[CJG888]

I have now had a chance to listen to my new P4. Initial impressions:
 
- A very clear, detailed sound with a good soundstage and impressive dynamics (for a portable),
- On the bright side of neutral with the stock op-amp configuration.
 
Overall, it seems like good value for money (1,499 RMB, about GBP 150).
 
So far, I have been using it primarily with my GR07s (for which, after all, I bought it!). The op-amp configuration is still stock (and will stay so until it is run in and I am familiar with the sonic signature), but I have switched it to low gain (otherwise the difference between inaudible and deafening on IEMs was about one degree on the volume control! I have also noticed that the sound quality has improved after this move, suggesting that either the impedance matching on low gain is better, or that the volume pot is not performing at its best at very low levels.
 
I tried it (on high gain!) with my HD600s, but was disappointed. It drove them, in the technical sense of the word, but the sound was flat and lifeless. Given its form factor and price, this wasn't entirely surprising, though. I hope that it will perform better with my new FA-003s (waiting for me back in the UK), as these are easier to drive and have a low impedance - and will figure in my "hotel room" system.
 
As I bought my P4 here in China, it shipped without English instructions. I have downloaded a very basic manual from iBasso's website, but there is very little information of op-amp rolling (other than an inventory of what is in the box). Is there a "beginner's guide" available to prevent me from doing something stupid? I have read that at least one contributor has already dispatched his P4 to the hereafter by plugging the wrong chip in the wrong socket.....
 
Also - what is meant by a "static-free environment"? Should I wear an earthed wrist-strap when handling the ICs? Do I need a special insertion and removal tool?
 
Finally, I have noticed that some of you recommend op-amps which are not included in the package. Can I obtain these from RS or Maplin, or are there specialised sources for these?
 
 

 

[HiFlight]

I have now had a chance to listen to my new P4. Initial impressions:

- A very clear, detailed sound with a good soundstage and impressive dynamics (for a portable),
- On the bright side of neutral with the stock op-amp configuration.

Overall, it seems like good value for money (1,499 RMB, about GBP 150).

So far, I have been using it primarily with my GR07s (for which, after all, I bought it!). The op-amp configuration is still stock (and will stay so until it is run in and I am familiar with the sonic signature), but I have switched it to low gain (otherwise the difference between inaudible and deafening on IEMs was about one degree on the volume control! I have also noticed that the sound quality has improved after this move, suggesting that either the impedance matching on low gain is better, or that the volume pot is not performing at its best at very low levels.

I tried it (on high gain!) with my HD600s, but was disappointed. It drove them, in the technical sense of the word, but the sound was flat and lifeless. Given its form factor and price, this wasn't entirely surprising, though. I hope that it will perform better with my new FA-003s (waiting for me back in the UK), as these are easier to drive and have a low impedance - and will figure in my "hotel room" system.

As I bought my P4 here in China, it shipped without English instructions. I have downloaded a very basic manual from iBasso's website, but there is very little information of op-amp rolling (other than an inventory of what is in the box). Is there a "beginner's guide" available to prevent me from doing something stupid? I have read that at least one contributor has already dispatched his P4 to the hereafter by plugging the wrong chip in the wrong socket.....

Also - what is meant by a "static-free environment"? Should I wear an earthed wrist-strap when handling the ICs? Do I need a special insertion and removal tool?

Finally, I have noticed that some of you recommend op-amps which are not included in the package. Can I obtain these from RS or Maplin, or are there specialised sources for these?

The P4 guide that you downloaded from the iBasso website should provide all the information that you need for swapping opamps. It is important to correctly identify which opamps are for L/R, and which are for the buffers.

The L/R sockets can use either single or dual-channel opamps, with the center socket being used for dual-channels. The buffers are only single-channels as is are the 2 outside G & V sockets for the ground. Just remember: Center socket=Dual-channel, side-by-side sockets=single-channel. Also, it is very important to insert the opamps with the correct polarity as shown in the User manual.

As the space is pretty crowded inside, I use a small curved medical gripper (haemostat) to insert and remove opamps. These are very inexpensive and can be found at nearly all flea markets. Avoid pressing directly on the opamps when inserting, rather press evenly around the edges of the adapter to seat it into the socket, as the tiny solder joints are rather fragile.

I have never used a grounding wristband for rolling opamps and have never had any static damage. You can always discharge any static electricity in your body by touching something metal that is grounded to earth.

IMO, the ground channel has as much influence on SQ as do the L/R channel opamps. iBasso has included a very nice selection of amps in the stock rolling kit. You might consider trying the AD797 in the G & V sockets. If using single-channel opamps in the ground sockets, both G & V sockets must be use with either dummy opamps or single-channel. If you use a dual-channel in the center socket, the G & V sockets can be left empty.

With the proper configuration, the P4 should prove to be an outstanding amplifier for your Senns.

 

[jamato8]

Quote:

Also - what is meant by a "static-free environment"? Should I wear an earthed wrist-strap when handling the ICs? Do I need a special insertion and removal tool?

In a humid climate there should be no problem. If in a dry one, like here in Tucson, AZ, static can build up and you need to ground yourself to discharge an static as that release of energy can ruin IC's. In China, there are few areas where it isn't humid so it shouldn't be a problem unless you are out in the desert. 

 

[SpudHarris]

Quote:

 
Finally, I have noticed that some of you recommend op-amps which are not included in the package. Can I obtain these from RS or Maplin, or are there specialised sources for these?
 
 

Being from the UK I can tell you that there are some places better than others for buying opamps. Maplin don't stock anything decent period! just the generic cheap opamps that are already bettered by what was supplied in the P4 kit.
 
I do get a few TI samples here and there from TI themselves but mainly I buy my opamps from Farnell or RS Components (normally Farnell). Anything exotic can be found via other reputable channels and some can be had here in the classifieds now and again. Ron (HiFlight) has been a source for the best opamp combinations of pretty much all ibasso amps over time. Like me he is a big lover of the ibasso amps as the majority punch way above their weight....
 
 
 

 

[estreeter]

I wasnt overly impressed with the P4 for the first 20-30 hours - by the 50 hour mark, I had stopped 'trying too hard' and that was when I really started enjoying the effortless power of this inexpensive little amp. 

 

[estreeter]

FWIW, I don't agree with everything Headfonia Mike has to say, and he should be wearing an 'RSA #1 Fan' t-shirt when he writes amp reviews (!), but I found this particular aside interesting when he compared various balanced amps to their single-ended competition:
 
 
Some people ask me how the amps would sound if they are only using the single ended section, perhaps because they haven’t got the proper balanced cable for every single headphones in their possession.

If you’re in the Ray Samuels camp, then I can say that you’ll be better off with the single ended amplifiers, either the SR-71A, the Mustang, or the Shadow depending on your needs. Those three amps will give you a better sound quality in single ended than you will get with the SR-71B or the Protector in single ended. If you’re in the Ibasso camp. Then I would gladly steer you toward the P4 Warbler, as it will give you a better sound in single ended than you get on the PB-1 and the PB-2.

Given that I've never heard the PB-1/PB-2, and Skylab made the point that the balanced amps take virtually everything up another level when operating in balanced mode, I might be quoting that sentence out of context, but ask yourself this : of the top-tier solid state desktop amps, how many support balanced output ? Even the Violectric V200 only has single-ended output (ok - balanced input for pro studio gear, and its sibling the V181 has balanced output), and many Head-Fiers who own amps with balanced out also use the unbalanced HO, simply because very few of us can afford cables/adapters for all our headphones. 

If there is a point to this rant, its that the humble single-ended portable may have been forgotten in the wild race to balanced amps, and that trend could well gain new impetus with the release of the Rx MK3 : for those with more frugal bank balances (and less money for cabling), I'm happy that the single-ended portable amp is still a good option in the ~$250+ market. 

 

 

 

 

 

 

 

[CJG888]

Thanks for the advice!
 
As I will be making my annual visit to the UK in a few weeks, can you recommend any good op-amps (other than those included in the kit that came with the amp) that I should pick up while I am there?

 

[SpudHarris]

Definately worth trying LME49990, OPA1611/OPA1612. My set up after many, many, many hours of listening/testing is: LT1678 in L/R with HA5002 buffers and an ISL55002 in the centre ground socket. Sounds like an amp costing many times what it actually did.

 

[uelover]

Definately worth trying LME49990, OPA1611/OPA1612. My set up after many, many, many hours of listening/testing is: LT1678 in L/R with HA5002 buffers and an ISL55002 in the centre ground socket. Sounds like an amp costing many times what it actually did.

Where to get the ISL55002? LME49990 should be extremely detailed, a little bright and lean sounding right?

 

[SpudHarris]

Quote:

Where to get the ISL55002? LME49990 should be extremely detailed, a little bright and lean sounding right?

The LME49990 is anything but, it's beautifully transparent, yes it is detailed but it is full sounding and not metalic or sterile which is what I found the LME49710 to be over time. Remember, that when opamp rolling, circuits are generally not optimised for the chip you drop in so results will vary. The P4 seems to work very well with a lot of chips but we will all have favourites.
 
Mine are: LME49990, LT1678, OPA1611, OPA1641, ADA4637B, OPA602BP.
 
I love the OPA602CM (TO99) in my EF-5, it is the best opamp I have heard but it's not suited to the P4 at all. Proof again that results will vary dependant on many things, I suspect power makes a difference on this occasion.
 

 

[Varley]

I'm very interested in the amount of switch and play that you can do with this amp, I may well be picking one up soon - I just don't have many IEM's / Cans that would benefit fully from the P4 

 

[uelover]

Quote:

I'm very interested in the amount of switch and play that you can do with this amp, I may well be picking one up soon - I just don't have many IEM's / Cans that would benefit fully from the P4 

You have much more iems/cans than I do that will benefit fully from the P4.
 

 

[iop5566]

hi. i am wondering, using only the buffers and opamp from the p4 package, which set up(in regards to opamp rolling) will be the best if i wish to get a more detailed sound? and also which set up will give me move bass? i am new to opamp rolling and  it would reallly help me and the community if someone could take a picture of the set up or link us to the post if a picture like this is already in the thread. sorry if i sound very demanding. i sincerely apologise.
 
Regards,
Someone who wish to maximise his p4's abilities...

 

[CJG888]

I have noticed that some op-amps and buffers come in surface-mount packaging. Obviously, it is then necessary to solder them to a small PCB in order to plug them into an IC socket. Where can I buy such PCBs? Oh, and - what is the best way to solder surface-mount ICs? Do I need to heat-sink each pin as I solder it? I presume I need to use an ordinary rosin-core solder (NOT silver) with a low melting point, to avoid frying the chip......
 
 
BTW - is it normal for OPA627BPs to cost over GBP30 each? No worse than NOS tubes, I suppose!

 

[SpudHarris]

Search e-bay for ''soic to dip'' adapters on e-bay.
 
OPA627BP are expensive and there are better chips out there costing a lot less. Most are listed in this thread.... I'm off to work now so don't have time to list now but will do later if you wish.