Dear friends I am interested to upgrade my caps in the tube preamp from Audio theta tin foil 3uf200VDC to Miflex1uf 240VDC copper foil what are your thoughts will reducing the value to 1uf affect the bass and frequency response or should I go with a higher value than 3uf  
Where is the cap? What is the circuit? In the absence of solid understanding the safest course is to use only same value caps. They can vary by a bit but in percentage terms, okay? The values you are talking while small in absolute terms are large in percentage terms.   

I have swapped caps out many times, and always with great results. But always paying close attention and keeping values identical or worst case within a few percent. Most parts are within a few percent tolerance anyway. Take this approach and you will avoid a lot of potential problems.
Get a 3uF capacitor. If I were you I’d go with a higher rated voltage. I cannot tell if you’ll roll off the bass by going 1uF without a circuit diagram, but I suspect you will.

Your post suggests these caps are on the output of your preamp, please confirm.  We need to know to output impedance of your preamp. Please share that. Also please share the input impedance of the amp you are using. With this info I can help you decide. 
I think the Milflex are good, but not great.  The VH Audio Odams sound better in every sonic way and are much smaller making for easier fit. 
Let us know. 
Message @dgarretson, the King of Capacitors for his input! Cheers,
the output impedance is 1200 ohms and the input impedance of the amp is 470000 ohms
It is my impression/memory that 2uF is the minimum size for a preamp output capacitor.

1uF ~= 8 kOhms at 20 Hz. Calculate the ratio of this to the amplifier’s input impedance to see how much you would lose.
If your amp’s input impedance is really that high - 470k, then even a .22uf is fine! To assure it works with most any SS amp you may get in the future, then I would suggest any value from 1.5 uf - 2.2uf. It is best to keep the cap value as low as is reasonable as it helps sound quality. Bigger value caps, of the same brand, won’t sound quite as good as smaller values in that output position. Your preamp’s output impedance is not crazy high, but likely varies by frequency and volume. Depends on the circuit.
To assure no bass roll off with most any SS amp in the future, coupled with my comment on larger cap values, stick with 1.5 - 2.2 uf. I see no reason to use a higher value cap. I have built many tube preamps with output caps values of .47uf to 1.5uf with no issues at all feeding SS amps with input impedances of 47k and over. A 2.2uf value VH Audio Odam is my strong recommendation.  

The preamp is C1800 of canary audio and amps are grand reference from same canary audio for your reference 
These are tube amps and I do not wish to change them in near future so kindly suggest something which will give a more 3D holographic image
Canary Audio amplifiers do tend to have high input impedance.
@jasbirnandra you're in good hands with guidance from @grannyring😊.
With tube amps you are good with output caps from .47uf to 2.2uf.  If you want a more holographic image I suggest two cap brands.  
- VH Audio Odams 
- Duelund CAST CuSn - tinned copper version 

What do you think of the Audyn, miflex or the Rike Audio Q cap if you have heard them.
I need 4 caps and the brand mentioned above are going to cost a lot. 
No doubt that the cost can escalate with having to acquire 4 capacitors depending on the particular one chosen (Interior space is a consideration as some capacitors are large). I can absolutely vouch for Duelund CAST Copper  foil capacitors. 

 Put them in my Speaker's crossover (Only required 1 per speaker) and as output coupling capacitors in my DAC. This was grannyring's suggestion to me years ago.   Simply superb sound quality outcome in both instances. Worth every single penny to do so.
If cost is the issue, then consider a smaller value VH Audio Odam. Perhaps a 1.0 uf. In the end if these are still too costly for you, then a Miflex will be better than the others you mention. Yes, I have used all the caps you mentioned.

Please be aware that the Miflex caps are huge and may not fit easily based on the value you decide on. Check for fit first.  Simply look up the dimensions and make a mock up using a properly cut and rolled piece of paper or thin card stock. 

@ Grannyring
I had 4 jentzen superior Z caps changed them and was surprised how the sound improved though they are not burned in as yet just 10 hours
I guess caps do make a difference wondering how the V cap Odam or the miflex copper cap will fare will it be better than the Jantzen caps.
I have same caps with lower value 0.33uf 600vdc in my tube mono blocks also do you think changing them will also bring a good difference
The Odams are much better than the Jantzen Superior Z which I am very familiar with. Different level of sonic performance and nuance to be frank. However, they do cost more.  Where are you located? 
India, that is the reason I am unable to decide, will be buying blind hence your expert opinion I am zeroing in on the Miflex or Odam.

What do you think about the amp caps I asked in my previous post what do you think I should do.

Do you mind sharing what value uF you used? I have a C800 and was thinking of upgrading capacitors too, but the CuTF VCaps I was thinking of using is not made larger than 2.0 uF. 
Thank you
3.3uf 800 vdc  that is temporarily because I intend to use 1uf 250VDC of miflex in the future was just experimenting and found the results to be better than the audio theta caps what amp are you using 

I’ve got the smaller model Canary amp that jasbirnanda has and it has the same 4 x 3uF caps. 

I follow what you said re the output caps, and I suspect Canary went for 3uF just to play safe. But why are the interstage caps also 3uF? Could it be that on the interstage such a large value is needed?



Thank you. I’m interested to hear if everything is ok when you try a smaller capacitor like a 2.0 uF.

I have Musicaps in my amp; they’re probably not as good as the Theta caps you have in your amp.


If the caps are not on the output, but interstage, you should stick with the value they have.  I am only talking about the output cap position.  The caps tied to the the RCA outputs! 

I have custom built 2A3 SET amps and I don’t know what the input impedance is. I doubt it’s even close to as high as your Canary 300B, but I think it’s high enough to use a cap much smaller then 3uF.

My big concern was the interstage capacitor. Grannyring’s post confirmed my concerns. For the interstage capacitor, I (and you) need to stick to 3uF. 
Post removed 
I have written to Canary to confirm what the 3uf capacitors are for output or interstage lets wait for their mail

I cannot speak for your pre, but I’ll share what I have on mine.

I have 4 x 3uF coupling caps.

1 pair (the pair towards the back of the chassis) are output caps. I confirmed by measuring the resistance between the output RCA and the cap’s red lead and measuring between the 2nd pair of 6SN7 (the pair towards the back of the chassis) plates and the cap white lead. 100% they are output caps. This pair I may consider going smaller to get the best quality cap.

The other pair are interstage caps. I confirmed by measuring the resistances of that caps red lead with the grid on the second pair of 6SN7s and the cap’s white lead with the plate on the first pair of 6SN7s (the pair towards the front of the chassis). 100%, they are interstage caps. This pair I will stick to 3uF.

My pre also also has 2 pairs of 0.01uF caps - one per 6SN7 tube. In both cases the red lead is connected to the grid of triode 1 and the white lead to the plate of triode 2. IOW the two triodes in each 6SN7 has a coupling cap. I’m going to do these first as this is much cheaper - I just have ordered some VCaps a few minutes ago.

Note, this is the C800 MK2. How your pre differs I don’t know. I’m simply sharing what I have found.

Why do you think changing caps will give you the desired results?  It's the entire preamp design, not one circuit component, that makes the difference.

You'd be better off selling the unit and searching for a different one that will give you the performance you want.  If you change one cap in the circuit, the manufacturer may decline to make repairs to such a modified unit.
2 uF is almost perfect.  It's got low reactance and most boutique caps aren't too physically large at this size.

Of course, if you have lots of space and lots of money go with 4uF. :)

With tube amps you are good with output caps from .47uf to 2.2uf.  If you want a more holographic image I suggest two cap brands.  
- VH Audio Odams
- Duelund CAST CuSn - tinned copper version

Given the wording of your post, I was wondering if the caps you mention had a drop off in performance with values higher 2.2uF? I was looking at using 3.3uF Odams. 

Bpoletti, I am sorry but in this  case you could not be more incorrect.  Honestly. 
Pauly, no worries as the 3.3uf will sound great. Just wonderful. Order matched sets within 2% from the supplier.  Also, be sure to make note of the outer foil end and directionality of these caps. 
Then why are you trying to correct an obvious design error rather than looking at a more carefully designed instrument?  
The Miflex caps offer great performance for the price. They are modeled on the Duelund caps which are insanely expensive.

Obligatto caps also offer great performance for the price. 
Used both brands when recapping my tube amp and have also used in other applications.

Miflex has served me very well.

As far as changing values, that is fully dependent on the circuit design…
I received a mail from canary the 3uf caps are signal caps so will a lower value be ok

Changing even a single component ( pairs in this case - left+right channel) can, and does, make a huge difference in sound. In many cases more so than going from bad speaker cable to good ones.

There is no "design flaw". A good analogy would be a motor car getting a new, and much better, tires. The car is still the same, but a good set of tires can increase mileage, shorten brake distance, improve handling and make the vehicle safer. Same for an amp. It still the same great amp as before but it's a little enhanced, a little improved.

It costs a couple of $100 to upgrade caps vs. the tens of thousands new pre - amps will cost. New pre-amps, which incidentally will have the same or similar mediocre capacitors we are replacing in the Canary pre amps; meaning we'll be back at square one looking to upgrade capacitors in our new pre amps.
If by signal he means they are on the RCA outputs, then yes you can change. Don’t change the value of interstage coupling caps. 
You are absolutely correct there is a brand I do not want to name he has 3 line stage the basic, enhanced and super enhanced and the only difference is the parts used but the price is almost 40% more in each step up 
In my shoes what would you choose for correct tone timber and transparency
the Odam or Duelund  
If money is no problem and they fit….the Duelund CAST Cu(Sn).  This is the best sounding capacitor ever produced in my opinion.  

 " the Duelund CAST Cu(Sn).  This is the best sounding capacitor ever produced in my opinion"

I'm not in a position to declare it the best sounding as I've not heard all upper tier competitors.  On the forums I see from time to time comments critical of the high cost of the Duelund CAST Copper foil capacitors. Some audio products are overpriced and overrated relative to  similar quality alternatives. 

In my humble opinion Duelund CAST is not overpriced.  In this instance you get what you pay for.  In fact I consider them a value choice because I believe that their performance level is that noteworthy.  As I've said before in regard to them, they are worth every single penny charged for them. A superb sounding product. If you can comfortably afford them, buy them. There will be no looking back. 

I came so close to doing that. To be honest, it came down to a combination of they are so big it would mean outboarding the whole crossover, which in itself would be a huge project, and then there was the problem of even getting them. At the time when I was looking into it everything was backordered, and I just was not into waiting however many weeks or months. Okay yes there was the factor of spending more on the crossovers than the speakers. But having done this I know the crossovers ARE the speaker!  

When researching mine I tracked down a fellow in Kirkland who I believe had built some speakers using these caps. Was focused at the time on selecting mine. But now you make me curious to go back and see about maybe hearing them. And seeing them! These things are HUGE!!!
I can certainly see Duelund CAST capacitors approaching the prohibitive price range if a speaker crossover has numerous capacitors and  in the higher uf ranges. I was fortunate/lucky.  I had Only a single 5.5uf capacitor between the midrange drivers and tweeter.

Replacing the Solens with the Duelund CAST was immediately heard as an improvement ( Even though quite honestly the sound was very good with the stock Solens). Sound quality continued to improve as the CAST accumulated hours of break-in. But fresh out of the shipping box  it was an obvious sonic step upwards.

I replaced the 4 small interstage caps in my pre. Given their small value of 0.01uF I elected to go with CuTF VCaps. I am blown away by the improvement given the mediocre 3.0uF signal caps are still in place. It sounds like angels are in my room singing to me. Strings just hang in the air and the low level detail is almost overwhelming. 


I looked at a picture of the C1800. It is very different to my C800 and even uses different tubes. However, it looks like you possibly have the same small signal capacitors I have. If you have a multimeter you can confirm. It is much much much cheaper to replace those small caps than those big guys. And they do make a big difference. 

I’m looking for 3uF caps and I cannot find Duelands of the appropriate value anywhere. The largest I’ve seen is 2.2uF and I’m way to risk averse to go that low.

I can get ODAMs but I see Chris V has some 3.0uF TFTFs available at a steep discount (albeit still not exactly cheap)

Have you compared ODAMs to TFTFs? I have used TFTFs in the past and I do like them but I’ve never heard the ODAM so any input would be appreciated.

Thanks in advance 
The Odams are far better! Nice job with the Cutf upgrade! Just wait till they break in fully! 
Thanks for your advice grannyring  - 4 ODAMs on their way. I’m not even going to put the cover back on. The ODAMs will be going in the minute they arrive. 

"I am blown away by the improvement given the mediocre 3.0uF signal caps are still in place. It sounds like angels are in my room singing to me. Strings just hang in the air and the low level detail is almost overwhelming."
Congratulations @pauly,  happy for you. 
I don't know  why some would question the benefit of changing to superior quality capacitors versus price point influenced stock choices.