ELNA Silks
I posted this on another thread -- NP had mentioned them a few months ago
I ran some simple tests with a distortion analyzer -- the ELNA Silk caps look pretty darn good.
I posted this on another thread -- NP had mentioned them a few months ago
I ran some simple tests with a distortion analyzer -- the ELNA Silk caps look pretty darn good.
An externally hosted image should be here but it was not working when we last tested it.
The yellow is a cheap cap I bought from Jameco decades ago, the Green is one of the lot I purchased from Tektronix about 5 years ago (they are actually quite good in power supplies). I took a look at a Solen 30u/400V and it was the best of the lot, but it would not be distinguishable on that particular chart, hmmmm, maybe if I...
An externally hosted image should be here but it was not working when we last tested it.
I've soldered my speakers terminals and the amp is mechanically finished 
I'm observing that, apart from BIAS, the DC offset drifts with temperature as well. I started with the trimmers in half position (250 ohm, measured), turned the amp on, and my DC output was an amazing 0.2 mV. Now it's raising, after 10 minutes running I read about 10mV. I suppose that the DC offset is to be set with the amplifier hot, like BIAS.
It's 23:45 here, my parents are goin' to sleep, but I think that nobody can deny me some low-level listening, this night....
Giacomo
I'm observing that, apart from BIAS, the DC offset drifts with temperature as well. I started with the trimmers in half position (250 ohm, measured), turned the amp on, and my DC output was an amazing 0.2 mV. Now it's raising, after 10 minutes running I read about 10mV. I suppose that the DC offset is to be set with the amplifier hot, like BIAS.
It's 23:45 here, my parents are goin' to sleep, but I think that nobody can deny me some low-level listening, this night....
Giacomo
Magura said:
Yes, the DC offset and bias setting, must be done at working temperature. Note that you will most likely have to re-adjust both, once you put the thing inside a box.
.......and please enjoy.
Magura
It's already boxed, I pull the cover off for adjustments. I decided to do this way for exactly that reason (thermal behaviour).
Now, dear Magura and dear all, BIAS is okay (250-248-252-etc. mV across the power resistors), DC offset too (0.1-0.3 mV), and it's definitely time for some quiet overnight listening...
)))Giacomo
since we are talking about bias and offset,i have a question--when i put my meter on the output to measure dc offset ---then turn the amp on,why does the offset spike to 5V then settle down to a almost zero in a few seconds????? also how much offset is to much ( to hurt your speakers) my offset will wander as it is warming up-i have reset it to zero after 1 hour but after 8 hours it will be off again
Just a short update:
- The Diode issue is fixed, the MBR1645 is a fine Diode. I simply had a mechanical break in one of the diode legs and replaced it, works well now.
Some of you may recall that I had a lot of different PSU-Caps on the bench to test which one will uncover the full potential of the F4 best.
I started with the Panasonic TSHA in a classical CRC with 0.11 Ohm as the "R" and 33000uF for each of the 4 Cs per channel. I use my F4 as mono-blocks, bridged.
With the Panasonics I had a very open and smooth sound. It could have had more transparency here and there in the trebles, but the mid-range was very good and lush and warm and transparent. I did not use any bypasscaps in the psu.
Now I have changed to Jensen's 4 Pole. I read in the data sheet that the Jensen have a kind of build in CLC, so I simply did not use a CRC, withdrew the resisor from the equation and have now four 25/47000uF Jensens playing per channel. They become warm, but not hot (in THIS SIZE, be aware that the Jensen have current ratings per physical size of the cap!)and give me even without the resistor 0.3mV (on the V+) rest-ripple, which is astonishing low, should normally be much higher with normal caps.
The caps are now playing for the first 24hours. Currently I would say, the sound more hifi and sound brighter, but as well more mechanical than the Panasonics. But I guess they are breaking in currentliy and simply need more time...I gave the Panasonics 4 weeks to break in and after that they played really nicely.
Question:
- HAs anyone experiences with the Jensen's ? Will they change or have I captured already their character ?
- Is the "R" in the PSU-filter only there to reduce ripple or does it as well do other stuff (it obviously enhance the impedance of the PU, which is normally not a good thing) which impacts the sound positively ? I have as well some nice chokes here around, but I ask myself if that makes any sense when you simply don't have any ripple to fight ?
- The Diode issue is fixed, the MBR1645 is a fine Diode. I simply had a mechanical break in one of the diode legs and replaced it, works well now.
Some of you may recall that I had a lot of different PSU-Caps on the bench to test which one will uncover the full potential of the F4 best.
I started with the Panasonic TSHA in a classical CRC with 0.11 Ohm as the "R" and 33000uF for each of the 4 Cs per channel. I use my F4 as mono-blocks, bridged.
With the Panasonics I had a very open and smooth sound. It could have had more transparency here and there in the trebles, but the mid-range was very good and lush and warm and transparent. I did not use any bypasscaps in the psu.
Now I have changed to Jensen's 4 Pole. I read in the data sheet that the Jensen have a kind of build in CLC, so I simply did not use a CRC, withdrew the resisor from the equation and have now four 25/47000uF Jensens playing per channel. They become warm, but not hot (in THIS SIZE, be aware that the Jensen have current ratings per physical size of the cap!)and give me even without the resistor 0.3mV (on the V+) rest-ripple, which is astonishing low, should normally be much higher with normal caps.
The caps are now playing for the first 24hours. Currently I would say, the sound more hifi and sound brighter, but as well more mechanical than the Panasonics. But I guess they are breaking in currentliy and simply need more time...I gave the Panasonics 4 weeks to break in and after that they played really nicely.
Question:
- HAs anyone experiences with the Jensen's ? Will they change or have I captured already their character ?
- Is the "R" in the PSU-filter only there to reduce ripple or does it as well do other stuff (it obviously enhance the impedance of the PU, which is normally not a good thing) which impacts the sound positively ? I have as well some nice chokes here around, but I ask myself if that makes any sense when you simply don't have any ripple to fight ?
