Sonic Impact Gen 2 mods (for a newb)

[Buckapound]

Chuyler1,

Any of the polypropylene caps on that PX page are worlds better than what's in there now, I think. So, just pick one.

Try the 1000uf Xicon, maybe two if you can fit them somewhere. The description mentions "low impedance," which is what you're looking for.

I did change the output cap on one or two of my little 2024 Tripaths, didn't notice any change. These are just for dumping RF crap to ground, so not directly in the signal path.

--Buckapound

[rhing]

Originally posted by chuyler1
Rich, do you have any photos of the mods you've done to the gen 2? I'd like to see where you placed everything inside the stock case.

Here is one shot of the SI Gen 2 T-amp I modded using the stock case.

[rhing]

Originally posted by chuyler1
Ok, so for mods, in order of priority I should do the following:

Upgrade Power Supply
The Skynet SNP-9037 is recommended as well as the Power-One MAP110-S148.
Where could I get the Skynet or Power-One or something equivalent? My google searches only turn up wholesalers for the Sky-net and i didn't see anything on All Electronics. Any more info on the Power-one # MPB125-S322 that BradJudy suggested?

I purchased a Skynet SNP-9037 directly from Skynet since they're in the Bay Area where I live. I prefer the Power-One MAP110-S148, but I do not know of anyone selling these anymore. I have been told that other Power-One MAP series switch mode power supplies offer similar performance. I would encourage you to search for a Power-One power supply.

Originally posted by chuyler1 Upgrade speaker output caps
Your original post mentioned replacing stock caps on the speaker posts with some Radio Shack (Xicon) 0.1uF/250V metallized Polyester film caps. Could you explain this a little? Is this mod necessary. I do plan on swapping out the spring posts with some banana style binding posts so i might as well do this mod at the same time. What from the Parts Express bin could I use?

The stock caps are fine, but when I tried to solder them across the Vampire binding posts, the leads were barely long enough. I decided to try the Radio Shack caps and they seemed to make the sound a bit smoother.

Here's another shot of my modded SI gen 2 T-amp.

[chuyler1]

Please excuse this newb question but it has been about 10 years since my last physics class...

For the input cap(s), I can use one 2.2uf or two 1.0f caps? If I use two do I wire them in parallel? A quick google search yielded the equation...

Cp = C1 + C2 + ...

That's correct right?

Now as far as audio goes, is there any sonic advantage to two small caps vs one big one?

Also, how do you determine the proper amount of capacitance for each of these mods? Is there some sort of rule of thumb...and why don't the manufacturers use the right amount? I understand they might use cheaper caps to save money but wouldn't they at least use the proper capacitance?

[chuyler1]

How does this sound.

For the input caps C3 and C4, I'll use Dayton 2.2uF 250V caps. I'll need two total right? one for each channel?

For the power rail cap C10, I'll use a Xicon 2200uF 16v cap.

Should I also get a pair of Xicon 0.1uF 100v caps for the speaker outputs just in case I can't reuse the ones on there now when i install new binding posts?

For connecting wire, how important is the 0.5mm Mundorf Silver-Gold wire you mentioned? Could I use single strands of CAT5 which is 24 AWG? Or should i buy something better? Do I need solid or stranded?

I have also added to my PE order two dual banana binding posts and a pair of chassis mount RCA jacks

[Buckapound]

That all sounds correct.

On the wire, this gets a bit into faith-based audio as people often have strongly-held beliefs about one kind or another. From what I've seen, the physics seems to be on the side of the less exotic solutions. I have a stash of various aerospace-type wire I bought at surplus, my thinking being that if it's good enough for a satellite or a fighter jet, it ought to do for my little amps. For short runs, the Cat5 ought to do you just fine. Easy enough to swap out later if you feel the urge to test the exotic waters.

Do twist the pairs of speaker wire--this helps prevent picking up stray RF or other EMF.

--Buckapound

[rhing]

Originally posted by chuyler1
For connecting wire, how important is the 0.5mm Mundorf Silver-Gold wire you mentioned? Could I use single strands of CAT5 which is 24 AWG? Or should i buy something better? Do I need solid or stranded?

I just happened to use the 0.5mm Mundorf Silver-Gold wire since I had some left over from modding a few Playstation One consoles for CD playback. I liked the results I got from using that wire with the Playstation output stage mods, so I figured it couldn't hurt in the T-amp. I also use Kimber Kable TCSS hook-up wire for other projects, but the 19AWG is a bit too big to solder onto the small pads. The Mundorf wire is sold core Silver alloyed with a bit of Gold, while the Kimber TCSS is stranded Copper. Both are Teflon insulated which I prefer. Like Buckapound, I have also used Mil-Spec Teflon-insulated Silver plated Copper wire, both solid core and stranded, that I have purchased from surplus electronic stores. I have had varying results, because the wire comes from different manufactures even though they all meet the same basic specifications. I think a great resource for audio wire and cable selection is Jon Risch's Web site:

http://www.geocities.com/jonrisch/index2.htm

[jannes]

In the usual Gen 1-mods R1 and R2 need to be removed as well as bridiging C3 and C4. When I look at the Gen 2 PCB I can only find R2 - R1 is located on the Volume PCB Is it sufficient to just bridge C3 and C4 on the Gen 2 boards?

Current mod-status: tank cap has been replaced by a 2200 uF Rubycon ZLH and speaker binding posts have been replaced by something much sturdier