Amazing Reference Marantz SC-7S2 Preamplifier with $3,000+ worth of JENA Labs upgrades / modificaitons (takes this amplifier into hyper performance competing with $15-20k preamplifiers). Have it priced at what I have into the preamp and mods. I could charge more to make a profit -- and willing to entertain offers more than my asking price. JENA Labs has been a respected modifier of Marantz Reference components for many years. JENA Labs has modified 6 Marantz mono amps for me, elevating performance on all of them to amazing levels (e.g., sold my Constellation Centaur amp when I heard the Marantz MA9S1 monos driving my Magicos....JENA Labs mods do many things, including to my ears creating a more spatial voluminous soundstage, lifting any veiling of the highs, removing last traces of any grain or electronic sheen, and introducing an ease and fluidity usually associated with much pricier components).
See the reviews and specs on this amazing preamp - as stock TONE Audio and other audiophile reviews praises its combination of liquidity, PRAT, and transparency ... along with stunning build quality and looks. The weight of this unit speaks to its serious build quality.
Jennifer Crock of JENA Labs spent weeks modifying and upgrading this unit .... leaving the best of the stock in tact and replacing other parts that created weak links...with the best of the best from her personal stash. See the description below. I just purchased this unit a few months ago and had the mods done. It replaced my $30,000 Air Tight ATE-2001 reference preamp. I since had the opportunity to buy (unseen and unheard) one of the first ARC Reference 6 preamps that just came out, which will mate with my ARC Ref 2SE phono preamp. I will receive this unit end of December / early January, so am selling this amazing Marantz to help fund that purchase.
Description of Modification Upgrades Performed by JENA Labs:
JENA LABS Modification project
Marantz Preamp SC-7
In keeping with our long standing philosophy, our first approach in working on any piece of gear is to first, do no harm. We do nothing to detract from the original potential life span that would be expected of the original OEM design. The second approach is a goal that simply states that we recognize that any piece of gear will have a designed-in inherent sonic character, and that what we wish to do is extract a higher level of performance and resolving power, while retaining that basic character or family sound, of the original design. It is our opinion at JENA LABS, that if one wishes to significantly alter that original inherent character of a piece of gear, one is usually far better served by selecting a candidate for modification or improvement that more closely matches the character that one is striving to achieve.
General Gain Design
The Marantz preamp presents with some interesting design approaches that are note worthy. Instead of using cheap monolithic op-amps for gain cells, commonly found in very expensive high end audio gear, Marantz instead choose to use some variations of their HDAM 'modules', a 100% discrete parts gain cell. We have extensive experience with Marantz gear that uses these design modules and have found them to be sonically excellent, far better than any monolithic op-amp we have ever heard.
In addition to the discrete gain cells used throughout the input and output sections, Marantz choose to use a FET ladder based attenuator chip for each channel. Although not as utterly transparent as the very best very expensive manually operated attenuators, they offer an affordable price point for mass production, combined with a very large number of small increment steps of attenuation that can be digitally addressed making remote control and alpha numeric display technically feasible to implement. We have retained the FET chip attenuators in this modification, for all the reasons of the advantages they have to offer.
Filter and Signal capacitors
Marantz choose an excellent capacitor brand and model for this preamp, from our favorite manufacturer, the Japanese company Elna. We usually have to remove caps from gear and replace them with Elna caps, but here the preamp is already built with them. We find a large number of Elna caps, used in both the DC power supplies at each HDAM gain cell, and also as DC blocking-signal passing caps here and the in audio signal path. In order to improve the already high performance of the Elna caps, we have installed NOS polystyrene caps on each and every Elna electrolytic found on both of the audio boards. The parallel polystyrene 'bypass cap' will keep the impedance of the capacitor network as low as possible, at even very high frequencies, where the self inductance of all electrolytic caps start to create a rising impedance. The Polystyrene caps we use are vintage 1980s, made in Germany. Caps of this quality are no longer made, due to problems with the toxic gasses emitted from hot styrene monomer. Currently made Polystyrene caps are of lower quality and sloppier tolerance. We are fortunate to have a private stash of these superior vintage parts to use on premium grade projects such as this Marantz.
Signal wire from the array of input and output jacks in the Marantz was typical of the generic copper stranded wire found in most consumer electronics. All that wire was replaced with JENA LABS Ultra-Wire in both 22G and 18G sizes, as appropriate for the available space, and the distance traveled. This particular preamp is also fitted with in and out jacks to connect a tape recorder. Because this is a mostly obsolete function, we simply left the original wire in place on these limited function jacks, as they will likely never be used in the “real world”. AC inlet wire is also upgraded.
All the audio connectors have been replaced with the best available parts from Cardas Audio. All the parts have been custom Liquid Nitrogen Immersion Cryogenic treated at JENA LABS, to increase their molecular density and improve the sound. Both the XLR balanced signal jacks and the RCA unbalanced jacks have been changed to premium Cardas with Rhodium plating.
Marantz wires the balanced polarity in all their electronics to a standard that was once used in the USA, but that was changed long ago. They continue to use the obsolete former USA standard. No one knows why this is. I have even personally asked the design team manager the question, and he refused to answer, stating only that that is the way they do it. The USA joined the IEC of Europe in their standard pin-out for balanced signals back in the late 1950s. Pin 1 is always ground, no matter the standard, so it does not matter if the polarity is reversed or not on PINS 2 and 3, a signal will flow, but the polaririty will be inadvertently inverted if an old standard device is used with current standard devices. This is especially true if the preamp is being used with its ability to accept and output both single ended and balanced signals and internally performing the mode conversion between these transmission formats. We have however corrected the polarity on both the input and output XLR jacks to be compliant with the current world-wide standards that have been in effect for over half a century.
SHELL Chassis Ground
PIN 1, Signal Common or “ground'
PIN 2, Signal +, or positive going side of the balanced loop
PIN 3, Signal -, or negative going side of the balanced loop
Every electronic audio component will benefit from reduction of vibrations. We approach the damping of vibration at both the component level and the chassis level. Almost every capacitor in the preamp has had Cascade Audio Engineering VB-2 applied to it. Smaller caps have the VB-2 held closely in place with heat shrink tubing. All through the chassis and cover we also apply VB-2 to address chassis born vibrations. In addition to 'local' coverage of the chassis with VB-2, we disassemble the metal 2-layer sandwich structire of the chassis bottom and insert a complete 100% coverage sheet of VB-2 as an internal damping element between the 2 metal sheets. This provides the most stable and non-ringing base from which the rest of the device is assembled. Addition of all this damping material adds to the overall weight of the preamplifier.
Marantz supplies a non-grounded AC power inlet on all their gear. In some cases, this may not provide the greatest level of noise reduction possible, but it does ensure the largest range of compatibility with other gear that may otherwise induce a ground loop hum or buzz when connected to the Marantz. We have replaced the AC inlet with a premium German made IEC of the 3 conductor grounded variety, indecently, also fully Liquid Nitrogen Immersion Cryogenic treated here at JENA LABS. However, recognizing that in some cases, a power-grounded chassis may well create hum and buzz from ground loops, we install a switch in the rear panel that allows the user to program the power ground. Once installed and powered up, just flip the GROUND SELECT switch from one position to the other. Select the position that provides the lowest noise floor in your system. Additionally, we replace the non-linear resistance of the AC mains protection fuse with a proper circuit breaker. This lowers the impedance of the AC current feeding the power supply, and improves the stability and noise figures of the power supply itself.
Our goal was not to revolutionize the sound of the Marantz preamp, making it sound completely different, but rather to extract a higher level of resolving power and inceased sense of dynamics, while retaining the basic 'family' sound or the inherent sonic signature the Marantz is known for. We have addressed the relatively common shortcomings of connector quality, wire quality, vibration abatement and capacitor improvement to achieve these goals.
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