dac

[goodguy]

Hello and thanks for taking the time to read this post.

I have purchased a new dac and am wanting to upgrade the tlo72cp and opa2604 opamps, as mentioned in this article: www.rock-grotto.co.uk/opamp.htm

It seems in the article the reviewer simply snapped in new opamps and compared the sound quality. Is this possible as i have been advised that a lot of work to the surrounding components has to be done and to simply insert opamps could actually sound worse or even go as far as damaging the amplifier.

Many thanks in advance. John.

[mrarroyo]

John, it would help if you state which DAC you have purchased.

[xerxes]

There are a few things you need to bear in mind with op-amps, and other members might want to add to these:

First is it a single or a dual channel op-amp and second, what is it's input voltage range.

If you search the net, you will usually find a datasheet for your existing op-amp:

focus.ti.com/lit/ds/sbos006/sbos006.pdf
focus.ti.com/docs/prod/folders/print/tl072.html

So you can compare that to the one that your considering and make sure that the pin configuration and voltage requirements are similar.

For example the OPA2604 is a dual op-amp, meaning it handles both the left and right channels and has a wide 4.5v to 24v power supply range. It would be useful to know what the voltage is in your piece of equipment, because if it's down around 5v, that will rule out some op-amps, like the AD843 or OPA627 that need 10v or more.

[goodguy]

Hi. Thanks for the reply.

The dac i have is the firestone fubar 2, i have changed all the capacitors, resistors and have put a new low noise power supply on.

The opa2604 voltage is 18 volts. Does this help at all in suggesting a upgrade for this opamp.

Many thanks. John.

[Deleted]

The LME49860 supports up to 22V.

[Deleted]

Feb 26, 2011 19:38:22 GMT @javier said:

The LME49860 supports up to 22V.

The LME49860 supports up to + and -22V or +44V if inplemented to use only a +VE supply rail.

[xerxes]

You might find this useful: www.head-fi.org/forum/thread/242034/fubar-ii-dac-op-amp-rolling

[Deleted]

Feb 26, 2011 20:45:45 GMT @sandyk said:

The LME49860 supports up to + and -22V or +44V if inplemented to use only a +VE supply rail.

Do you mean that it wouldn't it work in the OP's DAC at 18V?

I mentioned the 49860 because the 4562/49720 has a +/-2.5 to +/-17 range.

[goodguy]

Feb 26, 2011 20:54:25 GMT xerxes said:

You might find this useful: www.head-fi.org/forum/thread/242034/fubar-ii-dac-op-amp-rolling

Hi. Thanks for the reply. I did follow the link you gave and one person mentioned the opa627 as being a very good upgrade, i have heard of this opamp as it is very popular, would a pair of these be a pin for pin compatiable replacement for my opa2604, are there any voltage considerations? Could i use the opa827 as this is the newest version of the opa627.

And do you know an upgrade for the other opamp which is the tlo72cp.

How many classes above is the suggested LME49860 compared to the opa2604.

Many thanks. John.

[PinkFloyd]

Hey John..... don't know if you realise it but you registered as a female? Is is John or Joanne?

[PinkFloyd]

Feb 27, 2011 14:42:50 GMT goodguy said:

Feb 26, 2011 20:54:25 GMT xerxes said:

You might find this useful: www.head-fi.org/forum/thread/242034/fubar-ii-dac-op-amp-rolling

Hi. Thanks for the reply. I did follow the link you gave and one person mentioned the opa627 as being a very good upgrade, i have heard of this opamp as it is very popular, would a pair of these be a pin for pin compatiable replacement for my opa2604, are there any voltage considerations? Could i use the opa827 as this is the newest version of the opa627.

And do you know an upgrade for the other opamp which is the tlo72cp.

How many classes above is the suggested LME49860 compared to the opa2604.

Many thanks. John.

The OPA 627 is a single chip. the 2604 is a dual chip.... if you want to use 2 x OPA627 you will need a browndog convertor. You can buy this from Tangent (Warren Young) ... you need the Dip8 adaptor ($4) tangentsoft.net/shop/

If you want to stick with dual channel chips then the OPA2107 is VERY similar to the OPA627 in sound (chocolaty and warm) and you won't need an adaptor for it.

Replace the TL072 with the OPA2604, will be perfectly ok

[goodguy]

Hi. Many thanks for the reply.

Is it possible to bypass the opa2604 all together, my thinking is the best type of opamp is no opamp at all. At the moment the dac is running into a 300 watts rms amplifier, i am hoping that with all that power the music should still be loud enough.

Many thanks. John.

[Deleted]

Mar 2, 2011 3:17:48 GMT goodguy said:

Hi. Many thanks for the reply.

Is it possible to bypass the opa2604 all together, my thinking is the best type of opamp is no opamp at all. At the moment the dac is running into a 300 watts rms amplifier, i am hoping that with all that power the music should still be loud enough.

Many thanks. John.

John
The opamp is there for more than just making it louder.
It also isolates the DAC from interconnect cable capacitance, which DAC chips in general do not like much. If nothing else, it will make the output very sensitive to the cable length and capacitance.

SandyK

[goodguy]

Feb 27, 2011 14:51:02 GMT PinkFloyd said:

Feb 27, 2011 14:42:50 GMT goodguy said:

If you want to stick with dual channel chips then the OPA2107 is VERY similar to the OPA627 in sound (chocolaty and warm) and you won't need an adaptor for it.

Replace the TL072 with the OPA2604, will be perfectly ok

Hi. Thanks for the reply.

I went onto the texas instrumets website to order the opa2107 unfortunatly they stock the opa2107ap, au ,apg4, aue4 etc etc
Which should i go for, also they are sending me the opa827 as a free sample, i think this is a more modern version of the opa627 would this sound better than using the opa2107 i only ask as a few people have reported heat build up with the opa827 apparrently it pulls more power from the supply as it is 2 opamps and is faster.

Many thanks in advance. John.

[xerxes]

The OPA827 is a single channel op-amp, so you'll need two of them on an adapter to replace a dual channel OPA2604.

Also it looks like the OPA827 is not available in a DIP8 package, which looks like this:



It is available in a SOIC package which looks like this:



But you would need to solder two of them on to an adapter like this:



Where one single SOIC op-amp is soldered each side of the little circuit board.

However, you can buy them pre-mounted: cimarrontechnology.com/single-to-dualop-ampadapterpn020302.aspx

[goodguy]

Hi. Thanks for the reply. Unfortunatly your link does not go anywhere with firefox browser, can you please check or resend.

Many thanks. John.

[Deleted]

I think there is an "s" missing at the end of the url, try this:
cimarrontechnology.com/single-to-dualop-ampadapterpn020302.aspx

[xerxes]

Try it now.