TP Audio's Hi-Fi System Tips

Hi-Fi System Tips

Connectors

Use a solder type connector wherever this is practical. F, Faston, Molex, and spade connectors will usually be crimped, but many can be soldered. RCA, XLR/Cannon, 1/4" Phone, Pin, Banana, BFA, and BFS plugs should always be of a solder type. On most RCA and 1/4" plugs the ground tab is crimped or swaged in (this can be identified by a gap where the tab exits the body of the plug). Always solder this area if possible (the gap on 1/4" phone plugs is often too wide), being careful not to foul the threads (for the body) with solder. (Neutrik 1/4" plugs do not have this problem, and have a big solder bucket for the ground. Get them from Full Compass or All Pro Audio .)

Any multi-pin speaker connectors (XLR/Cannon, etc.) should be used without the supplied metal case, even if the case is made of non-ferrous metal. (Apparently the conductors capacitively couple to the case.) For safety purposes, the connections must be enclosed in heatshrink tubing.) Avoid XLRs with silver contacts, as silver oxidizes very badly. Use Neutrik plugs with gold contacts from Full Compass or All Pro Audio.

The best connector for any application (all other things being equal) will be the one that makes the best (lowest resistance) connection for the longest period of time. On speaker leads Banana plugs, BFA, and BFS connectors work much better than spades, pins, or bare wires in my experience. Why?

Spades: As I recall, two surfaces that are flat to within 1/10,000 of an inch, when placed together, have only 10% contact. It is doubtful that the surfaces of spades and binding posts approach this, no matter how tightly you crank the posts down.

Bare wire in the post's hole: Poor contact to the post (same reason as above), and most of the strands of the wire get their electrons from contact with another strand that got it's electrons from contact with another strand.....

Tinned wire in the post's hole: This connects all of the strands together, but you still have a contact area problem. Additionally, a soldered wire is softer than a plain one and thus tends to crush continually, requiring constant re-tightening.

Expanding (locking) bananas: The insertion force is very low, so there is little wiping action to scrub off the oxides and give you a clean connection. Additionally, most use a compression connection to the wire that is little if any better than just sticking the bare wire into the post's hole, making the plug a pricey redundancy.

Bananas: Most binding posts' banana sockets are crap. On many the inner diameter is oversized (4mm is the standard). Few are full depth, so a plug such as the Pomona cannot be inserted up to the point of it's maximum diameter = point of maximum retaining force.

With a proper socket, bananas are best sounding of all the choices *. The Mouser 174-5791 (black) and 174-5795 (red) are very good. They have a huge solder bucket, and the insulated body goes on AFTER you solder! They are fairly robust, and are dirt cheap ($1.74 each - less if you buy 10 per color). See the picture below for a close look at a pair.

(* I have not used SpeakOn connectors in a high resolution system, so I cannot comment on their sonic performance.)

Cable Routing

Keep mains (AC power), line level, and speaker cables separated whenever possible. Do not route them parallel to one another if they are close together. If cables must cross, route them at right angles to each other so as to minimize inductive coupling from one to the other.

When installing speaker cables, keep them as far from metal objects as possible. Always use non-metallic fasteners or hangers to affix the cables to cabinets, studs, joists, rafters, etc. If using multi-pin speaker connectors that have a metal case, discard the case even if it is made of non-ferrous metal. (For safety purposes, the connections must be enclosed in heatshrink tubing.) When metal is sufficiently close to a speaker cable the capacitive and/or inductive coupling between the object and the cables conductors will alter the load impedance seen by the amplifier and degrade the musical performance of the system.

Electrical Power
The electricity that powers your system system may be rife with noise, voltage spikes, or large voltage deviations (poor regulation).   There are many power strips and other devices that are manufactured for the purpose of improving one's system by curing such maladies. Laboratory measurements may prove that they accomplish the latter, but most fail to accomplish the former. Carefully compare the ability of any system to accurately convey the rhythm, melody, and emotion of the music both with and without these devices. Do not assume that they are at worst benign.

You should always have a dedicated power feed for your system. It may be beneficial to run a second dedicated feed for your system's poweramps. (This is because the amps pull tremendous amounts of peak current, and generate a lot of noise back into the power feeds.) As I have not played with this, you will need to determine for yourself whether it sounds better to have the amplifier feed on the same or on the opposite breaker-box leg as the feed for your line level components, and whether the best of those choices is better than having everything on the same feed. Then figure out which feed to plug the video equipment into.

Ground Blocker

A "ground blocker" (or "ground breaker") should be inserted into the RF antenna or Cable TV line whenever it feeds a a component that is connected to an audio system. This is in order to eliminate ground loops that which will cause an audible hum and/or degrade the musical performance of the system. The ground blocker also gives some protection from offset voltages and spikes that may be present on the RF line. (I spoke with one fellow who's cable TV system was carrying such a high voltage that the moment he connected his TV to his stereo system the preamplifier's aux. input buffer circuitry blew.) If the audio system is connected to multiple video sources that are fed by RF lines (such as a TV and a VCR), it will be necessary to insert a ground blocker ahead of both of these sources. (If said sources are fed by a the same RF line via a splitter, one ground blocker placed ahead of the splitter will usually suffice.)

If one is using a satellite dish, it may be necessary to insert both a composite video ground blocker and an audio ground blocker into the satellite receiver's feeds to the audio-video system.

Ground Blocker Sources

Jensen Transformers, http://www.jensen-transformers.com.   Available are the $169.95 ISO-MAX Model CI-2RR audio ground blocker, the $99.95 Model VB-1BB composite video ground blocker and the $49.95 Model VR-1FF RF ground blocker.

Axiom Home Theaters RF Ground Isolator, http://www.axiomaudio.com/groundisolator.html.

Holland RF Ground Isolator, http://cencom94.com/gpage.html8.html.

Xantech Model 634, http://www.smarthome.com/81285.html.

Cable Selection

I have listened to a lot of cables over the years. Several patterns have emerged from these many auditions:

The quality of a cable's musical performance is usually inversely proportional to the degree of "exotic-ness" of its materials and/or construction techniques. (Nordost Flatline SPM is a notable exception, but it is ridiculously expensive. See below for more recommendations.)

On "normal" speaker cables, all other things being equal, cables with "ropelay" type conductors (several bundles of very fine strands twisted together to form each conductor) will not give as good a musical performance as cable with conductors comprised of a single bundle of four to six dozen strands. Two good construction upgrades beyond "zipcord" or "lampcord" are "twisted pair" and "dumbbell" . In a twisted pair the conductors are wrapped around each other like the colors in a candy cane. In dumbbell cable, the conductors are separated by 1/4" or so as in old-time 300 ohm twin-lead antenna wire (viewed from the end it looks like a workout dumbbell). Both methods of construction accomplish much the same thing: each adds a bit of inductance, which offsets the capacitance of the cable. This keeps the impedance from falling as the frequency rises, and allows the transients from the amp to drive the speaker instead of driving the cable's capacitance. (A capacitor is seen by a transient as a short circuit.)   Most amps sound better (some a lot better) into a twisted pair or dumbbell cable.   One caveat: if the twist is too great (too many turns per foot) the performance starts to go downhill. Two to Four turns per foot seems to work well. Linn, Naim, and Exposure are very good sounding and affordable speaker cables.

Although multi-pair cable is very practical in active systems and in passive multi-amped systems, it's not a good choice for maximum performance. The current in each pair can induce low level signals into the adjacent pairs. In an active or passive multi-amped system, the amps "see" this much the same as "back EMF" from a speaker and the sound quality can be degraded as a result (quite a lot if the amps are not very good, which many are not). Even if the amps perform normally, the drive units will reproduce these low level signals, which could be as little as 40dB below the program material signal. This will also occur in a system that is single amped but is BiWired or TriWired.

With very rare exception, do not use a shielded cable for connecting amplifiers to loudspeakers. Even when the cable has a very low capacitance, the musical performance tends to lag behind that of a standard cable. Some amplifiers will become very unstable when connected to shielded loudspeaker cable.

For line level cables, the best sounding affordable cables have all been plain copper stranded conductors with a plain copper spiral-wrapped shield. In a professional system, balanced lines should be used whenever possible in order to provide interference rejection. In a properly configured home audio system this is not necessary, and I have yet to hear a musical benefit to using balanced lines. However, if the system has a ground loop (that is not caused by being connected to a video system, RF cable, or antenna) balanced lines may be the solution. For single-ended cables Linn Analogue Interconnect and Horizon LoZ1 (it's 2 conductor - parallel the hots) are very good.   The Horizon is my choice for balanced mic and line level cables as well. (I slightly prefer Gotham, but their US and Canadian distributors are useless.)

Cable "Directionality"
Every audio cable that I have auditioned has been directional. That this can occur or be heard is argued by many. (Pro sound folks vehemently deny the possibility.) If one cannot hear it, the reason is most likely that the system's source is of poor quality, the system is set up poorly, or one is not listening for musical changes as opposed to sonic changes. (Every video cable I have viewed has been directional as well.)

Acoustical Treatments

As with mains treatments, these items are often treated as though they can do no wrong. Such is not the case. They may indeed improve the "sound" of a room, but often the music is destroyed in the process. One highly regarded treatment device with which I experimented had the same detrimental effect on the pitch and rhythm of the music as would be caused by the presence of an un-driven transducer in the room (see below). Listen carefully.

Un-driven Transducers

Anything that is designed to turn electricity into a sound or sound into electricity will resonate in sympathy with the music playing in a room. The resultant output of this resonance will intermodulate with the music and markedly alter the rhythm of the music and the pitch relationships of the notes, making the music much less enjoyable. (This also makes it very difficult to set your speakers up properly.) The usual culprits are the microphones, speakers, buzzers and beepers in TVs, telephones and answering machines, electronic clock and wrist watch alarms, and burglar alarm components such as keypads, ultra-sonic motion detector senders and receivers, and glass-break detectors.

We have also found that things that are highly resonant may have the same effect.   Items such as an acoustic musical instrument, an auxiliary telephone bell, the bell in a manual typewriter, hollow metal or ceramic pottery and statuary, and spoked bicycle wheels have all been heard to alter the rhythm and/or the pitches of the notes of music being played in the same room. Decorative "dressing screens" (with tightly stretched coverings) and various types of acoustical room treatments can wreak havoc with the rhythm and pitches of music as well.   Hollow cavities such as large empty cabinets can have an effect as well. Open the doors and drawers, or fill them with pillow batting and/or foam rubber.)

FM Antennae

In many locales decent reception is impossible without a proper antenna. My friends tried four: a popular "whip" (used indoors), an expensive indoor "Urban", an omnidirectional on the roof, and a boom & rotor combo on the roof. On the whip they received one station. On the "urban" it was two. The omni worked well, giving them 24 stations. On the boom they received 48, with a larger percentage of those stations being sufficiently quiet and distortion free for serious listening.

I recommend that you hire a professional antenna installer. If you do it yourself (be sure to observe all of the manufacturers' installation instructions and recommended safety precautions!) the results are well worth the effort. (And once some time has passed, you'll be able to laugh about the torn shingles, the ladder through the window, and that groin pull that still twinges whenever you move just the right way.)

FM on Cable

Do not count on being able to make use of this facility. Many cable companies receive the local FM broadcasts on very inexpensive tuners. In such a case this rather defeats the purpose of having a quality tuner in one's system. Often the FM stations have been shifted to "abnormal" frequencies to which some tuners will be unable to tune. (This is done to prevent interference from the stations' regular frequencies leaking into the cable system, but it does not always work.)