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Old 20th December 2012, 06:16 AM   #51
Philfr is offline Philfr  France
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Hi,
Soution 3 :
use a 24 V dc to 12 V dc converter for TA2020 and dac..
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Old 20th December 2012, 07:25 AM   #52
Mooly is online now Mooly  United Kingdom
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Quote:
Originally Posted by Philfr View Post
Thank's Mooly..
Yes, yes I see the problem
Solutions :
1 buy a new 12 volt battery just for TA2020 and dac
2 build another TDA2050 for drive FE126eN
This requires reflection !
Actually its my mistake... sorry.

I thought you had two TDA2050's in the diagram and not a TDA and the 12 volt TA2020. So diagram A of yours is correct. A case of seeing what you expect to see and not what is there

So.............

The TDA runs on 24 volt.
The TA runs on 12 volt.
They and all the audio grounds share the same ground point on the negative terminal of the same battery.

That still leaves the problem of unequal current draw on the batteries.
A 24 to 12 volt "linear" regulator is easy to arrange but is inefficient at high current compared to a switching regulator. The switching regulator would be more complex and unless built from a suitable kit or bought "off the shelf" would, I suspect be beyond what is realistically achievable.

Your suggestion of two TDA amplifiers both on 24 volt seems the easiest and actually "best" solution. A simple linear 24 to 12 volt regulator for the low current DAC is easy, just one three legged chip and a couple of caps.
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Old 20th December 2012, 08:07 AM   #53
Philfr is offline Philfr  France
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Hi Mooly;
no problem..
So schematic A was good, another idea is to use two different batteries.
Left (on schematic) at 18 Amp/h and right at 24 Amp/h for example. That compensate the differences in uptake.
The TA2020 works starting from about 200 hz, and it's don't need high power.
I would have estimated the two power required to calculate value of batteries..
The dac (Musical Fidelity VDAC 2) require only 500mA..
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Old 20th December 2012, 08:19 AM   #54
Mooly is online now Mooly  United Kingdom
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Its OK for the power amps but the DAC needs to run off the other battery so that the grounds are correct.

Using different capacity batteries is OK in theory except you'll never come close in reality to equalising the discharge.

Does the DAC actually draw 500ma internally or is that just a marking on the box somewhere indicating an mains adapter rating etc ? I couldn't find any info on how that model DAC is powered
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Old 20th December 2012, 08:43 AM   #55
Philfr is offline Philfr  France
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dac details :
http://www.musicalfidelity.com/uploa...USB_manual.pdf
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Old 20th December 2012, 08:51 AM   #56
Mooly is online now Mooly  United Kingdom
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Thanks.

The specs say a 12 volt 500ma PSU is used. The DAC won't draw exactly 500ma, in fact it probably draws somewhere nearer 150-200ma at a guess. That's something you could measure for real but if you do use a battery then make sure you get the polarity correct. Check check and check again
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Old 20th December 2012, 11:38 AM   #57
Philfr is offline Philfr  France
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"Check check and check again"
Yes, with trial and error, my best way !
Maybe I can use a small battery or NiMh accumulators for only dac.
Wait and see after buiding the amp's.
Now I still have a lot of work to do :
finish enclosures for Fostex fullrange
rebuild pllxo for adapt new impedance
listing the part for TDA2050
build TDA's
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Old 20th December 2012, 11:52 AM   #58
Mooly is online now Mooly  United Kingdom
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Trial and error... or measure and be sure

Don't you think multiple batteries are messy ? Why not just have a normal mains PSU. It would be much lighter and smaller.
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Old 20th December 2012, 02:27 PM   #59
JMFahey is offline JMFahey  Argentina
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You are over over over thinking.
Build a +/-12V supply with 2 12V batteries in series, the centerpoint is ground.
Use a DPDT switch for on/off.
Feed the TDA2050 from +/- 12V rails , and DAC + TA2020 from +12V to ground.
Yes, the + battery will have a slightly larger load, so what?
When one of them goes below, say, 11.5V, you fully recharge both, simple as that.
How will you recharge them?
What I don't get is that it's a "sophisticated" setup, including straight digital output from your notebook, so you need to use a DAC to decode it, it's a biamped system ... and then you use a poor, passive X-over
I just don't get it.
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Old 20th December 2012, 02:51 PM   #60
Philfr is offline Philfr  France
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Mooly,
Many people often ask me this question ..
Gelified battery are not missy, no liquid, no odors when charging.
Cause it's not waf in a living room, but in a beautiful wood case, it goes unnoticed.
I have two system with it since few years, without particular problem.
Sounding : more quiet and silencious than 220 v (rf wifi electric meter and so..) and better low frequencies impulse and impact.
A gel battery can offer double power in a very short time than a classical battery.
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