[Cynips]

Oh, I was referring to the piece of music, so I am well familiar with it when I compare the different opamps.

 

[leeperry]

JRC2114D>LME49720NA is night and day, you won't be falling for placebo...I can tell you that

 

[mtan002]

Can someone point me the way to get some LME49720. Thanks.

 

[leeperry]

click on samples on LME49720 - Dual High Performance, High Fidelity Audio Operational Amplifier

BTW, it seems that this chip gives very clear trebles because of its very high slew rate...all the usual lousy chips(2068/5532) give 6 or 8V when the 49720 gives 20!

I wonder if any other chip could yield even lower THD? I've seen some OPA chips w/ 0.000022%, but these were not op-amps.....and it's even rarer in TO99 apparently.

 

[genclaymore]

I dont have HA's but I trying out 3xLME49720NA's just now. Just got done putting them in and taking out my fav of 3xOPA2277PA's. So far I liking this combo better. Gonna try it like this for a couple of days.

 

[ROBSCIX]

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif click on samples on LME49720 - Dual High Performance, High Fidelity Audio Operational Amplifier BTW, it seems that this chip gives very clear trebles because of its very high slew rate...all the usual lousy chips(2068/5532) give 6 or 8V when the 49720 gives 20! I wonder if any other chip could yield even lower THD? I've seen some OPA chips w/ 0.000022%, but these were not op-amps.....and it's even rarer in TO99 apparently.

Slew rate doesn't quite relate to "clear Treble" as your suggesting. Either of those "lousy" opamps you suggested has enough slew rate to handle full 20Khz sine wave within an acceptable output swing.
You cannot say, "wow, high slew rate great treble" doesn't quite work that way.

To also note, without understanding what a high and low slew rate is you cannot judge just by looking at a simple value. There are many opamps with much higher slew rates the the LME49720, do you think they have better treble response? -No....it doesn't work that way.

The TPA6120A2 amplifier chip has a slewrate of 1300 V/uS.... -That's your headphone amplifier chip.

The OPA627 has a slewrate of 55 V/uS and the 637 has a slew rate of 135 V/uS!

 

[leeperry]

well strangely enough some links on google back up my finding : http://www.icaen.uiowa.edu/~bme080/l...wRateNotes.pdf

Opamp and Capacitor Upgrades, PART-1

Quote:

"Speed" is important to sonic transparency — specified as Slew Rate, in Volts per microsecond or V/m S

I'm not saying that speed is the only important factor(and it prolly isn't!), but these 49720HA sound really impressive! I read good feedback on the THS4032(100V slew rate), I'm expecting some samples...a friend of mine will put them on browndog adapters for me, maybe I'll have a go at it when I'll be bored ^^

 

[ROBSCIX]

Yes, well strangely enough you can find all kinds of twists and incorrect turns on simple information.
Slew rate is important but as I said fast Slew rate does not just equate to "clear Trebles" as you were suggesting. The LME49720 has a slew rate of about 20V/uS so if that give your the clear trebles the LME has what would a slewrate of 150, or 1300 sound like? -As I said it does not work like that.
There are many opamps that are considered to have amazing high range and clarity yet are well below 20V/uS.

THS4032's are well regarded for I/V and.. well buffer also. They are recommended a great deal BUT given the speed of the opamp you can get into trouble just slapping them into a circuit without some knowledge about opamps.
Especially some know how on how to stabalize them in a circuit.

They may be too fast without some type of compensation and you will end up with a opamp that oscillates...which is bad. Considering this opamp was NOT designed for direct audio work they are designed for communication applications such as fibre optic amplifiers and receivers.

 

[leeperry]

well, I read that the 4032 were stable on a Prodigy HD2 for what it's worth

but anyway, the 49720HA sound out of this world...I don't think I'll bother any further w/ rolling op-amps

if that was for the 49720NA, I would have prolly continued, coz their low end bass response simply lacks..

 

[ROBSCIX]

Very possible, I am just saying fast opamps can be quite unstable in a circuit especially where sockets or adapters are used. Also, oscillation in a opamp can be very hard to detect.

 

[leeperry]

it was checked w/ an oscilloscope and stuff : AUDIOTRAK - User Community

but right when I had the STX, I didn't try the stock op-amps and instantly put the 49720NA...and the sound was indeed really strange, like constantly drifting and unstable

.....had to burn-in the card w/ the stock op-amps for a little while before I could put them back on.

 

[ROBSCIX]

Yes, Did you read the entire thread- the guy also soldered a cap on the adapter to help keep it stable.
Not to mention we are talking about two different cards with two different circuits.
With high speed chips there is always a concern about oscialltion in the circuit. Adapters and sockets don't help much either.
Your card do as you will.

 

[Cynips]

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif JRC2114D>LME49720NA is night and day, you won't be falling for placebo...I can tell you that

Well, I find it difficult to put into words, but I find the 49720NA to be more lush, with a clearer, more detailed presence, but also more fluffy in a negative way - like everything is a bit hollow. With the stock 2114 everything seemed to lack a bit of air, a warm signature - almost veiled, but on the other hand I think the overall sound was more pulled together, with more substance so to speak.
Overall, I think I prefer the 49720's paired with my DT150's as the combination seem to enhance treble for me.

I could be subject to placebo or just plain delusion, so I'll switch back to stock tonight or tomorrow to see if my memory serves me right.

 

[leeperry]

Quote:

Originally Posted by Cynips /img/forum/go_quote.gif Well, I find it difficult to put into words, but I find the 49720NA to be more lush, with a clearer, more detailed presence, but also more fluffy in a negative way - like everything is a bit hollow. With the stock 2114 everything seemed to lack a bit of air, a warm signature - almost veiled, but on the other hand I think the overall sound was more pulled together, with more substance so to speak. Overall, I think I prefer the 49720's paired with my DT150's as the combination seem to enhance treble for me.

well, the 49720NA is flawed, but still very "sexy"...try the HA when you have time, and let the NA burn in for a few days as it does seem to help

and you may wanna update to the latest drivers from the ST(needs minor .inf modding), I think they sound better

the 49720>2114 downgrade is where it gets ugly, I tried it........for 10 mins

 

[Cynips]

Quote:

Originally Posted by leeperry /img/forum/go_quote.gif well, the 49720NA is flawed, but still very "sexy"...try the HA when you have time, and let the NA burn in for a few days as it does seem to help and you may wanna update to the latest drivers from the ST(needs minor .inf modding), I think they sound better the 49720>2114 downgrade is where it gets ugly, I tried it........for 10 mins

Yeah, thought about the burn-in issue too, remembering your initial problems with them.

And actually, I already ordered the 49720HA