Sonic Impact Gen 2 mods (for a newb)

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Hi folks, I have read the original thread on the Gen 2 but being a newbie to amplifier modding I'm going to need a little more hand holding. I plan to document my progress with photos so that other newbies may learn from my mistakes...and that hopefully you won't have to answer the same questions twice. I'd like to make some improvements while keeping it in the original case, if possible. I don't know where to order parts from so if you make suggestions please point me in the right direction.

An externally hosted image should be here but it was not working when we last tested it.




First on the list, input caps? What farad, type, brand, and most importantly, how and where do I put them!

Second on the list, what other mods can I easily make while retaining the original case?

Third on the list, power supply? The original thread mentions a Skynet SNP-9037 switching power supply. Where do I get one and/or how do I build one?
 
No love?

I've been trying to research but there is just too much info out there since the original SI amp came out and I'm not sure where the finish line is as far as what mods to attempt. That in combination with the fact that the gen 2 is slightly different is overwhelming.
 
I recently posted this information about my upgraded components in my SI Gen 2 T-amp here.

Basically, most people have moved on from modding the Sonic Impact T-amps, because there are many better T-amps out there that are more worthwhile to mod and upgrade (Trends TA-10.1, Sure Electronics TA2024 board, 41Hz T-amp kits, etc.). I have a modded Sure Electronics board that performs better than my modded SI Gen 2 T-amp and a stock Trends TA10.1. This amp has even outperformed my Onix SP3 integrated tube amp.

From my own experience, I liked the Skynet SNP-9037, but dweekie, another diyAudio forum member, introduced me to higher wattage power supplies like the Power-One MAP110-S148. This is a 110 watt switch mode power supply that has been discontinued in production. Power-One currently makes similar power supplies that you can occasionally find at electronics surplus stores for a lot less than their $200+ regular price. I bought my Power-One power supply from All Electronics. Then I upgraded the nine (9) secondary stage smoothing caps on the power supply from the stock Nichicon caps to Panasonic FMs. Rubycon ZL caps also work well in this power supply cap upgrade.

As for other mods, Panomaniac (Mike Mardis) had listed his definitive mods for the SI Gen 1 T-amp here. This would also correspond to the SI Gen 2 T-amp as well.

Hope this helps.
 
I am out of town right now, but when I get back next week, I can pop open the lid and snap a photo. Basically, I removed C3 and C4 and soldered some 0.5mm Mundorf Silver-Gold wire to the pads. The pads are extremely small and delicate, so you have to be very careful when removing the SMD caps without damaging the pads. You'll have to use small diameter wire (22AWG or higher) to cleanly solder it to the pads. Anything larger can make things rather awkward. Next, I planted a drop of solder on top of the pads and positioned the wire on top of the solder bead before heating it. Some hot melt melt adhesive on top of the pad and wire joint will help as a strain relief. Then I soldered the shortened Axon cap leads to the wires and used some Blue Tack adhesive to dampen and hold the caps down to the chassis. I wouldn't spend too much money on the input caps, so something like the Radio Shack Model No. 272-1055 metallized Polyester film caps (1.0uF/250V; you'll need 2 pcs/channel) or the Axon 2.2uF/250V metallized Polypropylene film caps are fine.

To keep everything within the confined chassis space, I had to cut out the molded-in battery compartment to make room for the speaker binding posts and the input caps. A good hobby knife and a lot of patience will work here. I also had to bend the leads of the Panasonic FM electrolytic cap (C10) to orient the cap horizontally since the cap is too tall to fit under the lid standing up.

It sounds like a lot of work, but if you plan things ahead of time, it really doesn't take much time. The hardest part was removing the molded-in battery compartments without damaging the enclosure. Aside from the Vampire binding posts on the outside, it still looks like a stock unit. Your reward will be deeper and better defined bass, smoother and more detailed midrange, lower noise floor and a larger soundstage. As others have said, there are better T-amps out there. However, like you I just liked the challenge of working with the confined space of the stock enclosure while significantly improving the sound.
 
chuyler1 said:
How do you remove the original caps? Do you heat up the pad and just pull them out? Or do you clip them off?

Will I need a real soldering station to prevent damaging the board or will my current 15w iron work?

I wouldn't try to clip them off. Just heat up one pad and then the other quickly and the little thing should just come off. Alternately, slip an X-acto knife tip under one end as you heat it and lift one end GENTLY as you heat it. The do the other end to free the part.

I expect your existing iron will do the job. As rhing mentioned, those little pads are real delicate, and repeated heating melts the glue that holds them onto the board. I like to get the new caps in place and fastened securely, either with some kind of clue or a plastic strap, before connecting them to the board. If you're planning on wanting to swap out different caps, it might be worth hooking up small screw terminals that can be epoxied to the board somewhere, that the caps can attach to.

The other improvement worth making might be the power reservoir caps. These will be the highest-value (and likely the largest) electrolytic caps on the board. I can't remember what's on there now, but you might see benefit of up to 2,500 uf or so, and you can use one cap or two paralleled to reach that value. This theoretically can give you a little more oomph, especially in the bass. People like Panasonic FM series (Digi-Key), and I've had good results fom the equivalent Nichicon low impedance that Mouser sells. The original Si was especially deficient in this regard, but I don't know how needy this one is.

And while, yes, there might be better boards out there, the sound from the SI is amazing and well worth using. For the next step, look at boards or kits) like the Amp6 from 41hz.com) that use either the 2021B or the 2020 chips as they have a bit more power than the 2024, but still run on 12v.

Good luck.

--Buckapound
 
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?

Upgrade Input Caps
Replace C3 and C4, the input caps, with Axon True Cap 2.2uF/250V metallized Polypropylene film caps or Radio Shack Model No. 272-1055 metallized Polyester film caps (1.0uF/250V; you'll need 2 pcs/channel).
Is there anything at Parts Express that I could use? I have other stuff I will order from them and if one of the caps they carry will work then I'll go with that to save on shipping.

Upgrade Power Rail Cap
Replaced C10, the power rail cap, with a Panasanic FM 2,200/16V electrolytic cap.
Again, is there something from parts Express i could use?

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?
 
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
 
chuyler1 said:
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.
 

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chuyler1 said:
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.
 

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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?
 
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
 
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
 
chuyler1 said:
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
 
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 :confused: 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 :)
 
hi guys!
i bought a sonic impact t-amp gen2 and i want to replace the input caps as you explained in this thread

i sow the caps to replace are c3 and c4, the same of the 1st generation t amp
but the gen 2 has a different disposition of the components and they have diferent names.
for example the feed cap in the gen1 is called c10, but in the gen2 is ec1

so i have a problem to detect the input caps to replace with the 2,2uF ones
are they really c3 and c4 ???
i wouldn't burn it up
 
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