After a long period of going through trials and test, the new amplifier, QAQ6, to succeed the previous QA-M7U1 is finally ready.
With one input in the previous preamplifier, it has been an inconvenience, as feedback by customers, that the ability of the preamp is restrictive. QAQ6 has addressed this in a phenomenal manner by having 4 inputs and 2 outputs. The myriad of connections will surely be a welcoming aspect in connecting various equipment and STILL having the possibility to output to 2 power amplifiers!
But first, it must be familiar and easy to find Reisong Q6 online. There are so many qualities to the original Reisong Q6 that could be further expanded and QA has done some remarkable modifications to it, surpassing its potential significantly. This new preamp being an OEM product modded with components upgrade has value-added the whole unit in terms of performance and price by allowing modular upgrades to be done easily in the future by customers on their own.
Our QAQ6 is the unit where it is the factory advance set which includes 6V6 and 6J1 as part of the current stabilisation setup on the rectifier board. Widely available online is just a basic unit of Q6 which they use just capacitors and 6Z4 for the rectifier board. So please take note!
Similar to the previous QA-M7U1 in referencing from the classic Marantz 7, QAQ6 uses 3x 12AX7 driver tubes for the amplification. The unit comes in default tubes from either JJ or Electro-Harmonix (EH), both of which are clearly better than the basic Shuguangs provided in our earlier preamp. Despite all these tubes being newly production tubes, JJ and EH are probably the best starting brands for 12AX7 for their linearity and balanced sounds. They can definitely stay inside the QAQ6 for a long period of time until and unless vintage European or American 12AX7 tubes can be further afforded and sourced, of which the improvement will be significant. Golden pins of JJ and EH 12AX7 are another upgrade path one could go.
Metal tube shields are installed on the 12AX7 tubes to slightly reduce any nearby RFI that may interact with the tubes causing unwanted interference being amplified. They can be easily removed by pushing it down and rotating anticlockwise if the aesthetics of naked tubes are preferred.
On the same PCB board where the 12AX7 stands, the most significant and major work done by QA is the implementation of terminals at the coupling capacitors. This allows the coupling caps to be easily and freely replaced with any grades of capacitors to the users’ liking for different level of enhancements without the hassle of resoldering on every change. This implementation may not be new and unique, but to have it used here in QAQ6 is an elevation of quality what this preamp can deliver as the we go in detail further.
Securely fastened to the PCB board, each binding post terminal has a screw which will not fall off. Changing of caps is a straight forward chore of unscrewing the two terminals of each capacitor end, removing/inserting the leads of the caps you are replacing (they can remained uncut so they can be twisted up to make the most optimal contact, just make sure the leads are kept away from other components to prevent shorting), and tighten the screw back. Film capacitors have no polarity, so there is no need worry of inserting them the wrong way.
Secondary capacitors have been upgraded to the trusted WIMA MKP10s to improve on the clarity further from the stock caps. Filter caps are upgraded to the vintage NOS Philips to complete the audiophile grades of caps used in the output PCB board.
Together with the 6Z4/6X4 rectifier tube, the rectifier board in QAQ6 is another tri-tube setup of ensuring the most optimal current is supplied to the 12AX7s.
Stock units of Reisong Q6 does not get the ability to use 6X4 tube despite the socket being present without resoldering one of the leads of a resistor. So stock unit of Q6 can only work with 6Z4 tubes! QAQ6 has performed the modification and made the option easy for users, where either one of 6Z4 or 6X4 can now be used. 6X4 has higher grades of tubes that can be rolled and changed according to one’s availability on hand. But 6Z4 in QAQ6 has managed to impress us a lot, that using 6Z4 is in fact perfectly fine.
However, as the stocks tubes included in the rectifier boards are purely Chinese tubes, we could really do better. Hence in QAQ6, both 6Z4 and 6V6 have both been upgraded with the ‘Russian Rockets’, Soviet-made Reflektor 6U4n-Eb and 6n6c respectively. They may not be the most premium tubes, but they are very highly-regarded Soviet tubes that enjoyed great reputation amongst audiophiles to be of high sonic quality without the extravagant price tags. They drop in very well into the specifications of the preamp giving it the intensity of the bottom end pushing the vocals more forward.
The trusted GE JAN 5654W is used as an affordable upgrade over the stock Chinese 6J1. This tube also provides some sparkle of the midrange. The upgrade of these 3 tubes effectively smooths out the brash and harshness of the stock Chinese tubes.
On the exterior front are very well-made and polished front panel of large and heavy pots for the input selections and volume control. Aesthetically wise, there is an option to switch on the LED strip in front to light it up to either the colour of white or blue, probably good enough to harmonise with other equipment setup.
In terms of sound signature, QAQ6 is a relatively quiet preamp to begin with. Another crucial modification made from Q6 is that stock units came with very high gain, where hissing will be an issue in some sensitive setup, and volume cannot be cranked any higher after 8 o’clock mark without rocking the place. QA has corrected this with an internal attenuator of -21dB at the output path, cutting down on the line level without affecting much of the output impedance. Not only has this allow the volume pot to go higher towards 10 o’clock position with ease, the lower gain output now (which is still substantially very high) has dropped the noise floor further, improving on the signal-to-noise ratio.
Hence with the ClarityCaps CSA in place together with the various tubes upgrade at the rectifier board, the sound has opened to a very wide soundstage of immense imaging. Instrument placements has markedly improved with the different layerings of sounds which is now more prominent and evident. Vocals are very much alive with high clarity, where in this instance, the tubes are proving to perform to a very high level of resolution akin to solid-state based preamp but still with the enjoyable overtones of a tubey sound.
- Frequency response: 19Hz-43kHz ± 0.5dB
- Output voltage: 16.5V (Max)
- Total Harmonic Distortion: ≤ 0.2% (1kHz 5V)
- Input sensitivity: 1000 mV
- Signal to noise ratio: 95dB
- Input impedance: 100K ohms
- Output impedance: 1010 ohms (theoretical data after implementation of internal attenuator -21dB))
- Tubes: 12AX7 (Either EH or JJ) x 3, Reflektor 6U4n-Eb x 1, Reflektor 6n6c x 1, GE JAN 5654W x 1
- Dimension: 420W * 380D * 13.5H mm
- Net weight: 8.5kg
- Gross weight: 10.5kg
- Input Power Voltage: AC100V – AC240V(60Hz/50Hz)
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