holo dac spring r2r

Holo Audio Spring R2R DAC

CHF1.750,00 – CHF2.390,00

Delivery time: a few weeks if not in stock.

Contact us for information on our own modifications of the Spring DAC.

 

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Holo Audio’s Spring DAC

Patented R2R technology. This is the first discrete DAC that has linear compensation and this allows for ultimate music reproduction accuracy. Dual R2R network for PCM, and Dual Discrete optimized resistor network for DSD!

 

Reviews:

 

ComputerAudiophile by Ted Brady

Headphone Guru by Peter Pialis

AudioStream by Michael Lavorgna

AudioStream by Alex Halberstadt

Basshead Club by Luckbad

SuperBestAudioFriends by Torq

Head-Fi by Torq

 

General info:

Dimensions: 430 mm (W) * 300 mm (L) * 55 mm (H) additional 12 mm for machined feet

Weight: 8.5 kg

 

Does not include power cord, printed manuals, or remote control (the option for one is unavailable). Front panel controls only.

The Spring DAC is capable of DSD512 native on an Discrete Resister Ladder DAC. Patented R2R technology. This is the first discrete DAC that has linear compensation and this allows for ultimate music reproduction accuracy. Dual R2R network with advanced architecture for PCM, and Dual Resistor Ladder network with optimized architecture for DSD.

There’s an additional R2R ladder in the Spring DAC, it compensates the main R2R ladder. It works like trimming, but trimming is to change the resistor value. This additional R2R ladder is digitally controlled and will accurately compensate the resistor tolerance. For example, the MSB of 16 bits should have the value of 32768, but due to tolerance, it represents 32700 in real world results. Then that additional R2R ladder will compensate 68 into it. Thus it now becomes 32700 + 68 = 32768.  What this means is that it’s likely the most precise Discrete DAC on the market with near flawless linearity, lowest THD and highest SNR of any NOS DAC. The sound is simply something you must experience to fully realize how special this DAC is. It’s a patented technology exclusive to Holo Audio.

 

Holo Spring base model – LEVEL 1

Holo Spring  – LEVEL 2

(With four Jensen 4700 microfarad / 63 Volts added for ultimate power filtration and improved sound quality – For sound effects are more relaxed, transparent and details are more apparent. This is the most popular version that sell’s most often.)

Holo Spring  – LEVEL 3

(Same as level 2 plus 100VAC O-type (NOT toroid) 99.99% Silver custom hand made audio transformer.)

 

DSD is natively supported for the first time on this Discrete Resistor Ladder DAC
Holo Audio is the world’s first to support DSD natively on Resistor Ladder DAC, so far the only one. This is not the DSD converted to PCM before digital-analog converter, but directly by the discrete components of the DSD digital to analog converter. Supported currently on MAC (DOP)and Linux (DOP), and Windows/PC (Direct Native and DOP). Please note, the word ‘R2R’ is the name of a kind of architecture of resistor ladders. This architecture requires less resistors yet still is capable to deliver more than acceptable performance. Most DACs in the industry use this architecture. The DSD module of Spring does not use R2R architecture for the DSD, more specifically it uses a very specific architecture which is optimized to perform DSD to analog. So to be entirely accurate the DSD part of Spring is using resistor ladders, not R2R..
Spring’s input and output interface:

Digital input interface includes
USB (ground isolation)
RCA coaxial
BNC coaxial
AES
optical fiber
I2S (HDMI)
All digital input interface supports DSD (DOP mode).
Analog Output interface: single-ended, balanced.
Spring DAC R2R structure and design + Input/output Stage

Modern and popular delta-sigma type DAC differs from R2R within one clock analog value can recover a sampling point, and the delta-sigma is used to represent an analog signal after passing through oversampling and high-speed digital switching 0 and 1. In comparison, the conversion structure of R2R is most direct and pure, but delta-sigma is essentially a digital chip, high-speed digital signals 0 and 1 switch to the low-pass filter to process the analog signal and this process is prone to various problems, produce digital sound (digititus) and also in the super-sampling process will inevitably cause some ringing and distortion. But DAC R2R structure requires high-precision resistor network which the cost can be very expensive. And the digital delta-sigma DAC chip in comparison is very low cost. Patented R2R technology. This is the first discrete DAC that has Linear compensation and this allows for ultimate music reproduction accuracy. Dual R2R ladder network with advanced architecture for PCM, and Dual Resistor Ladder network with optimized architecture for DSD!

I/O stages: There is an Op Amp used for input stage and discrete component used for the output stage. The discrete output stage is working in pure class A.  The output voltage is 2.5 Vrms for single ended output and 5 Vrms for balanced output. The single ended is RCA. Balanced is XLR. They both use the same output stage. It’s BiPolar Junction Transistors, direct coupled. The big MKP capacitor you can see in the output stage is for the power supply, not for signal coupling. And the output impedance is 200 Ohm.

 

A true balanced circuit design

These two pictures can explain the true balanced design quite well. The bottom side has the same resistor ladders as top side. The dac module is a pure 24bit discrete R2R design (PCM) and discrete Ladder Dac optimized architecture (DSD).

XLR is using all of the circuit and RCA is just using half of them. The balanced output has better performance (THD, noise) and also better common mode rejection rate. If you’re listening environment contains interference, either from AC power or from EMI/RF then you will find a full balanced system can really help significantly.

 

With diverse and flexible sampling mode conversion mode

1: NOS mode: has no digital oversampling, the raw data is directly converted to analog.  Because digital oversampling will produce time-domain distortions, such as ringing, NOS avoids these problems. Generally NOS mode’s other performance indicators have a significant impact, but the Spring is designed to allow top performance while in NOS mode.

2: OS mode: PCM is over sampled to PCM at a higher frequency, DSD is over sampled to DSD at a higher frequency, and then digital is converted to analog.

3: OS PCM mode: in either PCM or DSD the data will be oversampled to PCM and then digital is converted to analog.

4: OS DSD mode: in either PCM or DSD the data will be oversampled to DSD and then digital is converted to analog.

 

What are the Spring’s sound characteristics?

One of the strong points of the spring is the spatial sounds stage presentation. It’s very wide and precise. It never sounds congested like many DACs. The high end is very detailed and never harsh sounding. It has the R2R goodness that many have come to know and love. R2R has almost a cult like following and this DAC will surely become a sought after DAC.  Everything comes effortlessly for this DAC. Bass is layered and textures, quite full and present without ever masking over the sweet mid tones that are produced. One special thing about the Spring is its amazing voltage regulation circuitry that has no more than 0.2uV noise! This along with the O-core transformer helps regulate the purest power which translates to audio clarity and accurate reproduction.

 

Technical notes:

About the resistor tolerance, his word is partly right, but not accurate. The MSB of 16bits value only represent 32768, not 65536, all 16bits is 65535, but the MSB is only 32768. There are techniques to reduce this requirement. For example, segment+R2R, using segment into the first few bits, then r2r for the rest of them. Rockna is segment+R2R, TotalDAC is all R2R. And you can see, Rockna’s THD spec. is much better than Total. Total uses foil resistor, but they used the simplest architecture. That results an unsatisfied test performance. To my opinion, it’s some kind of wasting foil resistors. Soekris also uses segment+R2R. MSB’s old model is all R2R, but I don’t know about their new models.

Anyway, There are ways to improve the performance, the segment+R2R is one way. Trimming is another way. There is an additional R2R ladder in Spring, it compensate the main R2R ladder. It works like trimming, but trimming is to change the resistor value. This additional R2R ladder are digital controlled and is to compensate the resistor tolerance. For example, the MSB of 16 bits should have the value of 32768, but due to tolerance, it represent 32700 in real world. Then that additional R2R ladder will compensate 68 into it. Then it became 32700+68=32768.

Actually there are other ways to improve performance, I just told you two stories. There are more stories behind the design. It is really hard. I must count every via holes in layout, every PCB wire has it’s impedance and must put attention on it. A via hole can be 50 m Ohm, it is 1/20000 of 1 kilo-ohm, and you see, it covers 32768 which is the MSB of 16bits. Also the switches has self-impedance which is about several ohms to 30 ohms. If you find this issue. Maybe you will go crazy, it seems to be an impossible mission. But a good designer will overcome all these problems. It’s our value at HOLO Audio.

All the resistor tolerance, switch impedance, line impedance, via hole impedance, finally reflect as linearity. There is a chart that shows Spring’s linearity, it’s excellent. But I suggest you to look at THD performance. Bad linearity must result a bad THD performance. But good linearity doesn’t mean there will be good THD performance. THD is dynamic performance, more critical than linearity which is a static performance.

If you look at the THD performance, you will find Spring to maybe the best among those competitors. I’m applying a patent which contribute a lot of that performance. But I can’t tell you how. It’s confidential now.

 

What is linear compensation?

No matter it is a digital switch or analog switch, they are built by transistors, can be either bjt, mosfet or jfet. They have self-impedance call Ron(impedance when at on state). If we expect a lower Ron, the a bigger transistor is needed. But bigger transistor has bigger self-capacitance that will cause switching speed to be lower. So there is no perfect components in the real world.

About long term drift, the modern resistor technology has made it much better than older process. But the most important thing is, we don’t care absolute drift, we only care relative drift. That means, if all resistors are drifted in the same direction and same speed. Then it will be no impact for this application. So, we make sure to use the same batch of components in a single board. That will minimize the problem causing by long term drift.

As I mentioned in the earlier email. Spring is not using trimming, but using compensation. Not matter it is trimming or compensation, their goal is same, to make the resistance much more accurate so the linearity and distortion can be improved a lot.

 

Oversampling and NOS mode.

The oversampling is done by AK4137, ‘OS PCM’ converts the input stream to PCM no matter it is PCM or DSD, then send to DAC. ‘OS DSD’ converts the input stream to DSD no matter is is PCM or DSD, then send to DAC. ‘OS’ over-samples the input stream. If it is DSD input, it over-sample to DSD256. If it is PCM input, it over-samples to PCM384K or 352.8K ‘NOS’ does no oversampling. send the input stream directly to DAC module.About DSD ‘native’, it is the way the USB transfer the stream. You know DOP, which is DSD Over PCM. DOP put the DSD into a PCM stream. At the receiver end, it just unpack the PCM stream and get the DSD back. DOP does NOT change any bit of DSD stream, just sending it with the package. So it waste some data rate. At the same data rate, DOP is 1/2 of DSD native, the other 1/2 is the package. So DOP and DSD native are all bit perfect. The DSD stream sending to DAC is all the same.So, now you should know, DSD native is just about the way it transfers the stream. Not describing the way it does digital to analog conversion. At the DAC stage, the DSD stream can convert to PCM then do the final digital to analog conversion. Actually, most DAC chips do this inside the chip. One point needs to be remembered, DSD streams can’t do volume attenuation. If this chip can do digital volume control under DSD mode, then is must converted to PCM already.Let’s go back to Spring. If Spring works in ‘NOS’ mode. There is no
oversampling, no conversion, just the original data doing the final digital to analog conversion. I will not explain how it does PCM conversion, you should already know quite well about it. There is a lot of resistor ladder
DAC, they are born to do this. I just explain how Spring can do ‘discrete DSD conversion’. Actually it is like DCS and CHORD. If you looking to DCS and CHORD’s PCB, you will find ‘discrete DSD conversion’ is also using
switches and precision resistors, like resistor ladder DACs. So, no matter it is ‘discrete DSD conversion’ or ‘discrete PCM conversion’, they all use the same discrete devices. Just work in different architecture. That makes
possible to combine these two modes in one device.

 

WARRANTY
3 years warranty, both parts and labor, cover one way shipping (return shipping once product is confirmed a warranty claim).