[jamato8]

Quote:

Although more expensive, the BP version is the best of the OPA627/637 choices.

Ryuzoh has stated he prefers the lesser expensive version of the 637 vs the BP. I haven't compared the two but have the BP version and have always enjoyed it. 
 

 

[SpudHarris]

Well I haven't tried any 637's at all as they weren't suitable for the P3+ and not brilliant in the P3. Are we ok to use them in the P4?

 

[HiFlight]

Although many of the specifications of the OPA637 are significantly improved over those of the 627, the 637 should only be used in applications where the gain is more than 5 and there is low load capacitance, otherwise it can be unstable. The 627 is unity gain stable and less tempermental than the 637. The overall SQ between the two is quite similar although the 637 is "faster" (higher slew rate) than the 627. Both require about 9v to meet spec and are fairly power-hungry.
 
Although the OPA627/637 are widely considered to be the ultimate in audio opamps, IMO there are a number of others that sound as good, if not better and cost much less.

 

[RedBull]

Has anyone page Skylab for review? 

 
Tried this to compare with P-51 Mustang with SE530.
P4 kills Mustang on mids, vocal fullness, piano fullness, bass, soundstage, neutrality, detail, treble, yuck. 
Changed P-51 gain to Mid, it helps to get better transparency, but still NO competition, hands down!!
 
Feel like I have to ditch my Mustang and get this, really.

 

[Vault101]

I am curious to see P4 versus stepdance.

 

[estreeter]

Quote:

Has anyone page Skylab for review? 

 

You might like to read his portable amps thread:
 
1. Rob is doing a final comparison of portable amps this weekend, then moving on to higher end reviews.
 
2. iBasso refuse to send him any more review samples after one of his reviews didnt gel with their expectations of glowing praise etc. He may have reviewed the P4 if someone had loaned him one when the amp was released, but that window has clearly come and gone.
 
 

 

[GeorgeGoodman]

Quote:

Has anyone page Skylab for review? 

 
Tried this to compare with P-51 Mustang with SE530.
P4 kills Mustang on mids, vocal fullness, piano fullness, bass, soundstage, neutrality, detail, treble, yuck. 
Changed P-51 gain to Mid, it helps to get better transparency, but still NO competition, hands down!!
 
Feel like I have to ditch my Mustang and get this, really.

I find this very interesting. Read this: http://raysamuelsaudio.com/products/p-51 All Ray Samuels has is Skylab's review, where Skylab gives it an A++ on mids. You say the P4 is better on mids and other areas. I am not bashing Ray Samuels as I believe bashing anyone is unfair. Ray is a really nice guy and I have met him in person. For all accounts he ships his products fast and does not even charge money in preorders until the amp is shipped out. Having said all that, I will do a matchup of the two amps. 
 
Prices: P4 $245, P-51 $375. 
 
Features of P4: 
Gain: 2 settings
Opamp rollable: Yes
Size: Fairly large for a portable.
Price: At the lower end of the portable spectrum, definitely has a lot of value.
Power: I can be reasonably sure the P4 has more power than the Mustang.
Looks: Not quite as nice as the P-51, but nice, neutral, and clean.
 
P-51 Mustang
Gain: 3 settings
Opamp rollable: No
Size: Very small, moderately thick.
Price: At the higher end of the portable spectrum.
Power: I can be reasonably sure the P-51 does not have as much power as the P4.
Looks: Very nice, stylish.
 
In conclusion, I think the P4 wins hands down. The Mustang still has its strong points such as size, features, and looks (which are debatable anyway), but the P4 is undoubtedly the better value and probably the better sound. I say probably because I like to have a few impressions before I decide what a product is like, no offense to you redbull, as experience shows this is the best course. 
 
I Ray Samuels' defense, the Mustang is fairly old and maybe Ray will come out with an amp with better value. But right now, the P4 looks like the way to go. 

 

[GeorgeGoodman]

Jamato, do you think you can do a mini comparison between the P4 and the Mustang? I know you are a big fan of each. Your opinion would be valued here.

 

[ztsen]

I sold my Mustang long ago. 2 major reasons, narrow soundstage and randomly generate noise when turning volume knob. I reported to RSA but he said is 'like that'. (unless his product have a dynamic volume for all my different albums) I do not have any such issue with iBasso considers it has cheaper price tag.  This P4 definitely value for money.

 

[GeorgeGoodman]

Quote:

I sold my Mustang long ago. 2 major reasons, narrow soundstage and randomly generate noise when turning volume knob. I reported to RSA but he said is 'like that'. (unless his product have a dynamic volume for all my different albums) I do not have any such issue with iBasso considers it has cheaper price tag.  This P4 definitely value for money.

Thanks. Portable amps march on, thanks to a very innovative and awesome Chinese company.
 

 

[estreeter]

 
Quote:

Thanks. Portable amps march on, thanks to a very innovative and awesome Chinese company.
 

 
Cmon, George - lets give credit where its due. If iBasso were the only company to release 'game breakers' in the last 12 months, I could see where you were coming from with this. This isnt a flame, merely a reminder that there is more than one player on the field.
 

 

[GeorgeGoodman]

Quote:

 
Quote:

Thanks. Portable amps march on, thanks to a very innovative and awesome Chinese company.
 

 
Cmon, George - lets give credit where its due. If iBasso were the only company to release 'game breakers' in the last 12 months, I could see where you were coming from with this. This isnt a flame, merely a reminder that there is more than one player on the field.
 

My statement wasn't meant to be all inclusive. The Headstage Arrow looks awesome, as well as the Hifiman stuff. Finally, Ray Samuels' SR71B is just a phenomenal amp with the HE-6. My dad and I have heard it, and I marvel at how such a small thing can produce so much good sounding power. Ibasso is not the only player in the market by any means. Other amps and brands have much to recommend them. To me, Ibasso amps give great value. 

 

[b0klau]

I tried rolling my p4 for the first time with great results:
TLE2141 in L/R
BUF364P in buffer
OPA604 in G/V
 
To my untrained ears, i noticed the bass tightened up and the highs have slight more "sparkle", than from the stock opamps. I was very pleased with myself and kept the combo.
 
I have one question: which way do the transistor buffers go? There seems to be no indication of pin #1 on the transistor buffs. Does it even matter which way it goes in?
 
Sorry for the noobiness, but any help is appreciated. Thanks

 
EDIT: i took a look at this post a short while later, and found the time posted was 6:24. the time i actually posted was 9:30... weird.

 

[b0klau]

bump

 

[jamato8]

Sorry, I didn't see your questions. Look at the transistor buffer. There is one pin with a square area of solder around it. That is pin one. Pin one is at the lower left of most op amps. That is the end where the notch would be, in other op amps, and that is way it would face, as the other buffers would. So you use that as a guide for placing it in the socket. If you are looking at the socket and the notch goes to the right, then that pin one of the transistor buffer, goes to the right.