TI's Tone control

[JojoD818]

Hi,

I meant 100K on both. A 50K-100K dual or single (for a dual mono setup) pot will do. This is an opamp circuit and should be able to accomodate such low resistance pots. I read in an article that lower resistance means lower noise.

HTH,
JojoD

[BC]

Hi once again,

[BC]

Hi once again,
Just a little more followup. Speaking with TI, they suggested not to use the OPA544, or OPA548, or OPA549 for the power amp if you want quality audio. They said that those ICs were biased Class B. I suggest using the National Semi. opamps Lm3875, or LM3886 or LM4780. These are designed specifically for audio and Nat. Semi states in data sheets that they are biased "quasi Class AB". They are also a lot cheaper. Also in the TI app. bulletin the Zoebel network filter R14 and C6 is wrong. R14 should be 1ohm NOT 1k ohm. More info about the LM 3875 etc. chips can be found throughout the ChipAmp section of DIY Audio Forum. Enjoy.

[wrenchone]

Did you ask about the OPA541?

[BC]

Sorry, no. I looked through my paperwork but had nothing about the OPA541.

[Tony]

hi,

ti parts are general purpose power op amps, dataheet lists applications for motor driver, servo amp, synchro-exiter, audio amps, programable power supply, in that order...

unlike ns parts which states that the chips were made specifically for audio use....

but i see no reason not to use ti parts for audio if one wishes to...

[JhonDoe]

Originally posted by joan2
hi,

you may want to try dual 250k linear taper for the bass, and 50k for the treble, also linear taper....

you can not remove the resistor after the input cap to the opa549 amp. it is meant to bias the input on the op amp...the 1meg is high enough and is better to leave it as is....

As i mention in my past post, the power amp is running in an Inverted topology I believed that in this set up i dont need the ground reference input resistor R12 in the that application.. pls correct me if i'm wrong.. but if the resistor R11 and R12 is really needed I will include it in my final set-up
thanks bro..

Originally posted by BC
Hi once again,
Just a little more followup. Speaking with TI, they suggested not to use the OPA544, or OPA548, or OPA549 for the power amp if you want quality audio. They said that those ICs were biased Class B. I suggest using the National Semi. opamps Lm3875, or LM3886 or LM4780. These are designed specifically for audio and Nat. Semi states in data sheets that they are biased "quasi Class AB". They are also a lot cheaper. Also in the TI app. bulletin the Zoebel network filter R14 and C6 is wrong. R14 should be 1ohm NOT 1k ohm. More info about the LM 3875 etc. chips can be found throughout the ChipAmp section of DIY Audio Forum. Enjoy.

I know most of the people in this forum prefer the LM chips, I hope national will send sample here in the philippines, I would like to try those LM3875, 3886 too but there are not available in my location.. I got a lot of TI's chips (544,548,541,549 even the opamp opa132,134,627,2134,4227,buf627) I got all those chips for free. i'm using it with every project i made and i dont see any problem...

[JojoD818]

Hi JohnDoe,

I completely understand your point about TI chips being free and all, but for just a few hundred pesos, I suggest that you try the "Overture" series of NS including the LM3875 and you'll probably understand why a lot of guys here (foreign and domestic) prefer them.

I have personally tried the TI chips (541-544-548-549) with excellent results though, so go ahead. Still, try the Overtures, or you'll be missing a lot.

JojoD

[Tony]

hi,

As i mention in my past post, the power amp is running in an Inverted topology I believed that in this set up i dont need the ground reference input resistor R12 in the that application.. pls correct me if i'm wrong.. but if the resistor R11 and R12 is really needed I will include it in my final set-up

in this case you can drop the resitor after the coupling cap....

i have a bunch of lm3875, lm3875fp, lm3886, lm3886fp i got as samples, i m willing to give you a pair, but you have to get it from my place....

offer is good while i am still here in pinas, i am going overseas for a job i a months' time...

tony

[JhonDoe]

Originally posted by JojoD818
Hi JohnDoe,

I completely understand your point about TI chips being free and all, but for just a few hundred pesos, I suggest that you try the "Overture" series of NS including the LM3875 and you'll probably understand why a lot of guys here (foreign and domestic) prefer them.

I have personally tried the TI chips (541-544-548-549) with excellent results though, so go ahead. Still, try the Overtures, or you'll be missing a lot.

JojoD

I'm not closing my mind to try the LM chips but as of this time money is too tight for me, you know what i mean.. almost all basic needs are getting higher but the salary still the same. Last month I found an LM3875 for the price of 400p in one of the electronics store in san fernando but 400 for me is too much and i cant spend that kind of money just for my hobby. i sould buy my little daughter's milk and i'm sure my wife will be happy for me!..

Originally posted by joan2
hi,


in this case you can drop the resitor after the coupling cap....

i have a bunch of lm3875, lm3875fp, lm3886, lm3886fp i got as samples, i m willing to give you a pair, but you have to get it from my place....

offer is good while i am still here in pinas, i am going overseas for a job i a months' time...

tony

thanks tony! bu i cant go there, need to work hard here!..
Good luck! dnt forget my pasalubong..hahaha... I hope u where not going to Iraq...