[Iron_Dreamer]

So this weekend I recieved and built the PINT kit sold by [ak]zip, and I must say, this is a fantastic DIY project. Great sound from a very small and inexpensive package, that isn't too difficult to put together. I am not fully informed on all matters concerning why this project was discontinued, but I really hope they are problems that can be resolved, simply because I hope others can have the opportunity to build the same great little amp.

It sounds a little strained driving my lower impedance cans (but then again, look at the only other amp I've got to compare it with). Anyone know what the ouput impedance of the amp in this Mini Cubed configuration is (I'd guess 33ohms, based on the ferrites, but I'm no expert)?

I'd never really needed a portable amp, and really only bought this kit to give my new Metcal station a trial by fire, but now that I have it up and running, it's a fun amp to have around (plus I don't have to max out my DAP's volume on occation with my K270S

). I can see very easily how a successful build can really get one into the DIY disease

So Tangent, thanks for the PINT design, and best of luck at coming up with a suitable replacement/successor.

 

[amb]

Quote:

Originally Posted by Iron_Dreamer Anyone know what the ouput impedance of the amp in this Mini Cubed configuration is (I'd guess 33ohms, based on the ferrites, but I'm no expert)?

More like < 1Ω at audio frequencies.

 

[tangent]

Quote:

Originally Posted by Iron_Dreamer I am not fully informed on all matters concerning why this project was discontinued, but I really hope they are problems that can be resolved, simply because I hope others can have the opportunity to build the same great little amp.

Thanks for your vote of confidence. I am indeed working on a successor, but my personal free time is rather constrained right now, so it'll be a while.

Quote:

Anyone know what the ouput impedance of the amp in this Mini Cubed configuration is (I'd guess 33ohms, based on the ferrites, but I'm no expert)?

No, the impedance rating of the ferrites is at their main frequency, which is way up in the double-digit megahertz range. What you're looking for is the DC resistance spec. The actual impedance will be very very slightly higher at audio frequencies, but it's such a small difference that the DCR spec is close enough.

 

[Andrea]

How do you find the midrange? I personally find the AD8397's midrange to be dry and lacking in refinement and transparency.

 

[Iron_Dreamer]

Quote:

Originally Posted by Andrea How do you find the midrange? I personally find the AD8397's midrange to be dry and lacking in refinement and transparency.

Well I certainly wouldn't say the midrange is bad, or recessed. Dry? That would depend on what you're comparing it to; a tube amp of course would sound wetter, but for a solid state amp, it doesn't strike me as being abonormally dry. Now I would say it's not as refined or transparent as my other amp, but jeez, that's comparing a $1000, 60W-heat-pump home amp to a <$100, single 9V portable amp.

I don't think the PINT is awfully lacking in any area. Sure it's not quite as nice as a big-leauge home amp, but considering the size, intended use, and price, I think its' performance is commendable.

 

[Filburt]

I'm going to be building an LM6172/LM6172 PINT this week (possibly today), so I'll let you know how that goes. I'm not a huge fan of the AD8397, either, but the PINT pretty much does the best job I've heard so far with that op-amp.

 

[Andrea]

Fliburt, good luck with your next PINT build! I like the LM6171s that are in my "Pengamp" amplifier, as they have that liquid and transparent midrange I cannot live without

Iron Dreamer, my negative reaction to the AD8397 came from comparing this chip (in a Go-Vibe 4) to either a $59 Zero Audiocraft unbuffered amp (but with an LT1361 as output stage instead of the stock OPA2134) or a $95 Shellbrook Mini Head (9V powered) which has OPA227s and HA-5002 buffers. What can I say, it fared very well in the treble, very detailed, and had power to spare, but... well, the midrange was clearly lacking at least in that implementation & with my HD650.

 

[Clutz]

Quote:

Originally Posted by tangent Thanks for your vote of confidence. I am indeed working on a successor, but my personal free time is rather constrained right now, so it'll be a while.

Oh sure tangent, put your personal life ahead of Head-Fi'rs achieving portable audio nirvana.

Seriously though, I got a PINT built by cire (I was too slow to buy a board myself) and I think it's really quite good tangent.

On an unrelated note, this is my 1000th post.

500 to go before I start to take over the universe!

 

[Filburt]

Thanks, Andrea. My expectation is that I will find it sonically superior to the AD8397, but I guess I'll find out when it's done.

 

[Filburt]

May have to wait a bit to find out now. Had a freak accident and a bunch of my PINT board is burned, so I will probably have to cannibalise one of my PINTs to get this one off the ground.

 

[Scimmia]

Filburt, I have to ask, what kind of freak accident could cause a bunch of your board to burn? Hooked directly to mains?

 

[Filburt]

Quote:

Originally Posted by Scimmia Filburt, I have to ask, what kind of freak accident could cause a bunch of your board to burn? Hooked directly to mains?

Nah, nothing cool like that. Just a shelf falling on the iron, smashing it against the board. Anyhow, I got a dual LM6172 PINT up and working now. I'll post impressions later. I no longer have the dual 8397 handy, though, as I had to use that board.

Gotta love the dc offset on it...0.0003mV ^_^. I had to break out the uber DMM to even measure it as the Fluke that went to three places just read 0.000mv.

 

[FallenAngel]

Hey Filburt, you saying the LM6172 is THAT much more stable then the AD8397. I've had my 2xAD8397 slaughter through batteries so I'm thinking it might have started to oscillate again.

I remember you also had a AD8397/LM6172 hybrid, how much of an advantage was it to put a LM6172 in ground? Or would it even make sense to put the AD8397 in ground and LM6172 on L/R, kinda funky since the ground is the one oscillating usually.

Definitly also post how the dual LM6172 sounds, maybe compared to dual AD8397 and the hybrid.

 

[gigit]

all this pint talk makes me really wish that i got in on getting some of the boards before the pint got pulled, oh well i guess there is always the kits, and being patint for the next generation...

 

[Filburt]

Quote:

Originally Posted by FallenAngel Hey Filburt, you saying the LM6172 is THAT much more stable then the AD8397. I've had my 2xAD8397 slaughter through batteries so I'm thinking it might have started to oscillate again. I remember you also had a AD8397/LM6172 hybrid, how much of an advantage was it to put a LM6172 in ground? Or would it even make sense to put the AD8397 in ground and LM6172 on L/R, kinda funky since the ground is the one oscillating usually. Definitly also post how the dual LM6172 sounds, maybe compared to dual AD8397 and the hybrid.

The LM6172 is _much_ easier to tame than the 8397. You don't even have to do the mini3 mod to stabilise it in unity gain, nor do you need C6. The quiescent draw per channel on the LM6172 is listed at 2,3mV, so x4 = 9,2mV quiescent as opposed to 50-60mV on dual 8397. As you can imagine, battery life is better.

I had the LM6172 in ground and AD8397 in L/R on one PINT. This one has LM6172 on both.

Preliminary impressions are as follows: Less aggressive in the high mids, as expected, compared to the hybrid. However, has more depth/weight in the lows, is faster, and has a bit more detail. Also has more instrument separation and soundstage. It has a bit more laid back presentation, slightly, in general. However, it's more involving and inviting in general, and it really keeps the rhythm better than the AD8397 does. Overall, I'd say the LM6172 is a much more proficient op-amp in terms of speed, detail, accuracy, and imaging. You may find otherwise, but that's at least what I've found so far. It also doesn't even get warm while in operation, heh.

The PINT does basically the best job I've heard with the AD8397, but the dual AD8397 is definitely shoutier and more aggressive in the high mids, with less presence and detail in the highs, and less soundstage, depth, and weight. The hybrid is a good comprimise if you want a bit more aggression as it takes on many of the traits of the dual LM6172, but it isn't as refined sounding and I kind of find I prefer the dual 6172 PINT overall. Basically the dual 6172 sounds like taking the differences between the hybrid and the dual 8397 and going a step further in it while gaining some more refinement.