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Old 20th July 2010, 02:19 PM   #471
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Default Measuring ampere

I finally arrived at measuring the current draw, first with the v1 amp. I did it like this: Connected the + powersupply to COM port on mulitimeter, and connected from 20A (unfused) out on mulitimeter to + input on amp. I set the multimeter to 200m A-DC. Then I read 1.1 on display. That would mean that it's drawing 110mA right? I turned on some music a turned up a bit, but no change from 1.1 I have sensible speakers, so maybe I didn't draw many watts..
Did I do this right?
Will try with v2 board also.
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Old 20th July 2010, 02:46 PM   #472
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Quote:
Originally Posted by hifimediy View Post
for pre-version of V2, we use T60.
What about the uH value on both the boards?
I assume coils are 10uH but I ask you.
And what changes in audio listening using a lower (or higher) uH value?
How to adeguate the output cap values if using other coils (lower or higher uH)?
Thanks!!
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Old 20th July 2010, 03:01 PM   #473
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Quote:
Originally Posted by Nick122147 View Post
I finally arrived at measuring the current draw, first with the v1 amp. I did it like this: Connected the + powersupply to COM port on mulitimeter, and connected from 20A (unfused) out on mulitimeter to + input on amp. I set the multimeter to 200m A-DC. Then I read 1.1 on display. That would mean that it's drawing 110mA right? I turned on some music a turned up a bit, but no change from 1.1 I have sensible speakers, so maybe I didn't draw many watts..
Did I do this right?
Will try with v2 board also.
I have sadly no idea if your connected points are right or wrong. And I am also not sure if a multimeter is suitable enough to measure power/current draws in that circuit you have choosen.

For example: Some people say that just only 1 watts per channel is enough to reach midle listenning levels in a bigger room. Only 1 watt ! But this is only a part of the truth. They probably mean the pure music power in the room.
I think there is not calculated the heat loss within the speakers to reach this 1 watt music power. To reach this you potentially need 5 watts/channel from the amp. This means 80 % loss in the speakers. Because of class-D/Tripath has abut 80 - 90 efficiency that means in the end 6 watts /channel from the powersupply.

V * A = Watts
If you take this calculation that means for 6 watts/channel (12 watts total) you draw at 30 volts supply voltage ----> 0,4 ampere = 400 mA

Hope this was right calculated and helped you a bit
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Old 20th July 2010, 03:09 PM   #474
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Quote:
Originally Posted by Nick122147 View Post
I finally arrived at measuring the current draw, first with the v1 amp. I did it like this: Connected the + powersupply to COM port on mulitimeter, and connected from 20A (unfused) out on mulitimeter to + input on amp. I set the multimeter to 200m A-DC. Then I read 1.1 on display. That would mean that it's drawing 110mA right?
I'm note sure. 1.1 could be 1100mA (1.1A).
Try to set the multimeter to an higher scale (for example, 2A or 5A) and see what happens, if the value increases when you push up the volume.
Maybe you could be out-of-scale @ 200mA on the multimeter.
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Old 20th July 2010, 03:15 PM   #475
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Quote:
Originally Posted by TheDealer View Post
I have sadly no idea if your connected points are right or wrong. And I am also not sure if a multimeter is suitable enough to measure power/current draws in that circuit you have choosen.

For example: Some people say that just only 1 watts per channel is enough to reach midle listenning levels in a bigger room. Only 1 watt ! But this is only a part of the truth. They probably mean the pure music power in the room.
I think there is not calculated the heat loss within the speakers to reach this 1 watt music power. To reach this you potentially need 5 watts/channel from the amp. This means 80 % loss in the speakers. Because of class-D/Tripath has abut 80 - 90 efficiency that means in the end 6 watts /channel from the powersupply.

V * A = Watts
If you take this calculation that means for 6 watts/channel (12 watts total) you draw at 30 volts supply voltage ----> 0,4 ampere = 400 mA

Hope this was right calculated and helped you a bit
Hi. Yes I was measuring current into the amp, not to the speakers. Just want to know if I do it correctly.

Also I think when people talk about loudness at 1W they mean 1 watt from the amp. Don't think you can talk about 1W music level from the speakers. They produce vibration/music, not watt. If you give them 1 Watt they produce a certain amount of sound, which can be measured in dB. All of the watts you give them are transferred into heat.

Quote:
I'm note sure. 1.1 could be 1100mA (1.1A).
Try to set the multimeter to an higher scale (for example, 2A or 5A) and see what happens, if the value increases when you push up the volume.
Maybe you could be out-of-scale @ 200mA on the multimeter.
I tried next step which is 20, and I get 0.1
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Old 20th July 2010, 03:17 PM   #476
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Quote:
Originally Posted by Nick122147 View Post
I tried next step which is 20, and I get 0.1
So you're reading 100mA, but seems too much low for a TK2050.
I will do the same test and I'll let you know (but not soon 'cause I'm very busy).
Bye!
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Old 20th July 2010, 05:46 PM   #477
Nisbeth is offline Nisbeth  Denmark
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According to the datasheet the "supply current" (by which I think they mean Idle current) is 60 mA, so the figure sounds about right to me with two channels running.

/U.
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Old 20th July 2010, 08:54 PM   #478
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Just a couple of techical questions.
1. Since this board already has a bridge rectifier and if we want to use a different psu - is it possible to solder the rectified voltage Vdc from (for instance) batteries directly to the legs on cap C48? - if so - what is the limit of Vdc here? ( I assume it is approx 31Vdc ?)
If we connect Vdc to the terminals would it not be rectified 2 times? I am not sure how that works..

2. Is the input caps really necessary?. Lets say we have output caps on the dac with value 3.3uf and relative short signal cables.
Is it then possible to solder the input signal directly to R4 and R1? (Assuming to use the board as a power amp) ?
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Old 20th July 2010, 10:57 PM   #479
teamacc is offline teamacc  Netherlands
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Input cap is rly possible, else, on low volume levels, the pot will short the 2.5v bias from the tc2000 which will not like it.

Output caps on the dac might not be really necessary, seems like a 50k pot might be well suited, but i dont have any experience.
I remember nick running his dac without output caps to this amp though.
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Old 21st July 2010, 12:02 AM   #480
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Quote:
Originally Posted by Nick122147 View Post
They produce vibration/music, not watt.
theoretically you can also measure the vibrations in the air which also lead in heat. This is usually notified in dB (you said it yet also). But current measurements are easier to handle than different sonic waves out from the speakers. For example you supply the speaker with 5 W amp power. If your speaker produces 4 W heat that means to me 1 W is converted in sonic or air movement, vibrations - call it as you like. That´s also heat/energy.

So I could also say that an amp produces current and not watt...
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