[vapman]

Dude is selling kits to head fiers and hiding the part #'s? Kinda lame...?

 

[zilch0md]

Dude is selling kits to head fiers and hiding the part #'s? Kinda lame...?

Ron (HiFlight) only color codes the op-amps in his kits to help avoid the mixing of pairs. They are all very smartly soldered and represent a nice collection of community favorites. It would take a lot of shopping to come up with all the pieces separately and already soldered to DIP8 PCBs. For those of us who don't solder, his kits are a great way to get started with rolling op-amps. He's also a really nice guy to deal with.

 

[Reima]

Dude is selling kits to head fiers and hiding the part #'s? Kinda lame...?

I don't see it that way, the opamp is so small that when he put a blob of paint on it for color coding it obscured the markings on the opamp. I got the kit second hand but I am pretty sure the original owner knew what he was getting from HiFlight.

 

[Makiah S]

  I don't see it that way, the opamp is so small that when he put a blob of paint on it for color coding it obscured the markings on the opamp. I got the kit second hand but I am pretty sure the original owner knew what he was getting from HiFlight.

I can see how that would be frustrating, 
 
Still though, I've been content with Dummy BUffers an LME 49990s in mine since I got them, I source out of my HM901 line out and it'll drive my HE 4 nicely!!! 

 

[snellemin]

Used a 65W laptop PSU with an old 3A step down dc converter to see if there would be any improvement over the stock PSU.  I max out the volume on some bass heavy music and the step down converter was complaining.  Added a 2200uf cap and things got better.  So I'm going to get me a better step down converter and enjoy massive power on the cheap.  
 

 

 

[zilch0md]

That's cool.  You're shooting for a 16V maximum, right?

 

[snellemin]

  That's cool.  You're shooting for a 16V maximum, right?

Yup 16V.  Drops to 15.7V under bass hits.

 

[Makiah S]

welp my PB2 is dead, I had an issue with a lot of noise on the Right Channel, any time I'd change the voulme I'd get some static. But my unit has always done that, I'd pop her open, remove and re seat everything, then it would be 100% silent for about a month... tonight I was listening, normal volume, lme 49990s dummy buffers with no issues.

Battery went dead, so I plugged it in, used the same charger and everything, and it was silent... couldn't hear the music while I charged it... couldn't hear anything but it was quite. Cut if off again, opened it up removed and reseated everything, including the little cable for the battery and now I get a LOT of loud Popping and noise when I plug anything into to it

plugged in and it's completely silent

any tips or suggestions? I tried different opAmps and still had an issue with the noise, Trying different buffers now

I swapped out the buffers and I can smell heat, as soon as I turn it on...

running back into my LME 49990s and Dummy Buffers everything smells normal, like metal

but what do you guys suggest I start with? As far as getting it repaired. It kinda went from 100% to zero in like a second

 

[zilch0md]

^ I have no recommendations, unfortunately, but I feel for you! How sad! Makes me want to buy another one as a backup, but I'll give you a chance to find one, first.

You could write iBasso and ask them if they are equipped to do repairs, for a fee, out of warranty.

Sigh...

 

[Makiah S]

^ I have no recommendations, unfortunately, but I feel for you! How sad! Makes me want to buy another one as a backup, but I'll give you a chance to find one, first.

You could write iBasso and ask them if they are equipped to do repairs, for a fee, out of warranty.

Sigh...

well it was pretty sudden, and I don't see any black char or anything physical dmg'd on the board. I'm tempted to start with replacing the Battery, but I've emailed Paul the iBasso guy here. As their website was pretty useless

The big problem I have now is what to replace it with? I don't really use to many of BIG balanced Headphones on the go, mostly my Audio Technica ES 10 now a days, or my Nhoord Red V1, I'm happy with HM 901 as a source, but amp wise since I don't need the power any more, what would work?

I guess this is kinda good, I bought the PB2 back in the day to drive my HE 4 any where. But it NEVER leaves my house... EVER, so really all of my other full sized Headphones are 4pin Terminated, and are all low impedance high sensitivity. So, what SE compares to the PB2 with LME 49990 and Dummy Buffers, while the Balanced output had... better everything, I'm hoping there's a SE portable amp that is well better

 

[snellemin]

Got me another set of 634U buffers and used 100 ohms resistors for the wide bandwidth mode. To my ears this sounds better then stacking the 634P WB buffers on top of the 634U's.

 

[zilch0md]

Got me another set of 634U buffers and used 100 ohms resistors for the wide bandwidth mode. To my ears this sounds better then stacking the 634P WB buffers on top of the 634U's.

Awesome! Oliver Twist asks, "Please sir, may I have some more current with my voltage sir?"

 

[Makiah S]

Awesome! Oliver Twist asks, "Please sir, may I have some more current with my voltage sir?"

mmmmmm that looks good man. Also, I decided on a HeadAmp Pico power to replace my iBasso PB2. I may honestly repair it here soon and start to tinker with it as I get deeper into my Electrical Engineering Tech program, but I don't intended to ever have to deal with the... sadness that over took me q.q I had my PB2 for like 4 years, and in a second it died... and rendered my Hifiman HM 901 completely useless! [I gutted out it's amp last year, to try and get more battery life plus I really only like it for the UI and DAC lineOut]

So here's to hoping I'm back here soon, tinkering as you guys do

 

[HiFlight]

Dude is selling kits to head fiers and hiding the part #'s? Kinda lame...?

I color-code the opamps to prevent incorrect installation and for the owner to be able to tell them apart, as after soldering, it is often impossible to read the numbers on the opamp. I have had to replace too many opamps due to incorrect installation by the owner of the Topkit to send the opamps "uncoded".
Also, not every Topkit is the same for the same device as they are custom build based on the purchasers sonic preferences and the type of headphones used. I am alway happy to tell the purchaser exactly what opamps are included and what color they are. The colored end always indicates the number one pin end. I make no effort to conceal what devices I use although some manufacturers do, including such reputable builders as iBasso and RSA (Ray Samuels)

 

[HiFlight]

welp my PB2 is dead, I had an issue with a lot of noise on the Right Channel, any time I'd change the voulme I'd get some static. But my unit has always done that, I'd pop her open, remove and re seat everything, then it would be 100% silent for about a month... tonight I was listening, normal volume, lme 49990s dummy buffers with no issues.

Battery went dead, so I plugged it in, used the same charger and everything, and it was silent... couldn't hear the music while I charged it... couldn't hear anything but it was quite. Cut if off again, opened it up removed and reseated everything, including the little cable for the battery and now I get a LOT of loud Popping and noise when I plug anything into to it

plugged in and it's completely silent

any tips or suggestions? I tried different opAmps and still had an issue with the noise, Trying different buffers now

I swapped out the buffers and I can smell heat, as soon as I turn it on...

running back into my LME 49990s and Dummy Buffers everything smells normal, like metal

but what do you guys suggest I start with? As far as getting it repaired. It kinda went from 100% to zero in like a second

Couple of comments/suggestions:
The scratch sound when rotating the volume knob is usually the result of some offset voltage. All opamps have the offset voltages listed in their datasheets from minimum to maximums In other words, you might be using 4 LME49990 opamps and each will have a slightly different offset voltage. Always try to select opamps with offset voltages specified in microvolts rather than minivolts. Offset voltage is NOT a good thing.

The crackling/popping sound you hear is typical of a shorted opamp. This can be due to a number of reasons, such as incorrect installation, excessive supply voltage, simple failure for no good reason or fake asian opamps to name a few.

Some opamps are relatively unstable for use in audio circuits and can initial ultrasonic oscillation. This can often be identified by touching each opamp or buffer. None should be hot to the touch. Needless to say, make sure you are using single-channel opamps in a single-channel device and vice-versa! Again the datasheet can be your best friend if you are uncertain which opamps are which.

For starters, I would suggest installing a set of OEM opamps that were included in the device when new, making sure that they are installed correctly. If you have a decent multimeter, check the supply voltage at the V+ pin socket and see if there is the proper voltage being supplied by the battery (or PS)

Generally speaking, the circuitboard component are pretty robust and it will be opamps that are the most prone to failure. Always start with the simple things and work up from there!

Good luck!