need of 10+10W stereo amplifier

[♪Musicl☺♥☻r]

Hi,
I got a pair of decent quality full range speakers of small 3" size. They are rated at a power handling capacity of 10W at 8Ω. A large magnet for its such a small size and looks almost like this:**broken link removed**
..so it can handle bass freqs at decent level and even trebles also. Further I have constructed suitable enclosures using thick speaker wood at mediate size.(40cm l, 12cm h, 15cm w box enclosing both speakers left n right).
So I'm planning to include the amplifier inside and controls between the center of speakers. Specs:
Power supply - 12-0-12V,1A/2A X'former.
Front controls - power switch,stereo vol cotrol, stereo bass control.
amp - IC

System should execute normal mids and a little boosted treble freqs all the time without use of a treble control and at acceptible level. Bass control allow me to go deeper at a level the little speaker can handle n shouldn't affect the mids and highs neither way. I am in request of valuable suggestions including good IC amp suitable for this speakers and circuit for specified tone control

I am insearch of a 10+10W amp IC but whats the max power these speakres can handle safely? all suggestions r welcome n hope you got my specs well.

 

[Ubergeek63]

probably not. the audio industry loves their specmanship: they tend to list peak instead of RMS or average power.

a 24VA transformer can only deliver 15W DC continuous. This is probably not a problem since most music is not overly bass heavy and is typically 1-2W average for a 10W peak-google "audio crest factor".

Your supply needs to be able to drive 3A peaks or more for loud bass notes. A speaker is an inductor and not a resistor, the impedance goes down as the frequency does, which makes bass notes harder on the supply and output drivers than you might expect.

Dan

 

[♪Musicl☺♥☻r]

I did some search. TEA2025 is only 3W. But works at 12V. I need at least 8W amp for a maximum performance from speakers.

 

[audioguru]

A tiny 3" speaker has no bass unless its enclosure is a huge and complicated transmission line.

Your 12V-0V-12V transformer will produce plus and minus 16VDC which is a total of 32VDC. A TDA2030A mono amplifier IC has an output at clipping of 10W into 8 ohms with this supply.

A TEA2025 stereo amp IC has an output of only 2.4W into 8 ohms with 10% distortion with a 12V supply which is only 2W at clipping.

 

[♪Musicl☺♥☻r]

A tiny 3" speaker has no bass unless its enclosure is a huge and complicated transmission line.

Need explanation plz. Do u think my spec'd box suits for the speakers?

Your 12V-0V-12V transformer will produce plus and minus 16VDC which is a total of 32VDC. A TDA2030A mono amplifier IC has an output at clipping of 10W into 8 ohms with this supply.

tda2030a,12-0-12V,2A,8Ω load.
What'll be the output of this conf and do u think it won't burn up my tine speakers?
Can I connect two amps to the same supply line for stereo operation. Will it affect current/voltage or power gain of the system. Thank u very much.

 

[ataul]

TDA 2030 is good choice. if u worry about for burn out your speaker you will try to build a single supply TDA2030 amp because a dc volt at output in a faulty amp cannot burn your speaker because of series capacitor in the output path of a single supply amp.and do not use low power amp because when amp output will over drive or clip, a sudden near dc flat voltage will flow throw the voice coil and if continue for 2 to 10 minutes it will be destroy your sensitive speaker.TDA 2009 is another good choice i use it sounds very sweet.

 

[audioguru]

Post the manufacturer's name and part number of your tiny speaker.
It probably resonates at about 120Hz in free air and the resonance will rise to about 150hz in your box. Then it will not have much output below 150Hz.
I think it is a Fostex FE83E with a resonance in free air of 127Hz. Its datasheet shows a pretty big complicated dual-chamber bass reflex enclosure for a response down to about 100Hz.

A few hi-fi speakers and sub-woofers go down to 20Hz.
Many sub-woofers and most woofers go down to 40Hz.
Almost any speaker goes down to 60Hz.
A cheap clock radio goes down to about 150Hz.

 

[♪Musicl☺♥☻r]

Nope. image is just for general idea of the thing. No manufacutrer or partno. on it but 8ohm 10W. It should be rms spec'n I believe. tda2030 is a good choice.How about the treble boost and bass control for this device?I will use 12-0,2A X'former. Is that ok?

 

[audioguru]

The Fostex speaker I posted costs $31.20US each ($28.08US each for a quantity of 10).
It is rated at 10W music power or 5W continuously.

Yours is probably a cheap Chinese copy.
Without a datasheet then you are just guessing.

 

[♪Musicl☺♥☻r]

Yours is probably a cheap Chinese copy.

Absolutely right audio guru
It is not even new pieces. I would tell 1year old I got from another person for a cheap price. Leave all those matters and I would tell they are excellent anyway.
8Ω,10W. That's all written over it. I will use tda2030 with above mentioned power supply. Help me out to design a treble boost and bass control prior to tda2030. Thank u.

 

[ataul]

hi musicl

I give u a complete integrated power amp circuit build with control amp it provide bass/treble boost/cut and volume control with balance, I show u one channel only pls duplicate for other channel.it looks complicated but this is the simple.no part u cannot simplified i build it many years ago. i remember the sound was very clean and good. if your power supply have good power and have big mfd u feel good punchy bass on its power limit. don't expect high power from this amp it deliver at least 9 watt/ch at 8 ohms this is more enough for your requirements and sweepable for your 8 ohm 3 inch spkr. if any problem don't hesitate to mail me at atahak@yahoo.com

so long.....

 

[♪Musicl☺♥☻r]

Hey thanks ataul for ur wonderful circuit, the same what I was looking for.
My Questions:
1. Amperage of X'former. Is it 2A ok? or 3A u mean. Mention clearly n plz tell me the spec'ns of the speakers u have used with this set up.
2. You haven't spec'd pin nos of tl072. But, sorry I haven't have any experience with it. Plz do specify.
3. 15V(?) zener before op amp. Will it induce breakdown noises to the amp.
4. 1N4007 is ok for rectifiers. Thank u.

 

[ataul]

1.You need at least 30w x'former, I use Chario cinthea200.it is lo efficiency speaker.you may use any hi efficiency spkr at least 8 inch driver.
2, tl072 accordingly pin1-output1. 2-inverting input1 (-) 3- non inverting input1 (+) 4-ground. 5-inverting input2(-). 6-non inverting input2(+). 7-output2. 8 positive
3. zener is no problem
4. 4001 no serious problem

 

[♪Musicl☺♥☻r]

ataul, yes! n I think u got my requirment clearly..a punching kid bass form the tiny 3" genius . Does tl072 op amp contains one more amp for stereo second channel.
Fostex recommendation for a double bass reflex enclosure hit on my head now..let me see for an updated system design. What kind of enclosure u used. MDF enclosure will be nice n u have any idea on lamination or painting. I couldn't understand the sound absorbent spec'd on he Fostex FE83E recommendation.

 

[♪Musicl☺♥☻r]

I check on datasheet of tda2030. In ur diagram there is no any 4001 diodes connected as in the datasheet. What's the purpose n y u omitted those
I've attached ur circuit modified for my second doubt. Is the ground goes to centre tap of X'former n tda2030's pin3 goes to -12V? Is it correct or wrong?
If I use 12-0-12V,3A. Will tda2030 handle this current.

 

[audioguru]

Don't use a lousy old LM358 opamp (noted on the amplifier's schematic), it has crossover distortion, has a very low bandwidth and is too noisy.

A TL072 is a dual opamp with low noise, low distortion and wide bandwidth.
A TL074 is the same but is a quad opamp in a 14 pins package.

All speaker enclosures contain sound absorbent material to stop sounds reflecting around inside and to reduce resonance inside the enclosure. If an enclosure is completely filled with loose sound absorbent material then its volume appears larger which makes the resonance frequency a little lower.

Your tiny speakers will not be as loud as bigger speakers with the same power from the amplifier.

 

[audioguru]

Your conversion of the single-polarity-supply amplifier to a dual-polarity-supply amplifier is full of errors.

 

[Nigel Goodwin]

All speaker enclosures contain sound absorbent material to stop sounds reflecting around inside and to reduce resonance inside the enclosure.

Would be nice if they all did, but many speakers (particularly cheap ones) have no such acoustic wadding.

 

[♪Musicl☺♥☻r]

Your conversion of the single-polarity-supply amplifier to a dual-polarity-supply amplifier is full of errors.

If the single polarity amp posted by ataul is ok, then I'll follow it. It seems to be very nice. Any advantage for dual supply over single supply? Then y can't u correct me on the schematic posted by me and tell the errors!
I have a plan to make a bass reflection box using MDF. So what material can I use inside as sound absorbant. Plz giv me a detailed reply. Thanks.
PS: So I can use single tl072 as dual amp for stereo. right?

 

[♪Musicl☺♥☻r]

Got it. my speakers are WEISHI speakers.