MSB-GOLD4-dac-sm维修电路原理图.pdf

Power DAC Users Manual Rev 3 (9/06) Sign Magnitude Ladder daC SpeCifiCationS inputS: CoaxiaL, toSLink, baLanCed aeS/ebu, MSb network rCa outputS: 3.6 V rMS (10 Vpp) output iMpedanCe: 50 ohMS at 0 db baLanCed output: 7.5 V rMS (20 Vpp) SaMpLing frequenCy: 32 khz to 384 khz digitaL fiLter: 16 tiMeS oVerSaMpLing SLew rate: 2500 V/MiCroSeCond SettLing tiMe: <90 nanoSeCondS dynaMiC range: 136 dba MeaSured noiSe fLoor: 130 db MaSter CLoCk: +/- 2.5 ppM Low Jitter ControL featureS: fiLter option battery Mode RadioFans.CN 收音机爱 好者资料库 Power DAC Users Manual Unique Product - a Battery Powered DAC? This product combines a unique combination of a very high performance DAC and the ultimate power supply - batteries. Batteries give an amazingly high instantaneous current with no noise. Nothing else can compare. A Simple Approach The Power DAC takes a different approach from other MSB products. We took the best of our own MSB DAC technology and put it with the best power supply technology in a no-frills package with no fancy features or upgrade options. The result in a level of integration that boosts performance and keeps costs low. The Power DAC has the performance of a Platinum DAC at the price of a GOLD. Setup and Quick Start This is easy. Plug it in and go. Power - The Power DAC will operate on batteries up to 10 hours but should be left plugged into the charger. A switch on the front allows it to operate on batteries only, and will automatically switch back to charging when the batteries are depleted. Inputs - The Power DAC comes standard with one MSB Network (CAT5), AES/EBU balanced, coaxial and optical digital audio inputs. Connect any digital input to any active digital audio source and it will automatically be selected. Outputs Connect the balanced or single-ended analog outputs to any amplifier and audio should be present if your digital input is active. Burn-In The concept of burn-in is little understood. Does it take your ears some time to get used to the incredibly detailed and life like sound of an MSB product or is something actually changing. The feedback we receive leads us to recommend at least 00 hours of burn-in on this DAC. Customers generally recommend one month. Battery Life and Replacement The batteries in the Power DAC should last 4 to 6 years depending on use. For maximum life the batteries should always be kept fully charged. As the batteries get older the battery play time will be reduced. It starts out about 0 hours of play without charging. When the play time is reduced to 6 hours, the batteries should be replaced. You may purchase replacement batteries on-line or from many suppliers. They are sealed lead acid batteries and used batteries should be recycled. To replace the batteries, purchase: ) Powersonic PS-670 or equivalent 4) Powersonic PS-6 or equivalent These should cost about $50. “Better” batteries will not likely produce better sound but they may last a little longer. Battery charge time varies but approximately equals the play time. So after 5 hours of playing, it will take 5 hours to recharge. The battery charger is very advanced and designed to always be connected. It will NOT ever overcharge but will optimize battery life. Charger The charger is configured for either 100 to 120 VAC input or is configured to 200 to 240 VAC input. Both configurations can be used at 50 or 60 Hz. It is supplied with a DIN cable and AC cable. Longer DIN cables can be purchased for remote charger placement. For best performance, do not place the charger on top of the unit. Storage To store the Power DAC, fully charge the batteries. Store in a cool place for up to 4 months. If you need to store the product for more than 4 months without recharging, remove the batteries and recycle. When you take the product out of storage, purchase new batteries. RadioFans.CN 收音机爱 好者资料库 Unique Technology - the past and the future Over 0 years ago early DACs were all 6 bit ladder DACs, with a precision laser-trimmed resistor creating the appropriate analog level for each of the bits. The DACs worked well and sounded good. They were quite expensive as very accurate resistors were required. Then along came the “single bit” DACs. Rather than using a resistor to create an analog level, pulse width modulation was used. Basically each bit was created by turning a switch on and off for the appropriate length of time. The resulting square wave pattern was filtered to create a smooth output. The expensive resistors were gone, and so was the good performance. Next came the Delta Sigma DAC. It used the same pulse width modulation but rather than creating a single large pulse for each data point, the data point was created with many small pulses. This allows the pulses to be smoothed with a less radical filter, and improves the sound. As you can see, upsampling the input signal to a higher frequency reduces the filtering requirements and thus improves the sound. This is the current state-of-the-art as exemplified in the LINK DAC III with the upsampling option. The Power DAC draws from the older, superior ladder technology, but with incredible improvements. The Power DAC has two 4 bit MSB DACs built-in. Each DAC contains one RR ladder DAC with a bit negative sign and one RR ladder DAC with a bit positive sign. Together this makes a true 4 bit DAC. This design allows the quieter moments in your music to be true to the music, without the linearity errors near zero that plague normal ladder and delta-sigma DAC designs. With a dual 4 bits of combined resolution, a 4 bit source gives a true 4 bit resolution without the losses and errors that make your normal 6 or 4 bit DAC perform far less than their actual resolution (normal 6 bit DACs only muster a meager bits of resolution). The Power DAC is carefully designed so as to require no DC correction in the output stage. This allows direct DC coupling on the output stage for pure, uncolored sound - with no output filtering to muck up your high end or smear your bass attack. And for those who require a balanced analog output, the separate positive and negative DACs directly drive the balanced outputs, with no analog output stage at all! Another major difference in the Power DAC is the type of output. Essentially all ladder DACs produce a current output. This is converted to a voltage output with a current to voltage converter. This problematic circuit colors the sound and introduces non-linearity. The Power DAC is a true voltage DAC with a voltage output right from the source. All amplifiers have slew rates greater than 2500 Volts/microsecond. The output impedance of the Power DAC is 50 ohms. Special Features The Power DAC has many special features. The following sections discuss these features and how they work. Upsampling and filtering As MSB technology has developed, so has our DAC architecture. Our advanced digital filter now replaces the asynchronous upsampling of earlier models. The 16X Digital filter goes way beyond our older 4X upsampling. To play a 24/192 disc the Power DAC only needs to be plugged into a DVD-A player with an MSB XPORT output. The new upsampling feature dynamically buffers and re-clocks all the data and clock signals to provide a virtually jitter-free source directly to the DACs. The selectable digital filter response permits the user to choose the filter design they prefer. It allows for the selection of a standard brick-wall filter or a slow roll-off filter, both at half the sampling frequency. Each provide a distinct, glorious listening experience. You may favor one or the other, or enjoy changing the filter response to suit the music you listen to. Music with less high frequencies may benefit from the slow roll-off filter. To play a 24/192 disc the source player needs to have an MSB Network or XPORT output. If your DVD-A player does not have the MSB Network output, it can be added. A 192k input will override the upsampling settings. Custom MSB Digital Filter The Power DAC has a custom DSP based Digital filter and clock module. We have created our own Custom Digital Filter for the MSB DACs. Previous versions of the our DACs used the Burr-Brown DF704, which at the time was the best Digital Filter on the market. Our Digital Filter is built to our specifications and standards, and is designed to get the most out of the Power DAC. The performance of this Digital Filter is amazing. Immediately youll notice the lack of fuzziness around voices and instruments of all frequencies. This filter also dramatically increases the resolution and dynamics of the machine. This filter is also completely customizable; By playing a special .wav file on a CD new filter coefficients, either temporary or permanent, can be loaded into our DSP. The Digital Filter is a 16x oversampling, single stage filter with 32 bit input resolution, 80 bit compu- tation, and 36 bit coefficients. About the Clock / Jitter Control Jitter control devices (and inputs on most DACs) normally reclock the input signal in attempt to lessen the jitter of that incoming signal. The Power DAC does no such re-clocking. We actually pay no at- tention to the clock on the input signal. All internal clocks are generated by an extremely accurate +/- 2.5 ppm temperature compensated clock. Since the input clock is no longer related to the clock of the Power DAC, an intelligent second buffer is used to maintain data synchronization. The MSB 6x Digital Filter is an ultra high-resolution digital front end. The combination of a high- speed on-board computer and carefully optimized software and hardware result in the best possible music quality. During the development of this peerless digital audio system MSB has accumulated a wide body of unique knowledge allowing us to design the ultimate digital filter. Sign waVe (0 db, 19.95 khz teSt tone SCope SettingS 2 V/diV, 10 uSeC/diV) upSaMpLing effeCt RadioFans.CN 收音机爱 好者资料库 4 More About the Digital Filter One of our primary goals at MSB is to provide the music lover with the most accurate musical experience possible. During years of careful design and improvement of our custom discrete DACs, which form the heart of your Power DAC, we realized that the Power DACs sound quality was no longer limited by them. We soon narrowed the problem to the Digital Filter which was feeding our DACs. While the excellent Burr-Brown (Now owned by Texas Instruments) DF704 Digital Filter had served us well in the past, it had became the bottleneck once we started using our new Second Generation DAC modules. After a thorough search of all the available off the shelf and custom DSP based Digital Filters we realized that little improvement could be had from any of them. With no other option in sight we decided to build our own solution. Converting the ones and zeros of Digital Audio into music is an enormously delicate and critical process. Each individual sample that makes up the audio stream must be converted into the high resolution, continuous analog voltage that can be transformed into the sound that you hear. Any misstep can corrupt the final result ending with audio that does not sound anything like the original recording. Errors in translation can make a harsh, veiled, muddy, and/or tonally colored result. Minimizing each potential problem allows the original recording to shine through. Audio reproduction starts when the DAC receives the binary coded information from the source. The first step requires recovering the audio samples, which represent the final output voltages, and the timing, which tells the DAC when to output those voltages. Next the sample rate is raised and the data is digitally filtered. While it is possible to feed the DAC with the original audio samples thereby avoid- ing the use of a digital filter skipping this step has many unintended consequences. After being digitally filtered the digital stream is feed to the DAC. The DAC receives the digital audio samples and converts them into a continuous analog voltage. The best DACs, such as our Second Generation DAC Modules or Signature DAC Modules, instantly convert the data into a precise continuous voltage waveform with timing determined by the DACs conversion clock. The digital filter is necessary because mirrored image frequencies created during the conversion process must be removed. If the DAC did not have a digital filter, an analog filter with an aggressive response must remove these image frequencies. These brick wall analog filters seriously damage the signal by corrupting the original phase of the sound and cannot fully remove the high frequency images. This results in harsh or rolled off high frequencies and poor soundstage focus. Traditional digital filter designs consist of cascaded FIR (Finite Impulse Response) filters, each of which raise the sample rate by two. The intermediate data between the filters is usually stored at less than 40 bit resolution. Since the next filter works with previously com- puted data the resolution decreases with each filter pass. This limits higher quality digital filters to a low oversampling rate (usually 8x) before the output starts to deteriorate. The loss in resolution is typically not apparent when using the best conventional digital filters with standard DAC chips, but in combination with our high resolution 4 bit Second Generation, or Signature DACs the problem is very ap- parent. The sound becomes muddy, veiled and un-involving when using any off the shelf digital filter. To counter this problem the MSB 16x Digital Filter does its filtering in one filter stage that raises the sampling rate by 16. FIR filters operate by multiplying each sample in the data by a set of filter coefficients and then summing the result. Most digital filters round the result of each addition before the adding next sample. This repeated roundoff results in a similar problem to the cascaded x filter approach, muddy sound. MSBs digital filter uses bit perfect accumulation in an 80 bit accumulator completely eliminating these debilitating roundoff errors. Only as the last step do we carefully convert the audio to the 4 bits our DACs require. The high sampling rate of the output allows us to include advanced ultrasonic dither and noise shaping techniques in this step to achieve greater than 4 bit effective resolution. Through extensive listening tests we have found that the choice of filter coefficients has a great impact on the tone of the music. We have found that steep, phase perfect “Brick Wall” filters tend to sound the most neutral but are also the most difficult to implement without problems. Improvements we have made in our digital filter, with its single stage design and 80 bit computation, allow us to use very steep filters with no compromises. Custom Filter Options We recognize that different people often have very different taste in their music. For those who do not like the standard choice of filter, or require a different filter response, we have provided a