed.
I routinely use highly compressed air (80 PSI). I lock the blades to avoid hyper-spinning the bearings. Some may argue that there is risk in contaminating poorly sealed bearings using this technique. The Panaflows (Panasonic) fans, in addition to the Pabst, seem to hold up pretty well.
F5 and electrostatic speakers - Volt versus Amps
Hi can anyone confirm or deny the following extract from an Australian site with regard specifically to the F4...
Excerpt follows....
It may surprise some to learn that the key challenge for amplification of ESL’s is not speaker efficiency. Compared to magnetic speakers ESL’s are many times more efficient. A magnetic speaker operates on current and is approximately 1% efficient. That is to say that 99% of its power is wasted as heat (via the resistive voice coil) with only 1% actually being turned into acoustic energy. In contrast, an ESL operates on voltage and is approximately 99% efficient. That is to say that virtually all of your amplifier's power is converted by the speaker into acoustic energy. None is wasted as heat. Since you only need a couple of acoustic watts to produce loud music, an amplifier that can deliver 20 watts is adequate.
However, amplifier ‘power’ is meaningless when driving ESL’s. What matters is the voltage an amplifier can deliver into the speaker’s impedance. Remember here that because an ESL is a capacitor (not a resistor) its impedance is inversely proportional to frequency. So the impedance of the KS-3000 panel ranges from a high of 125 ohms (at around 47Hz) and falls all the way to 1.8 ohms at 20 KHz.
Extremely loud music is around 10 acoustic watts. Because an ESL is so efficient, it needs only a few watts of actual power from the amplifier. So the fact that the power transfer (due to impedance mis-match) is poor in the midrange at high impedances is not a problem. There will still be sufficient power transferred to the speaker to produce high output levels. What is a problem is when the impedance is very low. Then the power transfer is excellent. With the amplifier coupled well to the load at low impedances, the amplifier can easily be damaged by the reactivity of the speaker, especially when the current and voltage are out of phase with each other as they are in an ESL. These are the conditions seen by the amplifier when driving an ESL at high frequencies, and it has been the instant death of many an amplifier!
The solution is volts and lots of them. Power is by far the most important factor when selecting a power amplifier for ESL’s and it therefore comes as no surprise that XXX Audio recommend high powered amplification.
Hi can anyone confirm or deny the following extract from an Australian site with regard specifically to the F4...
Excerpt follows....
It may surprise some to learn that the key challenge for amplification of ESL’s is not speaker efficiency. Compared to magnetic speakers ESL’s are many times more efficient. A magnetic speaker operates on current and is approximately 1% efficient. That is to say that 99% of its power is wasted as heat (via the resistive voice coil) with only 1% actually being turned into acoustic energy. In contrast, an ESL operates on voltage and is approximately 99% efficient. That is to say that virtually all of your amplifier's power is converted by the speaker into acoustic energy. None is wasted as heat. Since you only need a couple of acoustic watts to produce loud music, an amplifier that can deliver 20 watts is adequate.
However, amplifier ‘power’ is meaningless when driving ESL’s. What matters is the voltage an amplifier can deliver into the speaker’s impedance. Remember here that because an ESL is a capacitor (not a resistor) its impedance is inversely proportional to frequency. So the impedance of the KS-3000 panel ranges from a high of 125 ohms (at around 47Hz) and falls all the way to 1.8 ohms at 20 KHz.
Extremely loud music is around 10 acoustic watts. Because an ESL is so efficient, it needs only a few watts of actual power from the amplifier. So the fact that the power transfer (due to impedance mis-match) is poor in the midrange at high impedances is not a problem. There will still be sufficient power transferred to the speaker to produce high output levels. What is a problem is when the impedance is very low. Then the power transfer is excellent. With the amplifier coupled well to the load at low impedances, the amplifier can easily be damaged by the reactivity of the speaker, especially when the current and voltage are out of phase with each other as they are in an ESL. These are the conditions seen by the amplifier when driving an ESL at high frequencies, and it has been the instant death of many an amplifier!
The solution is volts and lots of them. Power is by far the most important factor when selecting a power amplifier for ESL’s and it therefore comes as no surprise that XXX Audio recommend high powered amplification.
It's pretty simple in practice.
You have to swing a lot of volts, equal to the bias voltage in order to move the diaphragm to full output. The input voltage required is proportional to the step up ratio of the transformer(s), which in turn is dictated by the way they are matched to the reactive impedance of the ESL cell itself.
The short version is that this usually means a "200 watt" class power amp, since the rail voltage on them is about right for most ESLs (too high for Quad 57s for example). So it is really rail voltage that matters - but most amps with high rail voltage are also designed for high power.
And since the load looks like a reactance, and is whatever the reflected impedance at the primary happens to be, you do need some current to back up that voltage out in the real world... and an amp that is stable and doesn't overshoot into reactive loads...
The claim of 99% efficiency is likely rather optimistic though...
The F5 would be a nice amp to match some ESL like the Quad 57, imo.
Although if you have a small space and don't like too loud, it will work with other ESLs... bridged might be more betterer... more voltage swing!
_-_-bear
You have to swing a lot of volts, equal to the bias voltage in order to move the diaphragm to full output. The input voltage required is proportional to the step up ratio of the transformer(s), which in turn is dictated by the way they are matched to the reactive impedance of the ESL cell itself.
The short version is that this usually means a "200 watt" class power amp, since the rail voltage on them is about right for most ESLs (too high for Quad 57s for example). So it is really rail voltage that matters - but most amps with high rail voltage are also designed for high power.
And since the load looks like a reactance, and is whatever the reflected impedance at the primary happens to be, you do need some current to back up that voltage out in the real world... and an amp that is stable and doesn't overshoot into reactive loads...
The claim of 99% efficiency is likely rather optimistic though...
The F5 would be a nice amp to match some ESL like the Quad 57, imo.
Although if you have a small space and don't like too loud, it will work with other ESLs... bridged might be more betterer... more voltage swing!
_-_-bear
Ah! the numerous will this heatsink work with my F5 questions........
It's my intention to build an enclosure that will start out with two of the heatsinks listed below and two F5 channels. From what I've read this heatsink should be quite capable of handling one F5 channel. So my question is. Will one of these heatsinks handle two F5 channels?
The enclosure I'm building will have enough room and power supply for four channels so the above question is key to my future plans.
Opinions anyone?
Regards,
Dan
It's my intention to build an enclosure that will start out with two of the heatsinks listed below and two F5 channels. From what I've read this heatsink should be quite capable of handling one F5 channel. So my question is. Will one of these heatsinks handle two F5 channels?
The enclosure I'm building will have enough room and power supply for four channels so the above question is key to my future plans.
Opinions anyone?
Regards,
Dan
Ehhh, no, I wouldnt count on that
barely enough for one channel, but the 70mm long finning helps a lotPersonally I would use two each channel/mono blocks
Ehhh, no, I wouldnt count on that
Personally I would use two each channel/mono blocks
Yes. After searching through 'millions' of heatsink posts I found post #6969 where it said,
So perhaps add one more inch to this heatsink to meet the recommended .31 *C/w.
Regards,
Dan
Hmm, its not ideal to use such "build up" method with this kind of cooling needed
Keep in mind that this is not a pepped up AB amp, but a real hot running design
With this kind of classA you need the most efficient cooling you can get
Too many "connections" means loss of expencive efficiency
You want to build a 4 channel amp, to save on cost, supply etc ?
I dont like the idea
You will need a HUGE supply to power that amp
Maybe its better to split them up in stereo amps
May even be less expencive, easier to build, and less messy inside
But why 4 channels ?
Also remember that 4 channels gets pretty hot in summertime
It could get unbareable to be in the room
And it could get really expencive with the power
This sounds like your first amp
Better keep it simple
Build a stereo amp, and see how it works
Who knows, maybe you will find another amp attracting next year..... M2 maybe, or BA-1 or 2
Below text is quoted directly from F5 Manual / FirstWatt (read the full manual, 10 times)
-------------------------------------
At 1.3 amps per channel, you will see idle heat dissipation of 62 watts. To keep the
temperature rise of the heat sink to 20 deg C. above the ambient temperature, you will want
a heat sink rated at about .6 deg C./watt for each transistor. An example of this would be a
chunk of finned aluminum, with a series of 2” fins attached to an 8” by 6” base. You will
need two per channel.
Keep in mind that this is not a pepped up AB amp, but a real hot running design
With this kind of classA you need the most efficient cooling you can get
Too many "connections" means loss of expencive efficiency
You want to build a 4 channel amp, to save on cost, supply etc ?
I dont like the idea
You will need a HUGE supply to power that amp
Maybe its better to split them up in stereo amps
May even be less expencive, easier to build, and less messy inside
But why 4 channels ?
Also remember that 4 channels gets pretty hot in summertime
It could get unbareable to be in the room
And it could get really expencive with the power
This sounds like your first amp
Better keep it simple
Build a stereo amp, and see how it works
Who knows, maybe you will find another amp attracting next year..... M2 maybe, or BA-1 or 2
Below text is quoted directly from F5 Manual / FirstWatt (read the full manual, 10 times)
-------------------------------------
At 1.3 amps per channel, you will see idle heat dissipation of 62 watts. To keep the
temperature rise of the heat sink to 20 deg C. above the ambient temperature, you will want
a heat sink rated at about .6 deg C./watt for each transistor. An example of this would be a
chunk of finned aluminum, with a series of 2” fins attached to an 8” by 6” base. You will
need two per channel.
solid plate between is fine so long as both surfaces are FLAT and TRUE, and there is adequate "clamping" (screws) between the two surfaces. Keep in mind that screws deform the surfaces!
random aluminum heatsinks and random aluminum plates are not likely to make a good thermal connection. You'll need to make 'em flat... the more the total surface area between the two the less critical that becomes, but it is still not a factor to ignore.
Do not confuse the thermal mass of the backing place (the time it takes to get warm) with the transfer to the finned heatsink extrusion. They're different things.
But, I agree, if it's yr first build keep it simple to start, and make sure it works before getting exotic.
_-_-bear
random aluminum heatsinks and random aluminum plates are not likely to make a good thermal connection. You'll need to make 'em flat... the more the total surface area between the two the less critical that becomes, but it is still not a factor to ignore.
Do not confuse the thermal mass of the backing place (the time it takes to get warm) with the transfer to the finned heatsink extrusion. They're different things.
But, I agree, if it's yr first build keep it simple to start, and make sure it works before getting exotic.
_-_-bear
this is a couple of years out of date but I think the references are still valid:
Vitalstates- Amplifiers
Ed