Question About Capacitor Upgrade in Tube Amp

@jaytor - Thanks for the reply!

Thanks for the replies so far.

Did anyone know if the .33uF on the B+ filter cap is just for noise filtering on the power supply or does it have any effect on the amp sound? I probably will just leave that one alone unless someone one here has some advice for that one.

I will check out those other caps mentioned.

Thanks!

Thanks! I will take a look. I have watched a few of his other videos before. Seems like a nice guy in addition to all his knowledge.

From my understanding the existing non-polarized caps are silver film. I do not think they are junk but for a reasonable cost certainly am willing to upgrade them.

So no love for the Mundorf Supreme SGO 1000VDC caps here? I had originally been thinking of those.

And thanks for the advice to replace all three of them.

The electrolytics are Nichicon so I will leave those be.

"Owning a Willsenton myself, I‘m curious about upgrade options. Please keep us posted!"

Yes to confirm this is the Willsenton R300. 6SN7 tubes driving 300B in single ended triode with dual 5U4G tube rectifiers.

I just received it and had bought it for a small system in a spare bedroom but when I tried it with my Klipsch Forte IV speakers I was blown away by the depth of the soundstage and the overall realistic and organic tone so I am thinking placing it in my main setup. Diana Krull, Melody Gardot, Leon...never sounded better. Just need to tweak a little more clarity.

The other tube amps I have to compare are Muzisahre X7, X9, X10, R100 300B 845, and past Willsenton R8 and Icon Audio Stereo 40 IV owner.

My other current equipment for comparison are Luxman L-550AXII, Naim Unity Nova, Naim Unity Atom, Hegel H120. Dynaudio Contour 30, Dynaudio Special Forty, KLH Model Five, Klipsch Heresy IV.

The frontend is Lumin U1 and Denafrips Venus II. I also have Matrix Audio for other smaller systems.

I am hooked on tubes though. I also know that a few relativity inexpensive parts can upgrade these Willsenton and Muzishare integrateds which are great values and made in the same factories as Cayin, PrimaLuna, and Line Magnetic but for half the price or less.

Thanks again for all the help. I will keep you posted on the results.

Once I get this one done I will take a look at the Muzishare X9 next. It is also a SET 300B and better built than the Willsenton. It also has the clarity of solid state with the warmth of tubes. But it is lacking in bass. It may improve with more run in but I suspect a few capacitor value changes will help. Although I am not knowledgeable enough about electronics to really follow what is happening in the circuit.

It certainly is a fun hobby and I appreciate all your expertise.

Yes too many amps right now. I ordered the Willsenton R300 and the Muzishare X9, X10 just in the past weeks with the intent of auditioning them and only keeping one or two. It is hard to decide before hand when there is nowhere to hear them before purchase.

The Muzishare R100 I have had for a while and is already for sale in the local craigslist. Very nice amp but I just do no need that much power or heat of the 845 tubes and it is also a bloody heavy thing to move. But no complaints on the sound quality. Very nice.

I have already decided the Muzishare X10 is a keeper as there is no other amp that I have that grabs the speaker drivers like those Kt150 tubes do. It would be the one for more modern / pop music. The bass is tight and bold and really gives you a punch to the chest when turned up.

Of course someone else may have different opinions as system matching is always much more important than the tweaking of capacitors and tubes.

Cheers.

I don't have any real experience modifying hifi gear so this will be my first attempt. I do not plan to change any cap values for the Willsenton R300 as the amp sounds good as is. Nice bass response etc. But I do believe the clarity can be improved with high quality coupling caps. 

The Muzishare X7 uses the same silver film coupling caps as the Willsenton versus the Muzishare X9 and X10 models which come factory equipped with Mundorf. I can definitely hear a difference in the clarity of vocals and the separation of instruments between the X7 vs the X9 and X10. So let's see how this upgrade works out once I get the parts.

I do have experience building tube guitar amps....initially from kits and then some scratch builds for Fender and Marshall schematics. So I can say from those builds I could even hear a difference in cheaper caps such as Orange Drops vs Mallory 150s in those builds. And a lot of musicians will pay top dollar for some vintage BumbleBee PIO caps for their Les Paul guitars claiming an improvement in guitar tone. So there has to be something there. It cannot be all imaginary.

But I take your point that often the expectation of an improvement colors our impression of whether or not an upgrade has really made a difference.

@charles1dad  I am glad that you see his point. I do not. He makes smug and arrogant assumptions about people he doesn’t even know. 

They are just words on a computer screen. Don't get mad at some LCD pixels.

Unless you are on Twitter and someone tweets a nasty message at you! That would be different. Thems fighting words! I'm a gonna start a Twitter war!

😀

whatever you do….run new parts in before passing judgement….

This is a very good point. I have been running the Kt-150 based Muzishare X10 for a few days now. Maybe still only 20-30 hours on it since delivery. But the soundstage is really opening up. Much more height and depth. Even though the amp did sound really good straight out of the box.

But for the Willsenton R300 I can see the coupling caps are of a cheaper kind so no problem swapping them without running the amp in more. Yes I will certainly run in the new caps for a while and report back on any improvement. I was able to source a set of the 3 needed Mundorf Supreme silver gold oil 1000VDC caps for only $100 total. But I am also going to order some of the other brands the folks here recommend to try them out and compare.

Thanks.

@millercarbon 

What I have found useful:

https://www.humblehomemadehifi.com/Cap.html

I just wanted to take a minute to thank you for the link. It was indeed very helpful.

Take pictures of every section you are working on before you start and after you finish

Very good advice. Especially when there is no schematic available!

I don’t see the need to excuse rude and obnoxious behavior.

I was just joking around a bit to ease the tension.

But to be honest I do not take any comments personally. Unfortunately there is always some character lurking around a forum who is unhappy and wants to share that negativity with others. I see it more as a cry for help than a personal attack.

Mind you this forum thankfully is pretty good and positive. When I was on some guitar forums there were a lot of mean spirited people attacking each other. I do not bother with those places anymore.

@boomerbillone 

Hey thanks for the reply.

The 300B tubes are around 300-350v with max plate voltage of 400V.

I see most of the caps being used in these type of amps at 600VDC and up. I ordered the 1000VDC Mundorfs just to be safe. The power in our house is pretty clean and all the amps are dead quiet. So I think primarily the coupling capacitors on the preamp tubes with show the most improvement in clarity but i will do the filter cap bypass as well.

@tomic601 

Interesting point on some caps being too big for the application.

But in this case I think the Mundorf Supreme SGO are in a similar size range to those being used - just better quality.

On the Muzishare X7 model I suspect the Muzishare silver label on the coupling caps is covering a Mundorf EVO silver cap. They refer to the cap as Germany in origin and has the same 1200VDC rating. I may have to try to peel the silver label off to see what is underneath. Maybe someone on here knows which caps Muzishare is rebranding?

The Muzishare X9 and X10 are using Mundorf labeled caps - EVO Supreme Oil.

I received the Mundorf Supremes last night and got them installed this morning.

Initial impression: Upper frequencies which were rolled off are now fully there. Cymbal crashes and other higher frequency elements that were in the background or missing are now fully there.

Bass that was previously full is now taught, well defined with some punch. Best bass in a 300B SET I have heard so far.

For a little over $100 and a few minutes of time the coupling cap upgrade in this Willsenton R300 is an absolute no brainer. It is a must do upgrade. The amp is sonically deficient otherwise. So for under $1400 for amp, shipping, and upgrade I have an amp that sounds amazingly rich, holographic, and musical.

Thanks again for all the advice. 

Yes given the cost of the map I did not want to spend too much on the upgrade but honestly I do not think it could sound any better. Bass, middle, and treble are all clear and in balance with each other. 

I am sure all the other caps recommended would have made a significant improvement as well. Maybe with just slight variations in bass or treble response. But the difference from the original cheap factory caps was much more than I had expected.

i personally would not spend so much on caps upgrade unless i know what trannies that are fitted on the unit.  

The amp comes out of the same factory a Cayin and PrimaLuna. I have seen it reported that there is some amount of sharing of parts. The transformers are indeed decent.

For the Muzishare amps they are made in the Line Magnetic factory. And once again some comments online and photos indicating identical components being used.

Electrolytics are Nichicon so just for the Willsenton they cheaped out on the coupling capacitors.

There was a very very slight smoothness added in the very upper treble after about 20 hours run in versus very sharp and defined treble notes when caps were first installed. 

Just last night I installed NOS RCA rectifiers and preamp tubes. So it will not be possible to report back any more cap break in changes. The resolution of the music increased along with the smoothness and musicality with the NOS tubes. I also tried new production Tung-Sol but they sounded gritty in comparison. Maybe new tubes need to break in as well so I am running them in another amp for now.

I am waiting on a delivery of PSVANE 300B TII matched pair power tubes as the last upgrade.

This is THE amp for my Klipsch Forte IV speakers. A perfect match.

Would I say it is the best amp I have in every case - no. The KT150 amp is better with my Dynaudio speakers for example. So system matching is still more important than these other tweaks.

@jaytor And most important, these amps have LETHAL voltages inside. Capacitors can hold a lethal charge for a long time.

So I should have been careful soldering that bypass cap on the 330uF 450V Nichicon filter cap from hot to ground terminal?

Oh dear maybe that is why it was so exhilarating doing the upgrade. A real exciting experience.

😀

But seriously that is good advice. Use the sorting cable with a suitable 10W resistor to discharge electrolytic caps first.

Each type of capacitor has a specific frequency response and voltage related distortion.

It should stand to reason that better constructed capacitors should have a better frequency response and less distortion. Whether you can hear the difference in reality or it is simply a fresh capacitor not being run in yet that sounds different I do not know for sure. But it seems in my case there was an improvement in frequency response and lower distortion replacing the cheap factory caps with one of better and different material construction.

In this article the title seems to take the opposite opinion but have a read thru and there is some information that at least confirms capacitor construction does impact sound quality.

Interesting.

NOS Allen Bradley Carbon comp resistors are all the rage for tube guitar amps. For their warmth and organic tone. I wonder how they fair in hifi? They do tend to drift in value a fair bit. So maybe not so good in hifi setting.

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

For example the Willsenton R300 amp uses a .33uF and is a slightly rolled off sounding amplifier while Muzishare amps are using .47uF on the filter cap and are brighter sounding amplifiers. PS audio apparently uses a .1uF

Is this power supply bypass cap impacting high frequency response? Or are the bass and treble response all in the various coupling caps and cathode caps etc in the preamp stage?

Thanks.

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.)

@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.

Capacitors of different construction types will have different sonic properties due to a number of factors (see below).

So as I understand it the properties of a silvergold in oil foil cap will be different than a copper foil in bees wax as they are impacted by voltage, current, and temperature.

As most with basic electrical circuit understanding would confirm, you can change the bass and treble response of a circuit by altering the capacitor value of coupling caps and cathode caps etc. Change from 0.1uF to 0.047uF coupling cap for example will reduce bass response.

So for just one specific example if the TC (temperature coefficient) of SGO Supreme cap of 0.22uF is different than Bees Wax cap of 0.22uF, then under operating temperatures in a hot tube amplifier their actual capacitance may be different and hence their bass and treble response will be different. How much of an impact that actually has or all the factors combined has is up to your ears to say. 

Some key properties of capacitors:

1. Nominal Capacitance (C). Capacitance refers to the amount of electrical energy a capacitor can store within its electromagnetic field. This value is represented in the unit Farad, including pico-Farads (pF), nano-Farads (nF), and micro-Farads (µF or sometimes uF for simplicity). Fixed capacitors have a specific capacitance that cannot be adjusted. Variable capacitors can be modified to achieve a desired capacitance within the available range of that capacitor.
2. Working Voltage (WV). The working voltage is the maximum amount of voltage a capacitor can receive continuously without damage or failure. Voltage can be DC (direct current) or AC (alternating current). The WV printed on the capacitor itself will typically refer to the DC rather than AC. The WV is affected by temperature, as the value listed only applies within a specific temperature range. Extreme heat or cold may affect the working voltage a capacitor can withstand.
3. Tolerance (±%). The capacitance value listed for a capacitor can sometimes vary more or less. The value can only vary by a certain range to be accepted, which is its tolerance. Tolerance can vary anywhere from real low tolerance like 1% all the way up to part with a -20% to +80% tolerance. Common tolerance values are 5%, 10% and 20%, this of course varies based on the type of capacitor it is. Capacitors are ranked in quality based on their tolerance. The lower the tolerance, the closer the actual capacitance is to the value listed by the manufacturer, thus the higher the quality of the capacitor (and oftentimes more expensive as well).
4. Leakage Current. A capacitor contains a non-conductive material known as a dielectric. The dielectric will typically allow a small amount of electricity through, referred to as leaking. Leaking happens because of the strong electromagnetic field that exists between the plates when voltage is applied. Extremely low leakage in a capacitor, such as in a film or foil type, is said to have a high “insulation resistance” (Rp). High leakage, which is more typical in electrolytic capacitors, is referred to as “leakage current.”
5. Working Temperature (T). Temperature affects a capacitor’s ability to store electrical energy. For example, extremely high temperatures can cause a liquid electrolyte in an electrolytic converter to evaporate and change the capacitance. In contrast, extremely cold temperatures could cause liquid or gel electrolyte to freeze and impact its capacitance.
6. Temperature Coefficient (TC). The temperature coefficient measures the change in capacitance that could occur within a particular temperature range. As temperatures rise, some capacitors increase their capacitance values and are considered Class 2 capacitors, such as this one GRM155R71C104KA88D, and others decrease their capacitance value. Capacitors that are able to maintain their capacitance within a temperature range are considered to be Class 1, like this one CC0402JRNPO9BN101. The importance of temperature when it comes to capacitance depends on the job at hand. If you know that temperature may be an issue, the TC is an important characteristic to be aware of.
7. Polarization. This refers to the charge of the plates within a capacitor. In most capacitors there is a positive end and a negative end, similar to a battery. When applying voltage it is necessary to match positive voltage with a positive terminal, and negative voltage with a negative terminal. Incorrect polarization can lead to severe damage within the capacitor and throughout the circuit and device.
8. Equivalent Series Resistance (ESR). This is a term for the total resistance of every part of a capacitor that resists, rather than conducts, electric current. It includes the resistance of the plates, the dielectric, the terminal leads, and the connections to the dielectric. ESR is the sum of all of these, measured within a specific frequency and temperature. This determines energy loss for a capacitor.

@terry9 

Thanks for the additional info.

I was just making the point that there are physical properties to capacitors that can alter the sonic characteristics - but the cut and paste text was more related to electrolytic yes.

Some people believe that a capacitor with a certain capacitance value must sound the same as another with the same capacitance value regardless of the type of construction. That goes against common sense for anyone with a basic understanding of science or materials.