| kanifee |
Finally got my lm3886 up and running after a very bumpy start, only thin now is im getting two differant volumes on each channel, i dont have a pot wired up just a power amp, ive had it wired to a couple of sources and no change. my right channal is conciderable louder than my left, ive gone through and checked all my wiring/solder joints and im using the same speaker on each channel aswell.
any ideas? |
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| Puffin |
kanifee. Is this a kit amp i.e a PCB based or a point to point ?
Inverting or non-inverting ?
I had this problem (which I fixed) , but am having difficulty remembering what the problem was ! |
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| kanifee |
Hi ts a non inverting amp kit from chipamp.com.
I have however changed the cap for new ones as i blew two and couldnt find the same brand ones so i replaced with all new 100uf 50v suntan ones. |
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| Puffin |
Mine was following the building of a point to point amp. I seem to remember that I had something tied to ground which was restricting the input signal. Have you checked that you have no solder joins.
How did you blow the caps ? Did you blow the caps on both boards or just one. If just one, is this the board that has the problem. Have you blown any tracks ? |
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| kanifee |
| replaced the board with a spare i had so shouldnt be an issue, ill go over it again to check for shorts, i did notice that the input only needs one ground from either input channal to get a signal though either channal which i though was strainge. |
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| pacificblue |
| Did you check the values of the gain setting resistors? Are the right values at the right places? And are they okay or may one of them have blown together with the caps? |
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| Puffin |
| pacificblue, kanifee says "replaced the board with a spare" but the resistors may be wrong. Good point. |
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| kanifee |
ok got it all up and running, i have no idea what it was it ust all of a sudden come to life.
I do however have another problem now, connected to a source that has seperate grounds for each input the amp works fine however hooked to my pc through the headphone jack i can only get a single channel at a time, its as if the amp doesnt like the shared ground of the head phone jack!
Its its the same when i have the volume pot solderd in. |
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| kanifee |
| sorry i lied, problem is still there with the channal being alot louder than the other |
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| Nuuk |
| quote: | | ok got it all up and running, i have no idea what it was it ust all of a sudden come to life. |
| quote: | | sorry i lied, problem is still there with the channal being alot louder than the other |
Sounds very likely that you have a bad solder joint somewhere! |
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| kanifee |
Bit of an update for you fellas, got the problem sorted, it was the interconnect :( all that fussing and hassle with the amp and it wasnt even that. of course the interconnects were home made, it was a dry joint on the earth of the rca plug.
A question now though, a shared ground on the left and right channel of the input.. a good thing or bad thing?
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| Puffin |
| Shouldn't make any difference. |
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| kanifee |
| Ah good, the sound im getting is great, really impressed with it. only need to fix my speaker now with a new driver unit, then i can test it in full stereo lol! |
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| kanifee |
HAHA! thats pretty smart, how big are the toroids that thing must be a hefty weight with 2 in.
Is there much advantage to the dual mono setup over the stereo?
I opted for a large 2x25v @ 4.5a a rail though it mesures 28v @ the secondries, im thinking its a little overkill though as cooling is a bit tricky at sustained high volume, i have a P4 heatsink on each chip for now and they get a bit hot to handle after 15-20 minutes of high high volume.
Im thinking about making a stepped Attenuator for it once i have my speaker driver replaced, as for a case at the moment its just in a cambridge audio A1 mk3 case untill i sort something a bit more perminant for it.
The power supply semes to be pretty highly rated for what it is, does this have a place in other projects or is it eally just for the chipamp.com kits? |
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| Nuuk |
| I hope it sounds OK Puffin. I have found putting two traffos in a metal enclosure sounds a bit 'off'! :att'n: |
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| kanifee |
| only thing i find with mine is at high volume the high notes seem a little over powering though i need another speaker on before i make final verdicts! |
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| Puffin |
Nuuk. You know I have never really listened to it for any length of time ! After I made it I got bitten by the bug to make a P2P version, then a bridged version, then 3875.......yawn..............etc etc. The trannys are only 80va each.
I look at it now as my "design project" as all other stuff built since sit on crappy bits of wood that I can find in the garage. I like to post pictures of it to show off !
Incidentally I don't know if you may have any ideas, I made some parallelled 3875's they work fine, but for some reason if I remove the input lead, I get a nasty screeching noise, which suggests that something is not right. I think I got the schematic from the ESP site. I will dig it out and post it. |
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| kanifee |
Im prolly not the best person to ask as my knowladge is limited to what i researched and learnt on this project, one thing i do know is with my when connecting my input as i insert the rca plug and positive center pin is the only thing making connection, as in no earth on the input i get a nasty horrible buzz/hum, now i dont know what your sound is like compared to mine but does it ring any bells form past projects as in a referance to the sound?
I only state as could it be a short on the live? |
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| udailey |
I got some terrible screeching until I resoldered my attenuator. Bad joints so every time it moved it screeched. Also screeched with some bad grounding with RCA connectors. This was a tube amp, but similar problems.
Uriah |
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| pacificblue |
Ever read an amplifier manual? Usually it says something like "don't connect or disconnect anything, while switched on"
The noise you hear is to be expected. You should always switch the amplifier (and all other components) off, before you connect or disconnect anything. That noise is not only ugly. It is also unhealthy for all components involved. |
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| udailey |
If the last post was in response to my previous post I have to say the tone is not called for. In response to your post, I did not disconnect anything. At all.
Uriah |
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| Nuuk |
I think the response was to Kanifee. ;)
And I don't think it was harsh to remind/inform anybody that you shouldn't plug/unplug anything before the amplifier while it is on. It's a bad habit that may not do any harm 99% of the time but could ruin your irreplaceable speakers on the 100th occasion! :att'n: |
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