I've ordered a pcm2706/cs4398 based usb dac pcb.
I went with a tube output on the MayDac(TDA1541A), and with this one I'll use edcor transformers between cs4398 and RCA-out.
I would like to use Jensen or Lundahl, but I can't afford them.
Thanks Dave, for pointing me to the edcor transformers.
I was planning on using 600:600 XSM, but was steared towards 10K:10K by some friends on another forum. Any thoughts?
Do I need the XSM 10K:10K or will a WSM 10K:10k do?
Any difference in SQ between the two?
Edcor XSM 10K:10K
Edcor WSM 10K:10K
DAC
I'm choosing between this box for it(plastic)
or one similar to my B1 preamp-build, but smaller.
The metallbox will be more expensive, plus the plastic one is on it's way.
But will a plastic box do the trick, thinking about grounding etc?
I went with a tube output on the MayDac(TDA1541A), and with this one I'll use edcor transformers between cs4398 and RCA-out.
I would like to use Jensen or Lundahl, but I can't afford them.
Thanks Dave, for pointing me to the edcor transformers.
I was planning on using 600:600 XSM, but was steared towards 10K:10K by some friends on another forum. Any thoughts?
Do I need the XSM 10K:10K or will a WSM 10K:10k do?
Any difference in SQ between the two?
Edcor XSM 10K:10K
Edcor WSM 10K:10K
DAC
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I'm choosing between this box for it(plastic)
An externally hosted image should be here but it was not working when we last tested it.
or one similar to my B1 preamp-build, but smaller.
The metallbox will be more expensive, plus the plastic one is on it's way.
But will a plastic box do the trick, thinking about grounding etc?
Last edited:
I'll order the Edcor XSM 10K/10K and upgrade to a Lundahl LL1540 later if I really like how it sounds.
Got the plastic box today, here it is in comparison to my iphone4(in need of cleaning).
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
I've used the XSM 10K/10K as isolation transformers in a soundcard based audio test system and was quite happy with them.
You need to try to keep your load impedance near 10K and they should work well. The 600/600 would not work well in this application as the impedance is too low for the DAC output to drive if the transformer were properly loaded.
You need to try to keep your load impedance near 10K and they should work well. The 600/600 would not work well in this application as the impedance is too low for the DAC output to drive if the transformer were properly loaded.
Thanks 🙂
Hope I'll be happy with them as well.
They'll drive a Lehmann BCL clone headphone amplifier. Not really sure what input impedance it has though.
Got this today, will desolder the smd resistors on the dac-outputs and solder wires to the edcor XSM 10K/10K transformers I'm waiting for.
May have buy a new box for it too.
May have buy a new box for it too.
An externally hosted image should be here but it was not working when we last tested it.
An externally hosted image should be here but it was not working when we last tested it.
The marked four resistors are to be removed and the solderpads used as solderpoints for the wires to the edcor xsm 10k/10k output transformers.
I will also remove the rca-connectors. I have no use for them and should I one day want to use opamp instead of transformers, I can easily solder wires to better rca-connectors.
An externally hosted image should be here but it was not working when we last tested it.
I will also remove the rca-connectors. I have no use for them and should I one day want to use opamp instead of transformers, I can easily solder wires to better rca-connectors.
Today I'll get the Edcor transformers and hopefully the enclosure. I've ordered the same one that I use for my B1 preamp.
The plan, if there's enough room, is to put the MayDus in the same enclosure as my Lehmann clone headphone amp since I'll only use it for that.
The plan, if there's enough room, is to put the MayDus in the same enclosure as my Lehmann clone headphone amp since I'll only use it for that.
Got everything I need now, just waiting for the holecutted I've ordered to arrive before I start this build.
What do you plan to drive with the transformer outputs?
Since the Op Amp you bypass performs the analog LPF, how will you implement it?
Since the Op Amp you bypass performs the analog LPF, how will you implement it?
If needed, I'll put a capacitor between the primaries. CT will be left floating.
This is not all that goes into connecting the transformers, but I'm writing from my phone now and have no access to the schematic.
This is not all that goes into connecting the transformers, but I'm writing from my phone now and have no access to the schematic.
The schematics I've seen on ebay for this design do not show pins M1,2,3 connected. However, the manual states they must be connected to gnd or Vcc. I found one PWB with a close up that shows them connected to ground, which is what I suspect for all of them. This puts the DAC in (M0-1) Left-Justified, up to 24-bit data and (M2-3) Single-Speed without de-Emphasis (32 to 50KHZ sample rates.
I believe that this will configure the device for Single-Speed (fast) Stopband Rejection per figure 20 on page 41.
Your dynamic range will be slightly degraded by not having the analog butterworth filter.
However, the output without a filter looks like it is better than 100dB. I suspect the filter gives another 20dB as they claim 120dB dynamic range.
You may lose some micro-detail and imaging without the filter.
It might be interesting to see if I can drive my sound card from the unbuffered output of the DAC to see how it looks on AudioTester.
I believe that this will configure the device for Single-Speed (fast) Stopband Rejection per figure 20 on page 41.
Your dynamic range will be slightly degraded by not having the analog butterworth filter.
However, the output without a filter looks like it is better than 100dB. I suspect the filter gives another 20dB as they claim 120dB dynamic range.
You may lose some micro-detail and imaging without the filter.
It might be interesting to see if I can drive my sound card from the unbuffered output of the DAC to see how it looks on AudioTester.
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