Doing a little cleaning out my favorites, I found this string from AC forum.
https://www.audiocircle.com/index.php?topic=114637.0
I found a tiny tweak in the up graded DAC's power supply, just a little cleaner in the upper bass, lower midrange.
I know, I know, I performed a tweak. Well, all I can say is that it was extremely minor.
cheers
steve
Hi Steve,
Audiophiles don’t forget great products. I imagine you occasionally get in an 11a or a 10a to replace caps or do some other maintenance. As to your dac, I’m assuming you are still using the Schiit Modi 2?
Hi Nick,
To answer your last question first, yes I am still using the hugely upgrade Modi 2. I adjusted the
power supply uf total just a hair as well as the voltage rating for one cap. What is sometimes irking
is that the shape and voltage rating of a cap affects the sonics. Of course higher voltage rating,
more conductor area, more resistance involved.
I have 16 smaller poly caps in parallel in the power supply for the analog chip gain stage. For
another tweak, I could change the other analog supply, with 5 caps, and go with a bunch of smaller
and see what happens.
I just can't stop tinkering for that final gram of improvement, and I thought I could go no farther when I
started this string. The title of this string makes me a hypocrite, so I changed the title to almost finally
finished.
Concerning your first comment, actually no 10As have come for at least a decade or more. The last one I
recall working on had the gold plating of a tube socket filament pin separate, causing an intermittent tube
filament from heating.
I have had two 11As that needed repair a very long time ago. The first was on the initial tour
(~17 years ago?), when a Mills military grade resistor became noisy. The second 11A, in Europe,
an intermittent audio output relay (in parallel) that sometimes refused to open after 45 seconds.
I have tinkered around, on my own 11A, with switching the initial electrolytic capacitor to poly, so it will
last forever (except for lightning strike). This does not affect the sonics because I use a hefty 5 filter
stages after it. I attribute the longevity for two reasons.
1. The caps have very little surge and repetitive peak currents; far far below max rated. Just a few ma.
(milliamps).
2. The operational temperature is just a few degrees F above room temp. I believe the general rule of
thumb is that for every 20 degrees F below max rated temperature by the manufacturer, one can double
the hours of useful life. By the way, the hours rating by manufacturer is at both maximum temperature and
maximum ripple current. Peak current is also minimal.
Just calculating by temperature, I arrived at 90,000 hours. Since the ripple current in the 10A/11A is just
a few ma., the life should be much longer.
One customer, I replaced a couple of resistors to Vishay naked Bulk foil after I tested them in my 11A.
Vishays have at least 20db less noise than other metal film resistors.
If I have missed something, please correct me, but I don't think so.
Cheers and happy 4th Nick and Gents.
steve