Class A vs. IC amplifiers for PC audio

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Im currently in the process of dreaming up a new amplifier and speakers for my PC, pretty much going for the sub and 4 satellites approach, but im not too sure what to do for the satellite amps, nor am i sure how to spell 'satellites' so im going to avoid saying that from now on and say small speakers instead.

My choices are pretty much this using 2 cone small speakers, I could either use 4 of the 20 Watt class A amps (http://sound.westhost.com/project10.htm) and use a passive crossover in the small speakers, or bi-amp each small speaker channel using 2 IC amps of undecided type (recommendations on type, power rating and crossover point would be really useful) but again with a total power of 20 W

I listen to losslessly compressed music on my PC so its CD quality, and run through an SB audigy, so im not really sure this is good enough to notice much difference in amps anyway, but it would be helpful to hear/read peoples suggestions on which i should do, or if anyone has any better suggestions i would be glad to hear them :rolleyes:
 
Hi,

I thought that P10 of Rod Elliot is SE so it will dissipate around 100Watt for 20Watt output. For 4 channels this is a lot of heat dissipation for computer speakers. I also think that 20watt is more than needed for computer speaker which usually are pretty close to the listener. Why not build 4 small (5 Watt ? ) BJT Class PP-amplifiers like JLH's.


gr,
Thijs
 
Hi Beggar,
I'm lately using an early sixties Panasonic tube reciever driving a pair of Boston A40 6.5" two ways, mounted either side of the PC monitor on my corner placed triangular desk.
This amp is tube class AB and about 15W/ch.
External audio line inputs are from a VCR and PC.

The speakers are rated at 88 dBA/1W/1m, and at 15W (approx 100 dBA) give plenty SPL at my nearfield (<1m) listening position, especially for sustained long term listening to music (fm tuner or PC) or video tape or broadcast tv.

At lower (normal) levels this combination gives long term listening enjoyment.

Regards, Eric.
 
thanks for the feedback dudes, i guess class A was a bit of a silly idea based on the power it uses up (especially considering im a poor(ish) student and i have nightmares about electricity bills) i probably will go with the IC amps, can anyone recommend a good combination of IC's to use for a bi-amped satellite 'channel' (of total 10-20 watts, i use my speakers for my entire room which is fairly big and i like music pretty loud too :) your right though tschrama it is over kill, but then again i like overkill/being stupid :D )
 
You can chose TDA7294 becouse it is cheap but very well made and the sound it is very good , too .

This is my sugestion : Make one bridge amplifier with two TDA7294 for subbass speakers [ 16 ohm or two 8 ohm speakers in series] and a 24dB/oct band-pass active filter [ 30 - 150Hz ].

Make 4 amplifiers with a single TDA7294 and band-pass 24 dB/oct active filter in front off them [ 150 - 22.000 Hz ].

Make the power supply : Toroidal transformer 400VA - 630VA with 2 x 27 V AC . Use bridge rectifier 25 -35 A and 2 x 10.000 uF for each amplifier and maiby capacitors for subbass amp ( 2 x 20.000uF) . It would be cheap at this voltage .

Put all this to a large hetsink and that all.

You can have a high-end multi channel amp with this performance:
Subbass Amplifier 100W / 16 ohm with only 0.01% THD and slew-rate 30V/uS.
4 Channels x 50W/8 ohm with 0.02% THD .

This all project cost 150 - 200$ plus your work . It is not " to much " becouse if you want a good sound you must have an amplifier with a lot off headroom ( 10 - 20 dB ).
 
I've heard nice things about the TDA7294 too. Implementation of these power ICs is pretty straigthfoward; try Rod's site, there's a couple of IC amp schematics there.

As for the sound, they're good :) Nothing like a heat-wasting class A, but again, GOOD. I think for your needs such a project would be perfect.
 
TDA7294

Lisandro_P said:
I've heard nice things about the TDA7294 too. Implementation of these power ICs is pretty straigthfoward; try Rod's site, there's a couple of IC amp schematics there.

As for the sound, they're good :) Nothing like a heat-wasting class A, but again, GOOD. I think for your needs such a project would be perfect.

see also
http://www.diyaudio.com/forums/showthread.php?s=&postid=43517#post43517

What Nelson suggests
is too much work
for little gained

I discussed this Chip TDA7294 once,
with John Curl, a super AMP constructor,
He said: "You have made a good choice, groman!"

So on this one I ASSURELY
agree with Argentina
not the YankieMaan of ours.
 
ok dudes, thanks and all, ive decided that for the sat amps I will use 2 lm1875's per channel and restrict output power to about 10w per amp(via signal attenuation as to avoid clipping at all costs). this is pretty much because after some research i found i can get them for £0.75 each, which doesnt sound too bad (TDA2050 was about 5x as much :( )

for my sub i would really like to use 2 of the TDA7294, but i was a little concerend as for the bridge configuration on the data sheet the frequency response curve showed attenuation of a few dB below 100hz, i could easily use 2 single amps to drive a single 4ohm cone each but im not sure if this avoids the problem as i could not see any frequency response curve on the data sheet for a single chip application, does anyone know?
 
Beggar ,
For subbass, bridge configuration for TDA7294 work very well in this range [30 - 100 Hz]. For simplicity, it is a good thing to have a small atenuation in infrasound range 10 - 30 Hz, becouse protect the speaker from mechanical stress . The speaker it is your biggest problem for this project and the choise of cabinet type.
If you want I can make the project for subbass cabinet if you can send me more details about your subbass speaker :
Fr ; Qtc ; Qes ; Vas ; Le ; Xmax ; Re ; Qms; Sd ; .
 
thanks for the info and the offer on building me the thing, but ive already built the enclosure for my sub cones, its just a sealed enclosure which im going to electronically equalise the response of (hopefully flat to about 35hz, i hope..) :rolleyes:

hmm, looks like im all set to go ahead and start building then, thanks for your help every one!!! :D
 
Or use the LM3875. One per channel is enough (for 30-40 W). For example try the Thorsten Loesch inverted amp. Quite nice amp, and you can build it very cheap. Or very expensive, and then it could be comparable to the more expensive discrete amps. I build one too, but I didn't compare it to a lot of amplifiers. But at least it is ten times better than my old Harman Kardon HK690. (when played softly, or with higher effiency speakers).

See: http://pub4.ezboard.com/ffakeidsfrm1.showMessage?topicID=116.topic
for more information...

Ciao,

Fedde
 
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