[speaker]

Can't seem to find the thread that contained measurements of the LF response for this amplifier. IIRC, it showed the roll-in starting at ~150Hz & up. DOes anyone else recall seeing this? I wonder if this has to do with where the pole on the input filter is set.

Any comments?

speaker

[albee]

My subjective answer to this is that I have no bass rolloff using two-way standmounted speakers.  They're  -3@49 and sound pretty well driven to that point.   Perhaps the lack of bass depends on the speaker system and how they are used.  I'm completely satified with what I have using three different Tirpath devices.

[ohenry]

Here is the thread (I think):
http://www.audiocircle.com/index.php?topic=16621&start=0

Here is a graph:
http://www.michael.mardis.com/sonic/start.html

It seems that the SI board uses 0.33uF input caps while the tripath eval boards use 2.2 uF input caps.  That seems to make a difference in my experience.

Good luck and have fun.

[speaker]

Here is the thread (I think):
[url]It seems that the SI board uses 0.33uF input caps while the tripath eval boards use 2.2 uF input caps.  That seems to make a difference in my experience.

Good luck and have fun.

That cap value would make a tremendous difference in bass response. The knee of the SI input filter is ~100Hz & the standard Tripath value ~DC if I calculated that correctly. Seems like changing the input cap should be the first mod to make on one of these.

It makes sense in the context of the SI as to why it has this filter in place. As it can be run on batteries, you would get much longer life from them by restricting the bass output.

speaker

[panomaniac]

The graph is also over on my site:
http://www.michael.mardis.com/sonic/Bass.htm

The tiny input cap on the S.I. board is the culprit.  I replaced it with a 4.7uF polypro. (2.2 will work just fine).

It made a huge difference. There is plenty of low end response now.  The modification is not difficult to do, just desolder the input caps and solder in some small wire leads to your new caps.  If you use something like a Panasonic or Black Gate electrolytic, you may be able to attach it directly to the PCB.

Here are photos of the board showing the input caps.
http://www.michael.mardis.com/sonic/inputmods.htm

Have at it!

[speaker]

The graph is also over on my site:
http://www.michael.mardis.com/sonic/Bass.htm

The tiny input cap on the S.I. board is the culprit.  I replaced it with a 4.7uF polypro. (2.2 will work just fine).

It made a huge difference.

Excellent feedback, thank you!

speaker