Closer Acoustics X Adam Sztaba
Every day presents new opportunities. Every day something seemingly trivial can happen, which can then lead to something bigger. And that is how an accidental meeting on a train two years ago, a fantastic intelligent conversation and making a new acquaintance, led to a completely different meeting, in a different place almost a year later. Maestro Adam Sztaba, visited us in our studio to listen to music on Closer Acoustics equipment. When a guest of this caliber visits us, I am a bit stressed, a bit like before an exam. In this case, when we are visited by someone who is known to have in his ears encoded exemplary, natural, true sound of a symphony orchestra - after all, who if not a conductor - then this stage fright is much greater. And what? Who would have expected which way the further fate would turn out...
After another year of intensive work we can present the fruit of our collaboration - an audio set consisting of Vigo EX loudspeakers and 300B Provocateur Signature tube amplifier, upgraded to the level that allowed us to obtain the Adam Sztaba Signature. It is a great event for our young brand, ennoblement and recognition of the quality of sound we offer our customers.
It is thanks to our customers that we can grow and give them in return a product that is a trigger of positive emotions for them, that allows them to authentically experience music at home. There's a reason I chose the slogan Take live music home for Closer Acoustics.
So what did we change in our system compared to previous versions? I'll start with the Vigo Ex speakers because we did less "digging" in them. We used Duelund internal wiring, a tinned copper multistrand wire in a cotton and oil dielectricum inspired by Western Electric cables of similar construction. In addition, we used the highest quality WBT Nexgen speaker terminals with silver connections.
We didn't have to improve the crossover because ... the excellent EMS LB12 Ex speaker doesn't need a crossover or any filters to "smooth" the response. The entire cabinet is made of birch plywood using our sophisticated resonance distribution technology. There is, of course, no damping material inside. Finished with acrylic stone panels for further damping of the cabinet side walls (sandwich) and grey Alcantara.
As for the Provocateur, the changes have gone far. We do not have any tube amplifiers in our offer. Only the 300B triode. And there is a reason for that. We are focused on having the best possible Single Ended Triode amplifier on that tube. Why this tube? Because in our opinion, and not only ours, it is the queen of tubes, designed and developed for amplifying sound almost a hundred years ago by an American company - Western Electric. A tube that when properly used can provide musical experience of the highest level. It is a low power tube, only 7 watts, and since our speakers have high efficiency - Vigo has 97 dB, it means that to be fully happy, it only needs those first few watts. But they must be of excellent quality. It's not quantity that counts, but quality. If everything is well composed, then we are rewarded with emotions and a message that squeeze tears and make shivers run down the body while listening to favorite music. There is dynamic range, energy, impact and detail. But for that to happen we need to provide the tube with the right conditions. I will skip the type, model or manufacturer of the 300B, because that is a separate topic, because in a well designed and engineered amplifier a cheap tube will sound better than the most expensive / best tube put into a bad 300B amplifier. So, to use a cook's reference, to get a delicious dish, we must have: a) a good recipe, b) good ingredients, c) a good cook.
So what have we improved in our already highly rated 300B Provocateur Signature? Probably, it would be shorter to write what we have not changed. Let's start with output transformers, whose quality is of paramount importance for the sound of a tube amplifier. On the picture you can see three types of transformers. The first one from the left is used in the basic version, the middle one with amorphous cores in the Signature version and finally the largest one (3kg each) in the highest version. The use of amorphous transformers reduces hysteresis and the influence of eddy currents on the frequency response, which has a direct impact on frequency response extension. Especially the high registers gain in clarity and purity of transmission. Increasing the cross section has an effect on the stability and foundation of the low frequencies.
In addition to upgrading the output (speaker) transformers, we increased the efficiency of the power supply circuit by using a 30% more powerful transformer, which allows even more efficient power delivery to the amplifier circuits. Of course, as you start messing with the mechanics and changing the size of the components, consequently you have to modify the design. The new Provocateur consists of 34 internal design elements, as you can see in the photo (only the back is missing, which was in the engraving at the time). You can see, also at the very bottom, the enlarged mains transformer. In the case of the top Provocateur, all transformers have been "canned" to minimize interference (cans in the upper left corner).
We managed to keep the size of the amplifier when viewed from the top, but it had to grow slightly upwards to accommodate the transformers. Thanks to Robert's extraordinary engineering gymnastics, who packed it on the proverbial razor blades (this is how we say it in Polish :), the increment was not large. Looking at the case from the outside, the increment is the bottom strip with embroidered lettering.
After transformers came the turn to capacitors and resistors. In the audio circuit we used some of the best - if not the best - audio capacitors currently manufactured in the world by an American company, V-Cap, ODAM series - reference-grade, specially selected with an accuracy of 1%. They offer unparalleled transparency, longevity and an unprecedented low noise level.
The resistors come from Kiwame, Ohmite and Amtrans. The former constitute the main element of the power supply circuit, Ohmite work in the cathodes of the 300B tubes, while the sensational carbon Amtrans of the AMRG series are used in the signal path.
Again, the consequence of changing the size and number of passive components was the need to redesign the circuit board... and since the new board had to accommodate the better class components, to improve the quality of the conductive paths they were gold plated and made on a thicker laminate. The photo below shows the Provocateur Signature and Standard PCB on the right and the Provocateur top version on the left.
In the next shot you can see the completed boards. Left Provocateur Signature, right Provocateur Signature Adam Sztaba (working designation Signature M - from Maestro :) The soldering of the tracks was done masterfully by Robert, using silver solder.
Finally, we modified the gain control a bit by using a Khozmo resistor ladder on relays with excellent quality Takman resistors. The ladder is remotely controlled, contains 64 positions, and has been calibrated by us to operate in a useful gain range from position one. Since good tube systems are characterized by the fact that you can enjoy listening at low volume in the evenings while enjoying good, filled sound, being able to precisely adjust the volume at low levels is very important.
As a result of all these changes, we got a system that brings the listener even closer to what he can experience while sitting in a good seat at a concert in a good concert hall.
And the most important thing for us is customer satisfaction, because such a system is chosen very consciously to be enjoyed for many many years.