[grkn]

"You need to find a wire that terminates in an N type plug to insert in the SI, however. "

Could someone show me how a N type plug looks like?
I have a 7A lead battery lying around you see

[TheChairGuy]

grkn,

An N plug is a fancy name for the connector that fits into most walkman and many, many other portable devices...it's 5.5 mm outside diameter by 2.1 inside diameter.

It looks like this..http://www.eyespyvideo.com/powersupplies/12voltsdc/pwr-500r.htm

...and is often the size that a 12v battery plug or wall wart terminates in.  If you have an old wall wart or 12v battery plug, clip the wart or cigarette lighter portion off, leaving two wires attached to the N plug.  Strip the wires to expose the conductors and twist on to the positive and negatie SLA terminals.  Insert the N plug into the SI.  

Ooola, you're done.

[grkn]

How wonderfully easy. I thought you had to open the damn thing

I have such a thing actually, and it looks like this:


And I couldn't wire it wrong? Don't want to fry the little fellow..
Here's how I've wired it:
[/img]

[TheChairGuy]

I think if you have the pos and neg sides on the right terminals of the SI, you're in business  

[grkn]

It worked! I guess was lucky What happens if you have the terminals wrong?

[Vinnie R.]

It worked! I guess was lucky What happens if you have the terminals wrong?

If the + and - are backwards, say goodbye to your SI when you turn it ON  

[grkn]

Lucky me!

[BillyM]

I combined it with a standard wall-plug 12v ( adapter to begin with, found some background noise and slight grain before 1/4-volume getting worse the higher I turned it.   I was anything but impressed.

I came back at it with some upgrades.  I tossed in a shielded audio cable, and dumped the crap 12v adapter.  I put in a set of fully-charged NiMH AA's and this removed all background noise.  The grain still came in around 1/3-volume.  

I guessed that the little amp could take a bit more voltage than the NiMH batteries or the wall socket were putting out, hoping to remove a little more grain in doing so.  Soldered up a 14v (13.4v actual) 5A printer powersupply and plugged it in.  This had no background noise (as with the batteries) and moved the "grainey sound" threshold to just under 1/2 volume (I believe this to be the limitations of the tripath chip).  Sound seperated a good deal between the channels and the bass picked up a little with the voltage bump.

Conclusion, this little sucker LOVES a good power supply /w a little higher voltage.

--BillyM

[TheChairGuy]

Tho I have not used it as such yet, the reported best way to configure it is with an analog preamp.

Open up the SI volume control to full tilt and adjust volume with the preamp in line.  The digital volume control of the SI is among the next weakest links after good power supply...it mya just be that hash/grain you hear.

I'll be configuring mine if I can find the time soon, this way.

[grkn]

A 13.5V 5A battery would probably work well too?
Hmm, what would be the better sollution of setting my soundcard (DMX 6fire) to limit the volume to, say -40db and turning the amp to full volume (a bit scary).

Or turning the output of the soundcard to full volume and limiting the volume with the amp.

[BillyM]

With the source unplugged, and running from batteries, I get speaker noise from the amp above 2/3 volume.  I have been running it at about 1/3 volume and adjusting from there with the soundcard output.  I have high-efficency speakers, so achieving volume is not a problem for me.  I honestly dont suggest maxing either the source or the amp with this setup.

--BillyM

[KCHANG]

The digital volume control of the SI is among the next weakest links after good power supply...it mya just be that hash/grain you hear.

Why do you say that the volume control in the SI amp is a digital one?  It is just a stereo 50Kohm pot that actually attenuates the input analog signals before they get to the Tripath chip.

By the way, I have three of these little amps.  I have already surgically removed the guts of two of the amps and put them in tiny wooden enclosures that hardly look like amps at all.  Just for the fun of it.  I plan to bring them to the next audio meeting to get "wows" out of people when they find out that the tiny wooden blocks are actually fully functional amps.  I'll post a few pictures when I get the chance.  The sound?  Perhaps not much different from how they sounded in the cheap origial plastic enclosures.

Kurt

[Vinnie R.]

  The digital volume control of the SI is among the next weakest links after good power supply...it mya just be that hash/grain you hear.

I'll be configuring mine if I can find the time soon, this way.

TCG,

The SI does not use a digital volume control.  It is really an analog "passive preamp" 50k volume pot that takes the input signal, attenuates it, and feeds it to the Tripath chip.  

The best thing for this amp is a 12V Sealed-Lead Acid (SLA) battery.  You can pick one up with a charger for a great price on www.batterymart.com.
They are clean and have plenty of current...  

I would not use the 5A printer power supply...it most likely is a switch-mode power supply, which has tons of high-freq hash   .  I'm surprised to hear that it removed noise.  

-Vinnie

[grkn]

What about a 14V lead battery?

[TheChairGuy]

I stand corrected guys..it's clearly not a digital volume control...merely a poor and cheap one.  

I got my info on it from an informative Feedback Letter to 6 moons.com a couple months ago about the configuration with an analog preamp.. have not looked inside, but thought I remember it was a digi volume control.  Nope, just cheap it is...whaddya' want for $39 list, eh?

I have a Scott Nixon battery powered DAC/preamp coming later this week, so I'll have my personal CDP, the Scott Nixon and the SI all on battery power.  Vinnie, I bought the 7 aH battery from Battery Mart...no grain at all I can tell with that running it.

Kurt, Dmason also liberated the SI guts and placed in a nicer looking cabinet...but I like the looks of this thing just as is (and plastic, as wood, adds no additional EMI/RFI).  I tried a strip of ERS cloth underneath, but more than half a pinky sized and it robbed the little guy of dynamics.  Can you beleive that a $39 amp has dynamics than can be robbed  

From 6moons.com:

==================

Hello Srajan,

You guys must spend a lot of time lurking on the Asylum and Audio Circles to have picked up on this amazing little amp [Sonic Impact - Ed.]. For what it's worth, I have a couple of suggestions I hope you will pass on to the reviewer to maximize the quality of sound from this little hummer.

First of all, the cheap volume control is the weakest part of this amp which sounds a lot better if you just crank the thing all the way up and use it as a basic amp with a good preamp. I have had good results using a quality passive preamp (inexpensive custom made by Scott Nixon) and even better results with several tube preamps, especially one without a cathode follower/buffer stage.

While the amp works well on 8 x AA batteries, you can improve the sound by using an inexpensive 12V battery booster as a power supply (I use a $30 one from Target that also happens to be color-coordinated with the amp). Another option is to use a 13.8V/3-5A regulated linear CB radio power supply which will give you an extra watt or two. Tripath's published maximum voltage for this chip is 13.2V but they told me that a tightly regulated 13.8V supply is okay and I have had no problem goosing the amp to that level. Some of the Audio Circle crowd use a $20 Pyramid linear power supply sourced from Parts Express. However, I recommend a higher-quality power supply made by Astron which costs about $10 more. As you can tell, I am a "spare no expense" type of guy. I recommend against using a switching power supply as Tripath chips put out a healthy dose of RF hash which doesn't need to compounded by its power supply.

Keeping with the theme of amazing bargains, I suggest the reviewer try using a Home Depot 14-gauge outdoor extension cord (the orange and black one) for speaker wire (an Audio Critic recommendation from a couple of issues back). Just twist the bare wire tightly and jam it into the cheapo spring connectors (careful or you will snap the plastic levers if you reef down on them too hard). A $4 Radio Shack stereo mini to RCA converter will allow the use of decent interconnects (Nordost Solar Wind in my case).

I use one of my Sonic Impact amps to good effect with my 93dB Loth-X BS-1 speakers. Sonic Impact markets this amp as 15 watts but it only puts out about six watts into 8 ohms so efficient speakers are a must. However, I have also had good results using two of these suckers in a bi-amped configuration to drive my 83.5db LS3/5As. In that set-up, I use the Astron AC power supply to drive the midrange drivers and the battery booster to drive the tweeters, which cuts down the high frequency system noise.

Obviously, you cannot tweak this amp into Bel Canto eVo territory but a little inexpensive DIY setup can produce remarkable results in a small room system. Hell, I enjoy listening to it in my main system but I am not a head banger or a bass freak. For the ultimate low-cost system, just add a Toshiba 1350 or 1360 DVD player for RedBook playback and you've got a very musical, satisfying el cheapo system. By the way, you can get this amp from Target Online for a mere $19.95. Is this a great country or what?

Thanks for reading these ramblings. I appreciate that you are open-minded enough to review something as offbeat as this amp. It has certainly increased my interest in your web 'zine and I predict it will help broaden your readership.

David Dye
Bethesda, MD


Hello David,

Jeff Day is the moonie responsible for landing this catch and I forwarded your loaded-with-tips note to him this morning. Thanks very much. This is exactly the kind of "audiophile community" type exchange I enjoy the most. The hobbyist underground element is what created hands-on excitement in the 'olden' days of HiEnd. Arguably, as the mainstream developed, some of that has receded or, at least, lost visiblity in the mainstream press. We're just as guilty as everyone else for being ignorant about some of the current trends in DIY and thus really appreciate folks like you 'working with us' by providing tips we otherwise might never come across. Thanks for giving us this opportunity!

Cheers,
Srajan

[TheChairGuy]

I finally (just) hooked the amp up to the big rig...well, I won't be selling my over-achieving JVC hybrid digi-wonder for it in this set-up.

Played thru 87db efficient Linaeums, the distortion is unbearable at 1/3 way on the Dynaco PAS-4 pre.  Background music is easier to listen to than any SS amp I remember in here, however.

I only have 60 or so hours on the Sonic Impact, so some portion of this distortion may be that Tripath chip (imfamously) breaking in.

[Vinnie R.]

Kurt, Dmason also liberated the SI guts and placed in a nicer looking cabinet...but I like the looks of this thing just as is (and plastic, as wood, adds no additional EMI/RFI).

Guys,

You may like the look of the plastic or wood enclosure, but putting this amp in a metal (I am using aluminum) enclosure is actually the best type for it.  A metal enclosure keeps noise from entering in and getting onto the board and polluting things.  Metal will not add EMI/RFI.  

Regarding the stock 50k pot, I find it actually to be better than I thought it would be.  The idea of using an external passive preamp and maximizing the volume on the stock pot is suspecious to me   .  Even when the stock volume is at its max, the signal still passes through it (degradation), and it is adding 50k of load to the source, which is useless because when using a passive preamp, it shouldn't be there to begin with.  If you are going to use an external preamp (active or passive), the BEST thing to do is take the signal directly to the board and bypass the pot and its connectors.  Keep the signal path short and sweet  

If you don't want to use an external preamp (IMO, I woudn't use one), the best bet is to convert it to a shunt-mode pot, which takes the pot out of the signal path and just uses it to "shunt" some of the signal to GND to provide the attenuation    This will make things really nice

-Vinnie

[Vinnie R.]

I finally (just) hooked the amp up to the big rig...well, I won't be selling my over-achieving JVC hybrid digi-wonder for it in this set-up.

Played thru 87db efficient Linaeums, the distortion is unbearable at 1/3 way on the Dynaco PAS-4 pre.  Background music is easier to listen to than any SS amp I remember in here, however.

I only have 60 or so hours on the Sonic Impact, so some portion of this distortion may be that Tripath chip (imfamously) breaking in.

TCG,

Thanks for your feedback.  I would really keep the SI away from speakers that are 87dB.  I'm using 90dB 6-ohm speakers and it does a really nice job as long as you don't make it LOUD.  

I'm itching to try some high efficiency speakers, like the Omegas (Fostex) or similar full-range drivers with > 93dB sensitivity.  I'm sure they will bring the SI up to new levels

-Vinnie

[TheChairGuy]

TCG,

Thanks for your feedback.  I would really keep the SI away from speakers that are 87dB.  I'm using 90dB 6-ohm speakers and it does a really nice job as long as you don't make it LOUD.  

I'm itching to try some high efficiency speakers, like the Omegas (Fostex) or similar full-range drivers with > 93dB sensitivity.  I'm sure they will bring the SI up to new levels

-Vinnie

Yep, I have some 90db Vandy 1c's in the closet that may do the trick tho.  87db is nooo good for the over-achieving SI.

[grkn]

So my:
Freq. Range -6dB at 52Hz and 30kHz  
Sensitivity 88dB spl (2.83V 1m)  
Normal Impedance 8 ohms (minimum 4.3 ohms)  
Power Handling 25W - 100W into 8 ohms on unclipped programme  
B&W DM303 aren't ideel :/