JVC SZ-2000 Balanced Mod (Basshead's Dream)

JVC HA-SZ2000 were released on Jan 1, 2004 (source) as a successor of HA-SZ1000.
The haedphones contains two drivers one of them dedicated for bass response. There are two models, Z-Series (Japan only?) and Live Beat. Z-Series is said to have a crossover circuit while Live Beat version does not have any. The production of these headphones ended long time ago, but they can still be bough from Ebay for example.

The following image depicts an internal design. The green chamber contains a bass driver. Stream Woofer Diagram image source

Common problems

Build Quality

The built quality of the headband is terrible. There are dozens of people having headphones with snapped hinge. On the other hand, others like me can take this as an opportunity to buy the broken headphones at cheaper price. A quality replacement headband would cost 50-100USD which is more than the cost of some new headphones. I currently own two pairs of headphones both bought in a bad condition, the first ones had cracked headband the other ones had completely snapped headband .

Bad sealing

The provided ear pads were not thick enough and also wear out pretty quickly as they are probably made of protein leather.

Non detachable cable

The cable is not detachable, the wires go through the headband to the other side. I have addressed this issue by adding two 3.5mm Jack connectors one to each side.

Mod

I have carefully filed the cable hole on one side and made a completely new hole on the other. This allowed me to put there 3.5 Jack connectors which I wired to the drivers.

I have also replaced the broken headband. Unfortunately the headphones are so heavy they cause discomfort after prolonged use. I tried to add a strip of neoprene and tied it using plastic string. It helped a bit but still would like something better in the future.

The pads were in a very bad shape, so I replaced them with lambskin ones. The sound is much better and the bass is stronger than it used to be.

Final mod

Source & EQ

As a source, I use Qudelix in balanced mode with bass heavy EQ. Config:

- DAC/AMP
    - PERFORMANCE: PERF
    - HIGHT GAIN: HIGH
    - OUTPUT: AUTO/2.5.mm (always use with balanced 2.5mm cable)
    - ACTIVE GROUND: OFF
    - DISTORTION COMPENSATION: ON (not sure if needed)
- DSP
    - HEADROOM [dB]: -12

EQ:

CH: 0 
TYPE: PEQ 
Preamp: -12.0 dB 
Xfeed: 1 0
Filter 1: ON LS Fc 10 Hz Gain -20.0 dB Q 5.000 
Filter 2: ON PK Fc 28 Hz Gain 10.0 dB Q 1.414 
Filter 3: ON PK Fc 55 Hz Gain 10.0 dB Q 1.414 
Filter 4: ON PK Fc 100 Hz Gain 9.0 dB Q 1.414 
Filter 5: ON PK Fc 500 Hz Gain 0.0 dB Q 1.414 
Filter 6: ON PK Fc 250 Hz Gain -20.0 dB Q 1.414 
Filter 7: ON PK Fc 2000 Hz Gain 0.0 dB Q 1.414 
Filter 8: ON PK Fc 4000 Hz Gain 0.0 dB Q 1.414 
Filter 9: ON PK Fc 8000 Hz Gain 0.0 dB Q 1.414 
Filter 10: ON PK Fc 16000 Hz Gain 0.0 dB Q 1.414 

Note: This preset is meant as a starting point, your hearing to certain frequencies will change during your listening session (especially when using high volume) thus it is really difficult to create a universal preset.

Sound

The provided preset is heavily V-shaped one but who cares, because the bass is incredibly strong and clean. As my coworker said, the headphones feel like vibrating jelly around ears. It’s not just the sound but also the feeling. I like to fire DnB tracks, especially Neurofunk which often uses deep frequencies around 36Hz.