ReMusic interviews Roberto Verdi from Vrel Electroacustic

13.08.2019..

The Vrel Electroacustic Bequadro speakers are one of the most interesting products available in Italy and outside of it in the last couple of years. It is not every day that you can come across a high-efficiency, high-impedance dipole project, equipped with the configuration D'Appolito, without crossovers and that comes along with its own power cables, ready for the biwiring. It didn’t seem real that we were able to find one product that was able to sum up all these characteristics. All these features make the Bequadro speakers a true all-in-one in the world of speaker manufacturers. Vrel is a real company not a garage-project. I’m going to give you an example: research, innovation, product, price, distribution, promotion, including tests and trade fairs, packages, guarantees, after-sales assistance; all these factors contribute to defining the Vrel singularity, a company that it’s expanding, with new and wider production facilities, to meet the demand of its loudspeakers.

For these and many other reasons, having tested some of the Bequadro speakers, which will soon be reviewed here by Maurizio Fava, I decided to ask some preliminary questions to the designer and owner Vrel Electroacustic, Roberto Verdi, who also directs another large company, Adcomm, responsible for the quality and independence of the Vrel production process: a wonderful example of constructive “homemade” synergy, that looks for excellence.

 

Question: Roberto, by listening and understanding your speakers I’ve come to some certain conclusions ... You know, I'm joking, but not too much, because for some time in my personal taste in speakers I was looking more for high efficiency, but your high impedance and other design choices are far beyond. So I wanted to ask you some specific questions, giving you the chance to make our readers better understand your project, which I find truly more unique than rare.

Roberto Verdi: Thanks, Giuseppe. In my professional life, but also as an hobby, I have explored many technical aspects, up to mature my own personal maybe limited conviction, to which I compare myself every day and that makes me ask: what I’m doing is needed? Maybe it’s not innovative, but will anyone need it? Can there be concrete implications? Well, your personal tastes go towards high efficiency, and this appears extraordinarily "healthy" to me, not so much for the choice itself, but for what a high performance can entail or better, for the change that can bring to an audio chain.

 

Vrel Bequadro Due

 

Question: In your presentation you talked about "modified dipolar functionality" to describe your speakers, can you better explain what it is?

Verdi: This definition identifies a different approach to the solution of the open baffle, which encompasses several measures that we had to undertake, all which lead to a final project closer to an acoustic instrument than to the usual "holed baffled". For the frame and the front panel we have adopted a rather complex harmonic structure, responsible for different tonal corrections, which is shared by the sound of these speakers, shaped so as to be connected to the floor taking full advantage of its acoustic load. Furthermore the woofer’s drivers, which are entirely built in our company − Vrel 255A and 385A, respectively 10" and 15" − are specially built for this type of use. They are located together with the horn-driver, which is composed by two phenolic membranes − Vrel 26AX/2 model of the HDPP dipolar type − in the D'Appolito configuration, but the horn driver is positioned a little off the median axis of the panel. The fundamental "electric" choice of our speakers, which are connected all in series, is to avoid adopting to adopt an electric crossover for the crossover frequency.

 

Vrel Electroacustic 385A

 

Question: Bequadro's "almost" full range woofers are connected in series. Now, if there is something that we know about this kind coupling system, it is that the loudspeakers must practically be "identical" for electrical and mechanical behaviour. If this was not the case, one would "pull" more and maybe the other "push" more or less, or one could play weakly and the other strongly, creating nothing but confusion and imprecision. I know you get what I mean, your woofers have to move in unison: how do you get this?

Verdi: I simply let them do everything in a natural way, without any kind of constraint, like in a dance. "Leave it to them" determines a particular sonic choice, also, in which I was able to intervene. You see, the whole point is to have a system that is as natural as possible, as it’s underlined by the name choice, Bequadro, a term that in English means a note executed in a natural way.

First of all: the loudspeakers used are substantially identical; they operate naturally and are not electrically filtered. Their frequencies extension reaches up to about 6 kHz, and then descends very gently on the upper end. The answer and, more importantly, the timbre to these drivers are imposed by well-known mechanical procedures, such as the treatment of cones and other techniques of "silencing" the structures that compose them. The fact of connecting them in series expresses well how much I hate the feedback, the imposed control. This is a significant first step. Each cone’s membrane moves on the panel, certainly in a synchronized way, reciprocally. What can change, among the various elements, is the time of attack and decay and in part the excursion, because different is the acoustic load offered by the environment. This creates an exciting synergy in my opinion. Getting out of my technician clothes, having struggled for many years with capacitors, coils calculations of the volumes of reflexes or tuned cavities, and regaining a certain sensitivity, which I had when I was young, made me fall in love again in this field. Finally, in an extended frequency range, the intersection − or the meeting of the crossover, as I like to say − takes place with the HDPP dipolar driver.

 

Vrel Electroacustic 255A

 

Question: Precisely, your HDPP Vrel mid-high unit is unique and present in all your speakers. It is a horn-tweeter, with constant directivity, not a compression one, in fact it is dipolar, meaning that it emits also from the back. How did you achieve this and what are its advantages and limitations, if any?

Verdi: Dear Giuseppe, the project is unique, but also the sound and the philosophy behind it. If this was not the case, we would experience various sounds from a single speaker or manufacturer, which for me doesn’t make sense. Vrel uses the same speakers throughout its production range and I see no other way. In all the models we obviously use the same cone driver and the same MCD horn. It is a dipole driver built by us, which incorporates two opposing membranes that operate in the same work volume, also in series. This type of approach ensures symmetrical functionality, and dipolar type, without load volumes, because the two membranes move in push-pull. Frontally, an MCD horn, a sort of constant directivity modified in an empirical way, accompanies the emission of one of the two phenolic membranes towards the listener. No compression, no acoustic re-phasing. Where it begins? In short, it was immediately clear and obvious to me that if I wanted the same performance of an open baffle, but in the musical content and transients at 8,000 Hz, I would necessarily have to deprive the back box of any commercial horn-driver. The first two models, from 2013, are like this. They mount the heavily modified old EV drivers back box deprived. I immediately realized the need to create my drivers in the company and the need to build them with two elements, in series, maximising the characteristics of response to the impulse. But above all, to improve the timbre coherence with the mid-low speaker, which is for me a fundamental aspect.

 

Vrel Electroacustic HDPP

 

Question: Still on your medium-high unit, the million dollar question: how can you not even put a simple high-pass crossover, a hint of a capacitor to protect the tweeter, and throw in watts and lower frequencies inside, without destroying it?

Verdi: Simply because I'm not going to give him so many watts at low frequency. For this driver I made an inductive and resistive limiter, nothing particularly innovative, but drowned in epoxy resin, which effectively limits low frequency energy. You will probably say it has beautiful strength, is it always a crossover. No, because a crossover operates at the crossover frequency. I cut the energy well before the frequency in which the HDPP system starts to emit sound. The action-point of the crossover is therefore mechanical and not steep at all. Thanks also to a certain robustness of the driver, the adoption of a special iron-fluid, which was created for other purposes but was later adopted for our needs, and the connection of all the loudspeakers’ drivers in series. In this sense, let's go back to the principle of the minimum imposed feedback, so each membrane synergistically balances its activity. One day I will let you hear how all this can sound differently and worse if we connect the membranes in parallel!

 

Vrel Electroacustic 385A e 255A

 

Question: The absence of timbre alterations, phase rotations, impedance collapses and ease of loading shown to the amplifier: that of the crossover-free speaker is simultaneously a dream and a myth. Everyone wants it, few can: why do you think? Why do we have so few crossover-free projects on the market? And how did you research and obtain it?

Verdi: Making loudspeakers without an electric crossover is very easy, you just do without, but it's very difficult at the same time. I have tried times and times again to return to a simple system, if we want also an archaic one, given that the dipole was the first speaker, but with an interpretation that would not have accepted compromises, and hopefully I have succeeded!

Explaining the matter in a slightly more technical way, I tried to obtain a full-range, in itself consistent, without having to suffer the many limitations. This involves using 15" drivers, to keep the distortion low, but at the same time not having timbre alternation, or better “characterizations”, as I always say. Hell, things get complicated here. In normal practice, I believe that, yes, to make speakers without electric crossovers, or rather, without using compensation cells and anything else, is complex. But it pays off, and you can hear it from the first notes.

 

 

Vrel Electroacustic HDPP 2

 

Question: Reviewing your speakers I realized how few amplifiers are willing to work above 8 ohms, even at 12 ohms, those of your speakers. But all this made me rediscover the value of Japanese audio amplifications, even vintage ones, which can easily work at 16 ohms. We know that once all the amps worked well at high impedances, with a few watts and section cables and objective quality ridiculous nowadays. Then, starting from the 80s of the past century, in the name of the acclaimed "precision" of the speakers, we went towards drivers with low impedances and "robust" amps in terms of power supply. Why do you think so? What did we start to lose then? What can we recover now? You often say that, I quote you, "many designers disregard Ohm's law": in what sense?

Verdi: Thanks for the question, Giuseppe. We have spoken of this several times in our conversations. Well, like all the fans, I keep all the sector magazines, from the first numbers and up. And then the memory of the reviews of the time, of extraordinary fixtures of the rising sun, of the finely brushed and milled panels, of the impeccable finishing typical of the Japanese taste. And at the time I was wondering: how is it possible that such a technological and planning effort should be subjected to the laughingstock of a reviewer and be subjected to the media only for not having added a couple of cheap transistors in the final stage? Those amplifiers, if connected to "normal" loads, would have sounded divine. But the various loudspeaker manufacturers, with few exceptions, have always insisted on lowering the impedance module. Accomplice a generalization of the components available, I'm talking about the speakers, all focused on the use of Power Like techniques, rather than on the musical characteristics of the product.

Thinking about it, it comes naturally to me to suspect it’s just a business trend.

Off you go: the race of the mini-speaker, to make the classic "shoebox" sound, in the absence of the cone surface. But this trend has spread far beyond that, and even the products of the most famous and efficiency-oriented brands have soon become difficult to drive, forcing us to equip ourselves with real "welders” instead of simple audio amplifiers. After all, the watts are always those, and the Japanese 80s had had more than a few of them. So, why go down? Why did Asia follow a different path?

Supply/demand: that’s the law of the market.

Designers do not disregard Ohm's law; they simply did what the market asked them to do. The market makes its rules, without thinking fully at the results. Perhaps in Japan, like nowadays, ethics and professionalism led to different path. I’ll leave it to your judgment.

 

Griglia Vrel Bequadro Uno

 

Question: A distinctive feature of your speakers is the effortless and straightforward sound. Why do you think we don’t have many loudspeakers like this one available on the market? How come most of them are icy, soulless, not instinctive, and so detached from the original sound?

Verdi: We have in part already answered this question. Do we want the hippopotamus or the dancer to dance? Are we looking for naturalness, harmony, absence or limiting the feedback effect since the planning itself of the speaker? You know, I've been dealing with automation and building of industrial machines for years now. There, the feedback is fundamental. And in the audio field, there are many professional applications where feedback is fundamental. But we talk about active control, complex procedures aimed at pursuing a specific purpose. In a normal sound system, things are very different. If we can witness a concrete sonic improvement of an amplifier, limiting the feedback, this shows clearly in a speaker. Any full range speaker behaves like this, it must be "played", given its lightness and speed, and a dipolar approach, without acoustic compression, doing so can only enhance its benefits.

Bequadro offers this in all its characteristics. High impedance, transducers in series, limited acoustic load, low feedback transducer type for magnetic system and suspension, choice of materials. We should not expect that the end of power necessarily has to stop the hippopotamus in his awkward dance, after he has managed to start it. The dancer on tiptoes of Bequadro starts with a fraction of a watt and with the same ease the amplifier will be able to stop her in her dance.

This determines naturalness, lack of listening effort, immediacy, but also and above all significant performance data: dynamics, maximum SPL, extension, timbre. A simple recipe, all the speakers should sound like this, as our advertising claim suggest.

 

 

For further info:

to Vrel Electroacustic website

write to Vrel Electroacustic

by Giuseppe Castelli
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