Bridged mode, is it easy?

[jrosado]

Hi:

How easy is to put AMP5 in bridged mode? Do i need any external components (like an inverter) or can it be done on the board?

Regards,

J. Rosado

[bryman79]

Hello,

I too am curious how to put the amp in bridged mode. I finally got the datasheet out today and have a few questions. BTW, here is the section of the datasheet for easy reference.

1. It appears to me that the only addition is the 20k resistor between OAOUT1 (pin 22) and INV2 (pin 26). Is this the correct value? Anything I missed?

2. How exactly is the output connected... is it like a balanced amp where the inverted signal drives the negative terminal? In other words, does OUT1 go to the positive terminal of the speaker and OUT2 go to the negative?

Thanks,
Bryan

[JuuL]

I've just bridged my amp2 like the same way.
- 20k is a correct value (amplification of 1x for the other channel)
- The output is connected between the outputs of each channel. So you dont have to connect a ground.

Out1 is an inverted output of the input and Out2 is an non-inverted output of the input.

[bryman79]

quote:Originally posted by JuuL:
Out1 is an inverted output of the input and Out2 is an non-inverted output of the input.

The TA2022 datasheet (i.e. the second sentence of the section I posted previously) reads: "OUT1 will then be a gained version of OAOUT1, and OUT2 will be a gained and inverted version of OAOUT1." Isn't this saying that OUT1 is a non-inverted output of the input?

Thanks,
Bryan

[JuuL]

This is how an inverting amplifier works:
http://www.societyofrobots.com/schematics_voltamp.shtml
Look to the picture and you will understand (I hope)

Both opamps are inverting amplifiers.
The input is getting amplified (R1 and Rf will setup the gain) and inverted. So the output of the upper opamp is an inverted amplified signal of the input.

This inverted signal is going to the input of opamp nr 2.
It's getting amplified 1x (Both resistors are equal) and inverted.
So the output of this opamp is an inverted, inverted (and amplified because the first opamp did this) of the input. Minus x Minus = Positive (2 time inverted) --> So this opamp is an non-inverted, amplified signal of the input.

I'll hope you understand, just look at the picture [8D]

[jrosado]

Hi:

I know how bridge mode works . My question was intended in other direction:

having the board made by jan for amp5, is it easy to alter the bard to put it on bridge mode? Does the board includes this option, by using a simple jumper, for example?

[JuuL]

I can't tell you. I only have an amp2 kit

But looking at the scheme of above, you can compare this one with the scheme of your amp (gotta make the scheme yourself).
You don't need an inverter.

[bryman79]

Juul... 100% clear now. In my haste, I didn't realize that these were inverting.

jrosado... I don't see a provision for this resistor, and to be honest, I haven't had time to trace back the respective pins and take a closer look at the most convenient location for the resistor. However, assuming the worst-case scenario, soldering to the pins of the TA2022 looks very do-able.

Thanks,
Bryan

[bearman]

If you go to the AMP1 forum, on page 4 you will see the post "Bridging AMP1" I believe Amp1 and Amp5 are the same amps with only the power supply being the difference.

I think this post will answer your questions.

[bryman79]

Hello All,

Just for completeness of this thread, here is the picture of the 20K resistor placed between pins 22 and 26 on the AMP1 (similar to the AMP5):

<img src=http://www.41hz.com/images/41hz/bridgedTA2022.jpg></img>

There are no holes for this resistor... it appears the easiest way to mount it is straight to the pins of the TA2022 as shown in the picture above.

Regards,
Bryan