thanks for the reply..
have you thought about replacing the stock adapter with DIY transformer? it's cheaper than the dexa regulator and i'm betting they will give bigger improvement over the regulator mod
to make one of those you just need to buy a good transformer with 12VAC 1.5-2A output, then make proper wiring and connection to fit the dacmagic ac jack, right? since dacmagic requires AC unregulated supply, i think this should be ok
this is one transformer i'm thinking: Buy Toroid Transformers Transformer,toroidal,30VA,0-230V pri,50/60Hz,2x0-12V sec Nuvotem 0030P1-2-012 online from RS for next day delivery.
btw, is it safe to use 12VAC 2.5A adapter with the dacmagic?
i saw little pinkie v3i has 12 Volts AC 30VA power output. which means the output current will be 2.5A? they say this psu works with dacmagic without any modification
if it is, i'm planning to make my own adapter with my own toroid
i saw little pinkie v3i has 12 Volts AC 30VA power output. which means the output current will be 2.5A? they say this psu works with dacmagic without any modification
if it is, i'm planning to make my own adapter with my own toroid
. The best capacitor: It does not put any capacitor.
If you measure the output of the opamps you will see it has very low voltage.
Is it safe to bypass. The highest yield is obtained when you make a direct coupling without capacitors.
The best possible combination of the output is to bypass capacitors and connect the balanced output.
A hug
Matias
In regards to the transformer, yes a better transformer will produce cleaner voltage coming into the regulator. However, the regulator is still very noisy and will make that clean voltage noisy all over again. Think of it as pouring bottled water into a dirty filter. But a clean regulator will with a so so transformer will help clean it up. The whole thing is a chain that must work together with each subsequent component in the chain producing cleaner voltage. This is why the companies that modify the Dac Magic focus on the 5 volt regulator. Also the benefit Toriod transformers is their size. However, they are inherently noisy and require shielding more so then normal transformers. This is why you do not see them in Tube Amps.
In regards to coupling capacitors beside filtering out DC they are needed in order to isolate stages unless a transformer of a coil is in place. If none of these devices are in use the internal capacitance or resistance of the next amplification stage can adversely affect the frequency response of the previous stage. As this makes an RC filter which is used to limit bandwidth. So yes in theory you can get away without them providing that your preamplifier has a set of input capacitors or transformers and you have calculated what the band width will be. Most do not have input capacitors or transformers . In my case I would rather spend $10 and know that the bandwidth of the DAC and my Tube preamp are not being adversely affected. For the same reason I would not purchase a DAC, preamp, or amplifier that someone had removed the coupling capacitors.
As far as the usage of the balance output this was to override the negative affects of the downstream OP275GS op amps. However this left the user with the negative effects of the balanced output usage of NE5532 op amps. Both are rated as commercial grade and not for audiophile use. The four LME49720 cost $12.32 and the 2 OPA1612 cost me $16.50. So for $38.82 I now have audio grade op amps on both the balanced and unbalanced inputs. I believe the conversion balanced to unbalanced cable is around $22. So the net cost is about $16. Seems like the better idea was to upgrade the op amps. Now this assumes that you have the skill to perform surface mount soldering.
All this said I also have a Benchmark DAC to compare against. The changes I made made it sound better then the Benchmark. I then went out and put in film coupling caps in the Benchmark and it was back on top. I am not sure what DACs other people have to compare against.
To each their own. I prefer to spend a little more, put in a little more effort and not take any short cuts that may have adverse affects
In regards to coupling capacitors beside filtering out DC they are needed in order to isolate stages unless a transformer of a coil is in place. If none of these devices are in use the internal capacitance or resistance of the next amplification stage can adversely affect the frequency response of the previous stage. As this makes an RC filter which is used to limit bandwidth. So yes in theory you can get away without them providing that your preamplifier has a set of input capacitors or transformers and you have calculated what the band width will be. Most do not have input capacitors or transformers . In my case I would rather spend $10 and know that the bandwidth of the DAC and my Tube preamp are not being adversely affected. For the same reason I would not purchase a DAC, preamp, or amplifier that someone had removed the coupling capacitors.
As far as the usage of the balance output this was to override the negative affects of the downstream OP275GS op amps. However this left the user with the negative effects of the balanced output usage of NE5532 op amps. Both are rated as commercial grade and not for audiophile use. The four LME49720 cost $12.32 and the 2 OPA1612 cost me $16.50. So for $38.82 I now have audio grade op amps on both the balanced and unbalanced inputs. I believe the conversion balanced to unbalanced cable is around $22. So the net cost is about $16. Seems like the better idea was to upgrade the op amps. Now this assumes that you have the skill to perform surface mount soldering.
All this said I also have a Benchmark DAC to compare against. The changes I made made it sound better then the Benchmark. I then went out and put in film coupling caps in the Benchmark and it was back on top. I am not sure what DACs other people have to compare against.
To each their own. I prefer to spend a little more, put in a little more effort and not take any short cuts that may have adverse affects
Ajcrock:
I respect your opinion. However I would ask what are the tests done on this circuit (I mean listen, not theory)
I've tried Muse BP, Sprague black beauty, Philips MKT and better sound (more detailed and more airy) happens when you do a bypass.
There is limited bandwidth? Maybe, but the advantages of a component is greater than under the theory of tuned circuits.
I've tried 49720's 1612's 627's, etc. The reality is that there is not much difference between the OP275GS and 49720 or 1612. To achieve radical changes need to change the system such as a discrete circuit or some operational amplifier with feedback.
I did all the modifications you can think of in the DacMagic (you can see the changes in the Argentine forum post) and I can assure that the most important changes were the clock and bypasswith OPA627´s output.
In audio less is more.
A hug
Matias
I respect your opinion. However I would ask what are the tests done on this circuit (I mean listen, not theory)
I've tried Muse BP, Sprague black beauty, Philips MKT and better sound (more detailed and more airy) happens when you do a bypass.
There is limited bandwidth? Maybe, but the advantages of a component is greater than under the theory of tuned circuits.
I've tried 49720's 1612's 627's, etc. The reality is that there is not much difference between the OP275GS and 49720 or 1612. To achieve radical changes need to change the system such as a discrete circuit or some operational amplifier with feedback.
I did all the modifications you can think of in the DacMagic (you can see the changes in the Argentine forum post) and I can assure that the most important changes were the clock and bypasswith OPA627´s output.
In audio less is more.
A hug
Matias
matiasro, what do you mean by clock? any specific recommendation regarding this 'clock'?
and what do you mean bypassing with opa627's output??
I remove the original oscillator and placed the PM Flea circuit with Tentlabs oscillator (the difference in the depth and air of the scene is overwhelming)
I regard the output bypass capacitors and only let 8 OPA627 JFETs biased in class A.
This is my mod (with translation for you)
Google Traductor
I regard the output bypass capacitors and only let 8 OPA627 JFETs biased in class A.
This is my mod (with translation for you)
Google Traductor
thanks for the link!
btw, i need to clear something up. will i get 12VAC 2.5A power output by simply putting dual secondary 12VAC 1.25A outputs transformer in parallel? i mean, putting the two + wires and two - output wires together.
and, where can i get this "PM Flea circuit with Tentlabs oscillator" thing?
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The circuit can be found in Flea
Got Fleas? - pink fish media
My friend Ray (who is also DIY'er) and lives in the Netherlands, sells the PCB. I am sending your address:
Ray's Audio Page
VAN DER STEEN
ra.vdsteen @ quicknet.nl
a hug.
Matias
Got Fleas? - pink fish media
My friend Ray (who is also DIY'er) and lives in the Netherlands, sells the PCB. I am sending your address:
Ray's Audio Page
VAN DER STEEN
ra.vdsteen @ quicknet.nl
a hug.
Matias
may i know the price estimation for the whole kit (i saw in your local forum you got the pcb with complete parts)? i won't bother contacting him if the price is out of my price range
and if you have the time, could you answer my first question? thanks
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I wonder if Ray will have all the components to prepare a kit. If you can build very expensive to feed the Flea original DacMagic Xo.
I think you have to work and read a little more because these reforms are already posted on this post.
Write to Ray and asked the price.
I did not understand your first question.
Matias
I think you have to work and read a little more because these reforms are already posted on this post.
Write to Ray and asked the price.
I did not understand your first question.
Matias
i thought you got all the components and pcb directly from him?
my question regarding transformer:
let say i have 12VAC 1.25A output dual secondary transformer, and i connect the outputs like this:
will i get an output of 12VAC 2.5A?
one more question. how could you use tentlabs oscillator in dacmagic while it requires 18v supply? dacmagic can only provide 12VAC or approximately 16VDC
Never tried connecting transformers in parallel, but as I read both primary and secondary must have the same relationship and must be connected in parallel primary and secondary as well.
You have to start flipping over your dac.
The rectifier circuit is a voltage doubler to the input of local regulators have 24 volts or so (taking into account the voltage drop). The PM Flea requires more than 18 volts, then connect it to the entry of 7815 for example. (in the PM I sent you and put me wrong when I should have written 7805 7815).
You have the circuit? you can find it in my post.
Greetings
Matias
You have to start flipping over your dac.
The rectifier circuit is a voltage doubler to the input of local regulators have 24 volts or so (taking into account the voltage drop). The PM Flea requires more than 18 volts, then connect it to the entry of 7815 for example. (in the PM I sent you and put me wrong when I should have written 7805 7815).
You have the circuit? you can find it in my post.
Greetings
Matias
I think that a little improvement,still to try , is to remove the swiching contacts of the output relays.
I mean (xlr out ) : shortig in RL4 and RL5 , the terminals 6 with 8 , 3 with 5 .
We should keep on shorting R97/R75 , R99/R98, to ground , by using 4 litles links across resistors .
If anyone is using the RCA outputs , the same must be done in RL3 . and R71/R70 .
This is done to eliminate the relays contacts of the sigal path.
May be this is a little improvement but only need only little effort and no money..
The muting circuit should still work .
Any opinion ?
I mean (xlr out ) : shortig in RL4 and RL5 , the terminals 6 with 8 , 3 with 5 .
We should keep on shorting R97/R75 , R99/R98, to ground , by using 4 litles links across resistors .
If anyone is using the RCA outputs , the same must be done in RL3 . and R71/R70 .
This is done to eliminate the relays contacts of the sigal path.
May be this is a little improvement but only need only little effort and no money..
The muting circuit should still work .
Any opinion ?
I have tried a couple of diferents transformers for my DM ( toroids and EI ) and I
did not find diference....
To answer to your question about AC voltages , it depends of the VA ratings and the regulation factor of the transformers you would like to use .
Dacmagic original TR , I think , has regulation factor about 10...13% .
Actually I am using a 12V/105VA EI type with good regulation ( about 9%..) .
To be safe , use the original ..... and save for a good +5V DAC regulator or a better clock....
cheers
Marco
really? but many people reported positive feedback after using russ andrews or little pinkie power supply. i would suspect the same since power supply plays a big role in a dac system