Is the right channel also the one where you ran out of trimming range? Maybe changing the order of the right-channel E88CCs already helps, swapping the bottom E88CC with one of the upper two.
By the way, the issue I had with the version of post #1495 affects both channels, so that's probably not it. When I wrote the SRC4392 went out of lock, I meant the slow sample rate tracking loops. (I connected pin 15 of the SRC4392 to a 1 kohm resistor and the other side of the resistor to the anode of a red LED with its cathode to ground. The LED lit up frequently, which it is not supposed to do.)
By the way, the issue I had with the version of post #1495 affects both channels, so that's probably not it. When I wrote the SRC4392 went out of lock, I meant the slow sample rate tracking loops. (I connected pin 15 of the SRC4392 to a 1 kohm resistor and the other side of the resistor to the anode of a red LED with its cathode to ground. The LED lit up frequently, which it is not supposed to do.)
Does it keep increasing or decreasing? Whether it's 0.4 V, 0.5 V or 0.6 V doesn't matter much, but it should not keep increasing without bounds.
I have the most recent verilog flashed I think. I remember I had just successfully flashed, then you posted an updated version and I reflashed that one, but I can double check. Definitely not removing the FPGA. Although wasn't adding the function to dip 3 that shows the current settings only in the recent version?
It doesn't seem to increase or decrease without bounds, usually within 0.05V or so, well within .4 and .6
It doesn't seem to increase or decrease without bounds, usually within 0.05V or so, well within .4 and .6
Ok, it was my optical setup.
Switched the tubes around which helped the noise floor issue a lot. I may have to upgrade tubes, I'm just using some cheap JAN Phillips.
Using BNC now and it sounds amazing! The only remaining issue is that there is a little pop occasionally, and it's not clipping. Just a random periodic pop, every 5-10 seconds, fairly faint but distracting. The different settings don't seem to affect it. The pop only happens with music playing. I'm going to let it burn in some and see if it improves.
EDIT: The pop seems to be getting better over time, sometimes not happening for a few minutes. Everything is good so far, though my 6.3VDC supply is running hotter than I'd like. Might need to rethink that heatsink setup and do something about the diodes.
Switched the tubes around which helped the noise floor issue a lot. I may have to upgrade tubes, I'm just using some cheap JAN Phillips.
Using BNC now and it sounds amazing! The only remaining issue is that there is a little pop occasionally, and it's not clipping. Just a random periodic pop, every 5-10 seconds, fairly faint but distracting. The different settings don't seem to affect it. The pop only happens with music playing. I'm going to let it burn in some and see if it improves.
EDIT: The pop seems to be getting better over time, sometimes not happening for a few minutes. Everything is good so far, though my 6.3VDC supply is running hotter than I'd like. Might need to rethink that heatsink setup and do something about the diodes.
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I'm really enjoying it so far, the heartache from the last few days is subsiding. Just hoping this pop continues to get better and better. It's much less frequent now.
I'm also considering getting the TentLabs filament supply. The diodes on this Pete Millet supply are getting way too hot for my liking.
I'm also considering getting the TentLabs filament supply. The diodes on this Pete Millet supply are getting way too hot for my liking.
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I'm glad to hear that there is a second working exemplar of my original valve DAC now and that you like it!
Is there any relation between the pops and electric equipment switching on and off? I noticed on my solid-state DAC that the SRC4392 sample rate tracking loops sometimes momentarily lose lock when I switch a lamp on or off (I mean a lamp meant to light up a room). This solid-state DAC has the exact same digital signal processing as the valve DAC, I use it for testing new configuration files before putting them into the valve DAC. I had a rather crappy set-up with a CD player connected to an AC outlet at the other side of the room connected to an S/PDIF input of the DAC via a cheap cinch cable with no S/PDIF transformer anywhere.
It could be that a digital PLL in my prefilter.v module loses lock and upsets the SRC4392. If that's the case, I have to see if I can make it more robust with a configuration file change. That said, over the past six weeks I have used my valve DAC with the LX45 module and the configuration file of post #1519 with no issues at all, using transformer-coupled S/PDIF inputs and sources placed close to the DAC and connected to the same AC outlet.
Is there any relation between the pops and electric equipment switching on and off? I noticed on my solid-state DAC that the SRC4392 sample rate tracking loops sometimes momentarily lose lock when I switch a lamp on or off (I mean a lamp meant to light up a room). This solid-state DAC has the exact same digital signal processing as the valve DAC, I use it for testing new configuration files before putting them into the valve DAC. I had a rather crappy set-up with a CD player connected to an AC outlet at the other side of the room connected to an S/PDIF input of the DAC via a cheap cinch cable with no S/PDIF transformer anywhere.
It could be that a digital PLL in my prefilter.v module loses lock and upsets the SRC4392. If that's the case, I have to see if I can make it more robust with a configuration file change. That said, over the past six weeks I have used my valve DAC with the LX45 module and the configuration file of post #1519 with no issues at all, using transformer-coupled S/PDIF inputs and sources placed close to the DAC and connected to the same AC outlet.
Is the pop on both channels or still only right? If you want to know for sure if it has anything to do with the slow sample rate tracking loops, you would have to connect a resistor and an LED to pin 15 of the SRC4392 using a wire thin enough not to short anything (0.2 mm enameled copper for example) and see if the LED lights up whenever you hear a pop. A red LED with a series resistor in the 470 ohm...3.3 kohm range should do.
Independent of whether it has anything to do with your problem, there are a couple of experiments I want to do, although I don't know when I have time to actually do them.
The first is to check whether switching on lamps also makes the SRC4392 slow sample rate tracking loops temporarily lose lock when I use configuration file version 1, which doesn't have that PLL I wrote about in post #1629. If that's the case, then there is nothing I can do about it anyway. If the problem is gone with configuration file 1, I have to load a modified version 2.1 to check where in the chain things go wrong. In principle glitches on the S/PDIF line should not affect the bit and word clock coming out of the DIX4192 much, as the DIX is supposed to suppress them, so it's a bit strange if they upset anything further down stream.
Independent of whether it has anything to do with your problem, there are a couple of experiments I want to do, although I don't know when I have time to actually do them.
The first is to check whether switching on lamps also makes the SRC4392 slow sample rate tracking loops temporarily lose lock when I use configuration file version 1, which doesn't have that PLL I wrote about in post #1629. If that's the case, then there is nothing I can do about it anyway. If the problem is gone with configuration file 1, I have to load a modified version 2.1 to check where in the chain things go wrong. In principle glitches on the S/PDIF line should not affect the bit and word clock coming out of the DIX4192 much, as the DIX is supposed to suppress them, so it's a bit strange if they upset anything further down stream.
Has everything stabilised now so you can enjoy the music without being on edge?
You have 50% more valves than in my project so I guess your 6.3V filament supply is being asked to deliver around 2.7A so it's working the rectifiers hard, how hard will depend on the type of rectifcation you're using? What regulator device are you using as that might be stressed too depending on how many volts it's required to 'burn'.
The Tentlabs indirectly heated filament supply is only rated for 1.5A? There is a 5A version of their DHT supply but that seems over the top for this use case. You just need a simple regulated supply with suitably rated components with suitable heatsinking - should be pretty easy to achieve.
You might consider a good quality, suitably rated, 6V SMPS? If you're worried about having that close to the DAC board use a 'brick' type.
You have 50% more valves than in my project so I guess your 6.3V filament supply is being asked to deliver around 2.7A so it's working the rectifiers hard, how hard will depend on the type of rectifcation you're using? What regulator device are you using as that might be stressed too depending on how many volts it's required to 'burn'.
The Tentlabs indirectly heated filament supply is only rated for 1.5A? There is a 5A version of their DHT supply but that seems over the top for this use case. You just need a simple regulated supply with suitably rated components with suitable heatsinking - should be pretty easy to achieve.
You might consider a good quality, suitably rated, 6V SMPS? If you're worried about having that close to the DAC board use a 'brick' type.
I did the first experiment, using the version 1 configuration file and my solid-state DAC with resistors and LEDs attached to pin 11 (!LOCK) of the DIX4192 and pin 15 of the SRC4392.
Switching the lamp often causes the DIX4192 to lose lock, and frequently the SRC4392 then loses lock as well. That is, it's not the FPGA configuration.
Switching the lamp often causes the DIX4192 to lose lock, and frequently the SRC4392 then loses lock as well. That is, it's not the FPGA configuration.
To clean the power coming into your hi-fi, IMHO there is nothing better than one of these (that exact model):
Monster Power HTPS 7000 MKII | eBay
I use one for the hi-fi and another for the bench.
Beyond that, my dac sits inside an emptied out steel file server case. Yes, the sound is better with it well shielded.
Monster Power HTPS 7000 MKII | eBay
I use one for the hi-fi and another for the bench.
Beyond that, my dac sits inside an emptied out steel file server case. Yes, the sound is better with it well shielded.
For completeness' sake I've done my experiment with versions 1, 2.1 (both LX75) and 3 (LX45) and I don't see any substantial differences. Maybe the percentages of cases where the DIX4192 losing lock causes the SRC4392's slow loops to also lose lock is a bit higher for 2.1 and 3 than for 1 (75 % to 80 % versus 50 %), but I'm not even sure about that. Pity this doesn't help to solve Sonny's issue.
It's probably just a grounding issue since it's kinda janked together right now using cardboard. The pop is totally gone on my solid state amp from what I can tell. It was only with the tube amp, it was about every 3-5 seconds.
It sounds amazing with both amps (other than the pop). I was wondering if there would be any bass roll-off, but I don't believe so at all. The staging/layering is so natural. Listening with HD580 and Borealis headphones. It really makes me want to upgrade the E88CC.
It sounds amazing with both amps (other than the pop). I was wondering if there would be any bass roll-off, but I don't believe so at all. The staging/layering is so natural. Listening with HD580 and Borealis headphones. It really makes me want to upgrade the E88CC.
I raved about how natural and organic the Valve DAC sounds so it's great to hear you having the same experience Sonny. Perhaps this will motivate some more of the other group-buy participants to progress their own projects.
All kudos to Marcel of course, what a special DAC and what a special guy!
Talking of listening to headphones, I've had a treat today - I completed my Transcendent Masterpiece 300B HPA project and have been listening to both my Valve DAC and DSC2 decoder thyrough it (BeyerDynamic DT880 headphones) - Wow!
All kudos to Marcel of course, what a special DAC and what a special guy!
Talking of listening to headphones, I've had a treat today - I completed my Transcendent Masterpiece 300B HPA project and have been listening to both my Valve DAC and DSC2 decoder thyrough it (BeyerDynamic DT880 headphones) - Wow!
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I have no idea if this will make it better, worse or not do anything, and if it is possible with your powder coating or even if it applies at all, but if the S/PDIF connector is insulated from the enclosure, you could try grounding its shield to the enclosure through a 100 nF or so (anything between 10 nF and 1 uF) capacitor with a small physical size and short leads. You then still cut any low-frequency hum loops, but have a more or less continuous Faraday cage for high frequencies.