Understanding and Choosing your Home Stereo Equipment - Part II

AMPLIFIER

As the second component of the audio chain, the amplifi er’s function is to exaggerate the weak signals from the player, making them strong enough to drive the loudspeakers. You cannot drive the loudspeaker without the amplifier. There are a few players in the market which come with a built in amplifier, but don’t expect wonders from them. You can go for any branded stereo integrated amplifier or a pre/power amplifier combination. The pre/power amplifier set up has certain electrical benefits or advantages compared to stereo integrated ones. Dedicated discrete pre/power amplifi er sets are able to provide the desired current that loudspeakers demand.

When buying an amplifier, look for the following features:
1. Input: The amplifier should have multiple analogue RCA inputs to connect to an external CD player, tuner, phono stage, tape, and auxiliary in.

2. Output: Pre out and/or record out would be an advantage. This can be used to connect an external active subwoofer, a recorder or graphic equaliser.

3. Tone Control: Basic tone controls are a must (i.e.: bass, mid, treble controls) as they are useful to manipulate the sound where needed.

4. Clip/ Thermal Protector: Basically, they are a part of the protection circuitry which helps protect
the amplifier from excess thermal heating and protect loudspeakers from amplifier’s signal clipping at loud levels of listening.

5. Speaker (A, B, A+B): This feature is nice to have for multi-room applications, where you can use two pairs of loudspeakers for separate rooms through the same amplifier i.e.: you can either use a single pair of loudspeakers for your living room or another pair for your bedroom. You can operate both pairs at the same time or separately, by switching between speaker A or speaker B or speaker A+B.

6. Watts: How much power do I need? We are not here to explain everything and add to the confusion. But the truth remains that loudness depends on the sensitivity of the loudspeaker, not the amplifier. So, buy any good entry level or a premium level branded 20–40- watts RMS per channel or more. For the same, use amplifi ers whose power rating is greater than/near about or equal to the continuous or maximum power handling capacity of the loudspeaker.

7. Nominal Impedance: This is a knotty issue. Nominal impedance is the minimum or lowest load impedance (impedance of loudspeaker) that an amplifier can handle. It is a clear indication that a
particular amplifier is well designed or capable to handle minimum possible load impedance eg: if your amplifier’s impedance is 4 ohms, it means it can handle a load impedance (loudspeaker) of 4 ohms or above easily, but may be struggling to operate below or lower than 4 ohms. So do not connect those loudspeakers whose impedance value is smaller than the amplifier’s impedance handling abilities. In general, the loudspeaker’s impedance should be equal or somewhat higher than the amplifier’s lowest impedance handling abilities. There are some amplifier manufacturers who have designed sturdy high current amplifiers which can easily support minimum to maximum loudspeaker load such as 2 ohms, 4 ohms, 6 ohms, and 8 ohms as well.

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LOUDSPEAKER

This is the last and weakest link of the entire chain owing to its variability. It is also subject to individual taste among all the links or components in the hi-fi chain. Even then, we can suggest a few must haves for a loudspeaker.

Size of Listening Room: There is no hard and fast rule to decide which loudspeaker will sound good for your room size. Of course, the room plays an important role if you are ready to do some basic acoustical changes with your room, which will help improve your loudspeaker performance. Experimenting with the placement of loudspeakers is important to get better performance as per your taste. If you are not ready for these experiments, don’t expect the best possible sound from your audio system.

Tower/Bookshelf/Sub-Sat System: You can use any type of loudspeaker to your amplifier, whether you choose tower, bookshelf or sub-sat system is left to you. The decision is about prioritising between floor space and sound quality. If fl oor space is not a concern and you have enough space to
accommodate the tower speakers you love, don’t hesitate to buy them. But if you are not able to use floor space due to some reasons and if you do not spot any sonic difference between tower speakers and good sounding bookshelf or sub/sat system, just buy the former.

2-way/3-way: It is also a head spinning quandry to decide which of them sounds good. There are some manufacturers who make their single full range driver loudspeakers with simple or complex
cabinet designs which sound nice and decent. Crossover: The crossover is a dividing network circuitry between the frequency bandwidth that sends signals to the appropriate driver. It sends high frequencies to the tweeter, lows to woofer and mids to mid-range driver.

Power Handling Capacity: Use amplifiers whose power (WRMS per channel) is greater than, close to or equal to the continuous or maximum power handling of the loudspeaker you are buying.

Frequency Response: It is good to have a loudspeaker which has a wide frequency response from 25/30Hz to 20kHz for the home-theatre application or 50/60Hz to 20kHz for music applications. Remember that no loudspeaker has ruler fl at frequency response, only a select few professional and expensive studio loudspeakers have them which is again a demand and necessity owing to their profession.

Nominal Impedance: A common myth is that a 4 ohm loudspeaker sounds better than 8 ohm. It is an established fact that a particular loudspeaker will provide a minimum/nominal possible load to the amplifier. Loudspeaker’s nominal impedance should be equal or somewhat higher than the amplifi er’s
minimum/nominal impedance (load) handling abilities. But loudspeaker’s impedance should not
be lower than the amplifier’s nominal impedance handling abilities. Please do not connect those loudspeakers with lower impedance value that it is not designed to handle. Consult your dealer for more details as they have deeper insight into these matters.

Material of Loudspeaker: The material of the loudspeaker cone and cabinet is not a matter of concern to us. What we are paying for is just sound quality; nothing else.

AUDIO REQUISITES

Do your homework: Impedance, wattage and other technical terms are very complex to understand. They do not explain how an amplifi er, speaker or CD player should actually sound. Never ever buy any audio product without experiencing it. Do not blindly rely on technical specsheet or any advertisement with boastful slogans. Listen to them first before taking them home.

Be realistic: There are a number of speakers and amplifiers around you, but limit your expectations. Do not expect wonders from any budget system as opposed to a premium class product. Bear in mind that premium product works well only with premium partners, so don’t expect the Ferrari to run with the tyres of an older Fiat.

First evaluate what you have and need: Using a subwoofer is very subjective; you can use any
8-inch, 10-inch or 12–inch active subwoofer with bookshelf or/and tower speakers. Only in the case of music that really demands low frequencies to perform, will you need to use a subwoofer, otherwise you could be happy with your existing bookshelf or tower speakers.

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You get what you pay for: Never expect your loudspeaker to sound good every time and for any genre of music or movies. This is not possible always for any loudspeaker or amplifi er. The limitations may be acoustical, electrical, mechanical or due to inferior recording and mastering. Of course, these limitations are somewhat limited with premium class equipment.

Understand the basics: Home audio is a completely different segment as opposed to pro-sound (professional sound). So, it would be silly to expect the punch and loudness of any DJ system or party or discotheque or cinema theatre from home audio. Professional audio equipment have their own parameters, ratings, standards, designs and of course, size. You have to use your amplifier’s volume control knob wisely even though it has enough power or with respect to your loudspeaker. Your preference for getting loud sound and punch for hours and hours will only harm the loudspeakers. Next time you come across any audible distortion (unpleasant jarring sound from your speakers), just turn down the volume control knob levels immediately. The signal might get clipped. This could be harmful to your loudspeakers, most probably for the tweeter and then for the woofer even though their power specifi cations perfectly match with the power of your amplifier. Clipping is the most dangerous phenomenon to the loudspeakers; you cannot eliminate it but you can avoid it. To control your thirst for long tem loud listening just pay attention to the volume control knob.

These guidelines are enough for anyone would wants to buy a system this festive season. And with that we hope you can walk into any audio store with a comprehensive checklist that helps you.


Published Date: Aug 17, 2010 04:52 pm | Updated Date: Aug 17, 2010 04:52 pm