Heatsinks will not be sized for that level of dissipation on a continuous basis. The fact that 600W is a bridged output should make it pretty clear.
A properly biased Class AB amplifier would see maximum dissipation not at maximum power output, but at 1/3rd power output. This automatically means that I would not use it for more than 10-12W/ch Class A, with about 40 Watts on the sinks. You, however, should try. Maybe we'd be pleasantly surprised and could learn something!
A properly biased Class AB amplifier would see maximum dissipation not at maximum power output, but at 1/3rd power output. This automatically means that I would not use it for more than 10-12W/ch Class A, with about 40 Watts on the sinks. You, however, should try. Maybe we'd be pleasantly surprised and could learn something!
Barely enough, but still likely good.
Go ahead and built it, and bias to operating temperature. - the first of either max 65C pin 2 of Mosfet, or 55C heatsinks.
Understand that it's going to run hot, and it will be necessary to ensure that there is at least 50mm of space under the heatsinks and 150mm above - this is to give ample room for the heatinks to pull a reasonable chimney effect for cooling.
In the original F5 article by Nelson he gives a number for minimum heatsink area per device, and this (just) meets the minimum.
It's also a nice looking chassis, so you might as well use it...
In the original F5 article by Nelson he gives a number for minimum heatsink area per device, and this (just) meets the minimum.
It's also a nice looking chassis, so you might as well use it...
Hello Guys
Thanks for all answers.
Initially I asked a very simple question because I thought someone had tried to use an A500 as F5 Chassis.
But it looks a too close call . A500 chassis should not be enough heatsink to have a F5.
After reading some a article on ESP . the F5 should dissipate ~25W per mosfet idling. so it gives 50W on a chassis made for a amplifier that has 180w rms into 4 ohms and a heatsink most probably sized to at most 60W of dissipation taking that a class AB has 70% efficiency.
So I guess I will look for another cheap chassis for my f5.
Amplifier Efficiency
Thanks
Thanks for all answers.
Initially I asked a very simple question because I thought someone had tried to use an A500 as F5 Chassis.
But it looks a too close call . A500 chassis should not be enough heatsink to have a F5.
After reading some a article on ESP . the F5 should dissipate ~25W per mosfet idling. so it gives 50W on a chassis made for a amplifier that has 180w rms into 4 ohms and a heatsink most probably sized to at most 60W of dissipation taking that a class AB has 70% efficiency.
So I guess I will look for another cheap chassis for my f5.
Amplifier Efficiency
Thanks
Understand that it's going to run hot, and it will be necessary to ensure that there is at least 50mm of space under the heatsinks and 150mm above - this is to give ample room for the heatinks to pull a reasonable chimney effect for cooling.
In the original F5 article by Nelson he gives a number for minimum heatsink area per device, and this (just) meets the minimum.
It's also a nice looking chassis, so you might as well use it...
Yes , a very nice looking chassis.
25v is too close to the working voltage for safety.
Minimum 35v or better 50v to be safe.
Those caps are a big part of the quality of the amp.
Save up and get something better rather than rushing in.
If they're anything like the cars they used to make, I wouldn't touch them with a barge pole.
Joca, you can order quality parts at a Lisbon store called LENAVE. google them.
You search the pt.farnell.com website, take notes of the part numbers you want and then send an email to LENAVE with your order. They will order from farnell and you don't pay for shipping costs, you just need to pick up the order in the store.
Farnel has a large selection of quality capacitors.
Just one more thing...noob alert here...
i am about to finish my F5. I don't have a preamp yet...
for the purpose of testing the F5, with music from a cd player, how can i do it? The volume will be at max...so, can i add a volume pot? if so...how? in the input, or output? What kind of pot?
In the meanwhile i am building the BA-3 FE but it will take time to finish and i am very curious to here this F5
Thanks for your help
i am about to finish my F5. I don't have a preamp yet...
for the purpose of testing the F5, with music from a cd player, how can i do it? The volume will be at max...so, can i add a volume pot? if so...how? in the input, or output? What kind of pot?
In the meanwhile i am building the BA-3 FE but it will take time to finish and i am very curious to here this F5
Thanks for your help
You can make a passive volume control with 4 rca jacks and a 50k log potentiometer. Many around at the farnell website. Or you order one from Robert Mauser Lda.
Portuguese store, fast shipping and good prices. Some items are better priced than in other international stores.
Portuguese store, fast shipping and good prices. Some items are better priced than in other international stores.
On my F5 and now F6 I use a 10k stepped attenuator between CD player and amp. Built into an aluminium case all from China on E-bay.
General thoughts about the F5 build
Just wanted to jump in here after 250+ pages since I last posted and note in case it's been a while...
... the performance and sound of the F5 is going to depend greatly on the specifics of the build, more than the circuit itself.
Since the amp is simple, and there are a range of active parts that can be used, these choices will alter the outcome more than usual. Also the power supply will play a big role in the final sound.
The amp will operate with a wide range of JFet values, and a wide range of output devices. For the output devices different types and brands have been used.
In the active circuit, the amp will function, but the harmonics and % of harmonics will vary depending on the match between N and P ch Jfets, and the transfer curves between N & P ch. The same is true for the outputs. The Toshibas had very close N & P ch curves, not the others. (does not mean that one sounds better than the other though!!)
So, a whole lot of parameter variation is there, and given the relatively low amount of loop feedback, it is going to show up in the output.
The circuit has relatively low PSRR, so attention to the PS can make a significant difference in what shows up in the output.
Bias seems to matter too.
I don't know a way to predict the results.
My experience with the circuit is that the amp can seemingly be "all over the map" in terms of subjective sound, running from somewhat "dull" or "round" to "lively" and "dynamic" all depending on the active parts, the passive parts and the power supply.
The good part is that I have yet to hear the amp sound nasty, no matter what the general tendency turns out to be.
Fwiw - "choose wisely, Luke Skywalker"...
Just wanted to jump in here after 250+ pages since I last posted and note in case it's been a while...
... the performance and sound of the F5 is going to depend greatly on the specifics of the build, more than the circuit itself.
Since the amp is simple, and there are a range of active parts that can be used, these choices will alter the outcome more than usual. Also the power supply will play a big role in the final sound.
The amp will operate with a wide range of JFet values, and a wide range of output devices. For the output devices different types and brands have been used.
In the active circuit, the amp will function, but the harmonics and % of harmonics will vary depending on the match between N and P ch Jfets, and the transfer curves between N & P ch. The same is true for the outputs. The Toshibas had very close N & P ch curves, not the others. (does not mean that one sounds better than the other though!!)
So, a whole lot of parameter variation is there, and given the relatively low amount of loop feedback, it is going to show up in the output.
The circuit has relatively low PSRR, so attention to the PS can make a significant difference in what shows up in the output.
Bias seems to matter too.
I don't know a way to predict the results.
My experience with the circuit is that the amp can seemingly be "all over the map" in terms of subjective sound, running from somewhat "dull" or "round" to "lively" and "dynamic" all depending on the active parts, the passive parts and the power supply.
The good part is that I have yet to hear the amp sound nasty, no matter what the general tendency turns out to be.
Fwiw - "choose wisely, Luke Skywalker"...
