Output level lower after replacing V2 output caps

[ehx]

Hi everyone,

I tried replacing the output caps of my V2, from 470uF to 1000uF (non-polar).

The output level of the amp is now significantly lower than before.
It is so low that even with the volume pot at max its not even at normal listening level. Before, I usually only turned it up to around "10 o'clock".

Is this to be expected, or should I suspect that there is something wrong with the new caps?

I'm using 2x32 ohm phones (filtered HD-681s) and have done the gain mod to the V2 (lowered it from the crazy high factory setting).

Should I just reverse the gain mod?

Cheers,

/Erik

[robertkd]

Mar 8, 2010 21:36:14 GMT ehx said:

Hi everyone,

I tried replacing the output caps of my V2, from 470uF to 1000uF (non-polar).

The output level of the amp is now significantly lower than before.
It is so low that even with the volume pot at max its not even at normal listening level. Before, I usually only turned it up to around "10 o'clock".

Is this to be expected, or should I suspect that there is something wrong with the new caps?

I'm using 2x32 ohm phones (filtered HD-681s) and have done the gain mod to the V2 (lowered it from the crazy high factory setting).

Should I just reverse the gain mod?

Cheers,

/Erik

Ok one step at a time to be honest I would expect the same sort of level with either 470uF or 1000uf the latter giving marginality lower bass response.

Check the solder joints on the capacitors you replaced if ok,

I presume the gain modification was done previously to the capacitor mod and was working ok?

Check you interconnects and that your headphone plug is plugged in fully only asking.

[Deleted]

Mar 8, 2010 21:36:14 GMT ehx said:

Hi everyone,

I tried replacing the output caps of my V2, from 470uF to 1000uF (non-polar).

The output level of the amp is now significantly lower than before.
It is so low that even with the volume pot at max its not even at normal listening level. Before, I usually only turned it up to around "10 o'clock".

Is this to be expected, or should I suspect that there is something wrong with the new caps?

I'm using 2x32 ohm phones (filtered HD-681s) and have done the gain mod to the V2 (lowered it from the crazy high factory setting).

Should I just reverse the gain mod?

Cheers,

/Erik

Erik
Why not put the original capacitors back in and see if that fixes the problem? Unless the new capacitors are faulty (unlikely) you are more likely to have disturbed something else. Capacitor changes like that should make very little audible difference in overall sound level. In any case changing from 470uF to 1,000uF is only likely to make minor differences,and mainly at the very low end.
Alex

[PinkFloyd]

Erik....

The output caps will NOT change the output level. The stock 220uF output caps are fine with high ohm 'phones (such as the Sennheiser 300 ohm types) but not so good with low Z 'phones like the Grado (32 ohm types)

Let me give you an example.......

The 220uF caps give a cut off frequency of 22Hz with 32 ohm 'phones ( 2.5Hz with 300 ohm 'phones).....

Fit 1000uF caps and things change.... the cut off frequency for the 32ohm load becomes 4.9Hz and for the 300 ohm load 0.5Hz.... so we can see, from this, that "more" capacitance in this position is better for both high AND low Z 'phones.

There should be ZERO change in output level (just a bit more bottom end delivery with low Z 'phones) so I would agree with Alex here and retrofit the 470uF..... it's "possible" (but highly improbable) that you have a dodgy cap...... My money would be on a crappy solder joint.

Go over the joints with a HOT iron and flood a small amount of fresh solder into the joint...... the soldered pads should resemble shiny "domes" and not look like volcanos.....

Let us know how you get on Erik.

All the best,

Mike.

[PinkFloyd]

Eric.......

Also make sure the pads haven't parted company from the tracks..... were these the ONLY parts you fitted? If so, then it's a simple case of double checking your soldering (unless the caps are faulty)...... if you've done anything else to the amp (at the same time) let us know.

Mike.

[ehx]

Wow, thanks for all the replies guys!

Its really helpful to know that the change in output capacitance shoul not have affected the output level.

Now its back to the solder joints then...

What I forgot to mention in my first post is that I also removed the input caps (replaced with jumpers) at the same time as I changed the output caps... so I'll have to check those solder joints too. ;D

Anyway, thanks a lot for all your help, I'll post again when I've had the time to open up the amp again.

Cheers,

/Erik

[ehx]

Allright, problem solved, all is good.

I would have loved to be able to blame the caps or anything other than my own stupidity... but alas, that was the real culprit... again ;D

Here's a great DIY tip: after having soldered new caps to your V2, do remember to trim the excess legs off, otherwise they might contact the casing and cause strange/bad things to happen!

Oh well, these things happen when you fire up the solder iron too late at night (some sort of time lock/breathalyzer switch might be a good idea)

Thanks again for all the replies, this forum truly lives up to its name - it rocks!

Cheers,

/Erik

[robertkd]

Oh that happens

glad it's all worked out for you then, enjoy.