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

[falke401]

Peete, You know your stuff!!! It worked!!! Now I just have to fix my volume knob because it hums when I turn it and hums all the time too.

[liquid steel]

Ok, right side is functioning now.

Left side, however, has no sound at all. Unless, of course, I change the volume. Then it sounds like someone is blowing in my ear.

There is also the distinct smell of toasted silicon in the area. I don't know if that is caused by/of the defect, but it probably is a sign that it is toast.

*looks around for replacement*

[Pricklely Peete]

Originally Posted by liquid steel

WINNER!

I flipped the DAC op-amp, and the dead side switched from the right to the left.

Where would I go about getting a replacement?

I guess I'll let Lawrence know.

Peete, I love you.

Thanks buddy Glad I could help !!! Do you have another opamp you can use until the replacement arrives ? A NE5532 or some other type that is a dual channel .....

Tell LC exactly what happened...it was put in wrong....so it's his fault. He should send a replacement and fire the monkey.

Peete.

[alxwang]

Originally Posted by Pricklely Peete

Thanks Alex...great job ....I thought you had custom audio-gd boards on order that were sitting in LA customs ? Sorry if you are not the one waiting on those....I found with 2 SUN and 1 Earth, the head amp lost all bass punch and the...well you know that part...anyway...I'm still waiting on my parts to test the 3 HDAM config and see if I can solve the power issue...it retuned to normal when I popped the LT1364's back in. I could take temps from the analog regs and post the numbers with LT1364 then dual SUNS...might be interesting to see if thermal stress is leaning out the current flow.

If you do have the reg boards...can't hurt to try them out...you may be pleasantly surprised by the result. I'b be very interested in your Lab results from the U....

Thanks Alex.......the cap mod takes a loooooong time to form....drove me bats when I first did it...then one day..pow...there it is...at least 250 + hours. Drove Pench a little crazy too...he kept asking me ...when does this thing kick in

Peete.

I have those reg boards already. I did not start to install them yet because I do not know where I put them. I have order those 1uf green cap. So if the output test shows me zero need more power I have to have extra box to put power board, HADM and caps and get 3 20 cm leads to connect them to zero. Actually leads is not problem because I think CAT5 network cable will be good fit. That's a big project for me so I really want to make sure before start.

About bass: I do not feel the bass is gone. HD580 is but sr225 and D2000 is not. but HD580 never works well anyway.

[Pricklely Peete]

Originally Posted by falke401

Peete, You know your stuff!!! It worked!!! Now I just have to fix my volume knob because it hums when I turn it and hums all the time too.

It has a ground wire on the side casing......check all ground points...heres a pic of the tiny wire that should be on the side of the vol pot casing connected to the pcb. If it's missing solder in a section of solid core wire, or stranded copper wire.



Peete.

PS If you have the stock pot the procedure is the exact same. Wiggle the pot slightly to see if the hum stops.

[liquid steel]

Unfortunately I don't have any around First venture into real headphones for me.

Sucks that I'm gonna have to wait for a replacement. Bah.

[falke401]

Ok. If i turn the volume half way up, it hums, but equal volume. I turn the volume all the way up, it does not get any louder, still hums, and only the right side works. The ground wire on the volume seems to be fine.

[Pricklely Peete]

Originally Posted by edguetzow

PP, you are eagle-eyed and brilliant. Yes, to me it looks like the DAC is in backwards. The notch on mine is facing the opposite direction - away from the twin black tower thingies (scientific talk, ya know!).

Originally Posted by falke401

Peete, You know your stuff!!! It worked!!! Now I just have to fix my volume knob because it hums when I turn it and hums all the time too.

Gosh thanks guys. I do what I can to help....just noriced the notch and bingo...light bulb went on

...I'm just about ready to add my Super Cap pak mods to the 2 Earth modules in my FrankenDAC !!!!...talk about a pain in the a-s-s soldering these damn things up has been.

I'll post some pics in 15 minutes or so when I have them both soldered onto the correct pin pads. They look awesome......bloody things will take forever to break in though....

Peete.

[sennsay]

Originally Posted by Pricklely Peete

I just noticed something....correct me if I'm wrong but isn't the 627 adapter in backwards ? The notch is supposed to point towards the rca jacks and digital ins......not the front faceplate...



Peete.

Good on ya, PP, you're onto it. I had to zip off for a bit. 627s in back to front is just plain shoddy work! Sheesh! Not enough good coffee in HK sweat shops, eh? I know it's not Mark Levenson, but hey, some QC would be nice.

[Pricklely Peete]

Originally Posted by falke401

Ok. If i turn the volume half way up, it hums, but equal volume. I turn the volume all the way up, it does not get any louder, still hums, and only the right side works. The ground wire on the volume seems to be fine.

Your 627s are most likely borked as well. Email LC for a replacement module and explain exactly what happened. Send him the pic you posted here...and he will notice the opamp in backwards.

You guys could try one of the LT1364s from the head amp section...just to test, it gets too hot if run to long in the DAC section so only run it long enough to check L/R channels for hum etc... Unplug the H/Amp section and pull both LT1364s....disconnect the gray wires (remember which conn goes where, mark them if you have to) from the main pcb board, disconnect the entire H/Amp card. This test will confirm if the 627's are fried. Disconnect the small black conn (that is power to h/amp board).

Obviously line out is the only way it will work when trying this...you'll need to feed it to a preamp or receiver and plug the phones into that to check.

If you guys don't want to try this that's fine. You should put in a request for samples from Linear Tech, they will send out a maximum of 5 opamps for free.

I got 1078's, more 1364's and one other that I can't seem to remember...

Just so you have others to roll...with the price being right (FREE STUFF Whooo Hoooo)


Peete.

[Pricklely Peete]

Originally Posted by sennsay

Good on ya, PP, you're onto it. I had to zip off for a bit. 627s in back to front is just plain shoddy work! Sheesh! Not enough good coffee in HK sweat shops, eh? I know it's not Mark Levenson, but hey, some QC would be nice.

Thanks S-Man, agreed, this type of thing shouldn't happen....I have a feeling the monkey at the factory is about to get his banana ration cut in half....and no flea powder for a week.

Peete.

[sennsay]

Originally Posted by Pricklely Peete

Thanks S-Man, agreed, this type of thing shouldn't happen....I have a feeling the monkey at the factory is about to get his banana ration cut in half....and no flea powder for a week.

Peete.

Heh heh! Scritch scritch Hey, I've been looking at the LD I+, do you know what op-amp they have in there? I can't see what it is in the pic I printed off. Doesn't look a lot of room for an HDAM in there, but hey, it hasn't stopped us so far! 1364 could be on the money? And one of dem NOS pots that we've got on the Zero and with the WE408A tubes .... mmmm ....

[Pricklely Peete]

S-Man the opamp in the LD I+ is MC33078P.....the pic(s) make the lettering hard to read. I'm uploading pics of the FrankenDAC to photobucket, I'll post some pics of the cap paks on the HDAMs then post some pics of them installed before I put the lid back on....Could you do me favor and look up the data sheet specs on the LD I+ opamp please.

Thanks bro,

Peete.

[sennsay]

Originally Posted by Pricklely Peete

S-Man the opamp in the LD I+ is MC33078P.....the pic(s) make the lettering hard to read. I'm uploading pics of the FrankenDAC to photobucket, I'll post some pics of the cap paks on the HDAMs then post some pics of them installed before I put the lid back on....Could you do me favor and look up the data sheet specs on the LD I+ opamp please.

Thanks bro,

Peete.

Righto, on to it.

[Pricklely Peete]

S-Man are these the right pins .....I need another set of eyes on this to be sure (pins 4 + 8 V- V+) It sure is Fugly



Peete.