RIAA equalization is a specification for the correct playback of vinyl records, established by the Recording Industry Association of America. The purpose of the equalization is to permit longer playback times and improve sound quality. The necessity for this equalization process arises from mechanical difficulties inherent in record production. In order to prevent the cutting needle from over-cutting into the next record groove in the bass, as a record is cut, some bass frequencies are attenuated. In the treble region, in order for high frequency sounds not to be masked by the noise inherent in moving a stylus over and through a modulated vinyl surface, some treble frequencies are boosted. With the application of the correct filtering techniques on playback, the result is a
flat frequency response with better signal to noise ratios.

There are four de-emphasis methods that can be applied at playback:

A. Active filters (Negative feedback types): Different quantities of negative feedback are applied, with deeper feedback to the high frequencies and shallower to the low frequencies. The benefits of this method are improved signal to noise ratios, low cost and consistent operation. Some of the shortfalls are looser bass reproduction and possibly a pinched and compressed high frequency playback due to excess feedback ratios.

B. Passive filters (CR type): The frequencies are filtered to fit the RIAA specification by varying the amount of attenuation at different frequencies through a complex capacitor-resistor network. This technique results in no voltage overload, purer reproduction (because there is no feedback), and more accurate RIAA compensation. However, there are problems because the system provides no gain, and insertion loss and impedance matching issues arise.

C. Hybrid filters (use of both CR and negative feedback types):  In this method, both types of filters applied separately; an active filter is applied to the low frequencies and a passive filter to the high frequencies. Unfortunately, both the advantages and disadvantages of each of these two types of filters, already discussed, affect the playback system at the same time.

D. LCR filters, which are used in the Allnic’s H-7000V : Two pieces of a linear reactor (a kind of choke coil) comprise the main part of these filters, assisted by precise CR filters, in order to lower impedances and insertion loss. In vacuum tube circuits, active and passive filters usually are operated on one hundred plus kilo ohms of impedance. An LCR RIAA filter’s impedance is a constant 600 ohms. Furthermore, an LCR RIAA filter’s series resistance is less than 13 ohms (as a comparative, some famous ones are 31 ohms). The lower the impedance, the more dynamic is the sound reproduction, with better bass response and speed. But LCR RIAA units have drawbacks as well. These drawbacks are high cost and the difficulty of impedance matching; the latter has been the primary hindrance to the commercialization of this superb method in the construction of phono stage amplifiers. However, Allnic Audio manufactures a high quality LCR RIAA unit and has developed a 600 ohms impedance matching method.

Allnic uses very large permalloy (Nickel/FeSi) core output transformers. This provides for higher inductance with fewer windings than other designs can provide and results in the great benefit of an extremely wide range of output frequencies.

In tube amp circuitry, there are two coupling methods; one is capacitor coupling and the other is transformer coupling. Capacitor coupling is the traditional, low cost method. It is somewhat stable but transfers only voltage, not wattage (i.e., not real energy).

With transformer coupling, about 90% of real wattage is transferred (there is still a transformer loss of about 10% of wattage–voltage is not affected). Transformer coupling is superior to capacitor coupling. However, all the advantages of transformer coupling depend on the quality of the transformer and on the choice of tubes.

Allnic Audio manufactures its own transformers and uses what it views to be the best core material, permalloy. Allnic Audio’s unprecedented, wide (16Hz ~ 75kHz,-3db), low distortional, and ultra-flexible(up to 20kHz square wave response) output transformer helps Allnic Audio to realize the ideal transformer coupled amplifier. Of course, gain tubes are also carefully selected for three critical factors for function with the permalloy output transformers : high gm, low internal resistance and high mu.

We can show you how beautifully a 20kHz square wave response is reproduced.

A perfect shield against electromagnetic noise. all other audio cable manufacturers definitely use copper or silver shielding for signal cables that are only effective for electrical noise, not magnetic noise. Allnic uses ‘Mu-metal’ as a braided shield on the interconnect cables (RCA and XLR), which completely protects from both noises, making it a world premiere in the world of audio.

Free from all disturbing magnetic noise With traditional copper or silver mesh shielding (shielding), it does not have sufficient protection against magnetic noise. Copper or silver could protect well against electrical noise, but very little against magnetic noise, since the magnetic signal freely penetrates copper or silver. Only Mu-metal (nickel alloy material) could protect your audio signal from electromagnetic noise. The data shows that Mu-metal reduces magnetic noise to 1/32 times (-32dB), of course, perfectly protects electrical noise.