What happens if i increase capacity of these two capacitors in T class amp?

Thread Starter

theCapacitors

Joined Oct 20, 2020
8
Hello all,
I'm replacing all of the capacitors (chinese low quality caps) in my current subwoofer (Q.acoustics 3070) with high grade , quality audio caps. However, I'd like to have your opinion about these two capacitors in amplifier board, i assume these are output caps?

They're 2x2200Uf 35V Thengx caps, i can replace with them 35V 2x3300Uf Panasonic FC series, or 2X2200uf Nichicon FW series.

Is it any better to replace with higher capacity like 2x3300uf? Would i gain stability or more power at higher loads? Or would it overload some other components in long run?

Thanks for your all advices.

Best regards.

amp board.jpg
 

Thread Starter

theCapacitors

Joined Oct 20, 2020
8
why you clearly said no? i'm interested in electronics but dont know much about it..it'd be great if you give a bit more information.Much appreciated sir.
edit: thanks for the detailed edit.
 

Papabravo

Joined Feb 24, 2006
14,685
why you clearly said no? i'm interested in electronics but dont know much about it..it'd be great if you give a bit more information.Much appreciated sir.
The likely purpose of those capacitors is either power supply bypassing or AC coupling.
In the first application of power supply bypassing you want to provide several paths to ground for AC noise on the power supply lines and bulk energy storage for transient power supply demands for current. In the second case you want to prevent any DC components of a signal from being transmitted to the speaker coil.
The reactance of a capacitor is:

\[ X_L= \frac {1} {2\pi f C} \]

As the the frequency f approaches 0, the reactance becomes very large. As the frequency approaches "blue light" (620-670 THz.) it becomes very small. Does that paint an appropriate picture?
 

Thread Starter

theCapacitors

Joined Oct 20, 2020
8
The likely purpose of those capacitors is either power supply bypassing or AC coupling.
In the first application of power supply bypassing you want to provide several paths to ground for AC noise on the power supply lines and bulk energy storage for transient power supply demands for current. In the second case you want to prevent any DC components of a signal from being transmitted to the speaker coil.
The reactance of a capacitor is:

\[ X_L= \frac {1} {2\pi f C} \]

As the the frequency f approaches 0, the reactance becomes very large. As the frequency approaches "blue light" it becomes very small. Does that pain an appropriate picture?
thanks a lot!
 

Delta prime

Joined Nov 15, 2019
576
Hello there:)
i'm interested in electronics but dont know much about
one would think that a capacitor is just a capacitor and that different types are interchangeable in practical use. In fact this isn’t so; capacitors differ drastically in engineering performance, and their sonic impact varies too. Capacitors don’t act like pure capacitance; As Mr.Papabravo just accurately stated, at high frequencies, capacitors exhibit inductive behavior, so their impedance actually rises with increasing frequency; a pure capacitor’s impedance would fall. At the transition frequency where the device changes from capacitative to inductive behavior, there is a minimum impedance that can be thought of as a resistance in series with the capacitor.
In theory, a capacitor blocks all DC and passes only AC (including audio). In practice, however, a capacitor will pass some direct current; some types, such as film capacitors, pass almost none, while many electrolytics leak a lot. (Incidentally, most power supply caps leak a great deal when the piece of equipment is first turned on; they stabilize after about 30 minutes, and leak less :)
 

Thread Starter

theCapacitors

Joined Oct 20, 2020
8
Hello there:)


one would think that a capacitor is just a capacitor and that different types are interchangeable in practical use. In fact this isn’t so; capacitors differ drastically in engineering performance, and their sonic impact varies too. Capacitors don’t act like pure capacitance; As Mr.Papabravo just accurately stated, at high frequencies, capacitors exhibit inductive behavior, so their impedance actually rises with increasing frequency; a pure capacitor’s impedance would fall. At the transition frequency where the device changes from capacitative to inductive behavior, there is a minimum impedance that can be thought of as a resistance in series with the capacitor.
In theory, a capacitor blocks all DC and passes only AC (including audio). In practice, however, a capacitor will pass some direct current; some types, such as film capacitors, pass almost none, while many electrolytics leak a lot. (Incidentally, most power supply caps leak a great deal when the piece of equipment is first turned on; they stabilize after about 30 minutes, and leak less :)
thanks for the reply...so you also think that changing capacity of the shown caps will not have any difference, right?
thanks again.
 

Delta prime

Joined Nov 15, 2019
576
You are learning electronics I could tell you as Mr Papabravo has done you will not hurt it if you change it. As an observer comparing before or after I you will not notice a change throw a scope on it you will see the change. Explore experiment have fun. And take all of this with a grain of salt because I don't know what a t-class amp is.:cool:
 

MisterBill2

Joined Jan 23, 2018
7,306
While increasing the value of the capacitors will not cause any problems, the damage done to the circuit board by incorrect unsoldering might not be repairable at all. That is a very real possibility. So the question is how good are your soldering and unsoldering skills? And will the TS be able to install the replacements with the correct polarity? getting either one reversed will certainly cause major damage.
 

Thread Starter

theCapacitors

Joined Oct 20, 2020
8
I have seen pictures of some soldering efforts on this site, and it would be hard to do much more damage without using an axe. THAT is why I bring up soldering skills. They matter quite a bit.
Helloo,
On shown side, there's no soldering done at all, it's from factory :) ,,, i'm good at soldering, did a lot of soldering without any damage so far. I can easily replace these caps, but would you recommend to increase capacity by %50 ? I was wondering would i squeeze a bit more power or stability at all..Thanks for your replies.
 

MisterBill2

Joined Jan 23, 2018
7,306
OK, If you can do it , good. I have seen photos of total disasters, which is the only reason for that comment. The big question I have now is what problem do you hope to fix by replacing the capacitors? Putting in better quality devices will improve the product lifespan, and avoid deterioration, but usually you may not see any change. Of course, I am not aware of how well it sounds in the present condition. It should not cause any problems.
 

Sensacell

Joined Jun 19, 2012
2,631
I would NEVER try "replacing all the capacitors" in a piece of audio gear.

1) the chances of ruining it are high.
2) the chances of you being able to detect any difference is vanishingly small.
3) the cost in MONEY is high.
4) the cost in TIME is even higher.

UNLESS- the gear was 40 years old, then it might be worthwhile.
 

Thread Starter

theCapacitors

Joined Oct 20, 2020
8
you may right about some items but torque/punch of bass is clearly very improved over original amplifier, espescially right after replaced reservoir caps (crap bran 200V 220uf replaced with 200V 680uf Nichicon PT series caps) ... I also noticed immediate punchier bass change even replacing crappy reservoir caps of 1200€ Dali Sub K-14F. Change is not minimal, clearly audible.
 

MisterBill2

Joined Jan 23, 2018
7,306
OK, And I am glad that the replacement was a success. 220 mF does seem a bit small for a power supply capacitor, but perhaps cost was more important than performance in the original design. That does happen quite often.
 
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