you have +/-55 rails. 4ohm load.
55x55/4=756.25W peak powerdraw out of the PSU
you will have some voltage loss in the circuit, so your voltagesving at the outputs will be a little less. i could Guess you are left With about 32V Rms.
32x32/4= 256W Rms at 4ohm. 500ish W peak. and then you have an efficiency of about 66%. and that seams about right for a class A/B amp.
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Well, this sounds plausible 😉.
I think speaker impedances of 8 Ω mainly are an over-the-pond phenomenon 😀.
Best regards!
I think speaker impedances of 8 Ω mainly are an over-the-pond phenomenon 😀.
Best regards!
bear in mind that all this talk about power and its calculations are based on sine waves...
so that a 100 watt sine power, seldom go beyond 10 watts listening to music...
the higher rating is important during transients where peak voltages are important,
but even then average power is still low...
in the home settings listening to music can be just a few watts...
we need the power spec so we can dimension components that will go into the building of our amps..
so that a 100 watt sine power, seldom go beyond 10 watts listening to music...
the higher rating is important during transients where peak voltages are important,
but even then average power is still low...
in the home settings listening to music can be just a few watts...
we need the power spec so we can dimension components that will go into the building of our amps..
indeed, and 8 ohms only at one frequency...again this nominal 8 ohms is needed in our calculations...
yes, but real amps with real psu's will have rails that sag at full power, by how much? unless we measure, we can not say for sure...different amps will have different psu's..
so what i propose instead is an FTC testing of the finished ampli using a scope, a dummy load of 8 or 4 ohms and a sine wave source, testing at 100hz, 1khz, and 10 khz is good...
the power at onset of clipping is the closer to the truth...
computations/calculations are good when designing amps and psu's
Yeah, but it is possible the calculate the output power for 20Hz, 21Hz, 22Hz, 23Hz...etc, if the loudspeaker manufacturer will specify the impedance for each frequency...
Sajti
Both of you are quite right! But that's exactly been my question in #3285:
And I'm adding: Will four smaller 24V 2.5A (which means 240 W DC input power) open frame SMPS's suffice if the HB will be connected to - nominally - 8 Ω exclusively and if I adjust them for +/- 54V rails?
Best regards!
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Ostripper. I have a cheap transistor testor a mega328 and tested some extra transistors for a 1 & 2 an hfe of 690 and 404 on q3&4 hfe 403 and 5&6 hfe 386 I did not check the ones soldered in but I could change them out but the matches would all have slightly higher hfe
690 and 404 , what a mismatch ! Ahh , next badger needs a servo !
@ 400 for your gain class , I would increase the emitter resistors by 50% on both the LTP and current mirror. Try to match for at least the 375-425 range on all 4 in the CM/LTP. A real high Hfe device can be used for the beta enhancement Xter in the VAS , great place for a 690 !
OS
@ 400 for your gain class , I would increase the emitter resistors by 50% on both the LTP and current mirror. Try to match for at least the 375-425 range on all 4 in the CM/LTP. A real high Hfe device can be used for the beta enhancement Xter in the VAS , great place for a 690 !
OS
it is the input ltp needs matching for hFE, choose a pair that is closely matched.....exact match is possible if you have hundreds of those....
the others, like the cascodes and the current mirrors i would not worry that much...
the others, like the cascodes and the current mirrors i would not worry that much...
Ocourse. There will be parameters that just can't be calculated in theory. I can only calculate with what i got.
But as voltagedrop goes. i doubdt it will be a voltage dropp of 20ish volt pr rail wich is needed for the amp not to draw way to much current. And if it would be that much of a voltagedrop, the sond would be pretty flat, lifeless and boring with about 1db room for peaks.
Now you are asking the for the same as before. Just with a different set of numbers. The answer is the same. iI you use the 5A PSU's and stay at 8ohm (whitout any dips to 4-5ohm under 100Hz) then you would be okei.
Yes. The only thing one got is best guesses. But the theory is never very far from the atcual situasion.
it is nice to remind readers about it from time to time.....reality is the best policy...
my take is....why calculate when you can always measure...
my take is....why calculate when you can always measure...
The answer is: Because you might want to design in order to avoid that magic smoke on the one and a massive overkill on the other hand.
Best regards!
Hy all,
I went through the BOM file available on diyaudio store and discovered there are some obsolete parts. Could we all help update the BOM with active parts or better than the ones published in official BOM? If we manage this update, it will also be updated on diyaudio store.
I'll try to track all your recommendations.
To start, here are some obsolete parts I found:
Q1, Q2: MPSA18RLRMG (was last shipped by manufacturer at 31 Mar 2015)
D1, D2: 1N4148,133 (is withdrawed 27 Oct 2013)
C10, C12, C14, C16: B32520C1104J
I went through the BOM file available on diyaudio store and discovered there are some obsolete parts. Could we all help update the BOM with active parts or better than the ones published in official BOM? If we manage this update, it will also be updated on diyaudio store.
I'll try to track all your recommendations.
To start, here are some obsolete parts I found:
Q1, Q2: MPSA18RLRMG (was last shipped by manufacturer at 31 Mar 2015)
D1, D2: 1N4148,133 (is withdrawed 27 Oct 2013)
C10, C12, C14, C16: B32520C1104J