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Old 19th December 2011, 02:10 PM   #4081
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Hi James

Dear Dady, your email doesn't work for me...message rebounds.

It seems I won an oscilloscope, two channels, 60MHz bandwidth.
2012 will see my return to the fields

Best wishes to all.
M.

PS: the two Kingston SD cards I own are very annoying to work with...
I hope newer ones are more reliable...perhaps we will have to a Wiki with tips on SD cards...
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Old 19th December 2011, 04:32 PM   #4082
jonners is offline jonners  United Kingdom
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Quote:
Originally Posted by maxlorenz View Post

PS: the two Kingston SD cards I own are very annoying to work with...
I hope newer ones are more reliable...perhaps we will have to a Wiki with tips on SD cards...
Kingston have given no trouble in my SD player; I've had to return a couple of Sandisk 16GB. I like the KomputerBay 32GB Class 10: Reliable so far, fast and cheap.
Perhaps if others are going to chip in we should start a new thread?
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Old 19th December 2011, 04:38 PM   #4083
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Thank you jonners,

I wonder if it is not a basic mistake I am making...even if I re-format them and record WAV 16b/44,1Khz files I get some problems like a high freq. sound on the middle of a track or not detecting the card at all... I will try to load them on another laptop.

Sorry for this little OT.
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Old 21st December 2011, 08:11 AM   #4084
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hi studiostevus,

Quote:
I am currently running on Salas shunts, and playing around with the local decoupling of the power supply lines. What are your findings there?I see you only use a 1uF acrylic at the tda.
Voltage regulators have limited bandwidth, this means that output impedance is likely to rise above this bandwidth. The inductance of wiring between regulator and load is likely to further reduce effective bandwidth.

These effects can be compensated with a correctly dimensioned decoupling cap. If the decoupling cap value is too high or too low, bumps or dips are created in regulator output impedance. This in turn can lead to undesired effects in connected loads and can lead to different perceived sound quality.

The coupling cap properties are also important here, two caps with exactly the same value can still have different impedance properties.


I use large bandwidth voltage regulators with approx. 7 MHz bandwidth (LM78xx has around 10 KHz bandwidth), so decoupling cap values can be relatively low. This enables the use of film caps.

I made some mistakes in common mode capacitance multiplier and pre-regulator. Here I used 470uF decoupling caps, this value is too high of course, so I replaced these with 1uF film caps for now.

I use a sweep generator and a scope to check voltage regulator impedance between 10 Hz and 10 MHz. I connect the sweep generator (50 Ohm output impedance) to the regulator output using a 180R series resistor.

The scope is triggered by the sweep generator by connecting sync out with the scope external trigger input. The scope input is connected to the voltage regulator output.

The scope now displays a real-time scan of the regulator impedance over approx. 10 MHz bandwidth.

The decoupling cap was tuned for flattest frequency response and lowest ringing / overshoot. Fine tuning was done using listening tests.


The DEM decoupling caps are part of a RC filter (R is located inside the TDA1541A), here C will also determine filter response.

Compromise has to be chosen between maximum capacitor value and capacitor impedance at the DEM clock frequency that is used. The impedance of caps with larger value / size is likely to increase with increasing frequency.

The 1uF film decoupling caps I am using offer low impedance (small size / stacked film) and relatively high value (1uF).

The wiring between cap and TDA1541A DEM decoupling pins increases impedance and reduces filter efficiency. That's why I soldered the SMD film decoupling caps directly to the TDA1541A decoupling pins as close to the chip package as possible.
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Old 21st December 2011, 08:45 AM   #4085
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Hi maxlorenz,

Quote:
PS: the two Kingston SD cards I own are very annoying to work with...
I hope newer ones are more reliable...perhaps we will have to a Wiki with tips on SD cards...
When you are experiencing problems with SD-cards in SD-players, the card could have too low throughput (it is not able to provide sustained high data rate), or it is a fake SD-card.

Major brands are often copied, these fake cards cause a lot of problems. I have already tested some of these fake cards that looked almost identical to the original.

Original SD-cards from Kingston for example have (bar) codes printed on them that can be used to check (Kingston website) if the card is original.

I use 32GB (rating 4) Kingston SDHC cards that are assembled in Japan. These work excellent and offer room for up to 54 CDs in WAV.


Quote:
It seems I won an oscilloscope, two channels, 60MHz bandwidth.
I lost my brand new Hameg 1500-2 scope (it ceased functioning correctly after few times of use). Over two months after returning it for repair I was told by the dealer that it couldn't be repaired and this type is already taken out of production.

I also lost my older Hameg scope (loud bang in the power supply, resulting in a very bright, 1cm wide trace). It couldn't be repaired either.

So that basically left me without suitable analogue scope. I lost my confidence in new measuring instruments for now, so I bought a second hand Philips/Fluke PM3065 (2 x 100 MHz) scope on ebay and that one works fine.
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Old 21st December 2011, 09:04 AM   #4086
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Is there any alternative to the FCA1210C105M-G2 1uF 16V?

Are you using 1uF SMD caps replacing all 470uF caps in the capacitance multiplier PSU stage?

In the zener regulator stages are still 470uF?
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Old 21st December 2011, 09:22 AM   #4087
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Hi dear -EC-

Quote:
I lost my brand new Hameg 1500-2 scope (it ceased functioning correctly after few times of use). Over two months after returning it for repair I was told by the dealer that it couldn't be repaired and this type is already taken out of production.

I also lost my older Hameg scope (loud bang in the power supply, resulting in a very bright, 1cm wide trace). It couldn't be repaired either.

So that basically left me without suitable analogue scope. I lost my confidence in new measuring instruments for now, so I bought a second hand Philips/Fluke PM3065 (2 x 100 MHz) scope on ebay and that one works fine.
Ouch! Sorry to hear.
Unfortunatelly, the used scope market here is narrow and good scopes are very expensive. I got this one with little use and at fair price. I hope it works OK and lasts. I will install some protection.

Cheers,
M.
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Old 21st December 2011, 03:30 PM   #4088
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Hi John, thanks for your elaborate reply.

Quote:
Originally Posted by -ecdesigns- View Post
I made some mistakes in common mode capacitance multiplier and pre-regulator. Here I used 470uF decoupling caps, this value is too high of course, so I replaced these with 1uF film caps for now.
Are you replacing all 470uF electrolytes with SMD film caps? So the only large cap is the 4700uF electrolyte....

-edit: just re-read...I gather that only the "last" cap is replaced (the decoupler)...

Could you share a picture of your power supply board?

Quote:
I use a sweep generator and a scope to check voltage regulator impedance between 10 Hz and 10 MHz. I connect the sweep generator (50 Ohm output impedance) to the regulator output using a 180R series resistor.

The scope is triggered by the sweep generator by connecting sync out with the scope external trigger input. The scope input is connected to the voltage regulator output.

The scope now displays a real-time scan of the regulator impedance over approx. 10 MHz bandwidth.

The decoupling cap was tuned for flattest frequency response and lowest ringing / overshoot. Fine tuning was done using listening tests.
I lack the equipment and, more importantly, the skills and knowledge to go as deep and thorough as you do on the design. I will just shut up and listen (and probably ask some questions as usual....)... this is all about the learning for me...

Thanks very much!

Last edited by studiostevus; 21st December 2011 at 03:32 PM.
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Old 23rd December 2011, 10:32 AM   #4089
dady is offline dady  Argentina
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Default I have my email on service

Quote:
Originally Posted by maxlorenz View Post
Hi James

Dear Dady, your email doesn't work for me...message rebounds.

It seems I won an oscilloscope, two channels, 60MHz bandwidth.
2012 will see my return to the fields

Best wishes to all.
M.

PS: the two Kingston SD cards I own are very annoying to work with...
I hope newer ones are more reliable...perhaps we will have to a Wiki with tips on SD cards...
Dear Mauricio (Max Lorenz) my email is on service. Thanks for your salutations.
For the excelent team of this eminent forum.
Best Wishes for Christmas time and Happy New year.
__________________
Esteban Bikic
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Old 23rd December 2011, 02:58 PM   #4090
galeb is offline galeb  Spain
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Hi,

If you pay the transport, I can give you my few used hameg of 35Mhz, dual trace.

regards,
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galeb saleh
Sarte Audio Elite´s technical audio department
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