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The Opamp thread - Page 256

post #3826 of 5604
Originally Posted by zilch0md View Post

Hi Mad Max,



This had to be directed at me, as I own the LCD-2, SE530, and HD280, but I can't figure out what you're asking me.  confused.gif


I don't know what it is that you're wondering if I've noticed with the LCD-2.


Here's the post you followed:






So even with LCD-2, you notice an improvement in transparency with dummy buffers?

I would expect for you to notice such an improvement with HD280 and SE530 due to how sensitive they are, but I figured that your ortho would sound better with (non-dummy) buffers.

post #3827 of 5604

You are right Mad Max. I've tried it for myself.... ES5 and W4 are nicer (slightly) with dummy adapters in buffer position. LCD-2 sounds ok with this but much better with stacked BUF634 or even better with HA5002 buffers.


The PB-2 does agreat job with full sized cans but it's still not as nice as the EF-5 but it's portable. If you want an amp that is flexible enough to use with IEM's on the go and full sized cans at home you need to look at the Fi-Q, this is an amazing amp in both scenarios... + you can ROLL - Yay!!

post #3828 of 5604

Mad Max,


I've only had the PB2 five days, now, and have yet to do any rolling. So, I've not tried running it with the dummy buffers (nor anything other than the stock configuration - OPA604's with with BUF634's - as shipped from iBasso).  I haven't even tried changing the gain jumpers yet - they're still at the default medium-gain position.  


This must beg the question, "What are you waiting for?"   Answer:  I'm waiting for balanced Silver Poison cables for my LCD-2 that just shipped out yesterday from the UK (by Frank at Toxic Cables).   I doubt I will ever want to go back to the stock, single-ended Audez'e cables on the PB2, so I'm trying to get as familiar as possible with the sound of the stock PB2 > single-ended > LCD-2 (without making any changes to it), so that I can more readily appreciate the difference made by going to the balanced cables when they get here.


Meanwhile, I've been doing a lot of reading about rolling op-amps - just trying to learn stuff before I start rolling with the balanced cables.


All that said, I hear you - it's more likely that I could hear an improvement in transparency (had by using dummy buffers) when single-ended into SE530 or HD280 (because they are sensitive) than single-ended into the less efficient LCD-2.


I'm nevertheless having a hard time finding any resource that can verify Headphonia Mike's suggestion that output current drops while transparency improves by using the dummy buffers. I'd like to know how bad the current loss is by running without buffers, and whether or not there are any other benefits or pitfalls to doing so.





post #3829 of 5604

The drop is big, most opamps pump out 20-50ma of current while BUF634 pumps out 250ma.  That's 250ma in addition to OPA604 (35ma).

post #3830 of 5604
Originally Posted by Mad Max View Post

The drop is big, most opamps pump out 20-50ma of current while BUF634 pumps out 250ma.  That's 250ma in addition to OPA604 (35ma).


That's huge!  I've read that LCD-2 wants current more than voltage, so going by your statement, here, it seems the LAST thing I'd want to do is cripple my PB2 by running it with dummy buffers!


So... Here's a theory question:   Can we say that the purpose of "buffers" is to increase the current coming from the source device while the role of the "op-amp" is to increase the voltage?  


(I know that buffers can themselves be op-amps, but I think you'll get the idea of my question...)


Thanks Mad Max!



Edited by zilch0md - 5/2/12 at 4:52pm
post #3831 of 5604

Something like that, I suppose.  =]

post #3832 of 5604

Can anyone give opinions of BUF634 used as an RCA -> AMP -> Speakers  setup?

post #3833 of 5604

Hello boys and girls, and ROBSCIX, leeperry and SpudHarris.


I was reading about 30 pages of your guys posts from "09 :P (after I bought the opamps unfortunately)

I'm on a quest to smoothen out a common problem with the STX, namely the harshness and bloated bass. This is especially a problem with the Denon D2000.


So I went and bought:

LT1057, AD797BR, OPA827AID, 2xLME49710HA and THS4032.

And wow bigger differences then I could have ever thought, I was worried the harshness was tied into the TI HP amp built into the STX, and since I am only rolling I/V opamps it limits things.


Anyway I thought I would throw back my feedback:

(Using MusicBee with Wasapi, 24bit/44.1kHz output and testing with the AKG K242HD for now, since its more analytical, makes it easier to spot differences.)


  1. JRC2114D
    • SS:harsh, dynamic, crisp, bassy
    • Bass:muddy and bloated
    • Mids: perfect
    • Highs: harsh
    • Soundstage: Big (naturally) with accurate imaging but not neccissarily great,
    • Speed: medium, slow with bass
    • clarity test: 8/10
    • Listening time: 35min at most
  2. AD797BR
    • SS: HARSHER!!!! very dynamic, very tight, unbelievable clarity, airy
      • NO resonances or natural overtones, ultra crisp.
      • I can see why they are one of the best, but definately not the nicest to listen to in this application.
      • has some burn in time, harshness drops a bit.
      • I can literally hear a musicians spit as he plays the sax
    • Bass: tight, balanced, has it when its needed, but isn't emphasized
    • Mids: overly tight, sharp
    • Highs: extremely tight, way way way to sharp, and more painfully harsh then the JRC
    • Soundstage: Big (naturally), bigger then JRC, great imaging
    • Speed: very fast - contributes to tightness and over sharpness
    • clarity test: 11/10
    • Listening time: 15 min
  3. LT1057ANC8
    • 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.
  4. THS4032 - perfect for AKG K242hd
    • SS: Smooth, tight, very dynamic, very detailed, intimate, warm and bright
      • Matches the JRC clarity, without bloating the bass and without being harsh.
      • treble can be a bit much
      • forgiving - doesn't clip
    • Bass: impactful, good extension, not overpowering, textured well
    • Mids: weighty, and slightly forward (prefect for akg k242hd) 
    • Highs: crystal clear, bright, emphasizes by the same amount as the denons naturally, crisp but not harsh.
    • Soundstage: large (naturally), slightly smaller then the JRC, GREAT imaging, best out of them all
    • Speed: fast
    • clarity test: 10/10
    • Listening time: 130min+ depending on songs, avoiding very bright songs
  5. OPA827
    • SS: very warm, bassy, bright, lacks dynamics, slightly harsh
      • more dynamic then LT1057, but way less then THS4032 and AD797BR
      • Brighter then THS4032
      • same amount of bass as JRC2114, and arguably same quality
      • artificial feeling? voices aren't intimate (can be on the odd occasion)
      • slightly sibilant in its over brightness.
      • mids are strange.
    • Bass: very textured, boosted by same amount as JRC
      • Subbass in spades, muddied a bit
    • Mids: natural sounding, if not a bit flat
    • Highs: Overly bright, fatiguing, slightly harsh.
    • Soundstage: medium-large (slightly artificial sounding) smaller then the JRC,  imaging is good, nothing special 
    • Speed: slightly slow
    • Clarity test: 6.5/10
    • Listening time: 35min
  6. 2xLME49710HA (yes i did make it fit, was the off-height twin leaning towers of piza)
    • SS: Tight, difficult to discribe, accurate, slightly warm, medium dynamics
      • feels slightly warm, but sound is slightly disengaging
      • more dynamic then OPA827, LT1057, but less than THS4032 and AD797BR
      • smooth, crisp, can be harsh if the song is.
      • can get fatiguing
    • Bass: tight, smooth, probably the nicest out of them all
    • Mids: seems a bit recessed, disengaging
    • Highs: neutral
    • Soundstage: Big (slightly artificially) with good imaging
    • Speed: fast
    • Clarity test: 7.5/10
    • Listening time: 180min+ (with a few breaks)


I'm busy trying to fix a faux impedance decreasing adapter, since v1 has some crosstalk issues, before I test with the D2k, because the impedance mismatch makes it too bright, and too bassy.




Unfortunately now i want to test:

OPA132UA, LT1364CN8 (Is it worth going for the LT1363 in an adapter?), LT1208CN8, LT1122, LME49990

and I'm broke after paying $700 to fix my Honda Blackbird.... sigh... And just as a side note I am after balance and smoothness, and as much clarity as I can get with that. So far the THS4032 is the winner, but I have a feeling the LT1364 will take the spot

post #3834 of 5604

My 4627 gets quite hot...must be oscillation....

What would be good bypass caps for them? And how? I lost track on this....

I have two on an adaptor, up and down,,,,do I need to by pass both chips?

Thanks guys!

post #3835 of 5604

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.

post #3836 of 5604

My experience with some OPA's

currently I like the OPA627

Edited by FritzS - 5/13/12 at 7:07am
post #3837 of 5604

Hi Guys,


The opamp marked U1090 has the print: 0828C, 16M and AP 55 G4( or Q4), can someone identify this opamp????









post #3838 of 5604
post #3839 of 5604

That definitely looks like TL082.  TLE2082 is supposed to be a direct upgrade from it.

post #3840 of 5604
Originally Posted by Avro_Arrow View Post

Here you go.



Originally Posted by Mad Max View Post

That definitely looks like TL082.  TLE2082 is supposed to be a direct upgrade from it.

Thank you very guys that was brilliant,  do you think that would be the later TLE 2082 as the TL082 is not made?  The DAC was made less than a month and it has LME 49990 in a XLR mode for balance?






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