[TzeYang]

NATIONAL SEMICONDUCTOR|LP2985IM5-4.5/NOPB|LDO REG | Farnell Malaysia

Did some searching and ended up with this. Is the STD version that much worse than the A version?

 

[TzeYang]

Okay sorry, I found it.

NATIONAL SEMICONDUCTOR|LP2985AIM5-4.5/NOPB|LDO REG | Farnell Malaysia

The part number on Amb's site is a bit outdated and i know how much fail farnell is when it comes to parts number consistency.

 

[Billyk]

Boy don't I know it. Seems like a fact of life at mouser. I finally went to order the parts for my y2 only to find they were out of two of the metal film resistors. Ordered about 50 carbon film and matched them instead. Sounds swell.
AMB lists an alternative op amp, I used that one.
Good luck.

 

[ShaneP]

Finished building a y1 and y2 a couple weeks back. I never realized I was listening to total crap coming out of my sound blaster card. Bass is much stronger now and I can't hear any static when I turn the volume all the way up with no music playing.

Only hitch was one of the screws supplied with the enclosure decided to shear off at the head after I screwed it in about a centimeter. Oh, and everything from Texas Instruments was out of stock

 

[francisdemarte]

Having some problems with my y2 mated to a y1 full. I'm not getting any output on either the mini-jack or RCA jacks. The output jack on the front is just outputting static.

I've double checked all solder joints and voltages they appear normal. Switch light turn solid green when I connect via USB and music is played.

I've also tried by passing up sampling by shorting JP2-1/4 this results in no output.

Y1 worked perfectly when both halves were mated together.

 

[amb]

francisdemarte, someone else experienced a similar problem, try looking through earlier parts of this thread to see if it helps you.

 

[francisdemarte]

EDIT: It's Working! Still not sure what was wrong.

To re-hash for anyone else having this issue:

Symptoms: No sound from RCA and Mini on Y2. Just static white noise on front Y1 mini.

I'm suspecting it was X1 crystal. Basically I put a larger flat screw driver tip on my iron and ran a clean tip across all the IC's and tried to reflow the solder under the crystal. So either this eliminated a small bridge or bad connection under the crystal.

 

[amb]

Did you mount the 1P header/socket at y1-JP1D to y2-J3? Does the y1 still work now when plugged into each other? If it does, but doesn't work when mated to the y2 (i.e., the WM8501 output at the front jack doesn't work any more), then check for connectivity problems at the board pin headers and sockets. Definitely check for solder joint problems on the y2 as well, and make sure all parts are mounted in the correct orientation.

 

[Masterrer]

I've been reading quite a lot on these forums the last several weeks.

Right now my brain is in overload mode from all the dac's opamp's cap's and their impact on sound quality.

I really need to choose a good dac for my PC. I'm quite into DIY and can do stuff like swap ram chips on wireless routers...

At this point I can't decide between the Musiland Monitor 02 and the Gamma-2
my budget for a DAC is about 200$.

If anyone can comment on which one may sound better, I would highly appreciate it!

P.S. The dac will be driving a Pioneer A400 stereo amp and JPW ML510 speakers. Probably will buy something like SENNHEISER HD555 later on.

 

[Beefy]

Quote:

Originally Posted by Masterrer /img/forum/go_quote.gif P.S. The dac will be driving a Pioneer A400 stereo amp and JPW ML510 speakers. Probably will buy something like SENNHEISER HD555 later on.

I can't help you with your DAC questions because I haven't heard the Musliand...... but IMHO the HD555 are just plain awful. There are MUCH better headphones in the same price range.

 

[luvdunhill]

amb:

on the y1 usb to SPDIF conversion circuit, isn't the result inverted from the incoming data? I'd expect a single hex inverter feeding the three paralleled gates I suppose.

Incidentally, it's hard to read some of the values on the schematic. For example, the reference designator of the inductor connected to pin 14 of the hex inverter.

 

[amb]

Quote:

Originally Posted by luvdunhill on the y1 usb to SPDIF conversion circuit, isn't the result inverted from the incoming data? I'd expect a single hex inverter feeding the three paralleled gates I suppose.

S/PDIF uses biphase mark encoding which makes it phase-insensitive. In fact some of the pulse trafos used for S/PDIF coax galvanic isolation are itself inverting, while others aren't, but it doesn't matter.

Quote:

it's hard to read some of the values on the schematic. For example, the reference designator of the inductor connected to pin 14 of the hex inverter.

L3U.

 

[luvdunhill]

Quote:

Originally Posted by amb /img/forum/go_quote.gif S/PDIF uses biphase mark encoding which makes it phase-insensitive. In fact some of the pulse trafos used for S/PDIF coax galvanic isolation are itself inverting, while others aren't, but it doesn't matter.

ah, right. Looking at the datasheet, I notice that there isn't a minimum propagation delay specified between the gates. Couldn't this be a problem for a usage such as this? If not (which I'm not convinced), why not just parallel all 6 together?

Also, what is the effective bandwidth of SPDIF? I'd think 10Mhz+? Again, aren't logic gates too slow for this use?

I'm thinking about doing the same thing roughly as you've done, but these questions are still nagging me a bit.

 

[amb]

I don't know which datasheet you're looking at, but TI's SN74HCU04 datasheet lists 7nS as the "typical" propagation delay. S/PDIF bandwidth is 2.8MHz (44.1K), 3.1MHz (48K).

At 3.1MHz the time period is 322nS which is 46x the typical 7nS propagation delay, thus it is more than good enough.

 

[linuxworks]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif Also, what is the effective bandwidth of SPDIF? I'd think 10Mhz+? Again, aren't logic gates too slow for this use?

well, my 'low end' spdif switch uses a variety of semi-low speed devices (rs422 buffers and cmos switches). I've used ttl, as well. spdif fits inside that just fine.

the 74hcu04 buffer is classic (at least 15 yrs old if not more). it passes the test of time if nothing else.