diy 2.1 pc speaker

[juggler73]

hi
i got a old 5.1 home theatre system and i wanna recycle it into a 2.1 PC speaker set.

well i took it apart and found that it has 5x TDA2003 and 1x TDA2030A and couple 7805, 7812 regulators a toroidal transformer and loads of capacitors and resistors loads of other stuff.
also one 6" woofer and 5 small speakers.
so i was looking up the schematics on the amplifiers and found that they could easily be used for a 2.1 speaker setup

so i was thinking that i could use 4 Tda2003's, 2 bridged for left and 2 bridged for right and the Tda2030a for the woofer.
i just need help connecting it up with the power and how to have the woofer for the bass.

thanks

[audioguru]

The TDA2003 does not bridge well because the output offset voltage are not matched for the two amplifiers like a monolithic bridged amplifier IC. But you might be lucky so try it.

With a 14.4V supply the bridged output at clipping into 4 ohms is 14 watts.
If your speakers are 8 ohms then the power is 8 Watts.
If the supply voltage is less than 14.4V then the power is less.

You should make an active crossover circuit.

[juggler73]

so let me get this right.
Theres a slight power difference in one Tda2003 to another even though there the same.
but with a 8pin dual amp would work better cause there together in one IC.

[audioguru]

I did not say that the power of the two ICs are not matched, I said the output DC offset voltages are not matched.

Look at the datasheet:
With a 14.4V supply, the quiescent output voltage is anywhere from 6.1V to 7.7V which is a range of 1.6V DC that when bridged will cause the voice coil of a speaker to be away from the middle of the magnetic gap and will waste power. The max output offset voltage for a monolithic TDA7240A bridged IC is only 0.15V which is over 10 times less.

[juggler73]

ok so there not that great

ok so i'll get 2 of the TDA7240a
should i use the TDA2030a for the woofer or is there another more efficient.

i was thinking that i could use 2 speakers in parallel or series which ever is better on each channel

ive been trying to find a active crossover circuit but ive only found ones for tweeter woofer speaker setup.
i looked up this TDA2320A datasheet as a crossover chip but im not sure if this is the right type.
thanks

[audioguru]

ok so i'll get 2 of the TDA7240a
should i use the TDA2030a for the woofer or is there another more efficient.

i was thinking that i could use 2 speakers in parallel or series which ever is better on each channel

You need to know the impedance of the speakers. Then you can find out the voltage from the transformer. Speakers in series have low power and sound boomy because then the extremely low output impedance of the amplifier cannot damp their resonances.

ive been trying to find a active crossover circuit but ive only found ones for tweeter woofer speaker setup.

Then simply change the crossover frequency to match your speakers.

i looked up this TDA2320A datasheet as a crossover chip but im not sure if this is the right type.

It will be the power amplifier for the woofer. An active crossover network uses two opamps.
thanks

[juggler73]

hi
the only info i found is this
Subwoofer output power 35 watt RMS
Output Power 5 x 7 watt RMS
and all that is on the speakers is 35P1 20021115A and the woofer has 65P83 20021101A

Ive emailed the Toroidal Transformer manufacturer and hopefully i will get some info.

Ive got a bunch of Lm272 op amps i used on a railsplitter project would they work?
is it a 2 way active crossover circuit needed?

so would it be better to put the speakers in parallel then

"Then simply change the crossover frequency to match your speakers"
this is getting a little, no alot over my head i thought this was going to be a simple project but i guess not

OK is there any info i could read for beginners to get a clear understanding of all this stuff
thanks

[juggler73]

i was looking into the transformer, trying to figure out how I'm going to get a + and - supply and its down to a bridge rectifier, so theres one on the board that came from amp box. its a 2w10m and on the other board theres a bunch of 4004 diodes which i can also use as a bridge rectifier

i didn't know that even the secondary windings on the transformer are still ac current and a bridge rectifier is needed to get DC + and -

please clarify

[audioguru]

The TDA2030A by itself has an output power at clipping int a 4 ohm load with a 32V supply of only 18W and it gets very hot.
The datasheet shows a TDA2030A driving two power transistors and has an output at clipping into a 4 ohm load with a 39V supply of 35W and the power transistors get very hot.

Your speakers have meaningless house numbers so you will probably never find their datasheets. Simply measure their resistance to guess at their impedance. If they measure 3 ohms then their impedance is 4 ohms. If they measure 6 ohms then their impedance is 8 ohms. An amplifier produces nearly double the power into 4 ohms as it does into 8 ohms.
I don't think you said what is the size of your little speakers. Are they "full-range" or are they tweeters?

Guess at a crossover frequency. Maybe your little speakers work down to 300Hz and maybe your woofer works up to 300hz. Then use a crossover frequency of 300Hz.

Of course a transformer produces AC. A bridge rectifier has an AC input and produces a pulsing DC output. A huge filter capacitor smooths the pulses into DC with some ripple.
The datasheet for the TDA2030A shows a single polarity supply with a huge output capacitor feeding the speaker, and a dual-polarity supply with the speaker coupled directly.

[juggler73]

well the speakers must of been in the range of the amps that were used in the 5.1 setup. i can remember that they where pretty loud for there size.
tda2030a was for the woofer and tda2003's were for the 5 satellites speakers
and where the speaker wires clipped to the back is has (speakers out 4ohms).

the small speakers are 3"

with the transformer, if i use a Spilt Power circuit would it half the power if i use just one 15.5v
so it would be better to use the single supply

[audioguru]

What is a "split power circuit"? Maybe a dual-polarity supply?

A TDA2003 with a 15.5VDC single power supply produces 5.25W into a single 4 ohm speaker or 4.3W each into two 4 ohm speakers in parallel.

[juggler73]

made that term up  ;D

[juggler73]

that dont seem that good to me 4.3w, need to make that higher

[audioguru]

that dont seem that good to me 4.3w, need to make that higher

A 3" speaker is used in a cheap clock radio. It cannot survive more than a few Watts. Maybe your 3" speakers are better and can survive 6W?
Where did you find "15.5VDC"? A 12V transformer when full-wave rectified and filtered makes 15.5VDC.

[juggler73]

it on the side of the of the transformer it was on the pic of the transformer

these speaker where part of a 5.1 system not cheap radio

[audioguru]

Was the 5.1 system made by Bose? Their sound systems are awful. Look in Google at "Bose Bashing" where people say how bad their stuff is.
It is a very cheap radio sold at a very high price.

[juggler73]

No it was a acoustic solutions DS533!

[audioguru]

No it was a acoustic solutions DS533!

All the reviews for it are different. One owner says, "Great value for money, but could be better" and "not good for music".

[juggler73]

but im sure it will be fine for a pc speaker setup

[audioguru]

I use my excellent-sounding speakers to play music, not the sound effects from games.

[Sukhbinder]

If you can change the amp ICs being used, you could use the TDA8510J from philips.
It is an amp designed for 2.1 speakers and is usually used in Creative 2.1 speakers.
The amp has the specs of a 26W BTL + 2x 13W stereo channels. Here's what the data sheet says:
The TDA8510J is an integrated class-B output amplifier in a 17-lead single-in-line (SIL) power package. It contains a 26 W Bridge-Tied Load (BTL) amplifier and 2 x 13 W
Single-Ended (SE) amplifiers. The device is primarily developed for multi-media
applications and active speaker systems (stereo with subwoofer).so it simplifies the design part a lot.

works from single supply rails of 15V with maximum 18 V and has a number of protection features like over heating, short circuiting to name a few. supports impedance to 4ohm for subwoofer and 4-2ohm for stereo. refer to the datasheet enclosed for more. but you will need an active crossover for the subwoofer (try googling for linkwitz riley crossover).

TDA8510J.pdf

[audioguru]

If you can change the amp ICs being used, you could use the TDA8510J from Philips.
The amp has the specs of a 26W BTL + 2x 13W stereo channels.

The numbers are from the sales department. The distortion is a horrible-sounding 10%, the BTL speaker is only 4 ohms and the single speakers are only 2 ohms each.

The power with only 0.5% distortion into 8 ohms is only 11W for the BTL output and only 3.1W for each of the single-ended outputs.

Philips audio amplifier ICs might not be made anymore.