I think you could do that without trouble.
The BOM is just a suggestion, although it is a suggestion which is "guaranteed" to give good sound. Deviating from the BOM is entirely fine.
People may "tune" the sound of the DAC for their own systems. As long as you are prepared to experiment and swap over parts if you are not getting the sound you want, then you are on the right track.
The BOM is just a suggestion, although it is a suggestion which is "guaranteed" to give good sound. Deviating from the BOM is entirely fine.
People may "tune" the sound of the DAC for their own systems. As long as you are prepared to experiment and swap over parts if you are not getting the sound you want, then you are on the right track.
I'm not sure what those orange caps are, but, they look to be of a large physical size for a 100nf capacitor. This indicates that they may actually be a good quality capacitor. If you don't have any complaints I'd be tempted to leave them installed.
If you do want to try swapping them out, only do two at a time on one chip, leave it a day or two, and see if you like the difference.
As a side note, in another audio device I have, there was a strange green capacitor which looked a lot like those orange caps, I swapped it out for another very good quality capacitor, but the original green cap sounded best, so the unknown (manufacturer and type) green cap went back in.
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Hey,
just finished my two DAC boards with the reichelt.de, i'm really really astonished, although a good long listening session will have to show details
.
What i'm wondering about is that my 7812 get really warm. Even with the overdimensional heatsinks i've bought accidentally its ... 50*C-75*C i'd say (taking 60*C as the point where your finger starts emitting slight pain signals). Does it get warm for you too? I must admit that my transformer is a little big with 15-0-15V (i've got 17v out idle, probably quite a bit more after rect/cap).
Thanks and Regards
- NebuK
just finished my two DAC boards with the reichelt.de, i'm really really astonished, although a good long listening session will have to show details
.What i'm wondering about is that my 7812 get really warm. Even with the overdimensional heatsinks i've bought accidentally its ... 50*C-75*C i'd say (taking 60*C as the point where your finger starts emitting slight pain signals). Does it get warm for you too? I must admit that my transformer is a little big with 15-0-15V (i've got 17v out idle, probably quite a bit more after rect/cap).
Thanks and Regards
- NebuK
Hi Yes I'm very happy with the sound now it's running in.
I am tempted to leave them expecting that the maker knew what he was doing fitting them. Looking on Ebay they look a bit like philips.
Having said that I would like to change caps around the opamp. As I have settled on an op amp. lm4562. Just a touch fat in the bass but ideal everywhere else.
Could someone please give a recommendation for the opamp caps.
There are posts about it getting warm but my supplied built one runs cool.
This is the transformer supplied with mine.220V/115v 30W R-Core Transformer for preamp 9Vx2 15Vx2 | eBay
Available from various ebayers.
Available from various ebayers.
Hey,
thanks for the replies. I've measured again, directly at the 7812 in->gnd, i get ~22v there, so the drop is ~10v. When connecting a powermeter 0-15X1 -> DAC (i tried both windings) i get around 0.07-0.08A - on both windings, that'd be around 1.7-2W... nothing that should get a TO-220 7812 hot like this, right (after ~45min of listening i can barely touch it for longer than ~20sec)?
Anyways, i'll try digging deeper ;P. Regards
- NebuK
PS: the regulators are bent off-board to fit my way-too-large-heatsinks, so the caps are kinda safe from the heat ... at least.
thanks for the replies. I've measured again, directly at the 7812 in->gnd, i get ~22v there, so the drop is ~10v. When connecting a powermeter 0-15X1 -> DAC (i tried both windings) i get around 0.07-0.08A - on both windings, that'd be around 1.7-2W... nothing that should get a TO-220 7812 hot like this, right (after ~45min of listening i can barely touch it for longer than ~20sec)?
Anyways, i'll try digging deeper ;P. Regards
- NebuK
PS: the regulators are bent off-board to fit my way-too-large-heatsinks, so the caps are kinda safe from the heat ... at least.
You're wrong. Close to 2W demands using a heatsink. Put one right away or you may lose your regulator.
In fact, a finger is the best heat tester. If you can't stand it, neither will the part.
Hey,
i already have my 18K/W TO220 slip-on-heatsinks installed. Fun-fact, i've just measured exact temps (54*C @ 7812), then measured some on... the one 1117-5V is at 48*C too, followed by the AK4393 @ 45*C. I somehow have a feeling that this is a little bit much for this little chip, right?
Oo what could be wrong? And how is it for you - do your AKs, 1117-5Vs and 7812s hot?
Thanks again, Regards
- NebuK
i already have my 18K/W TO220 slip-on-heatsinks installed. Fun-fact, i've just measured exact temps (54*C @ 7812), then measured some on... the one 1117-5V is at 48*C too, followed by the AK4393 @ 45*C. I somehow have a feeling that this is a little bit much for this little chip, right?
Oo what could be wrong? And how is it for you - do your AKs, 1117-5Vs and 7812s hot?
Thanks again, Regards
- NebuK
Ciao Anto,
I would use the 25V Cerafines (same timbre) but only if it avoid you making an order... if you're going to order something in a store that have Cerafines then order them.
A 50V part is much better than a 25V one.
Exactly.
NebuK,
tell me you're not using FCs at the output of the regulator...it's a very bad place for a low ESR cap...
The original BOM of kits use way too large low ESR caps and regulators get HOT, a good choice is a 100uF audiograde cap, like the Silmic II I'm suggesting.
Hey Dario,
thanks for the reply and hints again. However, i'm at a total loss here with my humble electronics knowledge (and here humble isn't ironic, i know that i know almost nothing).
If i observe my AK chip getting quite hot, observe the 1117-5v getting quite hot and the LM7812 getting quite hot, isn't the logical conclusion that the AK somehow draws (too?) much current from the 5v rail? Also i don't really understand why low-esr caps are bad for buffering the output voltage of linear regulators. I do understand that we do want some pulse-caps like our cermaics, tantal or something to be able to balance out pulses, as well as a larger eletrolytic capacitor to balance out the supply when slower, wider swings do happen. I do not understand why beeing low esr (thus having a low "inner"/serial resistance, thus "burning" less power - with all the internal pros of this) is bad for buffering the supply side of a linear regulator. Or on the whole, i understand even less why the choice of the capacitor to buffer my regulators would make my AK run hot?! I could imagine some mismatched output buffer, resulting it to swing, something like that ... but supply caps?
I'd really really love if you could explain to me what's happening here. As you see i'm totally confused :/.
Thanks in advance! And thanks for your help up till now!
Regards from Germany
- Dario
thanks for the reply and hints again. However, i'm at a total loss here with my humble electronics knowledge (and here humble isn't ironic, i know that i know almost nothing).
If i observe my AK chip getting quite hot, observe the 1117-5v getting quite hot and the LM7812 getting quite hot, isn't the logical conclusion that the AK somehow draws (too?) much current from the 5v rail? Also i don't really understand why low-esr caps are bad for buffering the output voltage of linear regulators. I do understand that we do want some pulse-caps like our cermaics, tantal or something to be able to balance out pulses, as well as a larger eletrolytic capacitor to balance out the supply when slower, wider swings do happen. I do not understand why beeing low esr (thus having a low "inner"/serial resistance, thus "burning" less power - with all the internal pros of this) is bad for buffering the supply side of a linear regulator. Or on the whole, i understand even less why the choice of the capacitor to buffer my regulators would make my AK run hot?! I could imagine some mismatched output buffer, resulting it to swing, something like that ... but supply caps?
I'd really really love if you could explain to me what's happening here. As you see i'm totally confused :/.
Thanks in advance! And thanks for your help up till now!
Regards from Germany
- Dario
Maybe the 7812 is oscillating?
Maybe its osclillation 'upset' the 5V reg? Or you're using low-esr caps at its output too?
Nebuk,
also my knowledge is limited but a good practice to acquire some is reading the datasheets.
In most regulators' datasheet it's recommended to avoid low-esr caps at the output since, due to their (much) lower resistance, they can cause oscillations and stability problems.
You should take in account that a chip it's not a 'black box', it contains circuits made of transistors, resistors and capacitors, in facts most of them are or contain an amplifier...
Transistor are polarized using resistors... if the circuit assumes that at the output there is at least a certain resistance and you put a much lower one at the output the circuit can loose its stability, doesn't make sense?
Some years ago I've modded a NAD AV receiver and in the power amp section I've swapped all elcos with low-esr ones, guess what happened?
After a pair of months It made flames... literally... I've seen fire inside it...
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Hey,
thanks for your elaborate reply!
I've read all the 78xx regulator datasheets i could find. If anything, they state that lowest esr capacitor types should be used to ensure lowest noise operation of the regulator as well as long capacitor life and slow degradation (from Murata). For "High- and Highest-End Applications" (TI) recommends even letting eletrolytics slide and using capacitor-banks of "zero-esr" tantal type capacitors.
It is true that all application notes and datasheets require a minimum load so the regulator will regulate properly and not overshoot in certain circumstances (which i, frankly, couldn't understand WHEN this would happen...).
Given that we drive both a 1117-5 and the positive opa from the 7812 the minum load is clearly there (the AK datasheet specs typical 60mA on 5V, the opa needs another ~1.5-2mA), so i couldn't see why i should use my capacitors to burn additional power (which, if anything, will damage them long-term).
I'm still at a loss where i could find information on why lower-esr capacitors should be bad for regulators?
On the other hand calculating the 60mA of the AK on its 5v, the temperature (which seems quite stable at 45*C) sounds roughly okay. Could someone of you measure again please?
Thanks again for everything!
Regards
- Dario
*EDIT: i've just checked the datasheet of the on-semi 7812 you like, they say:
"""
An
input bypass capacitor should be selected to provide good
high−frequency characteristics to insure stable operation
under all load conditions. A 0.33 mF or larger tantalum,
mylar, or other capacitor having low internal impedance at
high frequencies should be chosen.
"""
thanks for your elaborate reply!
I've read all the 78xx regulator datasheets i could find. If anything, they state that lowest esr capacitor types should be used to ensure lowest noise operation of the regulator as well as long capacitor life and slow degradation (from Murata). For "High- and Highest-End Applications" (TI) recommends even letting eletrolytics slide and using capacitor-banks of "zero-esr" tantal type capacitors.
It is true that all application notes and datasheets require a minimum load so the regulator will regulate properly and not overshoot in certain circumstances (which i, frankly, couldn't understand WHEN this would happen...).
Given that we drive both a 1117-5 and the positive opa from the 7812 the minum load is clearly there (the AK datasheet specs typical 60mA on 5V, the opa needs another ~1.5-2mA), so i couldn't see why i should use my capacitors to burn additional power (which, if anything, will damage them long-term).
I'm still at a loss where i could find information on why lower-esr capacitors should be bad for regulators?
On the other hand calculating the 60mA of the AK on its 5v, the temperature (which seems quite stable at 45*C) sounds roughly okay. Could someone of you measure again please?
Thanks again for everything!
Regards
- Dario
*EDIT: i've just checked the datasheet of the on-semi 7812 you like, they say:
"""
An
input bypass capacitor should be selected to provide good
high−frequency characteristics to insure stable operation
under all load conditions. A 0.33 mF or larger tantalum,
mylar, or other capacitor having low internal impedance at
high frequencies should be chosen.
"""
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