The iBasso P3+ Herron has made its way to my door and there are images and more . . .

[jamato8]

I will have to try that.

 

[HiFlight]

I have spent most of the day rolling opamps. I found a conflict when trying the same single opamp (OPA27) in both virtual and ground channel. I got a lot of oscillation. Also, found the unfocused soundstage with several combinations using both V and G.

I ended up using the LMH6655 as my only VG opamp in the center socket.

I also ran into some oscillation problems when using the transistor buffers and LT1028 single-channel opamps.

BUF634 seems to work best with most of the combinations I have tried so far.

I feel that it will probably be impossible to pick a Topkit consisting of one combination for this amp, but I am thinking of a interchangeable package similar to what iBasso sends...a mix and match of really top opamps.

So far, the very best sound I have found consists of the AD744 biased into Class A operation and BUF634 with LMH6655 in the center ground socket. I am going to make up a set of Hi-C BUF634s and see how that scales with the Class A 744.

This actually sounds better to me than my AD743 combinations.

As my benchmark, I was using (2) OPA627BPs in LR, BUF634 in buffer sockets, and LMH6655 in Ground. I am also going to work the THS4032 into the mix somehow.

The class A 744 beats the 627 IMO.

 

[jamato8]

Gaahhh. I think a number of my biased opamps are in storage. I do have a couple here. I have the 744 but can't remember what resistor to use. Ron?

So in this amp do you prefer the BUF634 to the transistor buffer?

Ok I have the stock opamp withthe 634 buffers and the 6655 in the AV. I have 744 opamps but none that are setup with biasing. I have some 5534's biased from when working with Xin's 3, which was my favorite.

My 744 are the KN. Used them in my power supply for my dac in my BIG home dac that I built. In that in the voltage supply they were the best sounding, which surprised me as they really should have influenced the sound due to much good filtering after the regulation circuit I have them in but they were the best.

 

[HiFlight]

Well, I have spent the entire day working with this bewitching amp. I made up a set of stacked (2x) BUF634s and also a set of Hi-C buffers. I then compared both of these with the Class A 744s in LR and with both AD8397 and LMH6655 in the center GV socket.

The stacked buffers clearly sounded better than the Hi-C...a more encompassing soundstage with much better imaging. One very big drawback to biasing the 634 to Hi-C is that the current draw increases to 15ma per buffer. About a 7X increase. The LMH6655 also was noticeably better as a ground opamp than was the 8397. Imaging was more 2-dimensional with the 8397.


I find that the 6655 is a hard opamp to beat for ground.

Tomorrow I will do some head to head comparisons with the AD743 agains the Class A AD744. I will probably feed the amp some squarewaves and see how each combo presents them on my scope.

I find that those amps that can pass a good squarewave invariably sound good.

It is easy to bump the tabs on the gain jumpers when re-inserting the board into the case. I wondered why one channel suddenly was louder than the other. I also discovered that with no jumpers, the gain defaults to zero.

Amazing how one can waste an entire day playing with tiny parts! Well, maybe waste is too strong a word. I could have, instead, been doing honey-do chores.

 

[jamato8]

Stacked buffers. I don't even think I have any extra 634's. What a bummer to have everything in storage 1000 miles away. I do have many different opamps with me but mostly the older stuff used with Xin's amps. Old, that is funny. They are maybe a few years old though I do have a couple of very hard to find 5534's from 1982 and they are better than the rest of the 5534's. Why I don't know.

 

[HiFlight]

The biased 744s were made by cutting off the #6 pin, then bending the #5 pin to fit into the #6 socket hole. I am going to make some up using SOIC case style, as it is much easier to make them up with an adapter. Just cut off a leg and a bit of solder bridging and you are done.

When I was making them up for my Xin amps, it was easy to break off a pin accidentally when bending it. With the SOICs, there is little chance to ruin an opamp. I was rather surprised that the Hi-C didn't sound as good as the stacked 634, as that was a mainstay in Xins SuperMacros.

I did find that with stacked buffers and using the extra sockets for the class A 743s, it is necessary to cut off the top of the gain jumper tabs, as you can't get the board back into the case unless the tabs are shortened.

I am pretty sure the biased 744 will end up as a Topkit selection somewhere down the road.

While there are combinations that seem to be synergistic, there are also combinations that either oscillate or exhibit some other type of artifacts. I have seen this mostly in the V and G channels.

 

[denging]

so guys, what is it all about anyway? a true improvement or merely a 'tweak' ?

 

[ryuzoh]

Quote:

Originally Posted by HiFlight /img/forum/go_quote.gif The biased 744s were made by cutting off the #6 pin, then bending the #5 pin to fit into the #6 socket hole.

That's same method as LISAIII

I think OPA27s, OPA627s and LT1028(A)s are too fast and requires more margin to compensate on G channel in spite of the fact that they are unity-gain-stable.
Also, the output from the G leads to capacitance like WIMA w/o resistance.
The fact will make the OPs on G unstable.

In Japan, we have reports of slider-noise with AD827JN.
Because biasing resistors is too high and lacking currents for biasing AD827s.

 

[HiFlight]

Quote:

Originally Posted by denging /img/forum/go_quote.gif so guys, what is it all about anyway? a true improvement or merely a 'tweak' ?

IMO, the performance of the class A AD744 with stacked buffers represents a major improvement rather than a tweak. Still examining the ground options, but LMH6655 sounds very good.

So far some of my LR favorites include the AD8022, LMH6622, AD743JN, and the class A biased AD744.

I found the Hi-C buffers to have less impact than the stacked buffers. It also draws MUCH more current. I will, however, try the Hi-C in the ground channels.

 

[arirug]

I have received my P3+ and thinks it sounds terrific! While I`m writing this I listen to Johnny Cash with my P3+, an imod 4th gen and Sennheiser HD600! And I`m still enjoying my D10. iBasso really makes some great portable amps to a bargain price! I have just tried the P3+ in stock configuration!

 

[HiFlight]

There is little question that iBasso has become a major player in the very high quality portable amp arena.

The P3+ has the best sound of any portable amp that I have heard.
Now, if we could just add the D10 DAC and call it the D10+!!!!!

The P3+ offers more opportunities for customization than does the D10, but I am predicting that the D10 will remain the DAC/AMP flagship for iBasso, while the P3+ will become their benchmark portable amp.

 

[arirug]

I use rechargeable batteries in the P3+. Do I have to take these out if I want to use the external power supply?

 

[GreenLeo]

Quote:

Originally Posted by HiFlight /img/forum/go_quote.gif There is little question that iBasso has become a major player in the very high quality portable amp arena. The P3+ has the best sound of any portable amp that I have heard. Now, if we could just add the D10 DAC and call it the D10+!!!!! The P3+ offers more opportunities for customization than does the D10, but I am predicting that the D10 will remain the DAC/AMP flagship for iBasso, while the P3+ will become their benchmark portable amp.

I look forward to seeing a D10+ though.

Can anyone tell me the difference between the P3+ and the P3 OEM in terms of the components and the SQ. Is the D10 2 channels? Can you please tell the advantages of 3 channels/4 channels over 2 channels as well?

Thank you.

 

[clasam]

Quote:

Originally Posted by GreenLeo /img/forum/go_quote.gif I look forward to seeing a D10+ though. Can anyone tell me the difference between the P3+ and the P3 OEM in terms of the components and the SQ. Is the D10 2 channels? Can you please tell the advantages of 3 channels/4 channels over 2 channels as well? Thank you.

Unfortunately, iBasso confirmed to me that there will be no D10+ coming out (as of right now)...perhaps there will be one if it uses the D1 enclosure

 

[jamato8]

I will be honest. I think the amp of the D10 is excellent. I don't think they really need to change it.