Since its debut in 2004, VTL\u2019s S-400 stereo reference amplifier has won the favor of music enthusiasts worldwide thanks to its high-power, high-performance tube design, ease of use, and refined, natural musicality. The newly released S-400 Series II inherits the circuit design of its high-end sibling\u2014the Siegfried Series II Reference monoblock amplifier\u2014and features an impressive, unified chassis. The incorporation of VTL\u2019s latest engineering innovations elevates the S-400\u2019s exceptional sound quality to a new level.
\nFor this second-generation product, VTL has completely redesigned the entire signal path. Upgrades include a fully balanced differential input stage driving a differential phase splitter, a lower-impedance push-pull output stage, and a significantly improved, fully balanced, enhanced interleaved-coupled output transformer. The S-400 incorporates the same “SmartTube” technology found in the Siegfried II\u2014featuring automatic bias and fault detection, precision regulated power supply technology, and bidirectional RS-232 control\u2014to deliver unmatched flexibility and ease of use.<\/p>\n
S-400 Series II employs a shorter, faster, and fully balanced negative feedback loop to achieve zero global negative feedback, thereby further enhancing sound quality. This feedback loop completely eliminates ringing, preserving critical phase integrity and signal information without the need for capacitive compensation. Consequently, the amplifier remains stable even under the most demanding loads.<\/p>\n
Adjustable, precision-regulated plate and bias power supplies maintain constant operating points for the output tubes\u2014even amidst AC line and mains fluctuations\u2014and stabilize critical power rails, thereby ensuring tonal stability and sonic integrity, particularly under complex, dynamic signal conditions.<\/p>\n
Another new feature is user-adjustable damping factor feedback control, which allows the user to regulate the amplifier’s output impedance by varying the amount of negative feedback. Impedance can now be precisely set to suit listener preferences and provide better control over the speaker load, thereby achieving optimal performance.<\/p>\n
Three possible settings are:<\/p>\n
The lowest damping factor setting offers superior speaker control and the most natural sound.
\nMedium \u2013 Offers good speaker control, though it has some impact on sound quality.
\nHigh \u2013 Provides optimal speaker control; while the impact on sound quality is slightly more pronounced, the sonic improvement is clearly evident for speakers that require such control.
\nFinally, the amplifier has undergone extensive retuning and incorporates high-quality Mundorf silver-in-oil capacitors, resulting in sweeter, more extended high and mid-range frequencies; the sound is more relaxed, natural, fluid, and cohesive. The input stage capacitors have also been bypassed.<\/p>\n
Even a brief listening session with the S-400 Series II stereo reference amplifier reveals the successful application of this new technology. The lower noise floor creates a soundstage of velvety purity, allowing more of the music’s nuances to emerge. The soundstage gains greater height and depth, while instrument imaging becomes sharper and more distinct. The mid-bass is more powerful and tightly controlled, and the crucial midrange exhibits an unprecedented sense of ease, faithfully reproducing the natural timbre and tonal quality of the instruments.<\/p>\n
In short, this new amplifier boasts stunning dynamic response; it delivers sound that is both agile and lively while effortlessly handling high volumes, as if possessing limitless power output. Listening to music through the S-400 II amplifier is an exciting and invigorating experience.
\nFully balanced differential circuit\u2014converts a single-ended input signal into a balanced output signal.
\nThe redesigned fully balanced differential input and driver stages enhance signal swing, bandwidth, and stability.
\nZero Global Negative Feedback
\nA shorter, faster feedback loop enables superior tonal control without phase shift.
\nImproved speaker load handling and enhanced signal stability.
\nThis amplifier is absolutely stable and requires no capacitive compensation.
\nIn single-ended mode, the new current source achieves superior audio integrity.
\nThe lower-impedance output stage improves speaker control.
\nVTL’s proprietary balanced reference output transformers significantly enhance interleaving and coupling, thereby achieving wider bandwidth and zero ringing.
\nUser-adjustable DF feedback control allows for adjustments to output impedance and damping factor to achieve optimal matching with speaker load.
\nSoftware microprocessor control
\nSwitchable tetrode\/triode mode
\nAutomatic offset, fault detection
\nInrush current limiting
\nStandby\/Mute function; reduces vacuum tube current to extend tube life
\nFull bidirectional RS-232 control
\n300 watts per channel in tetrode mode; 150 watts per channel in triode mode
\nUtilizes twelve 6550 or KT-88 vacuum tubes
\nAdjustable, precision-regulated anode and plate power supplies ensure stable operating points; independent regulated power supplies for input and driver stages deliver superior signal resolution and tonal quality.
\nThis adjustable, precision-regulated bias power supply enhances signal resolution and noise rejection while improving isolation from mains voltage fluctuations; the output operating point remains stable regardless of AC power variations.
\nAn improved automatic bias and fault detection system operates in fully balanced differential mode; the amplifier features comprehensive protection against output tube failure, and precise matching of output tubes is not required.
\nAll capacitors in the signal path are premium Mundorf silver-in-oil types.
Film bypass capacitors are used across the power supply capacitors to achieve superior high-frequency resolution.
\nFeaturing an extruded aluminum alloy front panel, it boasts a luxurious and modern look\u2014available in black and silver.
\nPrecisely regulated B+ and screen supplies
\nSturdy structure, improved ventilation, and lower operating temperatures.
\nUpgradable from Series I factory units.<\/p>\n
Vacuum Tube Complement 12 x 6550 or KT-88, 2 x 12AT7, 2 x 12BH7
\nOutput power Tetrode = 300W, Triode = 150W
\n20Hz \u2013 20kHz <3.5% THD
\nInto 5\u03a9
\nInput sensitivity Variable between 1 \u2013 2V, depending upon DF setting
\nInput impedance 48k\u03a9
\nLoad setting 5\u03a9
\nOptimum load range 4\u03a9 \u2013 8\u03a9
\nS\/N Ratio -90dB, 120Hz
\nPower consumption Idle = 560W, Full power = 1600W
\nB+ fuse ratings 100\/120V = 20A Ceramic Slo Blo, 220\/240V = 10A Ceramic Slo Blo
\nLogic fuse ratings 100\/120V = 1A Ceramic Slo Blo, 220\/240V = 1A Ceramic Slo Blo
\nInput fuse ratings 100\/120V = 2A Ceramic Slo Blo, 220\/240V = 1A Ceramic Slo Blo
\nFilament fuse ratings 100\/120V = 2A Ceramic Slo Blo, 220\/240V = 1A Ceramic Slo Blo
\nSecondary fuse ratings Plate 2.5A Fast acting 600V, Screen 0.75A Fast acting 600V
\nDimensions W x D x H 11.5 x 24 x 24 inches (29 x 61 x 61 cm)
\nWeight Net: 250lbs (113Kg), 350lbs (159Kg)<\/p>\n
S-400 Series II Since its debut in 2004, VTL\u2019s S-400 stereo reference amplifier has won the favor of music enthusiasts worldwide thanks to its high-power,…<\/p>\n","protected":false},"featured_media":127337,"template":"","meta":[],"pwb-brand":[10857],"product_cat":[10162,11106],"product_tag":[],"class_list":{"0":"post-130126","1":"product","2":"type-product","3":"status-publish","4":"has-post-thumbnail","6":"pwb-brand-vtl","7":"product_cat-post-amplifier","8":"product_cat-vtl-stereo-amplifiers","9":"product_shipping_class-c-class","10":"pa_color-black","11":"pa_color-dark","12":"pa_color-wood","14":"first","15":"outofstock","16":"shipping-taxable","17":"purchasable","18":"product-type-simple"},"aioseo_notices":[],"etheme_brands":{"errors":{"invalid_taxonomy":["Invalid taxonomy."]},"error_data":[]},"brands":[{"id":10857,"name":"VTL","slug":"vtl"}],"_links":{"self":[{"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/product\/130126","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/product"}],"about":[{"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/types\/product"}],"version-history":[{"count":0,"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/product\/130126\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/media\/127337"}],"wp:attachment":[{"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/media?parent=130126"}],"wp:term":[{"taxonomy":"pwb-brand","embeddable":true,"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/pwb-brand?post=130126"},{"taxonomy":"product_cat","embeddable":true,"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/product_cat?post=130126"},{"taxonomy":"product_tag","embeddable":true,"href":"https:\/\/soundglory.com\/en\/wp-json\/wp\/v2\/product_tag?post=130126"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}