Question About Capacitor Upgrade in Tube Amp

What I have found useful:

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

if you are trying to upgrade the coupling caps, the amps are to cheap in quality,  i don’t recommend it.   To me it’s a big waste of time, money and effort.  This is just my opinion!! 

@calieng 

I am going to respectfully disagree with the above comment that disparages upgrading your amplifier’s coupling capacitors. Tube amplifiers in general and particularly SET amplifiers have very straightforward/simple circuit layouts. With regard to the SET amplifier there is a lower part count.

Essentially one could argue that because of this, each part individually takes on more importance particularly in the audio signal path. I believe that changing to a higher quality coupling capacitor is a very good idea and money well spent. 
 

if you take the time to research and do further reading/investigation you will find a better capacitor that will contribute to improved sound quality. I’ve had splendid success with the Duelund CAST copper foils. Considerations are available space for a given capacitor and the cost. No doubt there are other excellent choices available.

I suggest that you reach out to @grannyring via site email. He is most definitely a knowledgeable and helpful resource.

Charles

I have inexpensive Jantzen (2.2) red colored caps in my Bottlehead Paramours that sound excellent.

Been thinking about going SS, but if I don't I may try the Jantzen silver colored caps which are said to have a bit more detail.

I don't recall what was in their originally (been using them for 20 years now).

I looked @ Audyn  copper when they first came out, but 2 of them cost twice as much as I paid for the amps/mono-blocks.

However, if you go with Zipost's advice don't stop there as you can also downgrade your speakers, cables, source gear and maybe even the tubes if you are lucky.

DeKay

I like these 

Bottlehead is a good example for illustration. They are inexpensive and thus a low barrier of entry for budget buyers. Although low cost, they are consistently well designed and engineered. They are good candidates for upgrading to better quality parts due to their solid engineered foundation. They will definitely respond to higher quality capacitors/resistors/transformers/tubes etc.

Charles 

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!

If you could fit one or more ClarityCap TC600 film caps in the power supply to replace the electrolytic, you’ll get a cleaner, blacker sound. They need 10 hours+ to break in from sounding plasticky. I've done this so I'm speaking from experience!

It all depends on the room ,if space is not a issue buy far the best is the 

Duelund Tinned Copper foil paper oil caps ,

I have been modding for over 20 years and yes Humble homemade Hifi capacitor test is very informative , I-use Duelund in my Coupling caps in my Coda preamp section , they are Big  and take 4-500 hours to fully settle in , I tried vh audio Cutf, Odam , Millflex, JupiterCopper foil , Duelund is the Standard all others are judged by , Their silver foil has slightly better detail ,but I feel the Tinned copper foil oil 

fantastic banace and naturalness ,they are 2x+ bigger then most anything out there

thats the only draw back.

Yes, much will depend on available interior space for capacitors and cost. If those are not limitations I’d choose Duelund for this project. Expensive but worth it based on my usage. How ever good this particular amplifier currently sounds, better quality coupling capacitors will take it further up the sound quality scale.

Charles

Let’s begin with the fact that capacitors are among the most non-linear parts of any amplifier -- so any real improvement is worthwhile. I don’t know what the existing caps are so none of us have any basis to comment on the upgrade value specifically.

Let’s assume they are not the best.  Would be better if you said. Do you even know this to be true?

You discuss two types of capacitors: 1) coupling caps which block DC and allow two stages to to be linked, pass the music signal, but allow two different DC points to exist. These are directly in the signal path and a better cap means a better signal. 2) you discuss what is called a bypass capacitor on the power supply (B+ to ground). Broadly speaking we can think of capacitors (electrolytic primarily) that are efficient, with large capacity for their size, and cost, but are very nonlinear, especially as frequency rises. Alternatively there are various classes of capacitors that are the revers - large size, small value, but very linear and good sounding. Good design combines the two allowing one to provide capacitance and the others to provie linearity and efficiency at high frequencies. The best of these are film type capacitors (Mylar, or better yet poypropolene). Ceramic are also very good but have only tiny values or low voltages for the monolithic multilayer types (like << 50V).

You can pretty much know what will be the best sounding from one value: dialectic absorption. A Poly type is typically something like 100X to 1000X better than a "lytic.

As to whether they matter: yes. They make the power supply, well, supply, at high frequencies!

So get polyprop caps of >> whatever the applied voltage is (more is better, but gets $$ and big) and put them in. Poly caps are NOT polarized, but there is often a band that indicates the end to be grounded.

Justme.

So, in case that was too techie and long, yes replace them all (if the ones you already have there are poor, we have no idea really).  My two cents replace them with polypropolene films caps of the same or slightly higher voltage and the same capacitance (or more for the bypass).

Dont worry about brands.  Paper is long term unreliable.

ANY cap upgrade is useful, power supplies included.

In general, the type of capacitor is more important than brand. From cheapest (and least good) to best: metallized insulator, film and foil, air gap, vacuum. There is a good discussion of this in 'Art of Electronics.

Next most important are the materials: polypropylene, styrene, teflon (insulators); aluminum, tin, copper, silver (conductors).

Polypropylene is not as clear, teflon can be a little harsh. To my ears, styrene is just right. Conductors are not as important, although there are differences. Aluminum is prone to corrosion and can be a little harsh. Copper is expensive. I find tin to be a good compromise.

I mainly use air gap and vacuum caps for the most important components, such as RIAA compensation. For amps, I usually use styrene.

For brand, I use MIT or Relcap for signal path, Solen for power supply. Phono stage uses Solen teflon for the final power supply filter. Good luck!

YMMV

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.

The small film caps that are put across the electrolytics, are bypass capacitors.

A small high quality bypass cap can greatly improve the SQ from the bigger electrolytic.

I recently recapped a tube amp and I put Myflex capacitors with great success.

Also recapped a Marantz 7T and because of space restrictions, used Audionote electrolytics with Myflex bypass capacitors on each one. Also sounds fantastic.

Deoending on how long you plan on keeping the amp, buy the best capacitors you can justify putting into it. They will make a difference. Humblehifi’s capacitor list has served me well in the past when deciding on what caps to use.

And ignore the comments about your amp not being worth the effort. It’ll be worth the effort. Anyone who has done a recap, either themselves or by a tech will tell you it’s worth it. 

Paul from PS audio on caps…

He discusses caps/bypass caps.

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.

@perkri 

Depending on how long you plan on keeping the amp, buy the best capacitors you can justify putting into it. They will make a difference.

Yes! 👍

Charles 

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

First: disregard zipost's rude comments. He's just grumpy because he only took second prize in the local village idiot competition. Hey zippy, better luck next time.

The Willsenton marked 0.33ufd cap is there to shunt any noise (high frequency crud) to ground. This is after the rectifying diodes where the AC is being converted to DC and any noise/hash not handled by the bigger cap is 'captured' by the small 0.33ufd and directed to ground, hopefully leaving the B+ supply in pristine condition. So to answer your fair question: Yes, it will most definitely effect the sound and the correct choice will do more than just improve tone. Think blacker background allowing more detail to be heard and all the benefits of that.

The purity of the power supply is paramount in any audio device as witnessed by the plethora of LPS units available to replace those cheap, small and generally noisy switching units. I have used a Mundorf Supreme (0.22ufd, think it was the Supreme) across the last cap in the PS with positive results. Do some research specifically on PS bypass caps.

Regarding the coupling caps: @charles1dad has some good advice. They will/can also have an effect on the end result. Duelund make a 0.01ufd cap for bypass duties and are very very good. In this coupling position you are preventing the HV DC from appearing on the output terminals and here you will find you can 'flavour' the sound. Ideally you are trying to 'do no harm' to your precious signal.

Miflex, Jupiter, Duelund, and many more to consider. The link to the cap shootout is a great guide.

@lemonhaze 

👍

Good insightful comments.

Charles

Lots of good info already post.  Parts are not that expensive so have at it.  If it was me, I would use the V-Cap ODAM as my first choice and see if that floats your boat.  We use them exclusively in our designs.  We have also use the copper Milflex with good results.  One of the best comments above is space.  Be sure to look at the size specs first to make sure things fit in.  Audio Note and Nichicon capacitors are excellent and so are the non-magnetic Audio Note resistors.  Things get a little pricey but if you doing the labor that is a cost savings there.  Last especially for tube equipment, look for AC filter chokes and other chokes to replace capacitors, etc.  All parts have sound but to me, chokes are a big benefit plus a lot cheap!

Happy Listening.

"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.

If your looking to upgrade coupling caps you can also play with the value of the

caps because they play a critical role in output impedance. For example,  I purchased a tube preamp which sounded terrible, no dynamics, no amplification.

Turns out there was an impedance mismatch between my amp(LSA class D) and the newly purchased preamp. After some research, I purchased a slightly upgraded cap with an increased value and surprisingly, it worked and am extremely happy with the outcome. Wanted to give my 2 cents cause coupling caps play a critical role, whether you're upgrading or changing the value, dismissing it's importance is  just anti-audiophile.

I've used most of the caps mentioned here and have found the Duelund Cast, in my case tinned copper version relegates every other cap to  a distant second place, really special cap, future plans for going into my speaker crossovers as well. I also like bypass film cap on electrolytic power supply caps if one doesn't have room for all film caps.

Charles is correct, SET circuits low parts count, so every single part change has bearing on sound. Resistor upgrades also worth investing into.

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.

@calieng

You certainly have quite the amplifier stash. I wrote earlier that the Bottlehead tube products were although inexpensive they are well thought out engineered components. A price point is targeted and so the best quality parts can not be utilized.

Well, it seems that this principle is applicable to the Muzishare and Willsenton amplifiers. Good solid design with decent but not the best quality parts due to cost restraints. So very good candidates for upgrading part quality to achieve better sound. I believe that your project will turn out fine.

Charles

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.

It's more complicated than just hanging a film cap across B+. If you assume the designer knew what he was doing, had good ears and related equipment, you could make things a whole lot worse by making willy-nilly changes.

Too often audiophools make changes that make ZERO difference but think they have due to everyday occurrences like fatigue, humidity, temperature, atmospheric pressure, line voltage / noise, etc. etc. etc. 

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.

@calieng 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.

I am glad that you see his point. I do not. He makes smug and arrogant assumptions about people he doesn’t even know. He has no awareness of the background and experience of contributing posters here (Who’ve provided insight and information).  Audiophools? Who are they? Again an ignorant and dismissive assumption.
A useless and unhelpful post in my opinion.

Charles

@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!

😀

Another quick thought, from personal experience. 
 

If you are doing the work yourself, one part out, one part in. Take pictures of every section you are working on before you start and after you finish. Speaking from experience here. Didn’t do that on my first recap project.  Nothing worse than being called away from the work, coming back and having a “oh crap, where does that go again…”

Please forgive the note if it’s already common practice, or if you are already comfortable with pulling every and then replacing everything.

@calieng 

I don’t see the need to excuse rude and obnoxious behavior. I appreciate that we view this differently and that’s fine.

Charles

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

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.

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.

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!

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.

Good points and I see more clearly your perspective. You have received some very good insight on this thread. I look forward to your listening outcomes.

Charles

@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.

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.

There’s a lot more going on than just the caps. Power, impedance, source, cables, loudspeaker, tube age, wire, sockets, etc. etc. Change one thing, change everything.

To those who don’t like the tone:

Are you fine with people being seen off by charlatans that give bogus reasons with ZERO supporting evidence other than their say so? They think their system sounds the same every day or that they can turn it off for some time, make a change and then determine a delta. Ha! Qualified engineers listen for weeks, making comparisons between a reference unit and the changed. Confirmation bias plays a huge part in an awful lot of opinions.

I’ve been at the HiFi game for more than 50 years, Grammy nominated engineer and if you saw a movie from about 1990 to 2010, quite possibly the soundtrack was recorded through something I designed.

Some posters blather on about changes without the slightest regard for rigor. To boot, they evaluate whilst intoxicated and at injurious levels. I endured too many sessions with doped up musicians to have any tolerance for audiophools.

PAX.

Engineers with ears pick caps where the evaluation circuit and signal allow them to be fully formed… in many cases those big monster caps never get fully formed… or stay formed…especially at reasonable listening levels…

Applaud the OP for diving in and trying….and learning…

Enjoy the music and the journey

Hello calieng!  Nice photography!  That cap looks pretty good. It's purpose is to keep high frequency noise from riding out on the B+ line. I would add a .01 capacitor in parallel as well. Keep the leads as short as possible. I'd use the fanciest Mundorfs (gold foil etc) with a voltage rating at least 100v higher than your B+ supply. I have lots of experience with power supplies and the noise that can show up on them. I used to live near a Navy base and discovered 2 volts of HF & VHF garbage on unused, unconnected phone lines in a rental house. How it got there, I don't know. I used to run a computer lab that had 51 PCs driven mad when someone plugged an extension cord through an open window and fired up a hedge trimmer outside! It took two days to get the lab back to normal. There is so much electronic stuff around these days that it is good to be as careful as possible. Please forgive those respondents with negative comments. This may be their only outlet for their hostility and it keeps them out of the bug house. Happy Listening.

@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.

The elephant in the room that no one notices is Power Supply Impedance and Phase. It is perhaps the most important and neglected aspect of HiFi design.

Capacitors have two frequency dependent properties, ESR and ESL, often ignored by engineers and almost certainly by Joe Audiophool.

The amplifier circuit, if perfect, does nothing more than regulate the power supply. If the power supply has poor phase and impedance, it passed on to the next component. Sequential components alter the preceding and this is why a really great component may get so-so response in one reviewer's system and sterling accolades in another.

Sequential components & cables all add their sonic signature.

Hence, when Walter Wannabe audiophool swaps out ReallyGoodMatch for  BigFatSilver caps, he is altering his entire system and any perceived change, improvement or not is only valid for his system.

Add in the $$$$ and time incentive, and of course it's better.

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. 

sounds like much more than an “ initial impression “….