The iBasso P3+ Herron has made its way to my door and there are images and more . . .
Jun 2, 2009 at 11:21 AM Post #16 of 302
Quote:

Originally Posted by HiFlight /img/forum/go_quote.gif
Couldn't resist....Opened it up and tried (2)AD743JNs, AD8022, and OPA2727 in LR, Transistor buffers, and AD797 in Ground. All sounded good. Of course, this is a virgin amp, with few hours on it. Like nearly all other amps, the P3+ really shines with the AD743s.

With all the possible combinations in this amp, I can foresee myself tied to my bench, ignoring meals, pets, wife, personal grooming....etc,etc!!!

I have not yet had a chance for head to head comparisons with my D10. That will be down the road somewhere after the P3+ accumulates more playtime.

X2 to Jamatos comments about the quality of both the exterior as well as the inside circuitry. Clearly very high quality of both. Even gold-plated battery contacts. It is obvious that much attention was given to even the smallest details of this amp.


Willing to try stack buffer?
 
Jun 2, 2009 at 1:12 PM Post #17 of 302
Quote:

Originally Posted by theory_87 /img/forum/go_quote.gif
Willing to try stack buffer?


I can maybe with the BUF634, but I think iBassos transistor buffers sound better than the 634. There are already 2 transistors on each adapter. It might be more worthwhile to put the BUF634 in Hi-C mode by adding a 220 ohm resistor across pins 1 and 4.

I think stacking might be a waste of time, considering the already great sound of this amp. More electronics in the signal path don't always result in improvement.

I really need to more fully understand the circuit of this amp before I try to do more than just roll the LR opamps.
 
Jun 2, 2009 at 4:08 PM Post #18 of 302
Oh, and the gain is more than I would ever need. In-other-words, the volume goes, way, way loud and to my ear, doesn't distort. I can not turn the amp all the way up, it is just too loud and may damage my phones.

What I am hearing already are notes that don't tie up with each other. There is no congestion that I hear on loud or complex passages. On dynamic music it is like the clash of the Titans.
 
Jun 2, 2009 at 5:31 PM Post #19 of 302
In 3ch architecture,
I recommend not to use dummies on both GND socket, and stick 1 single-OPAMP either 3/4 GND sockets, directly connecting each ground's 6-pin(output).
The reason why is TLE2426 can provide 20mA only.......
This is the best way to reduce DC output in P3+

John, I'll send you additional my HZ 3300uF caps for modding.
 
Jun 2, 2009 at 5:40 PM Post #20 of 302
Quote:

Originally Posted by ryuzoh /img/forum/go_quote.gif
In 3ch architecture,
I recommend not to use dummies on both GND socket, and stick 1 single-OPAMP either 3/4 GND sockets, directly connecting each ground's 6-pin(output).
The reason why is TLE2426 can provide 20mA only.......
This is the best way to reduce DC output in P3+

John, I'll send you additional my HZ 3300uF caps for modding.


Ok, but there is a G/V so is this a ground channel and a virtual ground channel? I am not sure how they work together or if you use one or the other, which would make sense.

So you are saying to use any single opamp in either the G or V?
 
Jun 2, 2009 at 5:51 PM Post #21 of 302
Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif
Ok, but there is a G/V so is this a ground channel and a virtual ground channel? I am not sure how they work together or if you use one or the other, which would make sense.
So you are saying to use any single opamp in either the G or V?


Affirmative, and connect wire from 6-pin to the other 6-pin.
OK, just moment...
I'll draw.
 
Jun 2, 2009 at 6:06 PM Post #22 of 302
Quote:

Originally Posted by ryuzoh /img/forum/go_quote.gif
Affirmative, and connect wire from 6-pin to the other 6-pin.
OK, just moment...
I'll draw.


I understand but this isn't going to be something everyone wants to do.

But how are V and G to be used if not used with the wire? What will be the difference in using just an opamp in V or an opamp in G? Or an opamp in both?
 
Jun 2, 2009 at 6:26 PM Post #23 of 302
p3c-project

I think V is better.
Because feedback resistor is higher and compensation cap is attached.
That can make OPAMP stable loading with capacitance.

Difference between 3ch and 4ch is separation of GND.
4ch is better for noise, but gives slightly DC to output.
3ch is better for reducing DC and simple.
 
Jun 2, 2009 at 6:38 PM Post #24 of 302
Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif
I understand but this isn't going to be something everyone wants to do.


Exactly...
Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif
But how are V and G to be used if not used with the wire? What will be the difference in using just an opamp in V or an opamp in G? Or an opamp in both?


If you stick different type on V and G, the voltage btwn V's output and G's output will get higher.
So... for reducing DC, I think you had better stick same kind of OPAMPs onto V and G, or to use dual type.
 
Jun 2, 2009 at 6:40 PM Post #25 of 302
Ok, but do you find any difference with opamps in the virtual ground socket?

On pin 6 to 6, many people are not going to solder a wire from pin 6 to 6 as they don't solder so there should be, must be, a different way to do this.
 
Jun 2, 2009 at 7:00 PM Post #26 of 302
Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif
On pin 6 to 6, many people are not going to solder a wire from pin 6 to 6 as they don't solder so there should be, must be, a different way to do this.


I'm realizing it.....but couldn't find other means to make higher current with 3ch architecture
frown.gif

So.... same single-type or dual-type is recommendable.

Quote:

Originally Posted by jamato8 /img/forum/go_quote.gif
Ok, but do you find any difference with opamps in the virtual ground socket?


The 2426 side socket is V.
You can see the resistor in yellow-purple-black-brown-brown.
The color bars represent the resistor as 4.7k Ohm.
 
Jun 2, 2009 at 7:08 PM Post #27 of 302
Ok, but I mean do you find a difference in sound with different opamps in the V or G?
 
Jun 2, 2009 at 7:19 PM Post #28 of 302
Okay....
The difference leads its expression of soundstage.
IMO, properly powerful OPAMP improves details or presence in sound, like AD8397, LM6172, LMH6655, LMH6643, or BUF634 on both GND.
As like Mr.HiFlight's recommendation.
Because they can quickly support mid voltage and the caps.
Expressing in atmosphere... or, finding distance.
When I sticked on different OPAMPs on V;BUF634 G;OPA627, my impression was very mellow and wide soundstage.
But couldn't focused enough (also provides 30mV DC).
After changing them to AD8397, the dull focus disappeared.
Thus I concluded GND must be higher current type and in same type.
 
Jun 2, 2009 at 7:31 PM Post #29 of 302
Great. Do you think in this position, any opamp is better than others?

I have 2 AD797's in the G and V right now. edit: I took them out. I don't like the sound. The soundfield was more spread out more but imaging wasn't very good. Bass was too pronounced (strong) also.

With the transistor buffers and the opamps being used run time is most likely around 10 hours on 800mA batteries.

So has anyone checked the actual output power of the P3+ with transistor buffers or BUF634's?
 
Jun 2, 2009 at 8:09 PM Post #30 of 302
Then, how about 3/4 (V and G) as AD8397, transistor buffers, AD743JNs in L/R?
 
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