Improving the Coupling Capacitors for Better Tone Sounding

[opacheco]

Hi to everyone!

I am trying to improve the tone quality of this tube amplifier at maximum! and I would like to know what kind of coupling and dis-coupling capacitors can I use in order to achieve this superior sound quality, instance to the actuals Mica cheap capacitors used actually?

I have attached the schematic for your considerations and advices.

Thanks in advance!
opacheco

 

[ruffrecords]

Use good quality film caps (e.g.MK) everywhere except the electrolytics (for you should use low ESR types wherever available.

However,

I would not expect these changes to make a significant difference to the the "tone quality at maximum". That depends mostly on the output transformer and the power supply.

Cheers

Ian

 

[opacheco]

Use good quality film caps (e.g.MK) everywhere except the electrolytics (for you should use low ESR types wherever available.

However,

I would not expect these changes to make a significant difference to the the "tone quality at maximum". That depends mostly on the output transformer and the power supply.

Cheers

Ian

Ian
Thanks for your fast response!. Ok I will more infor about the “MK” capacitors; o never hear of them.
Btw: this amp have very good output transformer and in this sense I won’t have trouble I think. The actuals capacitor look like very cheap and I thought in polystyrene capacitor, what do you think about?

Thanks again
opacheco

 

[opacheco]

How about the “Paper in Oil Audio”? I found some K40P-2 Russians NOS units.

opacheco

 

[Newmarket]

How about the “Paper in Oil Audio”? I found some K40P-2 Russians NOS units.

opacheco

No need for that. Audio myth stuff.

 

[k brown]

The most that signal path cap 'upgrades' can do is a very slight smoothing/sweetening of the top octave; will not change the overall 'tone' of the circuit.

 

[Newmarket]

"Better" caps in this context have lower / negligible voltage coefficient. Also tempco but that won't show over the short term. Lower HD. If wanting colour/distortion then go with the cheap caps.
Apart from that consider whether you want a specific cap to define a high pass filter frequency. If not then go for the largest value practicable.

 

[ruffrecords]

Ian
Thanks for your fast response!. Ok I will more infor about the “MK” capacitors; o never hear of them.
Btw: this amp have very good output transformer and in this sense I won’t have trouble I think. The actuals capacitor look like very cheap and I thought in polystyrene capacitor, what do you think about?

Thanks again
opacheco

I should have mentioned they are made by a company called WIMA. Much respected in pro audio circles.

https://cpc.farnell.com/w/c/electro...apacitors/prl/results?brand=wima&st=capacitor

Cheers

Ian

 

[soapfoot]

It depends to a degree on what your goals are for "improvement."

Let's start by setting expectations: most claims of capacitor "sound" are at least moderately-overstated. Typically, in most applications, capacitor technology is at most tinkering at the margins. Don't expect a transformation (however, if you do expect a big change, it's likely that your mind will convince you to hear one!)

If you want "straight wire with gain," this is fairly easy to accomplish without the use of anything exotic. Any nice polypropylene film-and-foil capacitor should do the job for medium-sized values, C0G/NP0 ceramic for very small values, and a nice-quality aluminum electrolytic for large power supply capacitors. In that last application, you could also try (very-physically-large) metallized polypropylene film (e.g. Solen "Fast") if you want to truly go overboard.

If you want "vibe" or "character," you can experiment with less-optimal technologies. Many older devices are loaded with tantalum capacitors (even in signal-coupling applications!)--The classic Neve 10xx modules everyone loves used a ton of them, as did the most sought-after Ampex tape machines--and these do have "a sound." Technically, it's distortion, but it's distortion some people subjectively like. Likewise for Class 2 ceramics.

Polyester (PET or "mylar") film will for all practical purposes perform much like polypropylene film, but are slightly less-optimal and some will claim to hear a difference.

 

[Matt Syson]

Doug Self wrote about some capacitor distortions and probides useful comments. Mylar and other constructions CAN have a mid freauency range 'distortion' that is strongly signal LEVEL (across the caps) dependent so as usual 'It all depends' where they are used and what they NEED to do. Just been looking at a 'Disco mixer' that is almost completely DC coupled and reportedly 'sounds great' BUT all the pots 'scratch and fortunately there are no signal cutting switches except the PFL switch otherwise all the DC offsets will make their presence HEARD. The High pass filter (to protect mega bass speakers) conveniently covers up the various random offsets (sneaky).