276°
Posted 20 hours ago

iFi SilentPower DC Blocker - Blocks any DC offset, IEC Connector

£64.5£129.00Clearance
ZTS2023's avatar
Shared by
ZTS2023
Joined in 2023
82
63

About this deal

CA1, CA2, CA3, CA4, CA5, CA6, CA7, CA8, CA9, CA10, CA11, CA12, CA13, CA14, CA15, CA16, CA17, CA18, CA19, CA20, CA21, CA22, CA23, CA24, CA25, CA26, CA27, CA28. During the ensuing years, the 8000A established itself as one of the most successful British amps ever produced, and was joined by a range of electronics including CD players, pre/power amps and an FM tuner. The brand switched hands in 1997, changing its name to TAG McLaren Audio; and it so was known until 2004 when audiolab became part of the International Audio Group and returned to its original name. PH15, PH16, PH17, PH18, PH19, PH20, PH21, PH22, PH23, PH24, PH25, PH26, PH27, PH28, PH29, PH30, PH31, PH32, PH33, PH34, PH35, PH36, PH37, PH38, PH39, PH40, PH41, PH42, PH43, PH44, PH45, PH46, PH47, PH48, PH49, PH50 As you can see, the normal idle current is not a sinewave. The small peaks at the right side of the half-cycles become larger as the transformer is pushed further towards saturation, indicating that the transformer is just on the verge of saturation in normal operation. This is deliberate. If a transformer is built using enough primary turns to ensure that no saturation effects are visible, it will have very poor regulation because the primary resistance will be too high. Enhanced performance for power amplifiers, offering a consistently clean and efficient power supply.

It's worth showing the effect of series resonance between the capacitor and transformer's primary inductance. The above graph shows the behaviour after the application of DC. The period between peaks is 2.12 seconds, which makes the frequency 0.47Hz. A calculation using 2,000µF and an estimated 40H gives 0.56Hz, and the figures are close enough to see that the effect is real. diyAudio member AndrewT is correct that a single 4-diode bridge rectifier module can indeed supply all 4 diodes of Figure 3. I've drawn this out in Fig.4, below. The normal idle current is shown on the left, and the current with 132mA DC offset is on the right. The asymmetrical waveform with DC present is very obvious - the current is drawn predominantly during the negative half-cycles. If the DC polarity were to be reversed, the positive half-cycles will create saturation. Note that the right current scale is 10 times that on the left. A quite cheap and not very sophisticated filter design, offering a substandard DC-filtration, unless the reqtifier bridge is not spec'd with higher forward voltage diodes. The decoupling is very rrudimentory as well and will do some good, but since no resistor loads are implemented it will not cancel possible resonances.I/O's are not decoupled so in almost any ofthe designs I have scrutinized, interconnects shield noise is landed right on to the PCB instead of grounded to chassis. The stray infects the so delicate 0 volt ref voltage to numerous IC's including the DAC chip. Do not take just my word for it, it is a friend of mine, studio technician, Master of Science educated, at least 40 years in the profession, who rebuild DAC's like dCS, but also cheaper versions like Topping D90SE, who claims that ground ref is is a design flaw in it self as are many other areas. The ground is then also challanged by the standard procedure of soldering e.g. pin1 but also shields in USB's, I2S UI, etc in the PCB. The PCB ground should not be used to land noise from cable shield in my opinion. So when decoupling, you should be able to trust the ground you decouple to., but you cannot. One thing so often overlooked is the use of filter and buffert electrolythic caps. They are in the analogue domain often soldered i pairs from the positive and negative to the ground, instaed of caring for the ground by having one twice the size directly between positive and negative only. The filter caps for purely decoupling is wired equally. Why? Some brands use local regulators some do not. In my opinion all voltage regulators should of top class with a few microvolts ripple if any, and locally, with a large buffer, zobel and decoupling almost at the same pin as it is designed to feed. Hifi grade el caps is a myth. The modern 105 degree offers in general better life expectancy and radically lowered internal losses for decoupling. The GND Defender is designed to eliminate a "ground loop" that creates an annoying electronic hum audible through speakers or headphones. But keep in mind not all hum comes from ground loops. Most audio equipment, and particularly tube gear, may have some hum component in their "self-noise" (which is why S/N ratio is important). Hum is also sometimes the result of interactions between unshielded interconnects and power cords-induced EMI, and hence the advice to have signal and power cords cross at right angles. Induced hum is also a common plague in turntable, step-up transformer, and phono stage setups where grounding can be a real bedevilment. And as you are most likely aware, sophisticated (and expensive) grounding gear has become the current "Last Frontier" for noise-adverse audiophiles eager to invest in more cables and components. There are a few older household appliances that can create a DC offset, although most are (probably) no longer permitted due to increasing problems caused by the DC component. This is more than compensated by various industrial processes, which for one reason or another manage to unbalance the mains supply sufficiently to cause problems. Even the simple act of turning on a large transformer causes a period of asymmetry... see Transformers, Part 2, Section 12.2, Inrush Current for details on this phenomenon. 'Sympathetic interaction' is a very real phenomenon. Second, it reduces the potential problem of popping or thumping when you turn on the power amp. If nothing is coming out of your preamp or other upstream device, such pops won't be too bad, but if said upsteam device has a DC offset, big pop/thump.

If the 500VA transformer is driven to full power (RMS current for the waveform shown is 2.06A), the ripple current through the capacitors will be the same as the transformer's current draw, but we determined the capacitance based on light loading. With 5.5A peaks, even high current diodes can be expected to have a forward voltage of at least 1V, and considerably more during the power-on inrush period. While studying various designs I stumbled across a TEAC DAC, that I personally found interesting as it took a grip of the dirty USB cable shield. It lands the USB port at separate pcb, hard coupled to chassis by a screw and just millimeters from the port, minimizing the lead reactans, the entire PCB is grounded to chassis. This is an example of a good design. Others in that DAC could be questioned in my opinion. Could not see, e.g. any signs of a grounded lead out from an electrostatic shield in the transformers.W. Hess, Digitale Filter, Stuttgart, B.G.Teubner, 1993. 10.1007/978-3-322-96768-8 Search in Google Scholar A surge protection with 250V rated varistor and 10A fuse (Schurter Slow-blow type) is incorporated at the AC input. Figure 8 shows the final (and recommended) design. While electrolytic caps can withstand a small reverse voltage (around 1V is typical), in the interests of longevity it is probably better to use the caps in series. Being in series, the capacitance of each must be doubled, and as shown the total effective capacitance is 2,350µF. Larger electrolytics can be used if desired, and a medium voltage rating will be required to ensure they can withstand the ripple current (this must be verified! ). Make sure the caps are well clear of anything that gets hot in operation.

If ever a product defined its market, the 8000A is the one. Reliability, ease of use, engineering excellence and a well-behaved sound are the pillars supporting the justified reputation of the 8000A. Over the years, audiolab’s no-nonsense, evolutionary approach to design has widely been recognised." How do they do this? They guarantee, by design, that no significant surge currents flow, which would place the bridge diodes in their high current, high Vfwd regime. If the 25% 'rule' is applied, this means that capacitive reactance must be 2 Ohms or less. Remember that we can use Ohm's law to make these calculations - at least up to this point. Calculating the capacitance needed means that we use the capacitive reactance formula, suitably rearranged...

About this Book

Likewise, I can't bear to hear/ read actual snake oil vendors claiming that you'll get "cleaner highs", "more authority in the bass" or any of the other stupid things you may read elsewhere. The purpose is to stop transformers from growling (usually at no or light load). There is no magic, and it doesn't improve anything other than reduce the acoustic noise from the transformer(s). Anyone who claims otherwise is probably lying. In the vast majority of cases we will not be able to install the cabinet doors to built-in laundry products as the fittings very rarely match up. We will try our best however if we are unable to do this we will still install connect to plumbing and put the appliance in situ. It's worth noting that the mains 'DC' observed (measured across the diode/capacitor network) varied by about ±25mV worst case - at least while I was watching!. However, this was measured in a residential area, and there is no doubt that much higher voltages occur from time to time. I expect that a circuit that has been tested to work with over 250mV as shown here will be more than sufficient for most installations. The circuit as shown will also work perfectly with 120V 60Hz, but it would be wise to increase the capacitance (double the value shown here). Although the caps will work better with the higher frequency, the transformer idle current will be higher than that of a 220-240V transformer.

Asda Great Deal

Free UK shipping. 15 day free returns.
Community Updates
*So you can easily identify outgoing links on our site, we've marked them with an "*" symbol. Links on our site are monetised, but this never affects which deals get posted. Find more info in our FAQs and About Us page.
New Comment