"quiet" chip amp but more power than tda7294

Status
Not open for further replies.
Jump to Latest
gychang

gychang

Member
Joined 2005
#1
"quiet" chip amp but more power than TDA7297

I like my tda7294 "lunch" priced amp in my bedroom running my 90dB sensitive 8ohm fullrange diy speakers. Matching with my Astron linear PS at 13V, it is dead quiet without any white noise.

I am looking for more power when playing from my netbook, (rather than CD player), since the volume is usually at max. I do not want to change to different speaker but want to add more power by changing the amplifier.

is there a "ebay" amplifier kit one recommend for my use?, I realize I may have to change to higher DCV powersupply (32V?) will result in significant more power output?, I have tried several class D amps, but they tend to produce "noise"...

thanks in advance.
 
Last edited:
#2
Hey There in Davis (I live, let's say, very near by)... are you saying that you are powering your TDA7293/4 using a 13V single ended power supply? The 7293 and 7294 can run from rails of +/-40V and higher.

Anyway, for a modern chip amp this has one of the highest power outputs that I can think of off the top of my head. If you want to give up some performance you can look into amps based on Sanyo ICs that can reach 200W into 8R. Not great for 4R loads, however, and the distortion performance is worse.

If you do want to go class-D, you might look into the L15D amps that are sold on Ebay. No noise problem. Drop me a line and I can direct you to some "economical" options sold on Ebay that I am aware of.

-Charlie
 
Last edited:
#3
From what you say sounds like you need more volume when playing from your netbook. Which you can do by increasing the gain of your existing amp. Then if its still not loud enough increase the supply rails. TDA7294s can play plenty loud enough with 40V rails for practically all domestic applications.
 
#4
abraxalito said:
From what you say sounds like you need more volume when playing from your netbook. Which you can do by increasing the gain of your existing amp. Then if its still not loud enough increase the supply rails. TDA7294s can play plenty loud enough with 40V rails for practically all domestic applications.
Click to expand...

I am told I need to solder SMD to increase the gain, which I am not able to do, old eye sight... How do I increase to 40V rails?, am guessing I will have to replace my Astron PS which I am agreeable to.

Will I have to change heatsink etc...? SOrry for the novice comments.
 
#5
Can't easily answer your questions without a pic - perhaps your heatsink is decent but its only a guess. Most people use way more than 13V for powering TDA7294s.

I have old eyesight too but get by with a large magnifier and reading glasses.
 
#10
For the quiet netbook, I suggest that you start with a preamplifier.
Just a pair of fixed regs and a pair of NE5534 may do very nicely.

However, if you have a headphone amp to spare (already built), try it as a preamp.

P.S.
I have an updated LM1875 design and Two TDA7293 designs that wouldn't need a preamp. But, otherwise you'll really want a preamp.
 
#11
abraxalito said:
In that case the absolute maximum voltage allowed is 20V - you'll not get much louder going to that voltage. You also can't increase its gain, that's fixed.
Click to expand...

The actual maximum for a standard car chip design (the many "12v" bridge amp styles) is 14.8vdc, which is what a car does with the engine on.
However, some of them are designed at the RV/marine spec of 13.5vdc.

In either case, 20vdc = smoke (if actually driving a real speaker for some time).
 
#12
danielwritesbac said:
For the quiet netbook, I suggest that you start with a preamplifier.
Just a pair of fixed regs and a pair of NE5534 may do very nicely.

However, if you have a headphone amp to spare (already built), try it as a preamp.

P.S.
I have an updated LM1875 design and Two TDA7293 designs that wouldn't need a preamp. But, otherwise you'll really want a preamp.
Click to expand...

My samsung N150 is super quiet, I have a USB DAC connected (ELE EL-D02) to amp. Not sure how to fix regs and ..., but I do have headphone amp (uses 9v battery) somewhere and I will try it as a preamp..., thanks
 
#14
gychang said:
. . .Not sure how to fix regs. . .
Click to expand...
Fixed reg = fixed voltage regulator chip

For example, this: MC7809: Linear Voltage Regulator, Positive, 9.0 V, 1.0 A

That's an MC series 9v fixed reg from onsemi. It may be eventually more convenient than running down 9v batteries.
Connect a diode from input to output (diode stripe faces input)
Connect a diode from output to ground (diode stripe faces ground)
Diodes can be 1n4007, or any similar or larger is fine too
That diode bypass is to handle cap discharges (by sending them around the chip reg instead of through it).
Connect a cap from input to ground (0.33uF or 0.47uF).
Connect a cap from output to ground (100n ceramic).
The above parts to be situated very close to the regulator chip.
After some trace length or a little cable, next is the electrolytic caps near your preamp chip.

Unlike the variable LM317, there's no resistors required for a fixed voltage regulator like a 7809.
So, for the fixed regs, you have only 5 parts:
reg chip
2 diodes
2 caps
That's it.

If you drop a minimal amount of voltage, such as 12v in, 9v out, (3v), then you probably wouldn't need to heatsink the reg chip. However, with more severe usage, do add a little heatsink to it.
 
#15
#20
With CD you get to 10% clipping at far below maximum volumelevel, considering 40times amplification, gain tda7297. You do not get there with pcm2704, but with volume full open I feel you should get to 1% clipping limit power tda7297, then music will only feel much louder with preamp. But maybe something is off with my idea.
 
Status
Not open for further replies.
Top Bottom