[halman]

aha, there is no program that can make a gerber out of a pcbexpress file?... in anycase since the layout and all hard decisions are already made it should be easy enought to even manually export the board by drawing it in another program...still the time that takes might not be worth the money saved..

In any case olimex are cheap and makes very good boards.

 

[dsavitsk]

Quote:

Originally Posted by halman aha, there is no program that can make a gerber out of a pcbexpress file?

Apparently the files generated by ExpressPCB are just encrypted gerber files.

Quote:

Originally Posted by cetoole practically forcing one to purchase boards from them.

Not just practically, but actually.

Some people have reported that the encryption is not hard to break. However, doing so violates not only the ExpressPCB license but also the DMCA. Further, the only real reason to do so would be to make more than 3 boards which violates the license I attached to them

-d

 

[dsavitsk]

Hmmmm. The first one of these I built had 1K metal film resistors for I/V and bias. Overall this combination works well but the sound can be a tad thin. I built a second one with Allen Bradley carbon comps using 2.8K for I/V and 1.4K for bias (the stripes say 2.7K and 1.4K, but they measure a bit higher.) The second one sounds fuller, more dynamic, more natural, and overall better, but at high volume there is a lot of high pitched background noise that is not in the other one. There are other difference like different bypass caps and a different voltage regulator, but these are all higher quality, lower noise parts, so it seems unlikely that they are the problem.

So, does anyone have any experience with AB resistors? I've heard they are noisy, but this seems absurd. Or, any other ideas as to where the noise is from? It sounds like grainy static, so don't think anything is oscilating, but what do I know. Oh, also the noise is most pronounced into my Melos which has a higher input imedence than my other amps, so that may be a factor.

 

[Francis_Vaughan]

Not sure about the noise, but something else caught my eye.

You have socketed the DAC. I guess you might be trying to preserve or protect them, but doing so rather voids some of the care taken to get the groundplane and ground returns so well set out. There is now a greater loop area between the signals and the groundplane. This may increase the interference between signals. This is even more an issue for this DAC with its one lonely ground pin - a design that makes it all the harder to control ground return currents.

As for PC layout software, most people use Eagle - which is also free for up to 4 x 3.2 inches - and runs under Mac and Linux OSes as well. It doesn't create encrypted, tied, output. In general it has become the preferred software for work in these forums.

 

[dsavitsk]

Quote:

Originally Posted by Francis_Vaughan You have socketed the DAC. I guess you might be trying to preserve or protect them, but doing so rather voids some of the care taken to get the groundplane and ground returns so well set out.

Actually, less to protect the chips than the rest of the board. I only had a couple of chips and they were from suspect sources, so I didn't want to get one in to discover it didn't work, then not know if it was the chip or something else. Now that I know it works, I'll pop off the socket and see what happens.

 

[dsavitsk]

Quote:

Originally Posted by Francis_Vaughan As for PC layout software, most people use Eagle - which is also free for up to 4 x 3.2 inches - and runs under Mac and Linux OSes as well. It doesn't create encrypted, tied, output. In general it has become the preferred software for work in these forums.

Is there anyone that will make $20 boards with standard files? If so, I'll switch for future projects. If not, I never need more than 3, but usually want at least that many, am pretty happy with ExpressPCB software, and am pretty happy with the quality of the boards.

 

[ATAT]

4pcb does $33 / board, and they free-expedite...

 

[eVITAERC]

Have you tried plugging in a TDA1545 ala diyparadise? Their approace seemd icky at first with the TDA1545 being used with a passive I/V (after all, it wants to see a stable voltage across its output for continuous calibration), but after using the Monica 2 for several months I'd say it sorta kinda works

 

[dsavitsk]

Quote:

Originally Posted by eVITAERC Have you tried plugging in a TDA1545 ala diyparadise? Their approace seemd icky at first with the TDA1545 being used with a passive I/V (after all, it wants to see a stable voltage across its output for continuous calibration), but after using the Monica 2 for several months I'd say it sorta kinda works

The TDA1545 takes a eiaj signal while the TDA1543 uses i2s. So, no, you can't plug the TDA1545 into this project. Infact, I think that to get a PCM2707 to interface with a TDA1545, you are going to need to add a bit of extra stuff, like a cs8414 perhaps?

 

[DaKi][er]

Quote:

Originally Posted by dsavitsk Is there anyone that will make $20 boards with standard files? If so, I'll switch for future projects. If not, I never need more than 3, but usually want at least that many, am pretty happy with ExpressPCB software, and am pretty happy with the quality of the boards.

http://www.batchpcb.com/
$10 setup per order then $2.50 per sq in. for double sided solder mask and silk screening and no minimum order

Good for one off's and small runs but gets costly if your boards get big, they did a perfect job on my dac board and I got some more boards on the way