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Post by chinook9 on Mar 26, 2015 3:06:19 GMT
It turns out that the unexpected CCS and shunt current readings I was getting during my initial adjustments were due to a faulty multimeter.
Using an accurate meter the readings under load load and playing are as follows:
Placid HD: 5.25 volts CCS 513mA and 50 mA shunt current.
Placid HD BP: Side 1 14.77volts 144 mA CCS 57mA shunt current.
Placid HD BP: Side 2 14.77volts 151 mA CCS 58mA shunt current. These readings are stable and vary little regardless of load.
The Placid HD BP runs very very cool and the heat sinks don't even get warm.
The Placid HD runs warmer with one of the heat sinks a little warm and the other much warmer. The warmest heatsink is still cool enough that I can hold it with my fingers for an extended time without discomfort.
I will post some pictures of the completed unit in the next few days.
I can recommend the Buffalo III single ended as a relatively easy project for someone with a bit of experience. I have had no problems at all, the unit has been trouble free, and it is a significant improvement over my previous DACs.
I can't say that it is or is not worth what it cost (around $850 including isolated USB to I2S adapter) but I enjoyed building it and I would do it again.
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Post by chris1967 on Mar 26, 2015 8:16:33 GMT
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Javier
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Post by Javier on Mar 26, 2015 9:08:29 GMT
Glad you are liking it, it is a very nice DAC and building one's gear it not only teaches you a few things but also makes you enjoy it more.
Sent from my GT-I9100 using proboards
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Post by chinook9 on Mar 27, 2015 3:06:33 GMT
Thank you for the links Chris and thank you Javier for all your help with the build.
I have done a bit of reading on the arduino and I will continue reading. I have also done some reading on the Soekris DAC. I like to build equipment and the Soekris, being an NOS DAC, should be somewhat different sounding than the Buffalo. I really like the cheap Valab NOS DAC I got from Taiwan for $200 and I'm sure the Soekris is much better. We'll see.
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Post by chinook9 on Jan 9, 2016 17:07:49 GMT
Javier, Frans, or anyone else. I have been using the SE outputs of the IvyIII into a headphone amp since I built this DAC. I have now started listing to headphones, through the RCA jacks, directly from the DAC/IvyIII. Is it possible to hook up the balanced outputs of the IvyIII to a standard 1/4 stereo jack and use the volume control on the BIII DAC. I would like to try the increased power of the balanced output but some of the headphones I use do not have balanced cables.
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solderdude
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Post by solderdude on Jan 9, 2016 22:25:06 GMT
The IvyIII stage is not designed to drive headphones directly.
When driving headphones balanced from these outputs you get a 40 Ohm output R C'Moy amplifier basically. Should be able to drive 300 Ohm headphones directly though when they have balanced cables on it.
You can't connect a stereo jack (TRS) to any balanced output.
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Post by chinook9 on Jan 9, 2016 23:37:26 GMT
The IvyIII stage is not designed to drive headphones directly. When driving headphones balanced from these outputs you get a 40 Ohm output R C'Moy amplifier basically. Should be able to drive 300 Ohm headphones directly though when they have balanced cables on it. You can't connect a stereo jack (TRS) to any balanced output. I suspected as much. I realized after I wrote this question that I need to do some reading on the difference between the SE and balanced outputs on the Ivy.
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solderdude
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Post by solderdude on Jan 10, 2016 9:42:46 GMT
The DAC out is symmetrical (balanced) from the DAC chip itself. The DAC itself puts out a current instead of a voltage. All 'normal' amplifiers have a voltage input.
This balance is done to get the best possible powersupply rejection/immunity.
It is very easy to convert a current to a voltage by simply running the current through a resistance. As the currents are rather small the resistance value needs to be relatively high. All capacitances etc. in parallel and input resistances of gear following it will thus 'load' that voltage conversion R and can f-up the end result.
For this the Ivy is made. It has 4 resistors R1 to R4 750 Ohm each (1 for each output) that is 'separated' from the loads by an opamp. The impedance of the load thus doesn't influence the output current/voltage any more. That I/V converter is then followed by a 28kHz 6dB/octave filter (which I would change myself to 90kHz) which is then followed by a 4x attenuator.
The way this is setup is to maximize the S/N ratio. This is all done balanced so balanced out is available by default. There is also a balanced to single ended conversion for RCA out.
Should it be my DAC then I would most likely have changed C1 to C4 with a 4.7nF capacitor. Less roll-off at 20kHz is the result.
Most people, however, prefer a slight roll-off at 20kHz and is probably why the -3dB point is at 27 kHz. The bandwidth of the stock Buffalo is very similar to the 'mid BW' setting of the Polaris amp and is why I designed the 'mid BW setting' on this amp. For some reason this slight roll-off is not heard as roll-off but perceived as 'fuller' sounding and probably why TP went with this setting. They probably don't believe in needing BW's much larger than that of human hearing.
When you have an amplifier with balanced in it is logical to use the balanced out. This is only somewhat beneficial if the headphone is 'balanced' as well or when you are running long line-level cables alongside mains cables or control cables. For short distances there could be some benefit when there is a ground loop present but only if the amplifier input has a transformer on the input (which most don't have). In the last case you may get less weird hums with a balanced out compared to single ended.
For home systems where you listen loud and don't hear any noises or weird sounds at full blast with SE it is pointless to go balanced. When the amplifier in question cannot deliver a lot of voltage (due to low power supply voltages such as portable equipemnt) balanced could be beneficial for high impedance or very low efficiency headphones because the output voltage can be twice as high (6dB louder).
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Post by chinook9 on Jan 14, 2016 15:41:17 GMT
Sorry I did not make this post earlier but I want to thank you very much Frans for this explanation.
There is a lot of very useful information in the post that previously I was not aware of. I don't fully understand it now, but I will read it a few more times and try to understand how it applies to DACs, amplifiers, and headphones that I read about.
I have dropped the idea of playing around with headphones connected directly to the IVYIII. Initially the AKG K812 sound very good connected to the SE outputs but I have not done extended listening. The only headphones I have with balanced cables are the LCD-3. At some point I may buy the required connectors but I doubt it would be worth the effort so its low priority.
I have been looking for a winter project so I've moved on and now I'm investigating the Soekris R2R DAC. I owned one R2R DAC which I liked and I figure this would keep life interesting for a while.
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Post by chinook9 on Oct 5, 2016 13:45:35 GMT
Javier, do you know if the ES9018 upsamples at the default settings?
All my music is 16/44.1 CD rips and I have always upsampled in Foobar to 24/192 and fed this to the Buffalo DAC. Last night, as an experiment, I changed Foobar to feed the 16/44.1 signal to the Buffalo. It was just a short listening session, but I'm not sure it didn't sound better.
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solderdude
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Post by solderdude on Oct 5, 2016 14:47:38 GMT
Everything (even 384/24) gets 'upsampled' in DS DAC's
upsampling 44/16 to 192/24 is an 'inbetween' step for DS as it upsamples all signals itself to higher frequencies anyway. In both cases the frequency range of the signal is both limited to 20kHz (maybe even 21kHz depending on the low pass used at the recording side) By the way it technically better to upsample a 44.1/16 to 176.4/24 by the way, not 192 which is a multiple of 48kHz samples.
Downside from PC upsampling is the PC is more 'busy' calculating the values inbetween the given values. Still a very easy 'load' for a PC by the way...
There is still a technical difference though. The low pass filter in the ES9018 is set to around 70kHz instead of 21kHz. Depending on HOW well the PC upsample algorithms low pass filter is designed this could perhaps be measurable (audible even ?) When you upsample yourself you have a choice of filter algorithms where one can choose the steepness and roll-off in the audible band as well as the 'band ripple' and pre/post or only post ringing, apodizing or other filters. All these different filters will still cut off everything above 21kHz and in the upsampled signal there won't be anything present unless the filter is crap and there is all sorts of aliassing garbage fed to the DAC which the 9018 by itself won't do. When feeding 44/16 into the 9018 there is only two types of 'filter' present (slow and fast roll-off) unless the signal processor before the DAC chip performs these functions in which case you have to depend on the filters used in that process.
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Javier
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Post by Javier on Oct 5, 2016 15:29:42 GMT
The ES9018 upsamples everything it receives to 1.5GHz by default (ie. An asynchronous sample rate to any base and most of the time using its PLL to get timing from a non sample related frq clock like 80 or 100MHz). It is possible to disable it using software mode though. In fact having a micro controller opens quite a list of possibilities
Sent from my GT-I9505 using proboards
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Post by chinook9 on Oct 5, 2016 15:47:46 GMT
Thank you Franz and Javier.
One of my projects for the winter is to see if I can learn to use the Arduino to open the possibilities with the DACS. I'm not a raw beginner at programming but I know nothing about the hardware side. I plan to start with a Vilros Uno Ultimate Starter Kit and go from there. I've read of other 70 year olds doing this so I guess its not too late for me.
If I am successful in my studies I may start by experimenting with the Buffalo III, however, I did order one of the DIYINHK AK4490 boards.
For now I'll enjoy what I've got.
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