pre amp -in +in connections

Joseph Hanley

Prodigy 130 points

Other Parts Discussed in Thread: OPA454, OPA549

Can a amplifier speaker wire be ran to +in and -IN on this chip and apmlify it out to 100 volts for an amplifier

Attempting build amp off speaker wire signal line extra 40 to 50 watts

Also to keep on Should I jump enable to enable making that circuit closed to keep running ?

OPA454AIDDAG4

over 4 years ago

0 Raymond Zhang1 over 4 years ago

TI__Guru 55381 points

Hi Joseph,

Could you share the schematic with us? I am not sure how you attempt to do this in the second question - Attempting build amp off speaker wire signal line extra 40 to 50 watts.

OPA454 can have output voltage swing close to 100V, see the attached image. However, its output drive current is limited, see Figure 23. It is unable to give you extra 40-50 watts of power. Are you trying to drive a speaker?

Best,

Raymond

0 Joseph Hanley over 4 years ago in reply to Raymond Zhang1

Prodigy 130 points

Yes i am trying to drive speaker in pre amp manner off speaker wire

0 kai klaas69 over 4 years ago in reply to Joseph Hanley

Guru 140200 points

Hi Joseph,

as Raymond already said, the OPA454 is a high voltage OPAmp but no high power OPAmp. You cannot drive a 4R, 8R or 16R load with it.

Kai

0 Raymond Zhang1 over 4 years ago in reply to kai klaas69

TI__Guru 55381 points

Hi Joseph,

OPA454 can not drive the final stages of speaker, which is low impedance as Kai indicated. The OPA454 IC can only source approx. 1W or so.

Best,

Raymond

0 Joseph Hanley over 4 years ago in reply to Raymond Zhang1

Prodigy 130 points

Thank you ! What is this used for computer cicuits ?

0 Raymond Zhang1 over 4 years ago in reply to Joseph Hanley

TI__Guru 55381 points

Hi Joseph,

OPA454 is a high voltage and high current (50mA) op amp. 50mA is pretty high for standard Op Amp IC package, which is operating at high voltage. However, it does not have the power to drive a speaker loads, see the Applications section in the datasheet. It can be used to drive Class AB amplifier in a final stage, which it may be used to drive speakers. For 40-50W audio application, the final audio amplifier stage (e.g. Class AB amplifier) will require to have good amount heat sinks to handle the heat dissipation.

Best,

Raymond

0 Joseph Hanley over 4 years ago in reply to Raymond Zhang1

Prodigy 130 points

Ok thank you what kind of op amp should i use to to power opa into a clas ab amp that is what i am trying to do drive a 120 4 ohm speaker but realizing my amps are off ??

Question was answered im new and understand alot more thanks for help!!!

0 Raymond Zhang1 over 4 years ago in reply to Joseph Hanley

TI__Guru 55381 points

Hi Joseph,

You mean that you have 120 speakers with 4 Ohm impedance in each speaker. However were you drive the number of speakers currently.

If you drive a speaker with each Op Amp, say you are driving 50W in each speaker, your voltage swing is approx. sqrt(50W*4Ohm)=14Vrms. I do not understand why you will need up to 100V drive previously. For the same audio setup, your output current is approx. 3.6Arms.

TI has OPA549 which is class AB amplifier (rated 8A continuous current) can work in the range of above application.

Please let me know the details of your audio setup, so that I can provide you with better recommendation. If you want keep the conversation private, please let me know.

Best,

Raymond

0 Joseph Hanley over 4 years ago in reply to Raymond Zhang1

Prodigy 130 points

Yes please i will send a photo soon of build like talk private

0 Raymond Zhang1 over 4 years ago in reply to Joseph Hanley

TI__Guru 55381 points

Hi Joseph,

You can send me a message through a private line via E2E (via friend request). Once the connection is established, the email can be sent through the private line.

Best,

Raymond

0 Joseph Hanley over 4 years ago in reply to Raymond Zhang1

Prodigy 130 points

Ok thanks email goes my private email i tried sending private message cliking on your profile page

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pre amp -in +in connections