[splaz]

I read it before and you said you gave it the amb and morsel seal of approval.

You're my new scapegoats

Yeah I understand though tangent. I saw someone that posted they had a really high DC offset because they hadn't done it properly. It'd be better for you to show and recommend the safest option and then if they're interested and knowledgeable enough they can look at replacing the input caps. Rather than you copping alot of complaints for wrecking peoples headphones by telling them to replace the caps.

Just wanted to make sure you didn't have any serious concerns.

The boards still haven't arrived yet... I hate waiting.

 

[morsel]

splaz, if you build it with high DC offset or hook it up to a source with high DC offset, it will just sound bad, not wreck your headphones. The fear of DC offset damaging headphones is exaggerated and generally unwarranted.

 

[The Monkey]

Quote:

Originally Posted by morsel splaz, if you build it with high DC offset or hook it up to a source with high DC offset, it will just sound bad, not wreck your headphones. The fear of DC offset damaging headphones is exaggerated and generally unwarranted.

Lol, every time I think about putting in input caps, I read something like this and reconsider. I don't know what to do.

 

[splaz]

It'd do more harm than good though right?

I'm still going to do it, possibly make one with input caps to see the difference.

Just wanted to know the possible consequences of a stuff up before I dive in. Good to hear it's not as bad as it sounds.

 

[The Monkey]

splaz, I would be very interested in hearing your opinions on the difference in SQ with and without the caps.

 

[splaz]

I wouldn't be very good at describing the differences though.

It's like beer. My comments are usually, "this ones good", "this ones better" and so on and so forth.

I notice the subtle hints in flavour but can't describe them well.

Same for audio. In fact what I said above describes it rather well. I think I have fairly good ears, I've picked up stuff like a singer making a very slight slurp, (you know just sucking that bit of spit from the corner of your mouth

) between verses. But don't think I'd be able to describe it properly.

I would still be happy to share my opinions. Just expect more, "Yeah it ahhh... sounds better and theres less of that hissing thing going on", than "The soundstage is much wider with a far less noticeable noise floor. Highs are more clear and defined while lows are somewhat less distinct." That probably makes no sense but you get my drift.

As I said though I'm not the best with the lingo and fancy ways of describing it, I'll still give it a go. It's going to have to get here first though... don't expect my views on it for another month...

 

[rsabo]

Just finished building mine about 10 minutes ago. Config is very unusual - mostly because I didn't read "Working with Cranky Op-Amps" closely enough.

R3 = 3.4K
R4 = 10.2K
U3 (ground) is an LM6172
no input caps (jumpered)

DC offset is fine - strangely low, around half of what Tangent's calculator said. Barring it exploding from some offset- or oscillation-related thing I might have overlooked or mismeasured, I am very pleased. It sounds good, too.

 

[Filburt]

Good to hear that it works with the 6172. I'm still debating over whether to go hybrid, or build one MINT with dual of each chip (I have 2 8397s and 2 6172s).

Okay, so I have a question now...

I ordered the jacks that tangent called 'high quality' from Digikey, but forgot to pay attention to the fact that they are non-isolated...doh! If I leave out the charging circuit, and use these jacks on one of the MINTs, will I suffer any ill consequences with them? They look to be extremely high quality jacks...too bad they aren't isolated

I also ordered some isolated jacks from Mouser just in case...

 

[cetoole]

Quote:

Originally Posted by Filburt Good to hear that it works with the 6172. I'm still debating over whether to go hybrid, or build one MINT with dual of each chip (I have 2 8397s and 2 6172s). Okay, so I have a question now... I ordered the jacks that tangent called 'high quality' from Digikey, but forgot to pay attention to the fact that they are non-isolated...doh! If I leave out the charging circuit, and use these jacks on one of the MINTs, will I suffer any ill consequences with them? They look to be extremely high quality jacks...too bad they aren't isolated I also ordered some isolated jacks from Mouser just in case...

I am pretty sure you need isolated jacks, even without the charger, because this amp has an amped vgnd for the output, and nonisolated jacks will short in gnd to out gnd. You could try isolating the jacks, paint some nonconductive epoxy or something over the holes in the case, or use a plastic case instead of a mint tin.

 

[Filburt]

Quote:

Originally Posted by cetoole I am pretty sure you need isolated jacks, even without the charger, because this amp has an amped vgnd for the output, and nonisolated jacks will short in gnd to out gnd. You could try isolating the jacks, paint some nonconductive epoxy or something over the holes in the case, or use a plastic case instead of a mint tin.

That's weird. If that's true, why would three of the four jacks on tangent's part list be non-isolated? The jacks I got from Digikey were listed in his parts list...

 

[cetoole]

Quote:

Originally Posted by Filburt That's weird. If that's true, why would three of the four jacks on tangent's part list be non-isolated? The jacks I got from Digikey were listed in his parts list...

Probably for people using plastic cases, or willing to deal with the extra work of isolating the jacks. I havnt actually read the Pint parts selection guide before, but just skimming it, I found this following bit, supporting my comment. I didnt actually look at which jacks they are, but if they are the ones I suspect, the nice metal panelmount CUI jacks are the nicest on the list. I actually have a bag of kobiconn isolated jacks from mouser I got for a project, only to find them a bit too long, so if you want to work up a trade or something, shoot me a PM.
Quote:

Originally Posted by Tangent If you're using a metal case, at least one of the audio jacks needs to be isolated from the case. Isolation, in this instance, means that none of the audio signals are connected to any metal parts of the jack that touch the mounting surface. Usually, this means the jack body and mounting threads are plastic, but not always. The most common way for a jack to be non-isolated is to have a metal shell that's connected to the ground signal. It's okay if either input or output ground connects to the enclosure, but if both do, the ground channel will be shorted out. At best, this makes the ground channel useless, and at worst it can cause the amp to become unstable. If you're going to connect one of the grounds to the case, it should be the input ground.

 

[Filburt]

Well looks like I messed it up somehow. I tried turning it on, and my ground channel chip got very hot. I don't know if it's destroyed or not. What it sounded like on my earbuds was some noise.

I wonder what happened...I guess I'll just start over. Looks like I'll be ordering some new parts from tangent (doh).

 

[Filburt]

Okay, I looked over it again. I have no idea why it isn't working...nothing is particularly wrong with it. I don't have any bridges, and things are well set and well aligned on the solder pads. Maybe the ground chip is just bad *shrug*. Oh well.

 

[69CamaroSS396]

I became very aggravated while trying to solder some of the resistors, etc., and decided to make this first PINT a practice session, because in my mind, I knew it was going to be a screw-up. To avoid damaging the AD8397s while "practicing", I installed the TS922ID in both U1 and U3, and used the input caps. Due to parts on hand, the gain is set at 2. I was dumbfounded when I connected everything and even had output. I was completely surprised when it sounded pretty decent with my 32 ohm cans. This is with my component Denon CD player. Nice travel on the pot. The gain will have to be set higher, of course, for use with a portable.

 

[Filburt]

Quote:

Originally Posted by 69CamaroSS396 I became very aggravated while trying to solder some of the resistors, etc., and decided to make this first PINT a practice session, because in my mind, I knew it was going to be a screw-up. To avoid damaging the AD8397s while "practicing", I installed the TS922ID in both U1 and U3, and used the input caps. Due to parts on hand, the gain is set at 2. I was dumbfounded when I connected everything and even had output. I was completely surprised when it sounded pretty decent with my 32 ohm cans. This is with my component Denon CD player. Nice travel on the pot. The gain will have to be set higher, of course, for use with a portable.

I didn't have too much trouble other than on the op-amps, and even then managed to do that OK. I just can't figure out what's wrong with it. I don't have the power reversed, I don't have the ferrites missing, and I don't have anything bridged. So...what the heck is going on!

Also note, I was getting no audio through whatsoever.