What Makes REL MultiCap Different from All Other Capacitors?
|Performance. Results of the MultiCap'sTM internal bypass design and superior construction show higher current capability, lower distortions and noise, greater dynamic range, better phase response, and more control of resonances.|
The MultiCapTM is a more complex capacitor than the conventional single, continuously wound products commonly found in audio and video applications - capacitors such as Solen, SRC, Kimber, Wima, Wonder, and the newer MusiCap and InfiniCap.
Many of these conventional caps have been in our lab for testing and evaluation, after which we send them to be evaluated by Reliable Capacitors, a company with a reputation for excellence in cap construction (with numerous contracts from the US government, the communications industry, and the military). The owner of Reliable, Bas Lim, invented the machine to make the MultiCapTM and for that reason shares the MultiCapTM patent with Richard Marsh. The tests performed by REL and Reliable show both performance parameters, such as capacitance, dissipation factor, and ESR, and construction techniques and build quality, which vary with design, materials, and proprietary construction.
The design of all capacitors other than the MultiCapTM conforms to the long-time conventional standard, that is, single-wind metalized or film & foil. Some have stranded leads or expensive lead materials. None of these alterations represents a significant change in basic design; hence performance will be similar among those caps, varying only with type and quality of materials used in the foil and the dielectric film.
The InfiniCap, for instance, is a typical single-wind film and foil capacitor with silver-plated copper leads. It is similar to the Wonder Cap and to Kimber, Solen, etc. - except that it does not have hermetically sealed ends (epoxy end fill). Both MlT's evaluation and Reliable's find this construction inferior, and we do not expect such a cap to provide a constant performance over time. Degraded performance can be expected as moisture and contaminants in the air enter the dielectric through the non-sealed ends. Reliable Capacitors suggests the following test: Dip the InfiniCap and the MultiCapTM into water and then perform an IR test. The MultiCapTM will not be affected by the wetting, but the InfiniCap will short out - as it can when a user installs it and then uses a fluid to clean the board. We also believe that the copper alloy end material is a poor material choice that will oxidize rapidly and reduce the performance of the part. In addition, the copper and capacitor plate material are dissimiliar metals that will corrode and generate false and unwanted signals due to electrolysis
Despite their claims for "special techniques," the conventional caps, including InfiniCap and MusiCap, on inspection, prove to be wound like any other standard capacitor. This is a construction method commonly used in the capacitor industry called an "extended foil construction." The literature describing these products is simply describing for the consumer an ordinary extended foil construction. There is nothing special or unique about how such a capacitor works. The method is neither new nor patentable, and will bring about no new performance benefits.
REL uses the same basic extended foil construction, but with many significant enhancements that improve the performance in a way that no other capacitor can (the techniques are patented). Note that a characteristic of any conventional capacitor in A/V use is that it must be bypassed. The other capacitors in use in audio have to be bypassed, externally, as some of their literature admits. The MultiCapTM alone is already bypassed internally (up to ten times), and we recommend further bypassing only for the very largest values. The MultiCapTM is not a single cap of 1000 + turns. It is ten smaller-value high-speed capacitors all wound in parallel to make up the total stated value. In other words, a 1 microfarad MultiCapTM is made up of 10 complete .1 microfarad capacitors joined internally in parallel. This is called "internal bypassing," or sometimes "self-bypassing." One MultiCapTM is like ten standard caps in parallel. And made with superior construction techniques.
In short, the REL MultiCapTM - like the conventional capacitor - may also contain 1000 turns or more. But we subdivide these turns into ten sections in a special (patented) way (see Figure 1 ) to further reduce audible problems that a continuous, single-section cap such as the Kimber, Solen, MusiCap, or InfiniCap cannot address. The MultiCap'sTM patented internal by-passing method is greatly superior to a conventional capacitor externally by-passed, because the internal construction further lowers parasitics - the stray inductance and resistance in capacitors that cause distortions. (See Figure 2.)
The performance results of this combination of superior design and construction are higher current capability, lower distortions and noise, greater dynamic range, better phase response, and more control of resonances.
Externally Bypassing a Conventional Capacitor Does Not Equal - in Measured or Sonic Performance - REL's Patented Intern Bypassing, Which Further Reduces Distortions
The artist's conception (right, above) illustrates two of the MultiCap'sTM up-to-ten internal (bypass) sections as if they were small separate capacitors. The graphs at both sides of the illustration represent measurements performed at the REL Laboratory on a goodquality film & foil capacitor, bypassed externally, compared to a film & foil MultiCap.