|
|
|
Selection Guide Although extremely tiny, SuperMacro-3 is designed to be of the highest flexibility for anybody, anywhere and anytime, at home or on road. It sets up a new standard for headphone amps on sound, benchmarks, size, weight, price, features, flexibility, looks, etc. The 4 feature switches are for customizing sound. These are the very unique features that only SuperMacro can offer so far; even full size amps do not have them all. These switches have very short signal wires and can all be bypassed and then they won't bring you any side effects. So, as long as your budget allows, get them. The impedance switch is mainly a convenience for ER4P headphones, to make them sound equal to ER4S, and is good for some very low-impedance and/or long-cable phones. Note that SuperMacro will not cause any hiss to any headphones including SHURE E5C; so you don't need to turn on this switch for that reason. The amplification gain switch is mainly for very low-efficient headphones such as AKG 501 and for people suffering from hearing loss. You really should not go higher gain, as long as you can get enough volume (even with the volume knob all way up). The bass boost switch is for bass lovers and good for ER4S/P alike, not so bassy headphones. The Crossfeed switch delays and mixes two channels, which is for those who like speaker-alike sound field and good for old Beatles songs that were recorded without channel mixing. To help you to remember the positions of these switches, try "It's ABC" - Impedance, Amp gain, Bass boost and Crossfeed (from left to right). The lite edition is for those who seek the best value and simplicity. We cut down those bells and whistles; so you can enjoy the same first-class sound at a very affordable price. All configurations allow you to swap opamps and to experience different tastes of different opamps. This is another very unique feature of SuperMacro-3; all opamps work well, unseen in other amps, portable or home. The opamp sockets are very shot to avoid any side effects. See the manual and this thread (many thanks to Alan) for how to roll opamps. Check this thread and see how SM3 owners have fun with this and get their dreamed sound. Most opamps benefit significantly from class-A (CA) biasing. Both the standard and lite versions are set to CA by default. Some opamps have an external compensation pin (5). By connecting this pin, instead of the output pin (6), to the buffer's input, the output stage of the opamp is bypassed, resulting to cleaner sound. However, not all opamps have this feature; NE5534, AD744 and AD829 are some of these. NE5534 and AD744 can be output bypassed and set into class-A at the same time for even more perfect sounding. Here is a list of opams tested in SuperMacro (here is their square wave responses):
Note: 1) Tested in the latest SuperMacros only (serial # > 05011900). Some opamps (such as OPA637) may not work well in early SuperMacro models (serial # < 05011900). 2) Only DIP and single opamps can be used in SuperMacro. SOIC type ICs need to be mounted on adapters and the adapters need to be filed to fit into SuperMacro's OP sockets. 3) Current is in mA per channel, voltage (min) in volt and speed is slew rate in V/us. 4) Although we cannot test all, but from above list you can see SuperMacro will work fine with pretty much any opamp you throw in, low or high speed, JFET or not, power hungry or not (thanks to powerful AAA batteries SuperMacro uses). 5) Most of the comments are for SuperMacro, may or may not apply to other amps. 6) For good battery life, select the ones with low current and voltage. Unique Architecture
There are two circuit boards in every SuperMacro. The bottom one is the main amplification board and has all the necessary audio components and traces on it. The upper board has the extra feature circuits such as power supply control, battery charging, auto-off timer, switches for impedance, amp gain, bass boost, crossfeed, etc. This unique architecture allows SuperMacro to produce the purest sound and meanwhile to provide full features, even more features than any desktop headphone amps can offer. As the charging and regulating circuit is not on the main board, no chance for them to ruin the sound; any cheap power supply and AC adapter can be used without any issues. The 4 switches, for example, each has 3 terminals per channel. Normally, a designer has to put 24 wires (4x3x2) in there, but I use only 10 wires total (my magic). And these wires are shorter than 1.5 inches! If one still worries about these wires, then one does not have to have them at all (the Lite version). The main board remains to be optimized for the purest sound possible. It is so tiny, so all the signal paths are extremely short. Plus, the components and traces are very carefully laid out to ensure the lowest distortion and channel crosstalk. Note that when distortion is controlled down to such low level (0.000x%), crosstalk becomes a significant source of distortion. Therefore, to reach very low crosstalk is now very important for one more reason. By using many sophisticated crosstalk control techniques, SuperMacro-3's channel separation is extremely high, even at the worst headphone-driving conditions. Super low level of distortion and channel crosstalk is unseen in current headphone amps and is not achieved by heavy feedback. As you know, heavy feedback decreases distortion but is very bad to audio quality. To reduce feedback further, SuperMacro does not use multiple feeadback loops. In order to reduce distortions, input impedance is ideally matched and output are buffered and stacked. All resistors are 0.5% thin film SMD for their excellent low noise and low harmonic distortion. There is no capacitor in signal paths. The large decoupling caps are extremely low ESR type and they are ideally positioned to minimize distortion. Some battery-powered amps use separated batteries for + and - rails and have problems of unequal battery draining. SuperMacro uses a unique isolated ground and all batteries will always be drained equally and un-equally drained batteries will not cause any problem. As you might have noticed, the batteries and capacitors take almost all the room of the amp. Most portable amps use expensive 9V batteries which cannot provide enough juice for the best sound possible, especially for hungry headphones, or the battery will last for only few hours. By using 8 AAA batteries, SuperMacro can be ultra tiny and thin and meanwhile provide more than adequate power to the most demanding headphones. Even so, the batteries last much longer than 9V batteries (5 times longer) and are far more economic. SuperMacro's such super high power capacity also allows the use of power-hungry opamps such as OPA627/637. And, if rechargeable batteries are used, they can be charged in the amp - very convenient. If you go on a trip, you don't need to take the charger (provided) with you; you can simply buy a pack of AAA (available anywhere) and your music never stops (wishing your iPod could last the same long). No matter how long your fly is (from this side to the other side of this world), your SuperMacro won't run out battery, I guarantee you. More powerful, more convenient, more economic, more playtime and more juice. SuperMacro uses as many as up to 4000uF of capacitors, to ensure the lowest distortion, the highest dynamic range and the richest sound. However, such high total capacitance could cause serious shock to the power switch and headphones when the amp is turned on or off. SuperMacro uses a unique electronic switch to handle the surge from these huge caps and the mechanical power switch that controls this electronic switch only passes very low current (1.5mA max). Thus, the lifetime of the power switch is hugely enhanced. Two bonuses from this: I then added easily soft delay to avoid power-on pops and an auto-off timer, all by a single tiny switch. The resulted sound? Extremely smooth, natural, detailed, accurate, fast and transparent, with huge and well positioned and layered sound stage and fully extended highs and lows. Benchmarks (tested with EMU1212M audio card and RMAA):
EMU1212M audio card only without amp:
Square Wave Response:
As you can see, SuperMacro's distortion and channel crosstalk are almost as low as the best audio card can detect. The channel crosstalk increase above 10Khz is introduced by the 3-ft connection cable, not by the amp. The -0.12dB drop at high-end frequency is also caused by the EMU audio card, not by the amp. Reviews: More coming. Instructions and Highlights: See the manual, or go to Cool Talk to talk with other happy users. |
|
Copyright © 2005
Xin Feng Company
|
