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The Opamp thread - Page 259

post #3871 of 4738
Quote:
Originally Posted by AmarokCZ View Post

Multimeter is useless, but you can try a HF probe like this and connect it to multimeter, but HF voltmeter (or good scope) has higher sensitivity.

Yeah I am only starting to get into DIY electronics and tinkering, this is a bit above me for the moment. And a good scope is most probably out of budget.

 

If its not going to break something, and it sounds good, I will live with it.

post #3872 of 4738
Quote:
Originally Posted by WiR3D View Post

is oscillation even audible? if not then whats the problem?

 

http://www.diyaudio.com/forums/analog-line-level/191389-swapping-op-amps-you-have-checked-see-its-stable-havent-you.htmlshimay.gif


Edited by leeperry - 5/21/12 at 11:03am
post #3873 of 4738

"Page not found."

post #3874 of 4738
Quote:
Originally Posted by Mad Max View Post

0.1uF ceramic on each chip across pins 4 and 7.

Then a 10uF tantalum on the adapter.  I tried adding the film cap on the top of the adapter and only one chip seemed to benefit, so add it under the adapter board instead.

The tantalum is polar, so make sure that the negative end connects to pin 4 of the adapter, positive to pin 8.  I've never tried adding it backwards, I assume it will kill the cap and/or your opamps.

Thanks!!

Pardon me, but why tantalum? I thought the material has a strong signature of its own, no?

I suppose this is a good combination that you have tried : )

post #3875 of 4738
Quote:
Originally Posted by Mad Max View Post

"Page not found."

 

the forum software likes to add spaces at the end of url's for some reason: http://www.diyaudio.com/forums/analog-line-level/191389-swapping-op-amps-you-have-checked-see-its-stable-havent-you.html

 

Opera is smart enough to ignore them ^^


Edited by leeperry - 5/21/12 at 11:04am
post #3876 of 4738
Quote:
Originally Posted by Pluto2 View Post

Thanks!!

Pardon me, but why tantalum? I thought the material has a strong signature of its own, no?

I suppose this is a good combination that you have tried : )

 

Neutral, as far as I can tell.  Kemet ones anyway.

post #3877 of 4738
Quote:
Originally Posted by Mad Max View Post

Neutral, as far as I can tell.  Kemet ones anyway.

Definately not neutral! ... but it doesn't matter when bypassing supply voltage (just like in case of ceramic = best cap for bypassing, but worst when placed in signal path).

post #3878 of 4738

MMM so oscillation = voltage peaks in the opamps. 

arg how much is a scope anyway? Can someone please post a link to an example? 

 

As long as the voltage is not being pushed through the headphones it wont be a major problem. It will be fine for now, but I do think my AD797 may be oscillating, owell I took it out anyway to give the OPA827 another shot.

post #3879 of 4738

Just put in the LT1057 again (in my STX + faux impedance decreasing adapter + D7000)... dont flame me yet

 

my previous impressions with the AKG K242HD were:

  • SS: naturaly Smooth and tight, loses some detail due to not being as dynamic, slightly oldschool feal?
    • Does not like medium or low quality files (256kb mp3 and lower)
      • reveals clipping issues and artifacts in MP3s(subpar files) very easily
      • not good to pair with analytical phones
    • Naturally smooth (doesnt artificially smoothen or sharpen), also it doesn't tame naturally harsh recordings
    • wonderful resonances especially on the entire drum kit
    • warm and cold: as need be
    • very good at detail retrieval
    • After burn in becomes much more involving
    • a bit of noise.
  • Bass: not overpowering, tight with good impact, maybe a bit slow, and distorts easily?
  • Mids: perfect balance, but resonates like hell
  • Highs: smooth and tight, pleasant
  • Soundstage: medium, smaller then the JRC, good imaging
  • Speed: fast but appears slow due to slight lack of dynamics
  • clarity test: 6/10
  • Listening time: 300min+ depending on songs, avoiding dynamic complex songs.

 

 

 

 

But now... with the Impedance decreasing adapter and the D7000.... just wow

  • SS: Smooth, tight, great imaging, euphoric, textured.
    • Does the odd strange thing with voices
    • lacks some dynamics, easily masked by the strong character of the D7000
  • Bass: Textured quite a bit with heavy basslines in a pleasant awesum way, slightly emphasized
  • Mids: brings slightly more forward, strange sound sometimes
  • Highs: slightly bright, smooth, but not painful
  • Soundstage: smaller then normal, better then normal imaging (AD797 still wins)
  • Speed: fast as hell
  • Clarity Test: 7.5/10, missing some detail, but masks it well
  • Listening Time: years.

 

 

With the D2000 they had something that was difficult to describe, and for a moment I thought I lost that with the D7000, the recessed mids still irk me, but whatever, this combination is just so euphoric... rawr, happy lion

post #3880 of 4738

I tried Kemet R75 caps, and dang, they color the sound.  Clean, refined, very airy, but very white in the mids and treble, yuck.  Fortunately, MKP1837 adds absolutely nothing of its own character, fully neutral while improving your favorite opamps' sound, not even detracting anything.

post #3881 of 4738
Quote:
Originally Posted by WiR3D View Post

MMM so oscillation = voltage peaks in the opamps. 

arg how much is a scope anyway? Can someone please post a link to an example? 

 

As long as the voltage is not being pushed through the headphones it wont be a major problem. It will be fine for now, but I do think my AD797 may be oscillating, owell I took it out anyway to give the OPA827 another shot.


Scopes are not so cheap, locally anyway. Owell

 

I was about to spend a fair amount on opamps, and I remember reading something about leeperry using the LT1364 opamps, and worrying about the input bias. Did this end up being a problem?

Because i just noticed the difference between Bipolar and FET opamps.

 

gulp...

 

Because a few of the opamps on my list are bipolar, and AFAIK the stx's stock ones are all FET.

post #3882 of 4738

You usually want to replace FETs with FETs.  Bipolars may work, too, if the input resistors to each channel are very closely matched, as far as I know.  Otherwise, you can get massive DC offset at the output of the amp or DAC you are using it in.

1364 has way too much speed anyway, so it would be better to go with opamps that will run more stable and hence sound better such as OPA2209, OPA1652, ADA4610-2B, etc.  AD8599 and OPA1612 aren't terribly finicky chips and sound stupendous.

Well, it all depends on how you use them.

I'm having loads more fun these days:

 

IMG_0090.JPG

 

Bad choices would be like ADA4627-1B, AD797, LT1364, ISL55001, and other opamps with huge bandwidth and lots of slew rate.  They are potentially awesome, I think, but not suited for "blind-rolling", which is all we discuss here, lol.  It's easier, and cheaper, to get OPA827, OPA1641, OPA602, and the ones I mentioned before to sound better.  Audio-gd opamps, too, are pretty well-behaved.  Their stock MKT caps kind of suck (little grey boxes on the sides of the opamp module), better to substitute those caps with ceramics and tantalums for far better sound or Russian K42-Y2 PIO caps.  And all of these cap upgrades are generally pretty inexpensive, best of all.

 

I made a new OPA1611 module with grounded bypassing using MKP1840 caps - good-bye treble peaks, soundstage boxiness, and upper mids funkiness that I would get before.  Now much improved, but still kind of warm.  I should probably switch to MKP1837.

post #3883 of 4738
Quote:
Originally Posted by Mad Max View Post

 

IMG_0090.JPG

 

 

 

I love this picture, Mad Max!  The back lighting and the way they are arranged make them look like cute little robots!  wink.gif   Mad Max or Mad Scientist?  Both seem appropriate.

 

I appreciate the advice you've given, too. 

 

Thanks,

 

Mike

post #3884 of 4738
Quote:
Originally Posted by Mad Max View Post

You usually want to replace FETs with FETs.  Bipolars may work, too, if the input resistors to each channel are very closely matched, as far as I know.  Otherwise, you can get massive DC offset at the output of the amp or DAC you are using it in.

1364 has way too much speed anyway, so it would be better to go with opamps that will run more stable and hence sound better such as OPA2209, OPA1652, ADA4610-2B, etc.  AD8599 and OPA1612 aren't terribly finicky chips and sound stupendous.

Well, it all depends on how you use them.

I'm having loads more fun these days:

 

IMG_0090.JPG

 

Bad choices would be like ADA4627-1B, AD797, LT1364, ISL55001, and other opamps with huge bandwidth and lots of slew rate.  They are potentially awesome, I think, but not suited for "blind-rolling", which is all we discuss here, lol.  It's easier, and cheaper, to get OPA827, OPA1641, OPA602, and the ones I mentioned before to sound better.  Audio-gd opamps, too, are pretty well-behaved.  Their stock MKT caps kind of suck (little grey boxes on the sides of the opamp module), better to substitute those caps with ceramics and tantalums for far better sound or Russian K42-Y2 PIO caps.  And all of these cap upgrades are generally pretty inexpensive, best of all.

 

I made a new OPA1611 module with grounded bypassing using MKP1840 caps - good-bye treble peaks, soundstage boxiness, and upper mids funkiness that I would get before.  Now much improved, but still kind of warm.  I should probably switch to MKP1837.


When I'm on my PC your gonna get a plus one. How are you measuring the fr? Recording the output?
I was already using the ad797 in my stx, gulp. I'm not exactly using it with sensitive phones though, akg k242hd, and denon dxk with a faux impedance decreasing adapter that chows almost 1w.

Now those treble peaks, I wouldn't mind killing the treble peaks the ad797 is giving off with the akgs, I have a feeling it could be oscillation.
So the LT 136x is a bad idea, but the ad8599 is ok?

Sent from my HTC HD2 using Tapatalk 2
post #3885 of 4738

Yup, checking the output.  Also, the peaks make K701 and A2000X painful to use.

 

AD8599/8597 seems to be pretty well behaved; perhaps it is very well compensated internally, who knows.

 

I don't think that you will kill anything with an oscillating, and hence over-heating 797, but for your convenience if you are deciding on what opamps to stick in your gear, it's a good idea to just forget that chip.

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