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iBasso PB-2 Pelican fully balanced portable, DB-2 Dac . . HiFlight recommended op amps page 16. . - Page 58

post #856 of 1207
Quote:
Originally Posted by spurxiii View Post

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

 

That's very astute of you to mention your source, as the input voltage from the DAC does influence the volume heard at the headphones, for any given gain provided by the amp.

 

So, this is where you need to increase the power output of the PB2 by using HA5002 buffers (which can each provide up to 250 mA of current).  What you choose to put in L/R can have an impact on power output, too, as that top row (closest to the battery) is the input voltage gain stage (affecting voltage, not current).

 

I vigorously recommend that you send a PM to HiFlight (Ron) and ask him to provide information about his "TopKit" for the PB2.  He has assembled, and continues to improve, a collection of some very desirable op-amps that are not included among those that iBasso provides.  Best of all, he does a great job of soldering the SOIC8 packages to DIP8 adapters, so that you can just plug them into your PB2 - no soldering required. Ask him, but I'm pretty sure he still includes the HA5002 buffer, which should help the PB2 to produce more gain.

 

While you wait for the TopKit to arrive (assuming you order one from Ron), try powering the PB2 with its 16V wall power adapter vs. the 12.6V internal lithium battery.  In any case, no matter what combination of op-amps you roll, 16V power will provide greater dynamics and bass control - especially for inefficient headphones - not at all for the most efficient IEMs.

 

If you can hear a difference at 16V and are willing to add and carry an external 16V battery pack to your stack for portable 16V operation, just ask for more info. (I'll spare everyone for now.)

 

Mike

post #857 of 1207

No need to spare us Mike, your posts are very informative and invaluable to noobs like me. I've learnt everything about portable sound from searching and reading posts like these in the last few of months. The only bad thing is, before I found Headfi in May this year I hardly had any of this gear and I was quite happy with my UE700 IEMs. Anyway, I diverge and I did order the HiFlight topkit from Ron yesterday against your advice from your first post to me. I've also tried the sound out of the 16V battery pack and although it did sound more livelier and dynamic it wasn't large enough for me to say that the improvement was there for sure. Perhaps it was some expectation bias. I have to try it again and give it a bit more time.

 

I started mentioning souces in my posts because I recently realised that not all sources produce the same amount of output and this was especially apparent when I tried using the pre-outs on my Yamaha AVR as a source for a power amp in a 2 channel speaker setup. The sound was so soft in comparison to a dedicated DAC I had. 

post #858 of 1207


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 #859 of 1207
Hi spurxiii,
Quote:
Originally Posted by spurxiii View Post

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

Are your Mad Dogs using balanced cables to connect to the PB2's Hirose connector, or are you driving the MAd Dogs single-ended? If it's the latter, you're only using half of the PB2 amp.

Mike
post #860 of 1207
No Mike, I had the mad dogs before I purchased the PB2s and they're SE. I bought the PB2s after a couple of recommendations from the mad dogs thread and reading the review of Headphonia. Is that you who wrote the review? Good review if it is. Sorry I'm really new to all this. Thanks for all this help by the way

I'm quite happy with the PB2s even as they are now and they have already passed my expectations and even before my Topkit arrives, it already sounds better than my budget desktop setup.

Would you recommend getting the SE upgraded to balanced if I am already happy with the current sound? i. e. I'm now listening to it at 80% volume on the mad dogs, will it sound the same at say 50%? Or will it be louder and present more dynamically and give me more detail?
Edited by spurxiii - 8/18/13 at 1:17pm
post #861 of 1207
Quote:
Originally Posted by spurxiii View Post

No Mike, I had the mad dogs before I purchased the PB2s and they're SE. I bought the PB2s after a couple of recommendations from the mad dogs thread and reading the review of Headphonia. Is that you who wrote the review? Good review if it is. Sorry I'm really new to all this. Thanks for all this help by the way

I'm quite happy with the PB2s even as they are now and they have already passed my expectations and even before my Topkit arrives, it already sounds better than my budget desktop setup.

Would you recommend getting the SE upgraded to balanced if I am already happy with the current sound? i. e. I'm now listening to it at 80% volume on the mad dogs, will it sound the same at say 50%? Or will it be louder and present more dynamically and give me more detail?

Hi spurxii,

I'm a different Mike, but it would be fun to work for Headfonia. :-)

If you're already happy with SE connection of your Mad Dogs to the PB2, then forget I said anything about balanced cables. I have no experience with Mad Dogs, but generally, the less efficient the headphone, the more it will "scale" to an amp with more power. Efficient IEMs, for example wouldn't likely benefit by going balanced with the PB2, from SE. Something like the notoriously power-hungry HiFiMan HE-6 would, however, appreciate the increase in power.

i think your Mad Dogs are somewhere in between, so you might enjoy audible benefits or you might not. ???

:-)

Mike
Edited by zilch0md - 8/18/13 at 4:43pm
post #862 of 1207

The MadDogs soak up power and having the single ended one, the PB2 powers it well but I plan to get the AlphaDogs balanced and expect a significant improvement.
 

post #863 of 1207
Quote:
Originally Posted by gikigill View Post

The MadDogs soak up power and having the single ended one, the PB2 powers it well but I plan to get the AlphaDogs balanced and expect a significant improvement.

 
judging by what others have said about balanced vs SE I wouldn't expect a significant improvement. A significant improvement for me was going from the JDS Labs C5 to the PB2s. I don't expect the same gains or should I? If so I'm in
post #864 of 1207

I wish I could say.  Ultimately, as with so many decisions in this "hobby" of ours, you'll have to try it to know for sure.  The good news is that spending the money to recable your Mad Dogs will not hurt the SQ in any way.  A small consolation, but true, nevertheless.  There's also the simple contentment of knowing that you would be exploiting 100% of what your PB2 money can deliver, instead of 50%. 

 

Another point to consider:  Many people argue that going balanced brings more to SQ than just the power offered by running essentially two amps instead of one (or four instead of two, in the case of the PB2's quad design).  But I'm not a big believer in those benefits being truly audible.  I'll admit that with single-ended output, the shared ground can cause impedance fluctuations on one channel to influence what's happening on the other, but is it audible?  I don't think so.  

 

To my knowledge, the Meier Audio amps, both his portable and desktop designs, are the only single-ended amps that offer what Dr. Meier calls an "Active Balance" feature - where he somehow compensates for impedance fluctuations so that each channel has no awareness of the other, despite sharing a common ground.  As he puts it (paraphrasing), you get the benefit of balanced cables without the expense and hassle.  Still, I can't honestly say I have ever heard these impedance fluctuation gremlins in any single-ended amps, including the Burson Soloist.  So, what good is a balanced design other than the extra power and driver control that can be had with an amp that has twice the components?  

 

While I'm on a soapbox about balanced vs. single-ended, I'm even less of a protagonist for using balanced sources.  At least with balanced output, you're talking about controlling the moving parts of a transducer that has mass and inertia.  But there's no such equivalent on the source side of an amp.  In my opinion, the only reason to use a balanced output DAC and cable to the amp is for really long cable lengths, where balanced cabling can indeed have a dramatic impact on reducing vulnerability to noise.  In my opinion, for our purposes, especially with portable gear using really short, shielded interconnects, balanced sources are a waste of money.

 

Ahhh..  I feel much better.  biggrin.gif

 

Mike


Edited by zilch0md - 8/19/13 at 12:49am
post #865 of 1207

Thanks for your thoughts Mike. I'm probably going to wait until gikigill does his re-cabling seeing as he has the same setup in the amp and headphones department. One other benefit of going balanced is that I can use speaker taps to drive my mad dogs off my speaker amps, the same thing I'm going to do with my HE500s. BTW you write like an engineer.

post #866 of 1207
Quote:
Originally Posted by spurxiii View Post

judging by what others have said about balanced vs SE I wouldn't expect a significant improvement. A significant improvement for me was going from the JDS Labs C5 to the PB2s. I don't expect the same gains or should I? If so I'm in

 

x2

 

I've done the SE Vs. Balanced thing with quite a few of my phones and IEMs and what small improvements I thought I heard were just that ''small''. Don't expect day and night differences.

post #867 of 1207

^ And that's saying a lot coming from Nigel - a guy who has demonstrably good ears! 

 

beerchug.gif

post #868 of 1207

Haha, thanks Mike....

 

My comments above were aimed at the PB2. I found going balanced via speaker taps of TP60 for certain phones (HE-6) yeilded more noticeable results. Again, not day and night but they were there none the less.

 

The PB2 is a fantastic amp however you are using your phones. 

post #869 of 1207
Quote:
Originally Posted by spurxiii View Post

Thanks for your thoughts Mike. I'm probably going to wait until gikigill does his re-cabling seeing as he has the same setup in the amp and headphones department. One other benefit of going balanced is that I can use speaker taps to drive my mad dogs off my speaker amps, the same thing I'm going to do with my HE500s. BTW you write like an engineer.

 

Yeah, now THAT is a great reason to get some balanced cables for your Mad Dogs!

 

I've been heavily pursuing the whole speaker-amp thing, lately.  I even sold my originally $999 Burson Soloist (1.28 Watts into 50-Ohms) in preference for the sound of a $189 Emotiva a-100 Mini-X speaker amp (8.0 Watts into 50-Ohm), in combination with a $597 tube buffer (the Decware ZSTAGE, currently equipped with a NOS Siemens 12AU7) to compensate the Emotiva's somewhat bright and harsh treble.  

 

Where the Soloist had amazingly smooth yet detailed treble, but was too laid back (tenth-row seating), and somewhat lacking in dynamics, the Emotiva puts you right on stage, with lots of punch and slam dynamics, thanks to 8 Watts vs. 1.28 Watts into the 50-Ohm LCD-2, which can really scale to the power (up to 13 Watts per Audeze support.)  

 

 

 

More on this subject can be found here:  http://www.head-fi.org/t/649107/speaker-amps-for-headphones/675#post_9711285

 

I'm now waiting on a $500 TBI Millenia MG3 Class D/B speaker amp that's supposed to ship today.  The amp's designer, Jan Plummer, is also sending me an impedance matching box ($110), with resistor values specific to my 50-Ohm headphones.

 

1000

 

 

http://www.tbisound.com/dsp_products_millenia.asp

 

The TBI Millenia MG3 will deliver 5.12 Watts into 50-Ohms, but it's said to be extremely musical, natural-sounding, organic, yet detailed, transparent, with great dynamics and having an inky-black noise floor.  Yes, all that!

 

And it has a battery compartment!  Allowing 12V operation with 8 AA alkaline or lithium batteries for 10 Watts into 8-Ohms (1.6 Watts into 50-Ohms - more than a Soloist's 1.28 Watts)!  Or, better still, you can power it with a 24-Volt battery system for 32 Watts into 8-Ohms (5.12 Watts into 50 Ohms).  Battery power = super clean sound.

 

Check out these TBI Millenia MG3 reviews from the the venerable John Hoffman of Absolute Sound (a highly trusted source of reviews in HiFi):  

 

In many respects the Millenia amplifier in battery mode is closer in sonics to my Electra Print 300B SET amplifier than it is any conventional solid-state piece. When revisiting the Lucia Hwong piece I found that high frequency notes had a longer decay pattern and had a greater degree of shimmer. The distinctive tone of the wood flute in the opening passage had gained a higher degree of realism. The vocal passages moved farther back in the sound stage and now floated in a space above the instruments, expressing the surrealistic feel of this composition. These gains in musical reproduction move the Millenia amplifier closer to what the Electra Print amplifier achieves, which happens to be a $4000 amp and preamp package. While the Millenia does not have the harmonic density, or the complete transparency of the SET amplifier, it comes shockingly close. Which is quite an accomplishment for a $500 integrated amplifier.

 

Quoting Positive Feedback Issue 67 (just five issues later, he felt compelled to revisit this amplifier with another review!:
The performance gap between my Electra Print amplifier and the Millenia amplifier has rapidly closed, as the latest cluster of improvements that Jan has devised for the TBI amplifier has effectively erased the largest flaws from the previous generation amplifier. Earlier versions of the MG3 amplifier had excellent sound quality for the price point, but there were always a sonic signature that was consistent with the Class D circuit design. Essentially, the music had a smooth and refined sound, but never could quite cross that threshold of realism that separated a SET, push-pull tube amp, or even a well executed solid state design from the chip amp contingent. The 2.0 version of the TBI amp has breached that meridian, and is a legitimate high performance amp that is within the financial reach of most any hobbyist.

 

Take this amateur's review with a grain of salt, but it's a fun read, just the same: 

 

Now I won't bore you with these details, but the TBI has the quickness of the best OTL's and Class A's, it has the transparency and detail of the best SET and Class A amps, is has the speed and quickness of the best OTL's and Class A's, it has the smoothness and aliveness of the best Set and OTL amps, it plays vocals like the best SET and OTL's, and it images like the best OTL and SET amps. That is why I call this the JCOTLSETCLASSAPASS amp. If John Curl or Nelson Pass came out with a tube amp, this is what it would sound like. I would love to be Nelson Pass's neighbor and take this wee tiny TBI amp and put it on his monster horns. Even Pass would be surprised. 

 

biggrin.gif

 

I think I'm going to make this both my desktop and my (trans)portable amp!

 

OK, that was seriously off-topic!  My apologies.

 

Mike

post #870 of 1207

I lost out by $1 on a TBI Millenia on ebay which eventually went for $251. I got so upset, I bought the Topping TP60 on impulse. I have some speaker tap cables coming from BTG Audio to drive my HE500s but won't be able to use it for the mad dogs even with a resistor box because the TP60 does not have a shared ground I believe. To keep this on topic I want to say that the PB2 sounds better than my current desktop setup for both the mad dogs and the HE500s. I hope to have a desktop setup which at least sounds better than my PB2 in the TP60.

 

Nigel, do you reckon I will get much of an improvement in SQ from my PB2 with a TP60 on my HE500s since you've used them with the HE6s it might give me some insight into what to sort of expect.


Edited by spurxiii - 8/19/13 at 2:24am
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