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iBasso PB-2 Pelican fully balanced portable, DB-2 Dac . . HiFlight recommended op amps page 16. . - Page 57

post #841 of 1128

Maddog and PB2 owner here, even on single ended the headroom is immense and you,ll be deaf before the volume knob is at 12oclock.

 

Its colder sounding than the C5 though. Stick to medium gain to prevent blowing out yur ears with the Maddogs.
 

post #842 of 1128
Haha I like that, blowing out my ears
post #843 of 1128
Look what came. I'm not sure what I do with the additional chips supplied. It came with no instructions

post #844 of 1128
Quote:
Originally Posted by spurxiii View Post

Look what came. I'm not sure what I do with the additional chips supplied. It came with no instructions

 

Hey!  Congratulations! 

 

Take those extra op-amps and ask someone you trust to hide them from you for at least a week, while you get to know the sound of your new amp, with the default configuration.  Then steal your mind in preparation for several weeks of rolling op-amps obcessively!  tongue.gif

post #845 of 1128
Thanks Mike. All those op-amps and buffers look the same, how do you tell what is what. Also, is there a gain switch somewhere because I've got the volume at 90% to get a decent sound?
Edited by spurxiii - 8/15/13 at 9:55pm
post #846 of 1128

For those who are already familiar with the stock op-amps...

 

I've been using LME49990s in L/R for several weeks now, to drive my LCD-2, either with HA5002 buffers or more recently, with dummy buffers, which sound much more transparent, but less powerful, of course, than the HA5002.

 

Still, I've come to prefer the clarity of dummy buffers with the LME499990 and there's plenty of headroom left with the fairly efficient LCD-2 (relative to something like the HE-6).

 

This evening, I finally got to try something I first thought about a couple of weeks ago:  

 

I'm using LME49990s as buffers, in addition to using them in L/R.

 

The result is wonderful, for my ears, my tastes, etc.  As buffers, they still don't deliver anywhere near the current that HA5002 would, but they do kick things up noticeably in terms of dynamics and bass control, just the same.

 

They also add body and fullness to what I was hearing with just the dummy buffers, without any apparent decrease in resolution or transparency.  It's just more of that same LME49990 goodness!

 

I'm using ebay seller frugalphile's LME49990 singles sold already soldered to SOIC to DIP8 adapters, but his PCBs are longer than the typical Browndog PCBs, so they end up overlapping each other with one row not seating fully into their sockets.  

 

So...  after trying to shorten the PCBs with a dremel (bad idea, really bad) and ordering another set of four from frugalphile, I decided to stack them atop four DIP8 sockets I ordered from Browndog, so that their PCB length is no longer a problem - they can be fully seated while not running into the other row that's sitting lower down, in L/R.

 

Joy!

 

 

 

This sounds great with LCD-2.  Me like!

 

 

Mike



UPDATE: The honeymoon is over! I can't recommend using LME49990 as buffers in the PB2, at least not with LME49990 in L/R. Now, some people might like it, but I've decided, after more hours spent listening, that it's too warm for my tastes AND there is a loss of resolution / low level detail / transparency, as compared to using dummy buffers with LME49990 in L/R. If you're into warm and syrupy sound and/or prefer a slight loss of resolution with absolutely non-fatiguing and airy treble, then you might want to check it out. 8x LME49990 has a thick, warm, and smooth sound.

Edited by zilch0md - 8/18/13 at 10:37am
post #847 of 1128
Quote:
Originally Posted by spurxiii View Post

Thanks Mike. All those op-amps and buffers look the same, how do you tell what is what. Also, is there a gain switch somewhere because I've got the volume at 90% to get a decent sound?

 

Have  look at my second picture, above.  Move those jumpers so that they each sitting on the closest pair of pins (closer to the camera when looking at that photo) and you will then be on High Gain.  Move all four jumpers at the same time, while the unit is turned off.  

 

The photo is showing Low Gain (with the jumpers just resting on one pin - not connecting any pair of pins).

 

You should be able to find a small Torx wrench (L-shaped) in the stuff that came with the amp.  Use it to remove the top set of screws only (two screws from each end of the amp) and you will then be able to lift off the cover.  Do all of this with it powered off.

 

I'm going to bed now, so more tomorrow, if you have additional questions.  Meanwhile - check the manual (short though it is.) And search this thread.  It's highly unlikely you can ask a question that hasn't already been asked and answered.  

 

biggrin.gif

 

But feel to keep asking questions.  I'll help whenever I'm on.

 

Have fun!

 

Mike

post #848 of 1128

Oh, and here's a labeled photo of what's what with the stock op-amps that come with the PB2.

 

 

 

Opamps that come stock with the iBasso PB2

 

The two columns of op-amps on the right can be put into L/R (the sockets that sit closest to the battery).

 

The three columns of op-amps on the left are buffers that can be put into the row of sockets that sit closest to the volume control.

 

The BUF634U have sockets of their own that allow you to stack BUF634P on top of them, if you want to try a different sound.

 

WARNING:  Make sure that you mount the op-amps with the little half-circle notches facing toward the volume control (away from the battery) - as shown in this picture (again):

 

 

 

That's it for tonight.    Zzzzzzzzzzzzzzz....


Edited by zilch0md - 8/15/13 at 10:20pm
post #849 of 1128
Thanks Mike. Will do these now
post #850 of 1128
Just changed the jumpers to high gain and it's not that loud. Still needs about 80% volume to get decent sound on the mad dogs via iphone4s LOD
Edited by spurxiii - 8/16/13 at 2:00am
post #851 of 1128

Has anyone try to do digital out the Fiio X3 through coaxial output (to bypass the internal DAC) and then line in to iBasso PB2?

If yes,  is there any significant improvement in sound quality?

post #852 of 1128

Cant connect coax to PB2  but line out will work. Coax is meant for DACs.
 

post #853 of 1128
Quote:
Originally Posted by gikigill View Post

Cant connect coax to PB2  but line out will work. Coax is meant for DACs.
 

Sorry. I mean the DB2 (the standalone DAC) and not PB2.

post #854 of 1128
Unfortunately I've already succumbed to the opamp rolling. I've swapped to the 797s and the high bandwidth

post #855 of 1128
The bass definition is better and the upper end is cleaner with the 797s and the high bandwidth buffers. I think I'll keep this till my HiFlight kit comes


Edited by spurxiii - 8/16/13 at 5:52am
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