Hi John, I'm sure no expert by any stretch but I'll tell you what I know.
The transformer you want is a 600/600 ohm line matching transformer capable of handling a +20 db signal, about 5V or so without saturating the core. There are many manufacturers and many different quality levels, some are damn expensive but there are always used pieces on Ebay if you want to experiment. They supply a comfortable load for the DAC chip and also give you a degree of high frequency filtering without intruding into the audio band at all. Good ones are totally transparent and my personal experience so far is actually increased dynamics over the PCM63 with the Borbely FET I/V stage, not at all like a passive line stage. I think magic must be involved, you must try it. Don't forget the link to the Jensen filter arrangement that legarem posted, very simple and effective.
Bill
The transformer you want is a 600/600 ohm line matching transformer capable of handling a +20 db signal, about 5V or so without saturating the core. There are many manufacturers and many different quality levels, some are damn expensive but there are always used pieces on Ebay if you want to experiment. They supply a comfortable load for the DAC chip and also give you a degree of high frequency filtering without intruding into the audio band at all. Good ones are totally transparent and my personal experience so far is actually increased dynamics over the PCM63 with the Borbely FET I/V stage, not at all like a passive line stage. I think magic must be involved, you must try it. Don't forget the link to the Jensen filter arrangement that legarem posted, very simple and effective.
Bill
john65b said:
Op amps whatever they are were designed to save costs and to simplyfy circuits. Their gain is controlled by tons of negative feedback so in a circuit like the CS4398 dac, they use a lot of negative feedback because the gain required is lower than 2.
Don't loose your time with the Aikido. I tried it with 6SN7 and while it is good, it doesn't reach the sound with a good transformer.
Another recommendation: Never use any Hammond transformer. They are cheap and you have for what you pay. Even their power transformers are always buzzing.
I can't answer that one, but if you have a couple you should try them and experiment with different series resistors. Keep in mind that they will be part of a voltage divider circuit so you will lose output voltage. If they have multiple secondaries you can wire them in series to retrieve some output.
I'm not sure I'd spend much money on items that weren't proven to operate optimally.
I'm not sure I'd spend much money on items that weren't proven to operate optimally.
john65b said:
The primary impedance of the transformer will depend of the load placed at the secondary.
With all the transformers I tried with this dac, you have to try many loads with each transformer to get the sound you like. It is easier to begin with a generator and a scope (as described elsewhere) but yo have to finish by ear.
This remains me when I was using a moving coil cartridge and I had to play with the load to get correct sound.
That should be fun, but subjective comparisons by an individual are not that useful to people unless they have similar musical tastes and hearing. They are all going to sound different but not necessarily better or worse for someone else. Still, it could demonstrate deficiencies in any of them such as premature rolloff or low frequency saturation. Should be very interesting.
Bill
Bill
I bought a pair of those Sescoms this morning.
I also just recieved my DAC yeserday. I put the LM4562 in both locations and fired her up. Sounds very nice!
A while ago I purchased these cheap trannies from APEX Jr on clearance for $8. With 14-0-14 and 9-0 taps it is perfect for this DAC, allbeit way oversized at around 200VA
I also just recieved my DAC yeserday. I put the LM4562 in both locations and fired her up. Sounds very nice!
A while ago I purchased these cheap trannies from APEX Jr on clearance for $8. With 14-0-14 and 9-0 taps it is perfect for this DAC, allbeit way oversized at around 200VA
examining this dac designs I see
cs4397 and cs8416 - two pcbs - one ne5532
cs4397 and cs8416 - one pcb - two ne5532
cs4398 and dir9001 - one pcb - two ne5532
which of the 3 is best
I think first - It Is claimed to do 192 kHz and you can do mods - change tha caps
the ones with dir 9001 got lesser jitter but no 192 kHz
what are your choices
cs4397 and cs8416 - two pcbs - one ne5532
cs4397 and cs8416 - one pcb - two ne5532
cs4398 and dir9001 - one pcb - two ne5532
which of the 3 is best
I think first - It Is claimed to do 192 kHz and you can do mods - change tha caps
the ones with dir 9001 got lesser jitter but no 192 kHz
what are your choices
just send me your choice under personnal email
Sorry for the silly questions.
In legarem's diagram in post #418, the black wire is connected to the ground connection. Is that the analog ground of the DAC?
http://www.diyaudio.com/forums/attachment.php?s=&postid=1817093&stamp=1241223954
Also, on the same diagram, is the type of capacitor across the transformer primaries important (0.0047uF)?
In legarem's diagram in post #418, the black wire is connected to the ground connection. Is that the analog ground of the DAC?
http://www.diyaudio.com/forums/attachment.php?s=&postid=1817093&stamp=1241223954
Also, on the same diagram, is the type of capacitor across the transformer primaries important (0.0047uF)?