[panomaniac]

Aloha all,
 For those of you familiar with my site and my work on the S.I. amp, the mods have finally paid off.

I was beginning to not like this amp, too thin, too brassy.  All that has changed now, the amp sounds sweet with modifications.  And the mods aren't finished yet.

Hard to believe that it's the same amp.   With the new mods there is plenty of bass, and a much more dynamic sound. Gone is the bright brassy sound. Soundstage and details are vastly improved. The sound stage seemed to get much deeper and higher, though not much wider. Percussive sounds are now much better, the slap of the skin on a conga will make your head spin.

Musical phrasing is much better now too, more expressive. Detail is improved, with room sounds and reverb more more pronounced.

Basically I replaced the input circuit, including the caps, the pot, the connectors and filter coils.  There will be more modification to come later.

You can read more about it on my site.

http://www.michael.mardis.com/sonic/news.htm

All questions welcomed.

[j_luke_12]

CONGRATULATION!!!!!!!
pls.. post picture of modified board

[JLM]

Can't wait for images.

What is the size of the amp?

How long the battery "safely" run per charge?

Can you set it up with two inputs?

When will you be done tweaking?  (It'd drive me crazy to buy today and improved versions out within weeks/months.)

[Panelhead]

Aloha all,
 For those of you familiar with my site and my work on the S.I. amp, the mods have finally paid off.

I was beginning to not like this amp, too thin, too brassy.  All that has changed now, the amp sounds sweet with modifications.  And the mods aren't finished yet.

Hard to believe that it's the same amp.   With the new mods there is plenty of bass, and a much more dynamic sound. Gone is the bright brassy sound. Soundstage and details are vastly improved. The sound stage seeme ...

Mike,
  I know it is still evolving, but when you are ready can you post frequency response sweeps for the modified circuit? I am interestd in seeing if things are close to the Tripath Evaluation board specs  now.
  One idea I borrowed from Vinnies Clari T is soldering caps directly the power pins for the 2024. I used small 120 ufd, 16v caps like the FM to keep from overstressing the solder pads. It seems this is a very good treak. The single cap was changed also, but like the idea of very short path from using  a pair here. The EB2024 uses a pair of 180 ufd for this, without the larger single cap of the SI.

                             Good Luck!
                            George

[panomaniac]

Hi guys,
 I will make frequency mesurements in a day or 2 and will post them.
When I have the project in a presentable case, I will post pics of that, too.

To answer JLM, size is TBD.  Will likely be about 9 x 5.50 x 4.50, or smaller if I can squeeze all the big caps into it.

No battery, I have not found that the battery offers any sonic improvement over my linear regulated PSU ( a big surprise to me).
  I will test again after the output filters are complete.

This is good fun!  Great when the mods turn out better than you think.  None of that "yeah... I think it has more/less grain..." sort of stuff.  These mods make a big difference.

[Occam]

Mike - and what sort of transformer have you settled on?
TIA

[panomaniac]

and what sort of transformer have you settled on?
TIA

At the moment a medium size toroidal of unknown VA from Parts Express.

I will go to a 3A external "wall-wart" unit when it arrives.  3 amps should be plenty, average draw is much lower than that. Even with music clipping the draw isn't much. Max current use on music is 250~350mA into 8 ohms.

I use a regulated PSU.