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HA75 Tube Head™ Headphone Amplifier

  • 100% discrete class-A audio circuit with 12AX7 tube drive
  • Variable Focus™ control to simulate listening in a room
  • Selectable load impedance to optimize with any type of headphones
  • Choice of unbalanced RCA or balanced XLR inputs

The Hafler HA75 is a ‘vintage inspired’ headphone amplifier that has been meticulously designed to produce Hafler’s legendary sound quality while adding excitement and character of a real tube circuit to optimize the listening experience.

The design begins with a 14 gauge steel casing to shield the internal workings from external magnetic fields and RF contamination. This is complimented with a black anodized aluminum front panel for clean, esthetic appeal. A choice of either unbalanced RCA or balanced XLR inputs are available. These are gold-plated to eliminate tarnishing over time while optimizing signal flow.

Inside, a 100% discrete class-A head-amp combines with a 12AX7 tube drive to power the headphones. This employs a unique non-radiating charge pump that applies 140 volts to the tube to maximize headroom as it delivers the character and warmth that so many listeners prefer over solid state counterparts. To simulate the response of listening to loudspeakers in an acoustic space, a Focus control may be engaged that brings the stereo image to the center via a fully variable potentiometer. This active control activates a matrix that delivers exciting results without collapsing the stereo image. A Vox function warms the tone akin to an old-school loudness control, addressing the Fletcher-Munson curves to deliver equal loudness when listening at low levels. The Vox control can also can be used and create a ‘boom-box’ effect for those that enjoy a more exaggerated response.

The headphone outputs on the HA75 feature an innovative Load selector, which allows the output of the amplifier to be adjusted for optimization with headphones of any impedance. Combined with the other adjustable controls and the powerful high quality tube drive circuit, the HA75 delivers plenty of warmth and character to truly enhance the listening experience.

Dial In

  1. Power
    Activates the device and the 12AX7
  2. Focus Control
    Brings the left and right channels to the center to simulate listening with speakers in an open room
  3. Level
    Used to set the headphone output level
  4. Load Selector
    Adjusts the impedance of the headphone output to optimize for any type of headphone
  5. Phones
    ¼" TRS output for headphones. Works with headphones ranging from 8 Ohms to 400 Ohms

Connect

  1. Input A
    Selectable RCA or balanced XLR connectors.
  2. Input B
    Unbalanced RCA phono jacks
  3. Thru-put
    Whichever input is selected appears at the thru-put in an unbalanced format
  4. Tube Out
    Add the Tubehead's warm tube character to a signal path between a preamp and power amp
  5. Power
    External power supply included

Specs

Audio Circuit:Discrete class-A with 12AX7
Inputs:Switchable RCA or XLR
Thru-puts:RCA (left/right)
Output:1/4" TRS Headphone
Impedance:8 Ohm ~ 400 Ohm
Gain:30 dB
Max Output:5 V RMS

Resources

Photos

FAQ

Can the HA75 damage my hearing?

Yes. Any time you are subjected to long periods of high sound pressure levels, you can damage your hearing. Always monitor your kids' listening levels and consult local health and government safety regulations to ensure you stay within safe margins.

What is the benefit of tubes?

Tubes introduce warm-sounding even order harmonic distortion that is pleasing to the ears. This is why most audiophiles prefer the sound of tubes over solid state counterparts. The other benefit is the distortion acts like a natural limiter. This tends to reduce ear fatigue.

Do I need to warm the HA75 up before using it?

Yes. It takes about 15 minutes to achieve thermal stability. This of course produces a better sound as all of the components reach their optimum temperature.

Why is there no digital input on the HA75?

Today, there are many choices when it comes to DACs (digital to analog converters) and since most audiophiles have a preference, we felt that they would likely already have one that they like. The other issue is constantly changing standards. A good headphone amp with traditional analog inputs will never go out of style.

Why did you incorporate a bass loudness switch?

Some will argue that true audiophiles may never use this function. However, when listening to music at low levels, bass energy can become too low. The Vox switch allows the user to add more bass to suit. This also allows users that enjoy listening to accentuated bass to share in the fun.

Why an external power supply?

External power supplies enable manufacturers to ship the same product around the globe without having to pay costly safety certificates. This makes the product more affordable for the end user. Further, power supplies tend to be the part of the circuit that is most subject to fail. This makes servicing easy. Finally, power supplies generate a ton of noise. This is particularly troublesome in small boxes. So removing the power supply lowers the noise floor.

Is there a previous version of the HA75?

Yes, the original HA75 had a slightly different feature set, but offered the same high-quality tube amplification as the current version. After receiving many positive responses from our customers regarding the Load Selector on the HA75-DAC, we decided to port this feature over to the HA75 and remove the Feedback control. The easiest way to differentiate between the two models is to look for the Load Selector switch that adjusts the output impedance - this is only present on the newer version. Here is a link to the manual for the HA75 rev 1.