Author Topic: Rear speaker mod...Fuzzy? (Read 7097 times)

Mythtron · « **on:** April 14, 2008, 03:08:39 PM »

Hi,

I recently completed my first mod which included the sound reactive trigger led's and a rear speaker wired up to an LM386

(I'll put up pics as soon as I can).

But anyways, there was a problem...which was the sound quality coming out of the rear speaker...it was fuzzy! I'm wondering if anyone else has had this problem, and what they did to fix it.

Thank-You,
Mythtron

Ch4rL13 · « **Reply #1 on:** April 14, 2008, 03:15:36 PM »

as far as i nkow only 1 person has done a rear speaker mod but it might be fuzzy cuz the its a old speaker or w/e. you might not have made a good solder. try resoldering

Mythtron · « **Reply #2 on:** April 14, 2008, 03:24:51 PM »

The speaker is not the problem....I've even tried connecting the speaker back to the portable dock I pulled it from...and it's clear.

So it's something between the psp and the speaker...I'm pretty sure the wiring is good (although, I didn't use flux as some people may recommend). Thanks for the suggestions tho, I definitely try resoldering if there isn't anything else I can do.

PS: only 1 person?!...there must be more ppl w/ a rear speaker mod!

ritaloruskov · « **Reply #3 on:** April 14, 2008, 03:39:30 PM »

i have the same problem . The quality if sound is very bad , i have test many circuit like the LM386 datasheet but the sound is always bad .
I don't know how to fix this problem .
I wait an answer

folklord36 · « **Reply #4 on:** April 14, 2008, 03:44:32 PM »

i think we need to ditch the lm386 for the speaker and try a different ic or another circut needs to be designed specialy for the psp input current

j.s2ghetto · « **Reply #5 on:** April 14, 2008, 03:46:10 PM »

i have heard that if u add a 10uF cap before the speaker it will clear up the fuzzyness

ritaloruskov · « **Reply #6 on:** April 14, 2008, 03:51:05 PM »

where do you ad the 10uf capacitor ?
You replace the 250uf capacitor which is between the pin 5 and the speaker ?

Timmy · « **Reply #7 on:** April 14, 2008, 04:12:06 PM »

either

a) Your speaker cant handle the amplified voltage

b) you have accidently hooked up the gain pin, resulting in distortion

c) resistence needs to be applied

d) capcitance may help but resistance is a bit simpler

ritaloruskov · « **Reply #8 on:** April 14, 2008, 04:33:06 PM »

can you draw a picture please ? where do you applied resistance ?
What is "hooked up the gain pin"
sorry i am french and its too late .

everlasting_will · « **Reply #9 on:** April 14, 2008, 06:08:05 PM »

Caps will probably help, as one of their capabilities is to filtering noise, there are info about filtering caps in the wikipedia for example.
Also your problem could be that the difference between the inputs of the lm386 are too big so you are causing the operational amplifier to work under saturation state so the output will be distorted.
In any case if you used the same diagram for the speaker than the one that is recommended for the reactive leds, that could be a problem too. That diagram has been thought for the leds not for a speaker, what i mean is that talking about leds you don't care if you are saturating the operational because the leds will light up too. But if you want to use it for a speaker entering in saturation state of the amplifier is the baddest thing as the sound will be distorted.
I would recomend to design another diagram where the output will be joined to the -pin of the amplifier with a resistor (that is called virtual short circuit (in spanish, don't know if you call it the same in english)) and to the speaker, but you will have to consider other things too. In the datasheet of the lm386 there are some examples, have a look there.

GhoSt · « **Reply #10 on:** April 14, 2008, 10:19:46 PM »

Quote from: Talos on April 14, 2008, 03:15:36 PM

as far as i nkow only 1 person has done a rear speaker mod but it might be fuzzy cuz the its a old speaker or w/e. you might not have made a good solder. try resoldering

lol dude many many people have done the rear speaker mod

, btw its probably cas u are taking that speaker above wat it should be used at. Check how mant Ohms and wats it is and post it up.

Luke · « **Reply #11 on:** April 15, 2008, 12:35:03 AM »

Quote from: TimmyDX on April 14, 2008, 04:12:06 PM

either

a) Your speaker cant handle the amplified voltage

b) you have accidently hooked up the gain pin, resulting in distortion

c) resistence needs to be applied

d) capcitance may help but resistance is a bit simpler

i agree on that 1

ritaloruskov · « **Reply #12 on:** April 15, 2008, 03:31:48 AM »

i have placed a resistance in serie between the speaker and the pin 4 .The resistance just diminish the power of sound and don't augment the quality of the sound .

folklord36 · « **Reply #13 on:** April 15, 2008, 08:42:24 AM »

the problem is not our speakers my speaker i tested i have my computer speaker wire spliced and hooked up to a sub i un gooked the sub and conected my speaker and turned it up to about 2 times as loud as psp with lm386 and no distortion occored i wouldnt mind buying and testing circuts if someone could explain how i would calculate the circut as far as resistance and adding caps

Mythtron · « **Reply #14 on:** April 15, 2008, 04:18:22 PM »

Quote

a) Your speaker cant handle the amplified voltage

Yes, at first I too thought that was the problem, but after connecting it back with the dock and increasing the volume...it couldn't possibly be the speaker.

Would simply putting some resistance on the + output of the LM386 to the speaker work? If not, I'll have to try the capacitor then....would this do the job?:
http://www.opamp-electronics.com/catalog/10uf-16v-radial-electrolytic-capacitor-pack-p-542.html

Thanks,
Mythtron

Mythtron · « **Reply #15 on:** April 15, 2008, 04:29:12 PM »

BTW: Here's the schematic I followed when making the mod...so if I have to add any more resistors/capacitors of what ever it is that I have to add...you can just use this picture:

PS: Right now, I have only hooked up 2 LED's

ritaloruskov · « **Reply #16 on:** April 16, 2008, 04:08:31 AM »

i have make a freestyle circut and the sound is not bad in 12V and 7.2V .
I think the quality of the speaker is very important . In fact , i have eard a big difference between 2 speaker 1.5W ; the first ( a big

recovered to an old radio ) the sound saturated a max while the second recovered to a tiny chaine hi fi the sound don't saturated and was rather good .
The only problem is that the speaker is to big to put it in the psp ( 77mm diameter and 25mm height )
Sorry for my bad english

Timmy · « **Reply #17 on:** April 16, 2008, 04:49:15 AM »

yeah its definitely a problem with your speaker

its not good enough to handle the amplified voltage, just run it in a series with the speakers normal

ritaloruskov · « **Reply #18 on:** April 16, 2008, 09:48:34 AM »

i finish my mod . Actually i connect the psp to the electrical catch because i have not enought space to put an internal battery , but the sound is very mighty and the quality is good up to the half at the max power of the psp .

j.s2ghetto · « **Reply #19 on:** April 16, 2008, 03:42:22 PM »

wat did u do to get the quality good

ritaloruskov · « **Reply #20 on:** April 17, 2008, 03:58:06 AM »

a good speaker, more voltage and a classical circut with a 4.7uf capacitor between enter sound+ and mass ,
10 ohm + 0.1uf between pin 5 and 4 , 470 uf in serie with speaker and pin 5 , 220uf between alim + and mass

j.s2ghetto · « **Reply #21 on:** April 17, 2008, 05:08:29 AM »

could u draw a diagram or explain a lil more dummied down

Mythtron · « **Reply #22 on:** April 17, 2008, 03:44:57 PM »

Quote

just run it in a series with the speakers normal

That's an incredibly great idea!

So will this spread out the amplified sound over the 2 normal speakers and my rear speaker? That would solve the problem I suppose.

I will give you a schematic w/ the series wiring, as I'm not entirely sure about it myself.

Thank-You,
Mythtron

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Author Topic: Rear speaker mod...Fuzzy? (Read 7097 times)