VTL MB-185 Series III Monoblock Amplifier

MSRP: Contact Us

The ’450s’ new little sibling, the ’185, is based on the ’450 but reworked to make the most of the EL34 power tube. A well-made EL34 is one of the gold standards for high-end, hand-wired guitar amplifiers and has a delightful sweetness and delicacy that, backed by a traditionally stiff and overbuilt VTL power supply, yields nothing in the way of traction and oomph in the lower ranges. The ’185-anchored system was immediately inviting, very much a “pour a glass of wine, put on some tunes and relax” system. I can’t imagine any real music lover not falling in love with the perfectly wonderful sound this system produced. Paul Bolin-The Audio Beat

Product Description

VTL MB-185 MonoBlock Amplifier Specifications

 

Vacuum Tube Complement 8 x EL34 or 6CA7, 1 x 12AT7, 1 x 12BH7
Output power
20Hz – 20kHz <3% THD
Tetrode: 225 Watts, Triode: 140 Watts
Into 5Ω
Input sensitivity Variable between 1-2V, depending upon DF setting
Input impedance 45kΩ
Load setting
Output load range 4Ω – 8Ω
S/N ratio 225W Tetrode & 140W Triode: -90dB, 120Hz
Power consumption Idle = 270W, Full power = 550W
Primary mains fuse rating 100/120V = 12A Ceramic Slo Blo, 220/240V = 6A Ceramic Slo Blo
Input fuse 100/120V = 1A Ceramic Slo Blo, 220/240V = 1A Ceramic Slo Blo
Logic fuse 100/120V = 1A Ceramic Slo Blo, 220/240V = 1A Ceramic Slo Blo
B+ fuse rating Plate Fuse – 1.5A fast acting 600V, Screen Fuse – 0.75A fast acting 600V
Dimensions W x D x H 18.5 x 18 x 9 inches (47 x 45.7 x 23 cm)
Weight 85lbs (38.5kg) per monoblock unpacked, 100lbs (45.4kg) packed

VTL MB-185 MonoBlock Amplifier Features

  • Fully balanced differential circuit – even single-ended signal produces balanced signal at output
  • Re-designed fully balanced differential input and driver stages for increased signal swing, bandwidth and stability
  • Zero global Negative Feedback
  • Shorter, faster feedback loop for greater tonal control without phase shift
  • Improved handling of loudspeaker loads for greater signal stability
  • The amplifier is unconditionally stable, without the need for capacitor compensation
  • Tube like JFET-type current source for lower sonic impact in single-ended mode
  • Lower impedance output stage for improved loudspeaker control
  • Dramatically increased interleaving and coupling in the balanced VTL proprietary Signature output transformer, for wider bandwidth and zero ringing
  • Variable user-adjustable DF feedback control to vary output impedance and damping factor for optimal matching to speaker load
  • Software microprocessor controlled
    • Tetrode/Triode Switchable
    • Auto Bias, Fault Sensing
    • Current in-rush limiting
    • Standby Mute function; with reduced tube current for increased tube life
  • 425 watts per channel in tetrode; 225 watts per channel in triode
  • Uses eight 6550 or KT-88 tubes per monoblock
  • Adjustable regulated screen supply for stable operating point; discrete regulated input and driver supply for greater signal resolution and tonality
  • Adjustable precision-regulated bias supply for greater signal resolution and noise rejection and improved isolation from mains supply variations; output operating point does not change with AC power fluctuations
  • Improved Autobias and fault sensing system to operate in fully balanced differential mode; amplifier is fully protected against output tube failure; no need for precision matching of output tubes
  • All premium Mundorf silver oil caps in signal path
  • Film bypass of power supply caps for greater HF resolution
  • Extruded aluminum front panel with luxurious, modern look – black and silver options available
  • Rack mountable
  • Rigid construction and improved ventilation for lower operating temperature
  • Factory upgradeable from Series II

VTL MB-185 MonoBlock Amplifier Overview

Following the footstep of the VTL MB-450 Series III, the MB-185 Series III Signature monoblock amplifier has gone through the same technological improvements as its bigger brother. The upgrade to the Series III platform is extensive with a complete rework of the signal path and new features added while retaining all the user friendliness of the previous model such as automatic tube biasing and comprehensive fault sensing.

Upgrades in the MB-185 include a fully balanced differential input stage driving a differential phase splitter and a lower impedance push-pull output stage. Also new is a shorter, faster and fully balanced negative feedback loop, with zero global negative feedback. The negative feedback loop completely eliminates ringing and requires no capacitor compensation to maintain critical phase integrity and information. The result is an amplifier that remains stable even under the most demanding loads.

Another significant change to the MB-185 is the switch to EL-34 tubes. Long admired for their rich, natural and open sound, the EL-34s bring a distinctive new sonic signature to the amplifier that emphasizes the integration and inner details of music. The output transformer has been completely redesigned and carefully matched to complement the midrange purity and quick, taut bass of EL34s.

There is also a new user adjustable Damping Factor Feedback control that allows the user to adjust the amplifier’s output impedance by varying the amount of negative feedback. Impedance can now be precisely set to suit the listener’s taste, and to improve control of the loudspeaker loads to deliver best performance.

The 4 possible settings are:

  1. LOW – Lowest damping factor, good loudspeaker control, most natural sound.
  2. MED – Better loudspeaker control, with some impact on sound quality
  3. HI – Best loudspeaker control, with a little more impact on sound quality, but on speakers that need the control the sonic improvement is clear
  4. MAX – Maximum damping factor, but sonic impact is noticeable

About Analog Audio of Minnesota

Analog Audio of Minnesota offers world class stereo equipment to the Minneapolis/St. Paul and greater Minnesota area. Located in Maple Grove, Analog Audio of Minnesota provides a unique environment to audition home audio equipment and the latest record releases. Come visit us for all of your home audio and two channel stereo system needs.

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Service

Analog Audio of Minnesota prides itself in its service. We offer in-home consultations in the greater Twin Cities area to learn about your goals and provide expertise to guide you through the purchase process. Of course, your stereo equipment will be expertly set up and optimized in your home by our service technicians. Questions with your audio equipment? Not to worry, our service staff is available to assist you.

To learn more about Analog Audio of Minnesota, please visit our About Us page. Ready to set up an appointment to audition a component or learn about our products and services?  Give us a call at (612)808-0709 or drop us a note. We look forward to hearing from you.