Review: ZERO 24 BIT/192KHz DAC/Headphone Amp/Pre-Amp - Page 511

Sorry about that...I thought you were ignoring the answers you were being provided with, hence my terse response. I do have one question though...if you weren't going to buy a transformer that response you posted certainly leaned heavily in that direction.....did it not ?


The EM field is pretty small...lots of people put their HDAM modules right next to it with no SQ issues. I have rested an HDAM (temporarily) on top of the toroid and also had no issues, so it's safe to say that isn't the problem...although new supplies of transformers could have an issue...My Zero is over 7 months old now so who knows if they are still built with the same OEM toroidal. They do look the same. Part no on mine is HB-100/1852. I could find no brand name on it. FWIW.

Peete.

Yea I know the PDIP is the right package after looking at the schematics. The LT1364 is 'dual and quad' but there are two needed for the headphone amp section, while LT1469 is 'dual' I guess if hte OP had shown a picture of something other than OPA627 in a brown dog I'd know OK before posting that I've gone through schematics on the various opamps, OPA627 schematics only show a single diode (? diode symbol at least) within the opamp package while the LTs show two and based on the pinouts of the LT1469 versus the OPA2604 the former should plug right in. *edit There are two 8-pin PDIP LT1469's: LT1469IN8#PBF and LT1469CN8#PBF the 'C' and 'N' are different. I'm not sure what that means, going by the LT1364 the 'C' would be the correct one but can someone verify that? *edit2: ha, ok I keep answering my own questions. C= commercial I = industrial and they refer to temperature ratings as seen in Section IV here: http://www.linear.com/purchase/ordering_info.pdf

I'm still not sure why the DAC uses one dual opamp and the HA uses two but maybe that's just up to the circuit topology or output requirements of the HA.

I swear, I never believed in semiconductor burn-in 'till I upgraded my Zero's HPA from the stock NE5532's to LT1364's. Too many of us have independantly had the same sonic experience for this to be a coincedence, IMHO. Or, we all go thru the same psychoacoustic adaptation to the new chips; I might give it that.

But either way, *something* of similar perception amongst us definitely occurs: Bass becomes more solid and articulate with better imaging; upper mids and highs develop clarity and resolution, resulting in a slight increase in timbre and detail, and the mids and highs become less "decongested" for lack of better words. Pretty wild experience, and I don't know how to explain nor account for it.

Quite a few peeps have gone the sample route...nothing taboo about that I'm aware of. I went thru Newark piggy-backing another order I was doing and didn't want to wait on samples (LT1341's were 4 bux/ea, IIRC).

Whatever works for you.

Just thought I'd share something I found after some poking around, and will include in my upcoming Newark order:

A Vpot knob upgrade

I mean, comon, two bux? How could I resist?

For 2 bucks that's a steal....and it's RoHs compliant (LOL). Solid Aluminum ? Great deal....what's the catch ....5 bucks for shipping ? .

Good find SC !!!

On another note.............................................. ............................

EDIT: See Sennsay's latest post for the word !!

Peete.

Just thought i'd float this comment: my zero runs fairly cool, its grounded (i.e. 3 pin plug) and doesn't get hot, but the unit has a slght hum. I'm running HDAM in DAC and op's in the h/a. Must say its sounding great, been running 24 hours.

Hi Tony,

That's most likely mechanical hum coming from the transformer (running at 240 V).

Peete.

Actually, the post is here: http://www.head-fi.org/forums/f6/fra...ml#post4931453

S-Man

Thanks S-Man...wonderful work as always.....I wish I could get my bypass caps to look as good as yours do.......green cap envy LOL.

Peete.

Well i've now hooked the zero up to my main rig, and its pretty decent out of lne out, seems more low end punch.
One downside, its humming/buzzing, quite audibly, how can i cure this? or will it quieten down over time.

Just to be clear, the noise is audible from 12 foot away, much much louder than when i first turned it on, and no where near quiet enough to use in my rack; it make more noise than my skytv hdd, can't use it

Tried tightening the nut holding the transformer? I remember someone else having this problem but I can't remember how they fixed it.

I felt some hum noise too. Then it disappeared after I removed and inserted the power cable of the H/Amp board a few times.

2x Dual to Mono Opamp PCB OPA2604 NE5532 LM358 > OPA627 - eBay (item 360092665039 end time Nov-25-08 10:41:22 PST)

Is that the adapter for two OPA627's?
And from whom I should buy these opamps and the adapter?
Ty.

I've tightend the nut , to be honest it was pretty solid. Tightened every screw and pushed home every cable. Still noisey, i guess its the transformer, going to run it tonight (but only 10 min in and the buzz is annoying me) and send an e-mail regarding a new transformer , can't live with the noise, in every quiet phase in thr music, 'buzzzzzzzzzz'. In fact, i can't stand it already.