iBasso PB-2 Pelican fully balanced portable, DB-2 Dac . . HiFlight recommended op amps page 16. . - Page 46

Mazer,

Good news.  I think it's cool that iBasso is willing to say that USB power will impact the DB2's SQ.  Good for them, but I suppose you can always just listen to see if you can hear any artifacts while using USB power with coaxial or toslink data.

Did your DB2 include the 5V AC adapter that's mentioned at the iBasso web site and in the DB2 manual?

Thanks,

Mike

Mike, you could be right about the AC adapter. I think mine is probably still in the box! I have a dual USB adapter next to my rig that came with something else so just plug in the cable when it needs it.

It's a great piece of kit.

I thought that maybe you didn't receive an AC adapter with your DB2 because your AC plugs are shaped differently in Australia.  

Mike

Hey, I'm from UK not Australia! Is it my text accent that made you think that?

The Holy Grail combo?

PB2 using OPA1612 x2 for L/R, with AD797 x4 as buffers!

To my ears, this makes my normally bass-shy Sony PCM-M10 source and LCD-2 sound like HD650s on a transparent source with a transparent amp:  Extended, controlled bass, clean highs, lots of detail across the spectrum, yet still airy and non-analytical.  Not neutral, but fun!

I think this combo works because as buffers, the AD797s are adding bass and warmth, while taking the edge off the top end that comes with the OPA1612s, all without destroying any detail.  It sounds like a really detailed, fast tube amp, with gobs of power controlling the bottom end.

I discovered this yesterday evening and listened to the combo for about three hours.  YMMV.

Mike 

I will try that Mike!

Cool!

I can't wait to hear your thoughts - whether they support my findings or not.  

Keep in mind that my chain begins with a "bright" source (the Sony PCM-M10), which is tamed by the LCD-2s shelved highs.  I suspect that if I started with a source that had a flat response, the combo I've recommended might be too dark with my LCD-2s.  

By the way, after about three hours of listening to this combo, the PB2 was warmer to the touch than I've ever seen it. Not hot, just warm, especially on the underside where it was resting on a side table.  I can't imagine why that's happening, but I've never really spent much time listening with the AD797s before - not even on the L/R stage, so maybe they just tend to run hot.

Mike

Quoting my earlier post:

Originally Posted by zilch0md 

Hi Mazer,

 

[snip]

 

While I'm conjecturing, you might also want to try using an Energizer XP8000 external lithium-ion power pack to power and/or recharge the DB2 without need of an AC outlet (at least until the XP8000 itself needs recharging):    

 

http://www.energizerpowerpacks.com/us/products/xp8000/

 

I've been using an XP8000 almost daily for about 18 months, with my Stepdance and, for the past month with my PB2.  I can't say enough about how friendly this device is and how many different voltages you can get out of it, using accessory cables.  You could literally recharge your DB2 and your PB2 simultaneously with an XP8000 - while out and about.

 

http://www.head-fi.org/gallery/album/view/id/647286/user_id/54793

 

Mike

Heads up!  

Just for grins, not having anything else I could use as a source that's USB-rechargeable, I hooked up my Sansa Clip+ to the 5V USB outlet of the Energizer XP8000, having already connected my PB2 to the XP8000 (via the WI16 voltage regulator cable).  

So far, so good, both the PB2 and the Clip+ were charging simultaneously.

But then...   I connected the Clip+ headphone out to my PB2 single-ended input, while both devices were still connected to the XP8000 and still charging.

I put on my headphones, turned on the PB2, then turned on the Clip+ - POP!! - I heard a loud noise and my Clip+ died a horrible death.  Now it makes a rhythmic popping sound that's unaffected by the volume control - no music.  I killed it!

Moral of the story:  I think I created some kind of loop on the power supplies of the Clip+ and the PB2, by having them both connected to the XP8000 -AND- trying to use the Clip+ as the source my PB2.   The funny (not funny?) thing about this is that I had actually hesitated with second thoughts before trying it, but now I know:   It's OK to charge two devices simultaneously with the XP8000, but be careful not to establish ANY other electrical connection between the two devices - not even a line out interconnect!

Mike

Interesting event.  At least you now have an excuse to head out and buy a new source!! 

Quote:

Originally Posted by zilch0md 

The Holy Grail combo?

 

PB2 using OPA1612 x2 for L/R, with AD797 x4 as buffers!

 

If someone gets a chance to try this combo with an ipod/CLAS source and likes the sound output, I could be tempted to source some of them.  What is the best place to grab them without needing to be able to solder etc?  Cheers

Quote:

Originally Posted by Kremer930 

Interesting event.  At least you now have an excuse to head out and buy a new source!! 

Ha-ha!  Good one!  Any excuse will do, eh?  

Actually, I've already satiated that desire (somewhat) by ordering another Clip+, just like the one I fried.  (Big spender, not!)  

It will be here Friday, then I have to Rockbox it.  

Joy!

Mike

Quote:

Originally Posted by Kremer930 

If someone gets a chance to try this combo with an ipod/CLAS source and likes the sound output, I could be tempted to source some of them.  What is the best place to grab them without needing to be able to solder etc?  Cheers

I wish I had a CLAS with which to answer your question, and more!  

As to how to you might obtain the opamps and buffers: The AD797's are the four blue op-amps that iBasso includes with the PB2 (along with some other pieces in their rolling kit).  So you might already be in possession of the the AD797's.

Here's a picture from Headfonia's review of the PB2 that shows all of the opamps and buffers that iBasso ships with the PB2 - the AD797's are blue:

For the OPA1612's, I recommend you contact Ron Kerlin (send a PM to HiFlight) and ask him if he could provide you with a quote for soldering two OPA1612's to the adapters for you - or you could just order his TopKit, which includes the OPA1612s.  Once you have all six parts, you can just open the case and swap them in - no soldering required.

I can send a picture of precisely where to place them, if and when the time comes...

Joy!

Mike

I tried the 797's as buffers with 4 x 1611's and while very nice I found that with IEM's the SQ was really grainy. Not noticeable with full sized phones like LCD-2 but a lot of noise with my ES5's

I am happy with my choice of now - 4 x LME49990 and 4 x HA5002 buffers. Clean, quite, transients and tube like micro details to die for..... I listen to a lot of Ambient Trance/Chillout and this combo is just awesome with all my phones apart from HE-6. The PB-2 just doesn't have enough juice to get to a loud enough listening volume, fair play though it doesn't clip, it just doesnt go quite loud enough.

I was up from 10:00 PM until 3:00 AM last night (this morning) listening to the OPA1612 (L/R) / AD797 (as buffers) combination, again.  

Having written so highly about it yesterday, I had some trepidation as I sat down for another session with this combo, but day two was just as exciting as my first experience.

I LOVE the way this combo sounds in the PB2, balanced out to my LCD-2!  It's PERFECT, for my tastes, anyway.  

Having only had the PB2 for less than two months now, I can't imagine going back to using an amp that can't be rolled.  I've done surprisingly little experimentation compared to several contributors here, but have already latched onto what, for me, is a very satisfying sound quality.

I can't get enough of listening to this rig, but the PB2 continues to get very warm.  I don't understand why this is happening when I've not witnessed this with other combinations (such as the OPA1612s with HA5002 buffers), so it must be the AD797s that are generating all the heat.  I'm thinking of taking the lid off the PB2 when using them - all that heat can't be good for the battery or anything else inside the case.

I just checked the AD797 datasheet - it says that the absolute maximum supply voltage is +/-18V, so my use of a 16V external battery shoudn't be causing any problems.

OK, I just found several posts at various forums saying that it's normal for the AD797 to get warm/hot while running.  No problem (except I'm still thinking of taking the lid off the PB2).  

I wonder if iBasso would sell me another lid, so that I can experiment with drilling vent holes in it...

Mike