Bass box adjustment issues / sound card

Good evening

Unfortunately: http://www.hardware.fr/articles/493-6/comparatif-11-kits-d-enceintes-2-1.html

This system does not have a subwoofer adjustment. You will therefore need to find a way to access it through the software.

A "potentiometer" directly on the wires... No, it's not that simple, there's a power handling issue; if you don't distribute the 10W into the speaker, they will be dissipated in the potentiometer (heat), so it's a special one, 10W minimum, coil-wound, expensive, etc... Furthermore, it requires a setup that presents a constant load to the amp, or you risk burning it out.

However, if you tinker a bit with electronics, you should be able to insert a volume control potentiometer at the input of the 10W amplifier that powers this subwoofer, essentially a very basic volume control.

--
One should never work the day after a day off.. @+ / Furtif

Hi and thank you for your help,

so on the software side, I've tried several things, but the result is not 100% convincing, and even if I manage to get a decent bass level with Windows Media Player for example, the problem persists as soon as I switch software like Winamp, Sonic, BSplayer, etc.... I need a software that equalizes the sound in the sound card setup, in Windows, I don't know if that's doable...

As for electronics, I do some tinkering, yes, but I'm not at the point of knowing where to place a potentiometer; I would need a little help because otherwise, I think it's something I could manage.... I play around with a soldering iron in my spare time ;)

So, I'm going to open my speakers to see where the amplifier is, if it's in the first speaker to which the wires leading to the other speakers connect, or if it's in the subwoofer, I'll check. From there, I'll take some photos to see if that inspires you.

That's it, talk to you soon, and thank you ;)

Bidibull

Wait before opening.

Tell me the wiring that is done: What is connected to what.
It will be faster.
--
** If you have a problem, and no solution, it's because you are part of the problem ** @+ / Stealth

Well, actually, the output cable from the sound card goes to the Right speaker. Two other cables come out of this speaker: one goes to the second speaker, and another large one goes to the subwoofer. The whole system is powered by a wall socket that connects to the subwoofer... I therefore deduce that the amplification is there, right?
I'm waiting for confirmation before opening it... thanks.

...to be continued this evening if possible, I'm off to work now... ;) @++

OK, if the power supply of the amplifier goes directly to the subwoofer, only that one needs to be opened.
--
** If you have a problem, and no solution, it's because you are part of the problem ** @+ / Furtif

OK
What is the cable coming from the sound card of the PC?
I think it's the red and black one that we see coming in the middle... is that it?
--
** If you have a problem, and no solution, it's because you are part of the problem ** @+ / Furtif

And then, also tell me the role of the 5 connectors that I see on the back panel, next to the power cord.

Is it an input, or does it serve another purpose?
--
** If you have a problem, and no solution, it’s because you are part of the problem ** @+ / Stealth

Re hello

Well, I'm not always around, so if it takes a while, here are a few pointers just in case:

Your 220V power cable / blue + brown, with black sheathing:
1 wire goes to the board, passes through the fuse and comes out towards... the transformer, in black (not in the photo).
From the transformer, there are 2 yellow wires that supply the board with low voltage AC.
Then it goes through the power section: the 4 rectifier diodes, the big horizontal filtering capacitor, and behind is the voltage regulator (black, vertical, on the left, just after this capacitor).

The integrated amplifiers are on the heatsink, with their respective circuits right in front

Just to clarify:
1) Where do the red wires (1 thick and 1 thin) and the black wire come from that arrive right in the middle of the board on a removable connector
2) The role (and thus the connections) of the 5-pin connector at the end of the board.... what do you connect to it?
--
** If you have a problem, and no solution, it's because you are part of the problem **
@+ / Furtif

Hello again ;)

Well, I'm going to try to answer your questions:

1) So the wires coming to the middle of the board (one red and one black/red on a removable plug) are connected to the subwoofer inside the box.

2) The connector (DIN plug if I remember correctly) is connected to the Right speaker. From this speaker, two other wires come out:
- one is connected to the Left speaker (double wire)
- the other is connected to the output of my sound card

SCHEMA: http://img117.imageshack.us/img117/2183/schema5dy.jpg

That's it, thanks again and see you later!

Otherwise, I have checked everything you described to me, you got it right, that's it.

@ to be continued ;) @+

Je suis là pour traduire, résumer ou reformuler selon vos instructions. Que souhaitez-vous que je fasse avec votre texte ?

Hello,

what is the next step please?

Re ... I just got back.

Your 10W amplifier is actually a "bridge circuit." It's classic when you want power from very small amplifiers.

What I see:
The "line" input to this subwoofer drives a phase splitter stage (the small black transistor alone in front of the 2 amplifier circuits), from there, 2 out-of-phase signals feed each integrated amplifier (mounted on the heatsink). The speaker is connected between the outputs (hot point) of these amplifiers, without a 0V (virtual) reference ... so a symmetrical bridge setup.
If the power supply holds up, it allows you to pull 10W with 2 small 2.5W amplifiers configured in bridge.
Do not touch anything on this side, if you lower the load further (currently around 2 ohms if your speaker is 4), you will fry the amplifiers or the power supply..

However, there is a doubt regarding the input.
I can't tell if it's a true 2.1, meaning 3 distinct outputs coming from the sound card, or if it's a pseudo 2.1, meaning: stereo at the sound card level, then filtered (to extract the bass) in the first speaker, and then the extracted "bass" signal directed to the subwoofer to be amplified again.

Can you try to take a photo of the circuit area near the DIN connector, and/or tell me how many wires actually come into the 5-pin DIN connector?
I believe there are only 1 or 2 wires, plus 1 ground.

--
** If you have a problem and no solution, it means you are part of the problem ** @+ / Furtif

Hi and sorry for the wait ;)

So I'm back at it, here are the photos:

http://img301.imageshack.us/img301/4717/image00120hw.jpg
http://img301.imageshack.us/img301/5267/image00117od.jpg
http://img129.imageshack.us/img129/8812/image00150rx.jpg
http://img129.imageshack.us/img129/4334/image00095rt.jpg
http://img126.imageshack.us/img126/5268/image00089fz.jpg
http://img126.imageshack.us/img126/5013/image00104hu.jpg
http://img126.imageshack.us/img126/890/image00184qa.jpg

...so there's no way to know what's connected where, the block that hosts the DIN socket is wrapped in some foam stuff, sealed with glue (I can still remove it if needed, but still...).
On the right speaker side, I thought about taking it apart to see how the 5 wires are connected.... but there's no way to open it, it's sealed with a block!!!! it doesn't come apart :s
Anyway, this is what I have in terms of info, let me know if you need anything else, and thanks for working on my problem, it's cool ;)
@++

Bidibull

up;)

Hi Furtif,

Well, I'm counting on you, I'm going to try what you told me...
Don't worry about the potentiometer issue, I'd rather you tell me that than have me do risky things with my gear, thanks.

As for the software, I tried the one mentioned above, but I can't really use it, do you know it well? And if so, how to use it? Thanks

Bidibull

It's R39 and R42 that create a summator for channels G and D to send to the low-pass filter (OPAMP). Two possible solutions:
1) Replace R39 and R42 with 1/4W resistors of 100K
2) Connect a variable resistor in series between [the common trace of R39 and R42] and [ground]

I have the same problem at home and just started working on it today (sorry, a bit late?!). I have an audio analyzer. I can therefore determine precisely the resistors to use for those who want solution 1.
I do not recommend solution 2 as a priority, as it will lower the input impedance of channels G and D... which is already 8K per channel, making it difficult for some low-end sound cards.
http://jmraudio.free.fr

Hello everyone, I also have the same problem with my speakers...
But I have another one, my transformer has failed, and I can't find a replacement. The brand seems to be Amc, but it doesn't ring a bell, and when I search, I can't find anything...
I tried to find something else, but an AC 11V/2.5A transformer is not a common item...
Does anyone know where I could get that???

Hi feenux...
yes, I also have the same problem with an Altec Lansing model 121i subwoofer amplifier where the power supply is dead too, but my brother told me that it is possible to replace the transformer with a power supply... but I don't know how to do it...