Products and choices

CABLES and Amplifier interface

approaches to high-efficiency and No-feedback amps see a more detailed section on Our Thoughts

All Royal Device loudspeaker systems are provided with BI-WIRING or BI-AMP connectors.

Our speakers have been designed, set up and engineered for BI-WIRING or BI-AMP connection thus RD-BW cable has been designed to interface all Royal Device loudspeakers. Each cable is made of N. 32 wires AVG 24 OFC particularly assembled and twisted with 4 internal shielded foils.

As many times it is difficult to choose on the market the right cables and customers are confused by so different offers available in terms of characteristics and costs we recognize that the suggestion on which type of cable can be used should be made by the speaker manufacturer itself.

For Royal Device speakers the best suggestion is to use the cable that has been designed and manufactured in our factory and that is normally used to design, set up our loudspeakers, other cables tested by us have not offered the same sound quality instead.

The following cables are available for:

OUR THOUGHTS ABOUT SPEAKER CABLES and AMPLIFIER INTERFACE

WHY NO CROSSOVER, NO FEED-BACK AMPS, BI-WIRING or BETTER BI-AMP

It has been proved that BI-WIRING (or better BI-AMP) connection improves reproduction quality. It does if the right BI-WIRING (or BI-AMP) cable is used. If not, the result may not appear. In general the changes are substantials in terms of:

What we personally think is that this type of connection is the minimum required for HI-end products. Any mono wiring connection will decrease and cancel sound quality in respect to the sound quality our speakers have been built for. Moreover:

In a system with NO-CROSSOVER and NO FEED-BACK these problems can be considered of minor worth or at least not even considerable on very Hi efficient systems. Moreover:

There are several physical reasons for this and the results depends a lot on the type of system used. The interconnecting cable between amp and speaker plays also a very important role.

To understand how much a speaker cable can affect sound quality we will have observe some simple rules. These can totally apply to systems WITHOUT FEEDBACK (Feedback Systems in fact have many more problems affected by the type of cable connection and type of speaker chosen and the following rules apply only in part):

PROBLEMS of FEED-BACK amplifiers

1 - Any Hi-fi Amp does not feed a single resistor nor single capacitive or inductive load (as normally measures are done during AMP tests).

2 - A woofer (out of his simplified equivalent circuit) when fed by an electric signal becomes an AC motor that produces energy (electric power). This energy is considerably high (bigger is the woofer more is the energy) and is sent back to the AMP and to other drivers in the speaker (tweeters and so on). Woofer is not a resistor nor single inductance or capacitor. [The considerations made for woofers can be applied to other drivers into the speaker towards to woofer and amp output].

3 - Woofer moves very very slowly in respect to the signal fed by the amp (amp is an electronic device while woofer and other drivers are electro-mechanic). This situation, plus the reasons explained in #2 above produce sound compression.

- FIRST CAUSE OF SOUND COMPRESSION: AMP velocity too HIGH

The best audio system that can be set up with the uptodate tecnology could be the one where the AMP velocity (this is is normally very high because proportional to its frequency response) is roughly the same of the drivers used into the speaker (this is normally very slow because electro-mechanical devices), so nearly impossible to obtain. Any Amp is still is too quick (hi-velocity) and the drivers still to slow. Even if many of you won't believe this, to achieve a system that we can say works good in audio environments, we should have an AMP that let the speaker working by itself without bother him too much. To understand this concept let's consider that the Amp starts to feed a first VERY FAST signal (a sine single wave burst) to the speaker and the speaker (later on because is slow) will release it to the air (The concept is that the two things do not exactly run at the same time so not in real time). Here is where the problems arise due to "compression of sound". If for istance the amp will try to feed a new second different burst signal to the speaker will force the speaker drivers to reproduce it. This of course means that the drivers into the speaker will try to correct the old situation (while they were still releasing the first signal to the air) into a new situation. The result is that the drivers will not finish to do their first job (they have not reproduced completely the first burst sound) trying to start the second one (riproducing the second burst sound). The result is that the driver into the speaker has not been able to reach the maximum escursion (forward and back) to reproduce the first sound fed. So it will be for the rest over on.Of course this is a very flat explanation of the concept but at the end this is the first type of sound compression introduced.

The woofer moreover produce energy that is sent back to the amp. This is of course completely out of phase (it depends on woofer velocity that in any case is tenth of times slower than Amp velocity). Tweeter moves faster and its out of phase signal is summed to the out of phase signal of the woofer and to the signal present on the speaker input at that time fed by the amp. Finally during any music program reproduction there are (in a two way speaker system) at least 3 main signals on the speaker connectors produced by different sources (woofer, tweeter and amp) all out of phase one to the other and with different amplitudes.

4 - It is not right to say that the output resistance of an amp is ZERO. This is only theory. Even if you have a lot of feedback the output resistance has a real value, could be low but a value. This means that the energy sent back to the amp by the woofer and tweeter is not really all short circuited. This small amount creates a lot of problems to feedback Amps. It really does not do to very good NO FEEDBACK AMPs.

- SECOND CAUSE OF SOUND COMPRESSION: AMP FEED-BACK

5 - The AMP feedback (finding a different output signal in respect to the one fed) will (try to) correct the situation sending back to the amp input the feedback signal from the modified output. Here the mess is then made. Here it is where the higher sound compression start to come from and distortion arise. This distortion is never measured but definitively heard by human ears as high annoying material. Rising feedback it does not reduce the problem because: even if it is true that higher the feedback is, more these out of phase signals will be reduced it is ALSO true that more correcting signal will be sent to amp input. Then distortion still will rise. The input signal will then be modified and re-amplified.

6 - It is true that a speaker with crossover will reduce the amount of energy sent back by the woofer. A coil in series to the woofer has a minimum of resistance. This helps reducing the problem, but crossover kills sounds quality in terms of music attacks and decays and modifies the signal itself.

- HOW A CROSSOVER MODIFIES SOUND QUALITY

To understand this concept let's take as an example a simple crossover at 6 dB/slope with a coil in series to the woofer and capacitor in series to the tweeter designed for a certain crossover frequency (ex: 3 Khz).

NOTE: There is no speaker with crossover in the world that reproduces music attack and decays as real live play does. No crossover speakers are normally the ones that most often reach this task near reality. [Electrostatic speakers even if have a good approach to the topic overmentioned do not have sufficient dynamic to reproduce live play (orchestras or drums sound pressures). There is no speaker of this kind that can reproduce 110dB/1W/1m. The same is for very low bass response (below 30 Hz)]. MONOVIA speakers have normally have lack of highs and lows and normally have to be Backloaded a lot to reach a slight bass response increase and front loaded to try to reduce peaks or else and in any case integrated by a tweeter on the high end. A monovia also have only medium efficiency].

7 - Sound compression can be completely avoided by feeding drivers (tweeters and woofers) with different Amps.

SOME RULES ON SPEAKER CABLES and AMPLIFIER INTERFACE

8 - Higher is the resistance of the cable, less the amp will have problems concerning energy sent back. This is GOOD for the AMP. This point does not introduce distortion but it reduces instead distortion produced by the amp.

9 - Higher is the resistance of the cable, higher will be the power loss. This is BAD for the speakers if is too much. This point does not introduce distortion but it reduces instead.

10 - Higher is the resistance of the cable, higher is normally the serial inductance (and parallel capacitance) and this will cut hi-frequency. BAD if it is too much. This point does not introduce distortion but affects frequency response in terms of hi-frequency roll-off.

11 - Higher is the resistance of the cable, less it will be the capability for the amp to force the woofer to follow the amp signal (damping). This is both GOOD and BAD. Good because the woofer MUST do its own electromechanical cycle. BAD because it reduces the woofer damping factor. In this case a good damping of the woofer can be achieved either rising driver B*L factor and not using only amp output resistance by itself towards 0 ohms). Woofer MUST then be accurately designed for flat frequency response and to control break-ups.

12 - Lower is the resistance of the cable, worst it will be the sound because the amp will have problems. This is VERY-VERY BAD for FEED-BACK AMPs. This point introduces a lot of distortion normally not measured by any set of instrument (nobody does measure amplifier THD and TID with the speakers of the customer connected to it but with a dummy load). Normally audiophiles listen to music with their speakers and without dummy loads. These problems are considerably avoided with NO feedback Amplifiers.

13 - Flatness on the frequency response can have a minor importance if it is not considered together with the room environment where the audio system works. Flat frequency response of speakers measured on axis at 1 meter normally fools the FINAL AUDIO system response. As an example Perfect Bass-reflex response designs of speakers many times do not sound good into a in-house environment (frequently people have to reduce bass response due to internal room resonance (standing waves normally below 200 Hz) by using some dumping materials into the reflex hole. An in-house frequency response measured in the listening point normally have amplitude range that varies from +/-15 dBs in the range up to 500-800 Hz. It is foolish to look at measures to correct even one or two dBs if room environment is not set for best results. In the medium frequency range it's a different story. In the High end of the frequency range there can be a lot of differences in terms of audio energy produced into the room if drivers are horn loaded or not.

Normally many speaker manufacturers use crossovers and correcting RLC cells to flat drivers response killing attack and decay music response. A good speaker MUST have both good flat response plus perfect attack (extreme velocity) and decay response. This cannot be achieved with Crossover.

A start can be to try to reduce the problems where distortion is generated by interfacing the audio systems chosen. This can also be made by designing the right speaker cable knowing the type of amplifier used.

CABLES

14 - It is not true that the best cable is the shorter cable or NO cable. Speakers are designed to use cables for connection and the best cable at least is the one used to design and fine tune the speaker by the manufacturer.

The cable is a media that MUST do 2 things and not only 1 as normally thought.

14.1 - INTERCONNECTING two completely different world: The AMP and the Speakers ( Motors that produce energy)

14.2 - DIVIDING two completely different world. More are divided the best it is.

The best speaker cable is not the one that gives more good bass response or more high response to the audio system but is the one that can perfectly interface the speaker and the amp chosen in terms of trying to reduce at its best all the overmentioned problems. It is clear that this will be a BIG overall compromise between:

14.3 - Type of amp

- feedback or not

- transformerless or not

- other factors

14.4 - Type of speaker

- crossover or not

- MONO or multiple way

- MONO, Bi-wiring or Multiple Wiring

- type of woofer involved (B*L factor)

- Type of woofer loading

- Velocity of drivers

- others factors

15 - Shielded cables help a lot to reduce electromagnetic influence between tweeter and woofer signals if a BI-Wiring system is used. It is very important at least to connect the amplifier in this modality as to obtain the maximum from the speaker in terms of sound reproduction.

Aliante s.r.l.

Viale dell’Industria 19

21052 Busto Arsizio (VA), ITALY.

Tel. +39 0331 354070

Fax. +39 0331 342445

e-mail: aliante@royaldevice.com