Biasing a Haze 15

Haze 40watt and 15 watt

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HAZE MHZ 15 HEAD- 15W, guitar head-unit, five-tube chassis, preamp: 3 X ECC83, power: 2 X 6V6, solid-state rectifier, two channels, reverb, echo, vibe, chorus, front gold control panel, single input, nine knobs (effects adjust, effects depth, r, b, m, t, OD v, OD g, Clean v), power switch, effects switch, channel switch, bright switch, rear panel: emulated line out, two speaker jacks (16 ohm, 8 ohm), effects loop with on/off switch, footswitch jack, two-button footswitch included, black covering, gray grille with white piping and white script Marshall logo, 20.5 lbs., mfg. 2009-2012.

HAZE MHZ 40C COMBO - 40W, 1-12 in. Celestion G12T-66 speaker, guitar combo, five-tube chassis, preamp: 3 X ECC83, power: 2 X EL34, solid-state rectifier, two channels, reverb, echo, vibe, chorus, front gold control panel, single input, 10 knobs (Normal Ch. v, OD Ch. v, OD Ch. g, t, m, b, p, r, effect depth, effects adjust), bright switch, boost switch (Normal Ch.), channel switch, boost switch (OD Ch.), effects switch, standby switch, power switch, rear panel: emulated line out, two speaker jacks (16 ohm, 8 ohm), effects loop with on/off switch, footswitch jack, two-button footswitch included, black covering, gray grille with white piping and white script Marshall logo, 44.7 lbs., mfg. 2009-2012.

HAZE MHZ112 SPEAKER CABINET - 1-12 in. Celestion G12-66 Marquee speaker, closed back, straight or angled front, designed for use with the Haze MHZ 15 Head, black covering, dark gray grille cloth with white piping and white script Marshall logo, mfg. 2009-2012.

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Biasing a Haze 15

Postby Pongpong » 01 Mar 2011, 23:41

hello i want to bias my tube amp marhall haze 15 watts.....can u tell me the factory settings pls...........for biasing that amp......and is it the marshal ahze 15 watts have a 1ohm trim pot or variable resistor???

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Re: Biasing a Haze 15

Postby SteveD » 02 Mar 2011, 04:17

According to our Service Dept; -

Haze 40 = 39mVDC

Haze 15 = 29mVDC

When taking measurements across a 1 Ohm resistor, millivolt readings on a multimeter equate to milliamps, so, if you measure 29mV at the bias test point, that means there are 29mA flowing through the 1 Ohm resistor that voltage is measured across.
Still my guitar gently weeps

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Re: Biasing a Haze 15

Postby dukealexan » 16 Aug 2012, 05:45

Just picked up a used Haze 15 full stack, all original tubes, those black 6V6 with the marshall badge, surprised to see all 3 preamp tubes with the red lettering and coding to all be JJ's. I used my Weber Bias Rite. The bias was 13+ for V4 and 18+ for V5, the plate voltage was reading around 368. I took the 29 and halfed it as 14.5 per tube and set it there the plate dropped to 354. I used a calc I've seen on the net, watt/plateVolt * .80 = bias. So 6V6 = 14 watt tube / 380 * .70 = .028. Now the haze is not a 28 watt amp so 1/2 of 15 is 7.5 per tube so I set the bias at 14 on each tube.

Will try some other tubes.

Question - With a bias adjustment pot for each tube is it true that a balanced PI in not needed and a match set of tubes is not needed?

If the above is true could I then use different brands of 6V6's say a JJ and a TungSol?

If I have a balanced PI and a matched set would I be better off with those ?

Btw the Haze 15 is a nice little beast great classic rock tone

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Re: Biasing a Haze 15

Postby Jamesm » 14 Sep 2012, 03:32

Yes, you could use miss matched 6V6s because of the separate bias controls.

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Re: Biasing a Haze 15

Postby surfnorthwest » 27 Jul 2016, 15:32

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