I have a 4x parallel TDA1543 DIY DAC rather similar to the Tnt-Audio Convertus design (no output stage).
I've had a real problem recently with a harsh and aggressive high end, especially sibilants. Or rather, I think the problem has been there a while, but it's really starting to bother me a lot.
I've tried a number of tweaks -- replacing the 7805 rectifiers with TL431 shunts, going to passive PS on the TDA1543, battery supply, various coupling caps (Auricaps, BG NPs), various IV resistors (Holco, cheap carbon film). I could try some more IV resistors....
I've noticed this with a number of different amps and IC cables, so I think it's the DAC.
Suggestions?
Nate
I've had a real problem recently with a harsh and aggressive high end, especially sibilants. Or rather, I think the problem has been there a while, but it's really starting to bother me a lot.
I've tried a number of tweaks -- replacing the 7805 rectifiers with TL431 shunts, going to passive PS on the TDA1543, battery supply, various coupling caps (Auricaps, BG NPs), various IV resistors (Holco, cheap carbon film). I could try some more IV resistors....
I've noticed this with a number of different amps and IC cables, so I think it's the DAC.
Suggestions?
Nate
Hi!
Only time I have experienced problems like You said was when my power supply was not good enough- are You sure that Your tl431 is in good working point - minimally 10mA through it. Do You have really good cap's after the tl431( like Black Gate's or similar- and on input receiver oscon's or similar)- TDA1543 won't be satisfied until it has REALLY good power supply. In my setup I have Riken on I/V and Vref and some silver PiO and MKP's in paralel as coupling cap's- maybe Your resistor and coupling cap's are the reason for that too.
happy diy is that
daniel
Only time I have experienced problems like You said was when my power supply was not good enough- are You sure that Your tl431 is in good working point - minimally 10mA through it. Do You have really good cap's after the tl431( like Black Gate's or similar- and on input receiver oscon's or similar)- TDA1543 won't be satisfied until it has REALLY good power supply. In my setup I have Riken on I/V and Vref and some silver PiO and MKP's in paralel as coupling cap's- maybe Your resistor and coupling cap's are the reason for that too.
happy diy is that
daniel
interesting
Thanks for the ideas. The PS capacitance is rather light, 4x 220uF Cerafines at the TDA1543s, bypassed with 0.1uF at the pins. I tried alligator-clipping in a 2200uF cap, but it didn't seem to have much effect. The TDA1543 supply is passive, a 12V battery with about a 20R resistor to drop voltage, then the capacitors.
The CS8412 (receiver) supply is two TL431s, capacitance is also light, only about 220uF (cerafine) per supply bypassed with 0.1uF after the TL431. I think the TL431s are shuntingtha about 20mA.
Thanks for the ideas. The PS capacitance is rather light, 4x 220uF Cerafines at the TDA1543s, bypassed with 0.1uF at the pins. I tried alligator-clipping in a 2200uF cap, but it didn't seem to have much effect. The TDA1543 supply is passive, a 12V battery with about a 20R resistor to drop voltage, then the capacitors.
The CS8412 (receiver) supply is two TL431s, capacitance is also light, only about 220uF (cerafine) per supply bypassed with 0.1uF after the TL431. I think the TL431s are shuntingtha about 20mA.
Now I'm no expert but since you have tried battery supply and all, guess that is not where the problem is.
Dunno if you have read about Doede's DAC. But he states very categorically that you need to trim the DAC with the right RREF and RLOAD AND voltage..to get the lowest distortion and best sound!
http://www.dddac.de/ma_dac23.htm
Hope this helps..
Cheers,
Bas
PS his voltages and resistance where calculated/trimmed for 8 parallel.
Dunno if you have read about Doede's DAC. But he states very categorically that you need to trim the DAC with the right RREF and RLOAD AND voltage..to get the lowest distortion and best sound!
http://www.dddac.de/ma_dac23.htm
Hope this helps..
Cheers,
Bas
PS his voltages and resistance where calculated/trimmed for 8 parallel.
Maybe omitting the 20 Ohm resistor and adding a discrete regulated supply for the TDA1543 will improve things. Or try a battery with lower voltage ( 6 V for example ) without any series resistor.
In other words: I think that 20 Ohm series resistance is not beneficial for correct operation the DAC chip. It also ruins the mOhm internal resistance of the battery so the advantages of using a battery are greatly reduced.
The advice to trim the DAC with the right Rref and Riv and voltage is a good advice too.
Hi!
Try to put TDA chip on a 5V and 1.5k for I/V and 1k for Vref. It is ( my opinion) best to do it with ELSO regulator - you can use LM329 in that regulator or TL431 (if you need higher ps for your TDA). I think that if You have tried battery on Your dac- ps is not Your problem (the minute I put battery in my dac there was no harshness in sound but I didn't like the sound overall so I have changed to regulators)- maybe as Bas said to try to change TDA working point. Also try 6.72V on TDA and 2k2 as I/V and 1k32 as Vref. Maybe 8V and 3k as I/V and 1k5 as Vref. If this doesn't work- see to find better resistors and cap's after the TDA- and if that doesn't work- well You are in trouble.
Maybe it is something wrong with input receiver than.....
TDA chip is great chip - only it is very sensitive to everything
daniel
Try to put TDA chip on a 5V and 1.5k for I/V and 1k for Vref. It is ( my opinion) best to do it with ELSO regulator - you can use LM329 in that regulator or TL431 (if you need higher ps for your TDA). I think that if You have tried battery on Your dac- ps is not Your problem (the minute I put battery in my dac there was no harshness in sound but I didn't like the sound overall so I have changed to regulators)- maybe as Bas said to try to change TDA working point. Also try 6.72V on TDA and 2k2 as I/V and 1k32 as Vref. Maybe 8V and 3k as I/V and 1k5 as Vref. If this doesn't work- see to find better resistors and cap's after the TDA- and if that doesn't work- well You are in trouble.
Maybe it is something wrong with input receiver than.....
TDA chip is great chip - only it is very sensitive to everything
daniel
I2S
Yes it does, combining DAC and transport is a future project, and also isolating the power supply (probably more batteries).
On that theme, does anyone have any criticisms about putting transport, DAC and perhaps amplifier in one chassis? I was wondering particularly about vibration from the transport motors etc.
Yes it does, combining DAC and transport is a future project, and also isolating the power supply (probably more batteries).
On that theme, does anyone have any criticisms about putting transport, DAC and perhaps amplifier in one chassis? I was wondering particularly about vibration from the transport motors etc.
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