Review: ZERO 24 BIT/192KHz DAC/Headphone Amp/Pre-Amp - Page 510

Transformer ? The IEM's low impedance IS the issue dude. DaMnEd is absolutely correct with his suggestion. If you want to use an IEM on an amp designed for higher impedance cans you have to either buy an adapter or change headphones.....you can change the transformer till the sky falls in you'll still have that hum. An adapter is a couple of bucks, new transformer is 25 -65US (Mercury Magnetics) for nothing, new headphones 250-450US......I think the adapter is the only choice that makes sense at this point unless you have a transformer fetish ( I know I do...R-Core's get me going ) or have a spare 400US laying around for HD650's. 2 of those choices will solve the hum issue, one won't do anything except cost money.

Peete.

Sennsay will be posting a small blurb plus pics ( I think) about his FrankenZERO installation experience in the FrankenZERO thread sometime in the next 24 hours for those that are interested.

Peete.

Where does everyone get their LT1364s? I got mine as a free sample (habit I picked up from doing grad school research), is that what others are doing or is this taboo? Hopefully I don't get buried in Linear Technology advertisements.

digikey.com

Thanks for your input. My initial thought was whether the EM field generated by the transformer may be causing a hum on my right channel. To answer that question indirectly, I asked whether the side of the amp board closest to the transformer controls the right channel. It's a simple yes or no answer. I'm sure people who have modded the amp know which side of the amp board corresponds to a channel.

I wasn't thinking of buying a new transformer at all.

Ok, credit where its due.

My amp has arrived, and I've poped the hood before powereing on.

All the Opams are in the correct locations, including the HDAM unit, and there is a distinct smell of 'used' amp about it, meaning that I'd have to agree that this has been tested and for some time, prior to shipping.

Now to turn it on (once I find a cable of course!)

Doh ..RTFM..

Ok everything sounds fine, will let it run for a day or so.

I've updated my FAQ, btw, to distinguish the two "upgraded" versions available. I need to get some more 3-pin power plugs to test my theory that a lack of grounding is bad for the Zero -- causing hum and the HDAMs I'm currently burning in to get hotter than usual.

Actually I was just about to ask if the Zero really wants a ground or not, I have both a grounded and un-grounded lead, but I went grounded first.

Yes, I'm using the zero's amp, I have 1 earth in the dac and 2 sun in the amp, I think that the 2xsun are quite better than 2xlt1364, I don't know if they can do better with external power or similar (probably would be a better idea buy a dedicated amp), but I have them, they are better than lt1364, than I use them...when I have time I will leave the 2xlt1364 to re-compare them with the 2xsun....

I think that zero's amp with the hd650 is a good combination, the volume is quite good to give ear damage in the long term, I would only get bigger soundstage and little more power for some songs and little better middle-low frequencies, but I have never tried standalone headphone amplifier to judge if using a standalone 200-300€ amp would be a real and ever justifiable cost...but I think in the near future I will buy one to try if there is a real and quite big step up..


I have read that, I hope they will improve with time, but every time I listen them is a real real pleasure....

P.s Peete after my first hdam cap mod "failure" (I have soldered the cap to wrong pins...desoldered them and verified that would be all ok) I will re-try to do the mod in the near future with the real mod photos this time...

In order to further assess the problem I'm having I want to get some opamps for the DAC section to test. I haven't ordered anything yet and am looking to get LT1364's for the headphone section anyway, I'd like to try LT1469 in the DAC section. I think I can guess based on the LT1364 recommendation but can someone please advise me which exact LT1469 version to get? And will it be a direct plug-in to the DAC board socket without a brown-dog adaptor?...it is called a 'dual opamp' on the LT page. Linear Technology - LT1469-2 - Dual 200MHz, 30V/μs 16-Bit Accurate AV ≥ 2 Op Amp LT1469-2

If it cannot be used without an adaptor I'd like other suggestions of opamps that plug directly in to the socket, especially if they're from LT as well. The OPA2604 is one I know will work, if there's not a better alternative which exact version of that do I get? http://focus.ti.com/docs/prod/folder...t/opa2604.html

X-Fi XtremeGamer -> Zero w/Lawrence HDAM DAC, LT1364 AMP -> Grado SR225

I performed the cap snipping mod. It now sounds noticeably more forward (almost annoyingly so), and some of my songs give me headaches listening to them. Some of the smoothness it had also seems to have dissapeared. I did only bother snipping one leg of each of the caps, which, given my limited knowledge of circuits, should be fine (I made sure there was no contact between the snipped ends). Is this normal and I'm just not used to the highs?

Well, the point of sniping those is to get the highs killed by the sniped caps, so, I'd say it is very normal, but you may not like the effect on your setup, that is a different issue.

If you really dislike the effect id say solder the legs, you get the "old" sound back again.

Yeah, definitely. I should've said I'm really more curious about the more forward, less smooth sound. Maybe it's just caused by my bad reaction to the highs, but it was mentioned a few pages ago that there aren't any negative side affects to the mod, so I just wanted the make sure I didn't bungle something. Though snipping two caps (didn't bother with the RCA caps since I don't use the output) really doesn't leave much room to mess anything up.

If you're looking for improvement, down the track an amp is worth it. My take on it is, if I'd never heard better, I would've been happy with just the Zero and the MB Quarts I'd had for 10 years. I've heard some very high-end hi-fi systems, so I'm ruined for life unfortunately.

I think it's the PDIP package you want. If the opamp is a "dual" you don't need an adaptor. If it's a "single" then you do. A "dual" opamp has two channels, which are used in the Zero (and much else) for left and right.

You could well not be used to the highs. I haven't ever tried a pair of Grados, only read that they are very bright cans, so this isn't a surprise.

I'm pretty sure this is it. I actually wouldn't recommend that snip mod for Grados (at least the 80s and 225s - the only ones I've owned) because it puts the already bright headphones over the top (to my ears). It did a lot of good for my Senns though.