Introducing our stereo vacuum tube preamplifier with mic/line-level inputs; the 652!

Using the GAIN control, the engineer can achieve 5 - 60 dB of gain from the uniquely-biased tube input stage, followed by a MASTER attenuation control in the output buffer stage. Want a clean yet musical replication of the source? How about the creamy saturation of an esoteric vintage preamplifier?

The 652's gentle drive characteristics allows for a broad tonal palette depending on how hard you hit it with signal. It is designed to interface with all types of microphones (including ribbons), and the line-level input pad allows you to add analogue warmth to any track from a digital audio workstation; making it an indispensable tool for adding colouration and harmonic distortion!

Two flavours, one box, all discrete, and proudly hand-crafted in Canada.
  • 12AX7 input stage with 12-position gain switch, 5 – 60 dB (5 dB steps)
  • High-voltage transistor buffer output stage (4x FJP5200)
  • Discrete Class-A operation, low-noise topology
  • Hermetically-sealed relay switching, with gold-plated contacts
  • Variable input impedance for mic: 300 ohms, 1200 ohms
  • Source selection switch: Mic and Line-Level
  • Phase inversion switch
  • Selectable high-pass filter of 10Hz, 80Hz, and 200Hz (first order)
  • Regulated low-noise power supply, with +48V DC phantom power
  • High-quality Beldfoil® shielded cabling throughout
  • Custom Lundahl input and output transformers
  • 2 Year Limited Warranty
  • Specifications
    Typical Test Parameters: 2mV RMS sine, 1 kHZ, 1200R input impedance, 100K output load impedance
    Input Impedance
    300 Ω, 1200 Ω (Mic)
    15 KΩ (Line)
    Maximum Input Level
    +4dBV (XLR, 1200R setting)
    -2dBV (XLR, 300R setting)
    Maximum Output Level
    +15 dBV
    XLR Output Impedance
    < 65 Ω
    Recommended Minimum Load
    300 Ω
    Frequency Response
    18Hz to > 50kHz (-3 dB)
    High Pass Filter Characteristics
    -3dB @ 80Hz or 200Hz, 20 dB/decade (first-order)
    Maximum Gain
    60dB (1200R XLR input - XLR output, unweighted)
    EIN Noise
    -128dBV (20Hz ~ 20kHz); -130dBV (A-wtg)
    Residual Output Noise (Master at Zero)
    -121dBV (1uV) 20Hz ~ 20kHz
    Noise Factor
    5dB re 150R source impedance (20Hz ~ 20kHz)
    0dBV to 15dBV, 0.03% to 2%
    Tube Per Channel
    1x 12AX7
    Phantom Power
    +48V DC
    Power Sequencing
    Soft-start for tube filament supply;
    Soft-start for tube high voltage supply;
    30s turn-on delay for output relays;
    Output relays mute immediately at power-down
    Power Requirements
    110-120V / 220-240V, 50/60Hz, 30VA max.
    Power Consumption
    24 Watts
    19” W x 3.5” H x 12.25” D
    483mm W x 90mm H x 311mm D
    6 kg
    Click here to download the 652 user manual
    Frequently Asked Questions
    What type of sound can I expect from the 652?
    The 652 gives the real sound of tubes and transformers without compromise or emulation, with a flat frequency response and incredibly low noise figures typically found in transistor preamplifiers. This gives the source material a naturally-variable harmonic content depending on the gain selection and input signal level, while preventing a “lumpy” low-end response from the crude feedback networks of days gone by. You can achieve that tube sound without accepting the inferiorities that vintage vacuum tube circuits have inherently, and without paying the ridiculous amounts of cash that new boutique and used tube equipment typically fetch.
    Does the 652 include a pad?
    Yes, the 652 has a 50dB pad (source switch) to allow the preamplifier to be switched between mic-level and line-level inputs. This means that the 652 can be used for more than just microphones, such as gluing together a mix buss, adding warmth to previously recorded tracks, and even as a mastering tool for adding subtle harmonics and compression of signal peaks.
    Which input impedance setting should I use?
    There are two selections for input impedance; 300R and 1200R. The net gain figures are calibrated in the 1200R setting and most microphones will interface best in this setting. The 300R setting is very low input impedance and will give a slightly altered frequency response depending on the microphone’s source impedance in conjunction with the 652’s input transformer. There is also about +4dB of extra gain in the 300R setting that may or may not be offset by impedance mis-matching. It’s recommended that you try both settings with each microphone to find the best flavour and sound for you.
    What makes the 652 different from other tube-based preamplifiers on the market?
    Many manufacturers try to get the lowest datasheet numbers with low distortion at large output levels. Why must they design tube preamps to be so clean and sterile? The idea of the 652 is to take the sonic warmth of vintage vacuum tube preamplifiers (soft asymmetrical clipping and transformer saturation) and combine it with the best qualities of solid-state preamplifiers (very low noise, wide gain-bandwidth product, calibrated gain figures, low impedance output buffer) for that harmonically-rich character at more useable output levels.
    Why does the 652 have lower output level capability than other preamplifiers?
    Many professional audio preamplifiers strive for the lowest possible distortion at output levels of +26dBu or greater, all while remaining relatively clean. Traverse Analogue does not desire to conform to these standards, and this is exactly what we don’t want in the 652! In fact, some manufacturers are now offering -6dB or similar level output jacks specifically so we can drive the preamplifier circuitry for more analogue character and harmonic content. Modern converters and audio interfaces can be driven into overload trying to achieve this sound. Therefore, the 652 was designed for achieving both copious amounts asymmetrical tube clipping and output transformer saturation at lower output levels. But don’t just take our word for it, try it for yourself and hear the difference!
    How can I try a 652 and hear it for myself?
    If you would like to try a 652 out for yourself, reach out to your sales representative or dealer and express your interest in trying our products. You can also contact our distributor HHB Canada to find the nearest demo on the road, or simply contact us directly and we’ll add you to our demo waitlist.
    In Canada, our products are exclusively distributed by HHB Communications Canada Ltd.
    For a list of authorized dealers, see here.

    For international inquiries, please contact us directly.
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