Question About Capacitor Upgrade in Tube Amp

Based on the good results with the Willsenton R300 I went ahead and upgraded the Muzishare X7 KT88 amp. It required four 0.22uF coupling caps and one 0.47uF filter cap bypass film cap.

I used the Mundorf SilverGold Oil 1000VDC again.

Similar results. Most noticeable change - the depth of the soundstage significantly increased and more holographic image. Slight increase in soundstage width. Better treble crispness and rounder fuller bass with better instrument separation.

Upgrade cost approx $200.

I am using Gold Lion KT88 and 5AR4 tubes with Mullard reissue 12AX7 and 12AU7s in the Muzishare.

Between the two upgraded amps, the Willsenton R300 has the edge in vocals and holographic sound. The Muzishare X7 has the edge in treble response and bass punch. Both are wonderful amps with the upgrade.

And if there was any doubt - after doing this for a second time, good coupling caps make a significant improvement in sound over the factory cheap caps.

I peeled the labels off both the factory branded Willsenton and Muzishare coupling caps and there is no label underneath. So the source of the factory caps is unknown. Although the Muzishare factory caps were much larger than the Willsenton with what looks like a better construction.

And once again the Willsenton R300 comes from the PrimaLuna/Cayin factory (Zhuhai Spark Electronic Equipment Co, LTD) and the Muzishare from the Line Magnetic factory (Zheng brothers Zhuhai factory) so other components in the amps do appear to be decent and not requiring an upgrade (Nichicon electrolytic, Alps potentiometer etc.)

Hi @calieng ,

You did right thing to chose relatively affordable Mundorf capacitors for your Willsenton R300 amplifier.

Duelunds and V-Cap CuTf are very good but they are overkill for such not expansive amplifier. With all respect coupling and power supply bypass capacitors shouldn't be the most expansive part in any amplifier.

Regards,

Alex.

@alexberger 

Yes the Mundorfs seemed to be a best bang for the buck. I found an online dealer selling them around $30-$40 each depending on the value for SGO Supremes.

And while the Willsenton at around $900 plus shipping might seem to be a cheap amp compared to other equipment discussed on here I do have to say that it sounds on a completely higher level than my Luxman or Naim soild state amps when paired with the Forte IV speakers. Like sitting in the front row of a jazz club. The music surrounds you and you can pick out the location of all the instruments. Mind you that is with Lumin U1 and Denafrips Venus II front end.

I firmly believe that we should support products from USA, UK, and others as opposed to from some other locations with questionable governments but if you are looking at buying products like Line Magnetic, PrimaLuna, Cayin, Icon Audio....The Willsenton and Muzishare can also be considered from the same factories and for less than half the price. Maybe just benefiting from a few capacitor upgrades as I have done.

People should also be aware that dealers from this country of origin can be pretty sketchy so for some the extra cost of a USA based dealer with the other brands is well worth it....but that is another discussion entirely.

And while the Willsenton at around $900 plus shipping might seem to be a cheap amp compared to other equipment discussed on here I do have to say that it sounds on a completely higher level than my Luxman or Naim soild state amps when paired with the Forte IV speakers. Like sitting in the front row of a jazz club. The music surrounds you and you can pick out the location of all the instruments.

I don’t doubt this observation at all. SET if properly implemented will connect you with the core of the music. Exceptional naturalness and realism  in my listening experience.

Charles

there was an improvement in frequency response and lower distortion replacing the cheap factory caps with one of better and different material construction.

Did you measure the C or look up the ESR and ESL of the caps or just read the value printed on the schematics / old cap?

Did you measure the frequency response, distortion, phase shift, transient response, etc. or just listen?

@calieng 

Does anyone know how the power supply bypass capacitor effects high end frequency response?

Capacitors have properties Capacitance, Equivalent Series Resistance [ERS] and Equivalent Series Inductance [ESL], all of which are frequency dependent. Dielectrics, foils, leads and geometry affect the frequency response of these properties. At some frequency the combination of these properties will make the system self-resonant. Hence a band limited digital system may exhibit different response when fed by a disc system with much higher bandwidth.

Most think the capacitors just filter the DC from the rectifiers. However, current flows in @ 60/120Hz [50/100Hz] and out of the capacitor bank @ DC to many kHz.

Add in additional effects of construction, circuit design, wiring, printed or otherwise, program, level, related equipment, environmental conditions and universality approaches ZERO.

The expectation that the sonic effect in one device will translate to all others is pure fantasy.