[kyrill]

hi

I want to "check" my 1uF Dynamicap output cap. I measure "nervous" DC swings of -20<->+20mV mostly between +/- 12 mV but i see occasionally swings of 45 mV at the output of the GK-1 in both channels. Is this the normal range?
Kyrill

Ps if DC ( measured by DC "sensor" of MM) changes voltages 10 times a second is it still considered DC by the cap?

[AKSA]

Kyrill,

In a word, every thing is OK.

Sub 10Hz changes in DC do not get through the cap.

But it should be reasonably stable, because all supplies are regulated.

Cheers,

Hugh

[kyrill]

hi Hugh
but i measure -30mV, +30 mV and everything in between so fast that my MM has trouble in getting to pace the changes in the last digit ( little lcd screen) and i measure this behind the cap and MM set measuring DC?
do i do something wrong?

[AKSA]

Hi Kyrill,

Something is wrong.  Are you measuring the SS section output, or the tube section output, after the cap?

Should be the SS output, at the output which connects to the pot.

Ground reference should be signal, not power.

What is the regulated rail voltage plus and minus on the SS section?

Should be 14.2 to 15.5 volts, plus and minus, utterly stable.

Cheers,

Hugh

[kyrill]

i measure behind the cap between "hot"and neutral at the output rca plugs, at the outside of the enclosure.
 R- as well as L-output.

it sounds wonderful but i have these "swings"


Kyrill

[AKSA]

Ah,

That's after the tube coupler, which blocks the 45-50V coming off the tube!!

This is random leakage on the cap, all caps leak a little, picked up by a very sensitive DMM.  Pay no attention, Bwana, this is mere bagatelle... 

Lie back and enjoy the music, preferably with a warm lady and a smooth whisky.....

Ciao,

Hugh

[Rom]

Hi Kyrill,

Since I'm the one who build your GK1, the records for the test and voltage test point in your module is within the specs.

Actually, yours measured better than mine.

ciao
rom

[kyrill]

So i learn

caps that suppose to block DC leaks DC

I have acquired a Burson Buffer amp and that little box has +6 dB and no signal caps in the path
Thus this leakage is 6db amplified
my local modder the man who mods my DEQX has a poweramp with no caps in the signal path either. but to protect the speaker a DC servo is built in the amp to cancel DC at the output
with the GK-1 in front of it and the burson buffer afer the preamp the servo trips at an average of 20 minutes uninterrupted play.

the dynamicap leaks once at the time beyond 45 millivolts ( at least at the rca sockets)
but not Hi Romeo, i learn that my GK-1 has even better values than yours? So your different capacitor leaks even more?

By the way
I am still experimenting but first impression is the GK1 sounds wonderfully bigger, more gestalt like, better presentation of the music and more dynamic with the buffer between tuner and GK-1 than between Gk1 and amp. This could well be the case with cd player and or DEQX Cannot confirm yet

i saw that the NAD receiver puts a 230 ohm resistor in series with the output to the rca socket just after the output cap? why??? Is the output impedance now highered with 230 ohms?

and Hugh Tuan, yes a good advice, but with warm ladies next to me i simply forget to listen to music, ah well..

[AKSA]

Kyrill,

Try putting a 100K resistor across the active and neutral at the RCA output of the GK1.

That will bring down the drift.....

Now, do you see why I do not recommend removing the input cap on the amp?  These drifts can't get past two caps, but they sure as hell make their presence felt with only one!!

(That wasn't meant to sound like 'I told you so', but the removal of blocking caps is sex without condoms for electronic equipment   )

Cheers,

Hugh

[kyrill]

ah tuan Hugh


it sounds soooooooo wonderfulllllll, a major BIG experience and if you want to reach heaven, how can you block parts that help you in getting there?

and you are a naughty musical LOVER too, no?

btw The R .. as always a good technical advice

[Rom]

the dynamicap leaks once at the time beyond 45 millivolts ( at least at the rca sockets)
but not Hi Romeo, i learn that my GK-1 has even better values than yours? So your different capacitor leaks even more?

Hi Kyrill,

I did not experience or even see , the same as what you notice on yours, remember that when you do some mod on yours and remove the input cap.
What I mean by yours measured better than mine is that, the measured voltage offset on yours for one is much better than mine, while yours is let say 1mVolt for example mine reads 8mVolts.

I hope that clears it.

ciao
Rom

[AKSA]

sama sama kembali, bapak Kyrill,

I am reminded of Sir Thomas Beecham, when he once said,

'The British know nothing about music.  They just like the sound it makes'.

That's me, Kyrill.  There, I've admitted it, I love music, and I hold its magic sacred, and anything which buggers it up must be expunged, like a witch from Salem......

Cheers,

Hugh

[rabbitz]

I've found the Burson Buffer best when used straight after the source.

[kyrill]

yes true

and you can tweak the buffer to have zero gain.

but still i do have occasionally ? 45 milli volts DC at the output, both channels. So it is structural
and indeed i dont have an input cap
but
i have an output cap at the source: Auricap/  does it matter that auricap is at the output of the receiver or at the input of the Gk-1?
I did not measure DC (yet) behind the Auricap

although the more caps the more leakage is blocked by the next cap..

[kyrill]

Kyrill,

Try putting a 100K resistor across the active and neutral at the RCA output of the GK1.
..)

Cheers,

Hugh

2 questions Hugh
1) does extra R across  lower or higher the output impedance of the GK-1 which was 150 Ohm (?)  and or does the GK_1 see a lower input impedance of the next amp?


2) is it a major exercise to lower the GK-1 output impedance to match better low-like input impedance of possible power amps and is it a major exercise to raise the input impedance of the GK-1 to match it better with higherish output impedance of cdp of radio?