hmmm... I've got nothing...
for start I would bypass the relay, and see what happens... for an example, distortions in sound, skips, crackles...
CS8416 shouldn't switch the relay for nothing...
It is pretty obvious that the fault lies in the opt input circuitry if the CS8416 chip is locking to the coax signal with no problems. You might have a faulty torx receiver or a bad solder connection. All 4 input pins on the CS8416 are identical so I would assume it is fine.
hi,
Check the signal level before you go too far and see where it's at here some info about all the dac inputs,hope this helps
S/PDIF - Wikipedia, the free encyclopedia
Check the signal level before you go too far and see where it's at here some info about all the dac inputs,hope this helps
S/PDIF - Wikipedia, the free encyclopedia
I was wondering if any one has experimented with different resistance values and types of resistors? For example I have 249 ohm metal film as recommended by Jensen for my JT-11P-1 transformers but the bass could be a little better. Will a lower resistance help? Are some types of resistors better for low frequencies, for example Vishay Nude Bulk Metal Foil?
Hi,
The resistance of R1 + R2 + transformer should be not lower than 1000 ohm according to CS4398 specs. Your Jensen has 600 (?) ohm, so your two resistors on primary should be not lower, than 2x ~200 ohm.
If you are using metal film resistors, than change to carbon resistors, the bass will be thicker and warmer, but no so lean and precise as with metal film.
I found in my diy box two Rikens 180 ohm. Can anybody advice me if going slightly under 1000 ohm (960) will be OK, or is it dangerous for the dac chip ?
Without series resistors
I run my Jensen JT11-EM or -FM output transformers direct from the dac chip with no resistors or filters with great results. The primarary of a 1:1 transformer will present the same load to the dac as whatever the secondaries are connected to. I my case, my stepped attenuators at the input of my amps, which present a load of 4k to 11k ohms depending on the setting. I started with 20ohms in series with each leg of the primaries but took them out as it sounds better wide open. Without the resistors the sound is just starting to show a slight hint of increased edge. Something around 10 ohms might be ideal in my set up with the CS43122 and Jensens. The fine tuning of damping/ isolation resistors and filters might be quite different depending on dac chip, trans and down stream system. I think the most wide open sound from these transformers comes from running direct and can be tamed down from there with series resistors on the input and a small cap if a less aggressive sound is desired.
I run my Jensen JT11-EM or -FM output transformers direct from the dac chip with no resistors or filters with great results. The primarary of a 1:1 transformer will present the same load to the dac as whatever the secondaries are connected to. I my case, my stepped attenuators at the input of my amps, which present a load of 4k to 11k ohms depending on the setting. I started with 20ohms in series with each leg of the primaries but took them out as it sounds better wide open. Without the resistors the sound is just starting to show a slight hint of increased edge. Something around 10 ohms might be ideal in my set up with the CS43122 and Jensens. The fine tuning of damping/ isolation resistors and filters might be quite different depending on dac chip, trans and down stream system. I think the most wide open sound from these transformers comes from running direct and can be tamed down from there with series resistors on the input and a small cap if a less aggressive sound is desired.
Wow, this is highly interesting. I have to make a "fast switchable test setup" and check it.
But why is Jensen proposing two 249R+2.2nF on primary and 1K+1nF on secondaries ?
What about filtering, trafo ringing etc ?
Which transformer needs correction?
Most engineers adhere to the inclusion of a filter to reduce the ultra sonic noise from the dac chip to protect the amp. I initially started working with the direct out scheme using the AK4395 dacs which have no ultrasonic noise so was able to run with no filter which showed me the advantage of getting rid of any un needed series resistance before the interconnects. The CS dac chips may benefit from a filter but I haven't tried it yet as I would rather develope one to fit across the secondary in order to take advantage of the series resistance of the coils. I have to see if this would become somewhat dependant on the load of the next stage though. The Jensen dac output circuit with the 1K+1nF values was based on the JT-11-SSP transformer which may need some correction. The JT-11-EMCF data sheet doesn't recommend any correction components although it does show a JT-OLI-2 isolator on the inputs. My quick change for comparisons is done by having two dac boards which sit on my coffee table right in front of me for fast cable swaps. I do run 8 foot interconnects which may make my system a little more sensitive to the output impedence of the source.Wow, this is highly interesting. I have to make a "fast switchable test setup" and check it.
But why is Jensen proposing two 249R+2.2nF on primary and 1K+1nF on secondaries ?
What about filtering, trafo ringing etc ?
Post trans filter an option
A post transformer filter should work well with the JT-11 output transformers which have winding resistances of about 40 to 60R each depending on the size. Values of .02uf to .01uf across the secondaries with no added series resistance should give -6db points of about 80KHz to 160KHz depending on the acutual output impedance of the chip which was measured to be about 80R per leg for the AKM chips.
A post transformer filter should work well with the JT-11 output transformers which have winding resistances of about 40 to 60R each depending on the size. Values of .02uf to .01uf across the secondaries with no added series resistance should give -6db points of about 80KHz to 160KHz depending on the acutual output impedance of the chip which was measured to be about 80R per leg for the AKM chips.
Bill,
I understand what you're saying here, but wonder where you got the specs from. The Cirrus CS4398 datasheet says:
Minimum AC-Load Resistance RL - 1 - kΩ
Maximum Load Capacitance CL - 100 - pF
I assume this means AOUT+ to AOUT-, but I guess I don't know for sure. I didn't see any DC output impedance specs listed.
In any case, the AC impedance presented by the transformer to the DAC will depend on the output loading and will be somewhat frequency dependent. A 600:600 transformer with a high impedance load on the output will present a much higher AC impedance than 600 ohms to the DAC output, so a direct connection should be OK from an AC impedance perspective. However, when I build mine I will have the RC network between the DAC and the transformer to reduce the ultrasonic noise.
I talked with Jensen for a while about which transformer to use and they suggested a JT-11P-1 10K:10K BUT said that it's important to keep the output capacitance low on this transformer. Use a short length of low capacitance cable to connect to the following stage. As soon as I find some free time I'll order a couple of transformers and start experimenting.
Cheers,
Jim