how can bridge my stk amp?

[amirdelta]

i have a stk4174 chip amp and i before used it for one small subwoofer
but now i want to use it to drive a pioneer 12" 306DVC.
it's a little weak and i want to bridge it but dont know how?
can everybody help me to do that?

i before used eliot's site bridge circuit with TL072 but did not work.
now how can i do that without any circuit board?

 

[Fenris]

Is there a datasheet for this amp?

 

[gmphadte]

STKs are not regarded good sounding and are not prefered nowadays as there are better ICs available. Bridging also reduces the performance. Remember u need to increase the power ten times to hear double the sound.

For a 12inch woofer u have to go for discrete or semi-discrete power amp.

Gajanan phadte

 

[amirdelta]

thanks for your answers

but it's sound quality is completely acceptable and i want to drive
one subwoofer with bass filter therefore a stk amp is suitable.
the output power is a little weak and this weakness solvable with
bridging amp because my subwoofer impdance is 8 ohm and with
bridged amp the output power is 4 times stronger and is sufficient
to me.
now what do you think about?


best regards:amir

 

[gmphadte]

Can u elaborate/draw what and how u did the TL072 circuit. It is the easiest solution if the schematic is not available.

Gajanan Phadte

 

[Sangram]

I've used a single resistor to bridge STKs and for the frequency range you're talking about, it should work fine. I used it before I knew better, and those amps run full range. It does increase the distprtion on paper, but didn't sound much worse then. I've built better amps since then, but those STKs ran fine bridged into 4 ohm loads from 42 volt supplies.

You can read about that method on Rod's webpage at sound.westhost.com

 

[amirdelta]

i used elliott's project 14 figure 1 to made bridge adapter
but it did not work.

dear sangram please describe how to do that?
where i shoud place the resistor and all ather wirings?

best regards and wishes :amir

 

[Sangram]

It's a little complicated to describe.

http://sound.westhost.com/p20_fig1.gif

Is how you will do it.

The exact pins, I do not know and cannot describe.

Read this: http://sound.westhost.com/p20_fig1.gif

All the best!

 

[amirdelta]

thanks a lot!
but there is a problem! ! !
what is element's specification?

best regards:amir

 

[Sangram]

The same value as the feedback resistor from output (Rf). Varies from 10K to 47K, though it may be higher or lower. Do you have a schematic of the amp in question? It's quite easy to figure out what it is just by tracing a circuit.

It is the highest value (in resistance) resistor connected to the output (usually there would be just two resistors connected to the output of an STK amp, one is for a Zobel and the other is for feedback, if there is a third resistor it would be a stopper in series with the load with an inductor wound around it). Normally a low wattage type. Without the circuit in front of me I can't really tell you what the exact value is.

Hope that helped...

Also watch, STKs are easy to blow and the way you're planning to use them sets them up for a quality explosion effect. The 4 times power is strictly theoretical, and you will hit the chip's thermal limit much before you hit the 4 times output current. Watch for heat before you turn it up.

 

[amirdelta]

thank you sangram.
i got it.
i have it's schematic from datasheet and with your helps i sure i can do that.
there is no worry about heat because i used an amd cpu heatsink with
fan to keep it cool, in fact there is no heat and noise.

best regards amirdelta