[lunchbox739]

I got a portion of the wiring done on my pack this weekend and starting having an issue with the sound. All the sounds from the crix sound module are very faint and distorted even with the sound turned to maximum. Here is a rough diagram I put together in paint.



Its been said in other threads but ill list what I'm using again here for clarity...

Crix Light and sound
Lepai 20W amp
Spongeface battery eliminator and pre amp board

Does anyone have any thoughts on what my issue could be here? To my knowledge no one has ever used this particular amp with a crix sound kit so I cant help but wonder if the amp is the overall problem and just doesn't like the way Spongeface's pre amp board outputs signal.

The cable from the pre amp board is a piece of speaker wire with an RCA plug soldered on to jack into a RCA splitter that plugs into the inputs on the amp. I mention this because I doubt spongeface had off the shelf amps in mind when he designed his pre amp board.

If I remove the pre amp board the sounds play at the correct volume but heavily distorted.... I am open to any suggestions at this point.... If the general consensus does end up being that the amp is the issue...what would folks here suggest for an amp other then the standard 7watt rig? I picked up this lepai looking to do a system with a little more power and volume capability. Perhaps this as an alternative if need be? http://www.canakit.com/20w-bridged-audi ... uk193.html I welcome and appreciate any input you boys can put forth towards this.

[Ejgunth87]

Have you tried not hooking up the speakers in a series? It might be too much or too little impedence on the amp. I'm using a custom Crix chip and a Lepai amp for my containment unit build. I noticed that Crix's chip is mono, and the amp is stereo. I had to insert both sets of speaker wire into the same terminals on the amp to get sound from both speakers.

[lunchbox739]

The speakers are wired in series for 8 ohms....I've had them wired parallel and parallel bridged and the amp would kick off at 40ish percent volume.....series is the only wiring method so far that I've been able to get any semblance of acceptable volume level and the amp stay on

[Ejgunth87]

Maybe just try using one speaker

[lunchbox739]

I'll hook 1 speaker up alone when I get in from work and see what it does on the pack sounds. Tracks played through the MP3 player connected to the MP3 port on the amp play clear and loud..... Its just the pack sound from the Crix board through the pre amp board that lowers the volume.

[Spongeface]

The spec sheet and photos of the Lepai LP-2020A indicate there are two rca jack inputs (this is a stereo amplifier) and a 3.5mm stereo input. It appears that the amplifier should work fine!

The amp is rated for 4 ohm or 8 ohm speakers, so you might try one speaker to each channel and then see if either channel or both sound fine with a "normal" input from some stereo component.

You can also try connecting the "vol-pot, GND" from the pre-amp to each RCA input jack independently and see if both left and right channel inputs on the amplifier behave the same.

[lunchbox739]

The spec sheet and photos of the Lepai LP-2020A indicate there are two rca jack inputs (this is a stereo amplifier) and a 3.5mm stereo input. It appears that the amplifier should work fine!

The amp is rated for 4 ohm or 8 ohm speakers, so you might try one speaker to each channel and then see if either channel or both sound fine with a "normal" input from some stereo component.

You can also try connecting the "vol-pot, GND" from the pre-amp to each RCA input jack independently and see if both left and right channel inputs on the amplifier behave the same.

when I first got the amp I had it plugged into the wall and had the speakers wired as you just said...1 speaker for each channel. With the MP3 player plugged into the amps 3.5mm port the amp would kick off at 40ish percent volume... that's why I never went back and tried it again with the sound chip....so far the only way that has allowed for clarity of sound and general volume output is to have the speakers wired in series for a 8ohm load on the amp.

I will try all of these suggestions this evening when I get home (replying to these messages at work obviously isn't getting the problem solved but it does give me a list of things to do when I get in tonight) At one point I had the vol/pot cable plugged into the amps 3.5mm port using an RCA to 3.5mm adapter and got the same result on the pack sound...low volume at max volume setting and heavy distortion....but when I plugged the MP3 player back in, the music on the MP3 player was crisp and loud... this test is what pushed me into believing that perhaps there was an issue with the pre amp board or the amp itself. At the time I didn't know of anyone who had tried using this model amp with a crix sound module and figured that it could be some fluke with the amp...however since Ejgunth87 says he is using a similar setup for his containment unit build and its working for him the two devices are obviously compatible. Since the Crix module is loud yet distorted when removing the pre amp board from the equation that suggests to me that whatever the problem is, it is between the pre amp board and the amp.

Ill post up the results on everything you guys suggested this evening after I have had a chance to mess with it a bit....

[CPU64]

I just got a Crix sound card today and so far I don't even get a sound.. Does it have to be hooked up to an amp? All the demo videos he had showed either with or without.. So now I'm kinda lost.

Also, why are you using both a pre-amp and amp in the system?

[lunchbox739]

Pre amp board bud. If you go back into some threads here crixs sound module had a issue with some setups that caused distortion in the sound....fossilized arts thread comes to mind when I speak about this....sponge face created a little 2x2 board that solved the distortion problem AND eliminated the need for multiple batteries....that is the board I speak of when I say pre amp board. There is actually just 1 amp in my rig...the lepai 2020a....and I'm trying to power it all with a 12v lion Chinese battery brick.

It seems like the vids I saw of crixs sound module required at least a 7watt canakit amp but I could be wrong there....search the forums though


Sponge said above that what I have should be compatible and work fine....so I will default to his much more educated judgement and go home this evening and make sure this isn't a SFU error (Stupid Fuggin User) on my part.

[Ejgunth87]

http://www.gbfans.com/community/viewtop ... =7&t=32667

If you scroll down, you'll see the youtube vid of a demo I did with that setup

[lunchbox739]

Good looking containment unit build sir...

[Ejgunth87]

Thanks man, its coming along. And boy does it weigh a ton. I'm on vaca this week, so I'll do another demo and take pics for ya so you can see my sound setup. I had your same issue with my first pack, only I was using the Canakit 7w amp. I had 2 speakers hooked up. I tried Spongeface's device, and it only helped so much. When I only wired up one speaker, problem solved, no distortion. Let me know how the trial n error goes later on

[lunchbox739]

I'm having mixed feelings with that then I really want both speakers cranking...we shall see this evening

[CPU64]

I got the board to work..

So is that the reason why when I hooked it up right now, it sounded ok straight to a speaker, and totally distorted with an amp attached??

[Ejgunth87]

Yes. It has something to do with how Crix's output is different than the input needed for either amp

[lunchbox739]

Ok folks Test result time....I had a couple of PMs in to Spongeface earlier, so to avoid going back and forth to PMs and just so there is a thread in case someone else has a similar issue, ill put all the suggestions that were made here followed by the result of the test ran. here we go....

The amp is rated for 4 ohm or 8 ohm speakers, so you might try one speaker to each channel and then see if either channel or both sound fine with a "normal" input from some stereo component.

my speakers are 4 ohm... I hooked up a single speaker and got the same results...low volume at max volume setting with distortion.... I tried a single speaker on each channel and the results were the same.

You can also try connecting the "vol-pot, GND" from the pre-amp to each RCA input jack independently and see if both left and right channel inputs on the amplifier behave the same

I took the splitter off the amp and tried each RCA jack independently. The result was the same as above...low volume at max volume setting with distortion....

Maybe the pre-amp output signals (Vol-Pot and GND) are backwards? The audio amp may not sound too good if those were swapped.

I checked my connection and the polarities are correct...The speaker wire I used to make the "signal" cable is 18 gauge speaker wire...one wire looks silver the other copper. I soldered the silver wire to the center pin lead of the RCA plug and the copper to the shell lead. Silver is positive, copper is negative...it appears to be hooked up correctly.

Does the amp sound fine if the Crix board is using batteries and drives the amp directly?

When I power the crix board with AA batteries and hook the signal cable up to the speaker leads on the crix board it plays well... clear and loud.

Does the amp sound fine if you are using some other signal source instead of the pre-amp connected to the same input that the pre-amp used?

the way this question is worded I wasn't 100% sure what you meant...it sounded to me like you were asking if I had tried hooking up another signal source to the amps RCA inputs to see if it would play clearly...if that is what you were asking then the following test applies if it wasn't please clarify...

I used a RCA to 3.5mm adapter with a female RCA to dual male RCA splitter... plugged that into an MP3 Player and then plugged the other end of the RCA cables into the amp. The system played clear and loud from the MP3 player through the amp...

The pre-amp can drive a speaker, just not very loud. First disconnect the speaker from the CRIX board and re-connect the speaker between the Vol-Pot and GND connections. Then connect the CRIX board speaker connections to the pre-amp connections (SPK+. SPK-). This should sound OK, but not have much volume.

This yielded nothing... no sound...at least not anything I could hear. usually with the system turned all the way up if it seems like its working I at least get a little hiss in the speakers but with the above configuration I got no sound at all.

Have the Crix board directly drive the speaker, but use the preamp board to power the Crix board. Hook up the 12V battery to the pre-amp's +Vbat and Gnd connections and also hookup the pre-amp's +Vsnd and GND connections to the Crix battery inputs. Then hook a speaker to the crix board in the usual way. The Crix sound board should work just like it does with the separate batteries.

I saved this one for last because this test gave me a nice little scare....When I powered the system up and started the GB theme from the crix board it was the right volume level but very distorted... I just happen to have my finger on the voltage regulator on the pre amp board...and noticed that it was getting warm....less then 5 seconds later it was hot...like really hot....I quickly hit the kill switches and sat the thing down....I had the system in my lap sitting on the floor and If I hadn't had my hand where I had it I am pretty sure that in a few more seconds that thing would have melted down....

I think I covered everything that was suggested so far....the last bit did give me a hefty scare though...... I snapped a couple of photos... I don't know if these will help or not... if there is a specific shot anyone might need please let me know and ill do my best to get a pic....





on the close up pic the black chip sitting at a angle with the hole in the top is what I was calling a voltage regulator....at least that's what I think it is... the metal piece on top is where I had my finger resting....it got hot fast....

the amp and battery are mounted to the back of the mobo...

[Ejgunth87]

A ground loop isolator might be needed

[lunchbox739]

I thought about that...but here is why I am iffy about it..... none of the lights are in the pack...just the sound board and the pre amp. The thread that comes to mind here that I am basing this off of is Carpeteria's install of the now defunct Mighty board in his pack... the distortion he was getting seemed like it was in tune with the scan of the power cell lights....which suggested that he had a ground loop somewhere that was causing his sound system to pick up distortion from the lights themselves....If I were to install a ground loop isolator and it cleared the distortion in the sound...would a ground loop affect the overall volume capability of the system? Clearing the distortion wouldn't mean a lot if I cant get enough sound to hear the pack in my living room... to say nothing about a convention or some other event. It also doesn't explain why the voltage regulator on the pre amp board heated up when I attempted the test with the pre amp powering the Crix sound board with a speaker wired to the sound board speaker terminals...

the same ground loop isolator Carpeteria used is available off the shelf at the local wal mart down here for 11 bucks....ill happily drop 11 more dollars into this thing if it will get it up and running properly...

[CPU64]

So without that pre amp, the crix card is useless? Dang it, I wish I knew about this before buying it..

Hey, any idea if the crix chip is compatible with the gbfans pack blaster? i have both.

[lunchbox739]

No I didn't say it was useless without the pre amp board. If I eliminate the 12v brick and pre amp and run it on its standard 3v AA power supply jacked into the amp it runs fine....I am just not content with changing batteries every event and want more volume with longer run times.... thats me...its a preference. That preference is what is causing issues as it requires a more complicated setup which in turn generates more ways for something to go wrong.

[CPU64]

Oh, my problem is that the crix card is super distorted though any amp, and normal without the amp...

[Wharin]

Dude, twist your wires together

[CPU64]

I soldered them.

[Wharin]

No I mean physically twist them together, as in twisted pair.

[lunchbox739]

Mine works as intended.... I don't think Crix built this thing with 12V supplies and large amps in mind.... with its standard power supply its fine...

The concern I have with my rig right now is I'm afraid there is something wrong with the pre amp board not Crix's sound board. ...there are plenty of folks who have properly operating packs right now with a similar setup. It can be done....

[Ejgunth87]

Yeah with my C.U. setup, I have seperate power supplies for the amp and sound board. My first pack has a Crix chip and the 7w Canakit amp, and I have those running on seperate power supplies as well. Both work fine.

My second pack has the MIghty in it, and I needed a ground loop isolator in order to run everything off one 12v LiPo battery. When Cerperteria installed the first Mighty, he had to use a GLI in order to get rid of the distortion as well, which is what prompted me to buy one as well. Definetly worth the extra $11 if you want to use the same power supply.

[lunchbox739]

I am waiting to see what sponge says about the voltage regulator heating up on the one test I made...and his thoughts on the pre amp board being the culprit in general. Its tough to diagnose stuff like this through a forum..especially since 9 out 10 times the problem is something that the user wired improperly. I've poured over this thing several times...tested every connection with a multimeter to check polarities...I'm almost convinced its a problem with the pre amp board I have. Either way I may pick up a GLI on my way home this evening....what's another 11 bucks in the grand scheme of things right?

[Ejgunth87]

In my opinion, the GLI is worth its weight in gold. It'll save you from having to change out batteries periodically (which I hate). I'm no expert when it comes to this stuff. I'm just speaking from experience from the 3 packs I've built.

[Skully]

Dont mean to butt into you guys going back and forth about the multiple issues you guys are having in general ....But I run both the Crix sound board and also the Spoungeface preamp /power dist. chip..Without issue as CPU has seen in person....And he will tell you its Holy shit loud and crystal clear ....

The distortion that is being created from the chip to these cheap hobby amplifers comes from the voltage level put out by the Crix chip itself.....The amplifers are set to handle only a small amount of voltage on the sound input side ...and the crix chip is more than likely exceeding that level......also i am running a simple mono Canakit mono 20 watt amplifer with zero distortion...the sounds coming from these chips are mixed to mono not stereo so using a 2 channel amp is pointless.... hope this helps...

[mburkit]

There's a reason why I ended up using (and suggesting) the CANAKIT 7W amp. Both Replica Props and the Crix chip are supposedly amplified at 1.5watts. When I was originally working out the bugs with Rob at Replica Props before I did my DIY write up, I had a 20watt amp and was getting the same distortion. He then suggested I try the 7W mono amp with the 2 different inputs. I suggest the CANAKIT amp because of it has both High/Low impedance inputs (the "WIN" input in particular). I believe the distortion you are getting is because the chip has that 1.5w amplification. This is probably why the chip works fine by its self, but gets distortion when you hook it up to your amp.