I’m constantly amazed by the results of upgrading Yaqin amps of which I’ve now completed quite a few. I remember my nervousness upgrading the first one as the received wisdom was ‘Chinese transformers are no good’. Yaqin’s transformers are made in house and they claim, are made of Japanese steel.Whatever the ingredients the result is an amplifier that sounds very decent as standard but which can easily be improved with some simple upgrades.
Circuit wise the amp is a fairly standard ultra linear output stage with input and phase splitter. The upgrades this time were to add improved Mundorf coupling caps, to change the grid stopper resistors on the output valves and to add Elna Silmic bypass capacitors to the output valves.
Once installed the amplifier performs at a new level. The light graininess of the sound disappears, vocals become more breathy, and bass and dynamics improve. All these improvements were heard with the stock Chinese valves and of course these too can be swapped for improved Western designs or NOS types.
The Onix Melody is an Australian design made in China and runs 6L6 valves or equivalents. It had a pretty decent sound for the money when released in early 2000 and one of its main claims to fame was the use of a stepped attenuator.
Another feature is its use of Russian military paper in oil capacitors (in the green cans in the picture above). These are not bad in terms of sound quality, but can be bettered with a decent audio grade capacitor. So, after discussion with the owner, we agreed we would upgrade the cathode bypass capacitors with Elna Silmics and the coupling capacitors with Musicaps. I also installed an earth lift system to stop the amplifier interacting with other equipment.
Overall the result was a very decent uplift in performance.
This preamp dates from the early 90s when it had a reputation for great sound quality. It stands the passage of time well and still sounds very decent. It had had various mods and servicing over the years, including main electrolytic capacitors, valve sockets etc.Someone had also replaced the ribbon connector with some Cat cabling.It is a hybrid valve /solid state design, with transistors used for the phono stage and valves for the line stage.
My work was to upgrade the coupling capacitors, and add a choke power supply by adding a choke and additional smoothing capacitor. Once this work was complete it transpired the original main smoothing capacitor was pretty spent, so that was replaced too.That took a while to find as it broke down after around 2 hours use, but was fine up until then.
The result was very worthwhile, performance has been lifted to a very pleasing level. The pre operates with a much quieter background, displays subtleties better and is more dynamic to boot.
This iconic little amp came in to the workshop for some TLC. Not much wrong really. A blown internal fuse but bias and every other parameter measured fine. So once checked and the fuse replaced the amp works fine and sounds good. There is a noticeable thump on switch on, which is typical for an amp of this age as capacitors and transistors age. A recap and change of transistor would cure this but for an amplifier of this age, I often simply install a slow start module as a cheaper fix for switch on thump. It really depends on how much the owner likes the amp and wants to invest in its future.
I’m selling these on behalf of a client who’s upgraded to my KT150 amps and preamp. These have been converted to cathode follower design as an improvement over the original hummy WAD design. These have been converted to cathode follower design as an improvement over the original hummy WAD design. The build contains every possible upgrade including: Tocos carbon pot in shunt mode with Vishay naked foil resistors, Vishay naked foil grid resistors, Jupiter beeswax signal caps. The power supply has an upgraded 30 Henry choke, Schottky heater diodes, and Hexfred HT diodes.*The valve is an ECC88 gold pin Mullard. Excellent sounding line pre in daily use. Front panels in good condition, some scratches on sides of black chassis.
These two Canary CA303 mono blocks came in for re-biasing and an open-ended ‘could I do anything in terms of upgrades?’. Like a lot of high end American gear, the componentry is top notch, so there’s no easy wins in terms of upgrading capacitors, resistors, or rectifiers for example. But what I did do was to install a switch for the negative feedback. With feedback switched off, with my speakers, these amps really hit their stride, open up and become seriously dynamic performers.
Those with keen eyesight will notice an Audio Innovations 700, and an LFD integrated solid state amp, both of early 90s vintage I believe.