Just a thought....these boards reportedly vary as to whether x=connection or o=connection....
Is it possible that J1 (not used for anything according to vendors) controls which is connection...?
ie J1 on then x=connection J1 off then o=connection
Just thinking aloud...will unbox my V 1.04 this weekend and test that...
Is it possible that J1 (not used for anything according to vendors) controls which is connection...?
ie J1 on then x=connection J1 off then o=connection
Just thinking aloud...will unbox my V 1.04 this weekend and test that...
THS4012
I have confirmed using various opamps in this DAC that Slew Rate and Settling Time have a huge impact on sound and naturalness of timbre especially for Sabre DACs. Someone mentioned ADA4938 so I tried that too but THS40xx are better because of the higher slew rate and lower settling time.
Currently I am running this board AS IS with THS4012 and it sounds ethereal. Apologies for using words to describe what I hear but measurements aside, if someone wants to try this with a THS4012 - you should do so. I have tried the current mode and yes - I would certainly say the voltage mode is much more dynamic. No comparison even though the 2nd and 3rd harmonics are 10-15db higher.
As a point of comparison - this has now clearly bested my ES9018 reference with Lundahls which also after several trials - I settled on voltage mode (impedance presented to the DAC is 390ohms)
The rest of my chain is a preamp that is a single stage JFET drain follower with a mosfet source follower as a buffer -> Mundorf SIO -> IRAUDAMP7S driven by toroidals
Speakers are Razored Magnepan 1.7s with Series crossover (Caps are Mundorf SIO || Sonicap)
The opamp is cheap - someone should try this out. Use your ears as a guide - set aside measurements for a bit.
I have confirmed using various opamps in this DAC that Slew Rate and Settling Time have a huge impact on sound and naturalness of timbre especially for Sabre DACs. Someone mentioned ADA4938 so I tried that too but THS40xx are better because of the higher slew rate and lower settling time.
Currently I am running this board AS IS with THS4012 and it sounds ethereal. Apologies for using words to describe what I hear but measurements aside, if someone wants to try this with a THS4012 - you should do so. I have tried the current mode and yes - I would certainly say the voltage mode is much more dynamic. No comparison even though the 2nd and 3rd harmonics are 10-15db higher.
As a point of comparison - this has now clearly bested my ES9018 reference with Lundahls which also after several trials - I settled on voltage mode (impedance presented to the DAC is 390ohms)
The rest of my chain is a preamp that is a single stage JFET drain follower with a mosfet source follower as a buffer -> Mundorf SIO -> IRAUDAMP7S driven by toroidals
Speakers are Razored Magnepan 1.7s with Series crossover (Caps are Mundorf SIO || Sonicap)
The opamp is cheap - someone should try this out. Use your ears as a guide - set aside measurements for a bit.
@ madds1
Bold claim though I am willing to give it a try....😉 🙂
From RS here at the End of the Known World I can get THS4012D and THS4012 CD
Operational Amplifiers | RS Components
any preference you advise ??
Bold claim though I am willing to give it a try....😉 🙂
From RS here at the End of the Known World I can get THS4012D and THS4012 CD
Operational Amplifiers | RS Components
any preference you advise ??
🙂
I just got it from eBay 1PCS THS4012CD ON DIP ADAPTER | eBay and I soldered a 100pf MLCC across +- to reduce oscillations/ringing. Without the MLCC the ringing causes a bit of fatigue. Would love to get your feedback on your system
I tried THS4012 CD and it gets very hot, could oscillations cause this, I haven't put 100pf cap on, should I?
The 100pf cap only removed some perceptible glare (possibly caused by ringing). Didn't affect the temperature
Did you remove or short the output DC blocking caps? These fast opamps don't like capacitve loads (cables) so better to short the output caps and make the series resistance the first thing the opamp sees prior to the cable capacitance.
Anyhow - My supply voltage is +-15V and the opamp sits at nearly 70C with an ambient temp of 22C
I don't know if the powerpad has thermal paste, if it is well seated, what the thermal coefficient of the PCB is etc. But I am not worried. The chip can tolerate a 150C junction temperature
As an aside - I read that THS401x draws nearly 8ma per opamp so that is 16ma for the chip. With a 30V supply differential - is it nearly 1/2 W
dissipation. Assuming you are not driving a heavy load - 0.5W on a low K PCB will sit at about 90C according to the graph on page 19 for a ambient temp of 20C.
So things seem reasonable
sorry for my asking which are the dc blocking caps? are they outputed directly off the chip, I can check with a multimeter from the rca sockets?
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Removed and shorted out the decoupling caps and the THS4012CD still gets very hot so hot it could burn my finger I don't think its stable at this temp. might check the voltage tonight, I don't think its a match somehow. any ideas?
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Mine can burn my finger too at 70c. Yours is probably higher if your air temp and humidity are higher. Orientation matters too. They can easily go up until 100c and it will work just fine. The CD version is rated to work in 70c ambient air temps
listening tonight and i think this pcb design does not bring out the full potential of this dac, to my taste it does not come close to my direct out ak4395
absolutely my opinion too !! 🙂
by that i have another dumb/stupid question; sorry about that..
for testing i´ve used a HP-printer power supply with 32V, 625mA and converted it down with a step down-module to 15V, 625mA..
but my 9028Q2M (via I2S on a Pi) is only "stuttering" with these low Ma..could that be possible ? i raised the buffer-size and so on, eliminate all other maybe problems..
are these 625mA too low for these boards ? then i guess 1.5A is minimum..
by that +15V sounds far better than 12V+ on these boards (but this everybody knows; this was written everywhere->just to confirm)..
You don't need that much current.
It sounds more like the HP power supply or the step down module becomes unstable at low loads. Some switch mode power supplies need a minimum load current to work correctly.
It sounds more like the HP power supply or the step down module becomes unstable at low loads. Some switch mode power supplies need a minimum load current to work correctly.
Do I understand correctly that the +-15V supply is used for analog output stage (5532) only and the DAC itself is powered via 5/8V pre-regulator and AMS1117-3.3 regulator? If so, the output stage could be modified for smaller voltage in order to decrease the heating. Must the THS4012CD be run on +-15V or would +-9V be enough?
Extended Listening Session
Gentlemen
After extended listening sessions - here are some conclusions
1. Leaving the tonality aside - which is cleared influenced by the 2nd and 3 harmonics - the DAC has a spectacular ability to resolve and enlarge the music scene
2. THS opamps allow the DAC to reveal the details and advertise it potential
3. However - in longer listening sessions - the lack of involvement is perceived. The details/resolution/separation/attack/slam etc are all there but it doesn't draw you in like a transformer coupled output does. It does make me sit up and anxious (if that make any sense). I had noticed this with opamps before until I decided to get rid of them from my chain. Seems like I forgot the effect of opamps and it is clear again as to why discarded them.
This is not easily discernible in an A/B compare. In such a compare this DAC with THS beat the ES9018 with transformers.
What is left to do is to put a transformer on this DAC and test it out. or directly couple it. I have a feeling it will beat the ES9018 once and for all. The ES9018 with any opamp was unlistenable for more than 5 mins (even with current mode). The scene was flat and uninvolving. This DAC is at least listenable for a while with an opamp. The scene is not flat but it uninvolving
@Peterma/DRONE7 - if you are used to NOS DACs, transformer coupled or directly coupled DACs - I would say this THS is not the way to go. I ll report back on this thread when I am able to get this board to sound better. Right now it is darn close and yes - it's potential is unlocked at this price.
Oh. One more thing - current mode may measure well but for me with my setup - it is a step in the wrong direction. YMMV
Let keep experimenting 🙂
Gentlemen
After extended listening sessions - here are some conclusions
1. Leaving the tonality aside - which is cleared influenced by the 2nd and 3 harmonics - the DAC has a spectacular ability to resolve and enlarge the music scene
2. THS opamps allow the DAC to reveal the details and advertise it potential
3. However - in longer listening sessions - the lack of involvement is perceived. The details/resolution/separation/attack/slam etc are all there but it doesn't draw you in like a transformer coupled output does. It does make me sit up and anxious (if that make any sense). I had noticed this with opamps before until I decided to get rid of them from my chain. Seems like I forgot the effect of opamps and it is clear again as to why discarded them.
This is not easily discernible in an A/B compare. In such a compare this DAC with THS beat the ES9018 with transformers.
What is left to do is to put a transformer on this DAC and test it out. or directly couple it. I have a feeling it will beat the ES9018 once and for all. The ES9018 with any opamp was unlistenable for more than 5 mins (even with current mode). The scene was flat and uninvolving. This DAC is at least listenable for a while with an opamp. The scene is not flat but it uninvolving
@Peterma/DRONE7 - if you are used to NOS DACs, transformer coupled or directly coupled DACs - I would say this THS is not the way to go. I ll report back on this thread when I am able to get this board to sound better. Right now it is darn close and yes - it's potential is unlocked at this price.
Oh. One more thing - current mode may measure well but for me with my setup - it is a step in the wrong direction. YMMV
Let keep experimenting 🙂
Well, I paid USD33 for this board and given the flaws of the design, I will probably hesitate to add another USD250 for two transformers ;-(. However, I intend to try the THSs or NJM2068, eventually desolder the AMS1117-3.3 regulator in favor of small ultra low-noise 4,7uV regulator board. Both mods up to 10 bucks.