FAQ
Why does BAT make both solid-state and vacuum tube electronics?
Just as there can't be one best wine for all meals, there isn't one best amplifier or preamplifier for all music systems and tastes. We believe that properly designed vacuum tube and solid-state electronics can and should coexist and complement each other, very much like red and white wines complement fine cuisine and coexist in the real world. BAT's mission is to give our customers choices that fit their lifestyles, budgets, and system needs. Our goal is to make a contribution to the art in any product undertaking. BAT's vacuum-tube and solid-state lines have been recognized for such distinctive contributions as automatic biasing (VK-60), two-stage high-power amplification (VK-500) and the Unistage® signal path (All BAT preamplifiers). We are pleased to offer industry-leading designs in all these areas. Customer response has overwhelmingly supported BAT's multifaceted pursuit of excellence.
Why should I buy from Balanced Audio Technology?
Please read our VK-60 white paper, for more insight into the extraordinary level of development and the meticulous execution that goes into each of our products. Then visit your BAT audio specialist to hear these exciting components in a well-set-up system. The main reason to buy one high-end brand over another should be that it plays music better. We're firmly convinced that you'll hear the difference with BAT. As one satisfied BAT customer told us: "Your product (VK-5) looks great! When I opened it I came to appreciate that it looks even better on the inside than the outside. After I plugged it in, what impressed me most is that it sounds even better than it looks!"
What cables should I use with my BAT system?
We haven't designed our electronics to work with a particular type or brand of cable. BAT electronics are wonderful at revealing cable differences and at providing a high level of performance with even modestly priced cables. Let past experience, your budget, and your ears be your guide.
Is the requirement for minimum input resistance dictated by the output resistance of your preamps?
No. However, this is a popular misconception. It is common to apply some old rules-of -thumb to things like preamplifier to power amplifier interfaces and state that there should be some magic ratio between the output resistance of the preamp and the input resistance of its load. People commonly mention numbers in the 10:1 or 20:1 area, some as high as 100:1. Unfortunately, there is no truth to such claims. As many of us know, one can perfectly transmit a signal in a system where the load impedance is equal or even lower than the source impedance (witness any cable TV system). The unusual design of Balanced Audio Technology's preamplifiers allows their gain stages to drive loads with resistance much below what their specified output resistance ratings would imply. For example, the VK-50SE preamplifier can supply a load with 65mA peak current - an amount well beyond that of the great majority of preamplifiers on the market today. However, it is also important to understand the role of the output coupling capacitor, present at the output of BAT preamplifiers. It is the size of this capacitor that will dictate the minimum power amplifier input impedance, not the output resistance of the preamp.
Why use an output capacitor at all - why not incorporate a servo, etc., as found in some competing designs?
Balanced Audio Technology has built its reputation for superior sound largely due to its trademark use of very short signal paths, with only a single gain stage used in its preamplifiers. Any single gain stage known to man today will shift the DC level of the signal. A typical gain stage will introduce anywhere from 10V to maybe 400V as the output DC component (depending upon its technology - tubes or transistors). Op Amp circuits can ostensibly get around this by being internally composed of three or more gain stages as well as relying upon a tremendous amount of negative feedback. This type of penalty is unfortunately typical when trying to "defeat" the DC component in the output signal without the use of output coupling capacitors or transformers. In order to remove the DC component resulting from the normal operation of a tube amplification stage, at least one additional gain stage (often a cathode follower) must be used, in conjunction with some type of DC servo circuit. Needless to say, such servo circuits will incorporate the same "dreaded" capacitors and Op Amps. The penalty of having additional gain stages, coupled with servo circuits typically built around integrated circuit Op Amps, is usually far greater than the perceived benefit of not having an output capacitor. We believe that the least intrusive way of removing an unwanted DC component from the signal is through the use of the highest quality capacitors - the simplest and still the most efficient way of doing it. Replacing a $20 capacitor with $2 worth of servo circuit components might look good on the preamplifier spec sheet, but doesn't fit our expectation regarding the best possible sound. The custom paper-in-oil signal capacitors used in the BAT preamplifiers enjoy international acclaim as some of the most musical and desirable components in existence.
How often will I need to replace tubes in my unit?
We expect minimum tube life to be in the four year range. Your tubes may last substantially longer depending upon usage. This is due to low stress factors designed into BAT components and soft start circuits incorporated in them.
Should I consider replacing the stock tubes with "upgraded" models?
We strongly believe that the tubes used in our products offer the best combination of sound quality, reliability, low noise and microphonics. However, there are many other tubes on the market, both new and NOS, that may offer a different sound character when installed in our equipment. The final value judgement regarding the sound quality as a result of such substitutions rests solely with the customer. However, there are certain things to consider. Given the wide diversity of various brands and models, Balanced Audio Technology can't guarantee the final results. Some tubes may not function properly in our equipment. It is always important to work with a vendor who stands behind their product should any problems develop. Finally, any repair work required as result of using tubes models and brands other than those originally specified by BAT would not be covered by warranty.
What makes the BAT electronic shunt volume attenuator so special?
In most preamplifiers the volume control works as gatekeeper of sound quality. Any damage done to the sound by an improperly implemented volume control will then be further amplified by the gain stage. This is why we had to develop our own solution to this critical function (please see the i-series white paper for more information on this subject). We were not satisfied with the traditional implementations available and undertook a costly but rewarding search. In our opinion, the best way to implement the volume control in a preamplifier is through an electronic shunt attenuator that puts only one high quality resistor in series with the signal. In many traditional implementations there will be dozens or even hundreds of components inserted in the signal path, plus multiple solder joints. A typical integrated circuit (IC) volume control found in many high-end preamplifiers may also place operational amplifiers in series with the signal. This would contradict our philosophy of a short and unobstructed signal path. The low cost of integrated circuit volume controls makes them attractive in low cost products. However, a $5 volume control hardly deserves a place in any true high-end preamplifier.
Why should I be concerned about an integrated circuit volume control at my preamplifier input?
Besides the above-mentioned drawbacks associated with the IC volume control's complexity, they usually also suffer from very limited signal headroom. A typical part in use by some manufacturers will clip the signal as low as 3V. Many of us might recall numerous discussions by leading designers regarding the importance of signal headroom. Put simply, in order for a circuit to deliver low distortion and clear and transparent sound, it must be able to handle a signal with a magnitude many times larger than the normal level encountered in a music program. Many respected designers believe that a circuit must be able to handle a signal of at least 10 to 20 times above its normal value. Some go even further. No one would consider 5% to be acceptable headroom for an audio circuit. The typical audio signal produced by audio sources falls between 1 and 10V. To handle such signals properly, the preamplifier must have an allowable input voltage range of at least 20 to 100V.
What happens when you apply the 10V signal to a typical IC volume control with its allowable input range of only 3V?
The answer should be obvious. Needless to say, the input voltage range is rarely specified for preamplifiers. A 3V limit should hardly be considered adequate. All Balanced Audio Technology preamplifiers, on the other hand, are capable of handling virtually any input signal magnitude, limited only by power dissipation in the volume attenuator. Input signals as high as 100V or even 200V would not present any problem. When considering a new preamplifier purchase, ask the manufacturer about this important parameter - the allowable input signal range.
Should I use a power conditioner with my BAT equipment?
Balanced Audio Technology first recommends that our equipment be connected directly to a good quality power line. A single dedicated power circuit will usually produce the best result. The presence of electrical noise or common impedance interaction may, in some instances, warrant the use of power filters or conditioners. However, because every system is different, always make sure you try the system both ways - with and without the conditioner, in order to make the proper buying decision. When employing any kind of filter or conditioner, please make sure that BAT preamps, including the VK-P10 phono-stage, are treated as you would normally treat a power amplifier in terms of power requirements. Some conditioners may have limited current delivery on the "preamplifier" outlets and will not be able to handle the 150 watt requirement or the turn-on transient from our preamplifier's massive power supply.
Should I use separate dedicated power lines to power amplifiers and my source components?
Contrary to popular belief, the answer is most often NO! Every system is different and it is hard to come up with a general rule. However, in order to minimize the chance of ground loop noise and signal degradation, it is advisable to assure that no large voltage differences exist between the chassis of different components in the system. These voltage differences will be more pronounced in a system incorporating several separate power lines. The voltage differences will be higher in the case of longer power lines and stronger current demand by heavy components (i.e. power amplifiers). Usually the safest approach is to run one strong (probably 20A) power line to your listening room and plug all your audio components into it. This approach creates a STAR power distribution system that should be less prone to ground loop problems.
My circuit breaker panel is over seventy feet away from my listening room. The total current draw of my system is above the maximum that a single power line would allow. What should I do?
In many cases the best possible way out of this predicament would be to install a new sub-panel close to your listening room. You must consult your local electrical code and qualified electrician, but usually a new 60A or 100A panel can be installed. Several short (ten feet or so) separate power lines can then be connected to outlets. Use short dedicated lines, (preferably 20A rated), from this new sub-panel to your audio components. Make sure that all audio components are connected to the same phase of the power line. To do this, check the locations of the circuit breakers that protect the power lines used the for audio system. The panel is arranged so that two vertically adjacent breaker positions are the opposite phase. This is so 240V breakers can easily connect to the two phases. So to get two breakers on the same phase, there must be an odd number of positions in between. Horizontally adjacent breakers should be the same phase. Do not be fooled by "tandem" breakers. They have two circuits in the space occupied by a normal single circuit breaker. They are both connected to the same phase and only count as one position.
I am using a combined Audio/Video system and get a lot of ground loop noise. What is the solution?
Very often in such an installation the culprit will be the grounding in the cable TV circuit. The surest way of solving it is by buying a cable TV ground isolation device (transformer) that is available from many high-end dealers.