[netsky3]

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif The point of having the capacitors inline on the BantamDAC is that the PCM2702 output mid-rail (~2.5V) DC and the capacitor blocks that. As for the sound of the capacitor? That is a religious debate. Black Gates, Vitaman Q, Wima, Silmic, Cerafine, Muse, Solen, Vishay Roederstein, etc all have been said to have different sounds. It comes down to personal preference to determine which one you like. The grubDAC doesn't need a DC blocking cap. The WM8524 uses a charge pump to generate a negative rail and outputs a low offset signal. So you are trading the capacitor for a technology to create the negative rail. So the grubDAC and the BantamDAC are different beasts in the output stage and they sound different. Some people have commented already in this and the Carrie thread, so you can get some opinions here and there. A few more vocal builders would help out a bit in this regard

Quote:

Originally Posted by Juaquin /img/forum/go_quote.gif Well no capacitors means you don't have bass roll-off. That's not a problem with the Bantam anyways, though. And of course, if you believe capacitors audibly color sound there's that too.

Thank you

 

[tomb]

Cobaltmute is being diplomatic and I appreciate his efforts.

However, netsky3 - remember when I said that hopefully one should find a proportionate increase in sound quality with increase in price? The GrubDAC PCB is twice as expensive as the BantamDAC PCB. I'll leave it at that, except for commenting on capacitors in a general sense -

There are good audio capacitors and there are not-so-good audio capacitors. Some might even be called great in their sound. However, considering equal circuits behind them, there is no capacitor that sounds as good as not having a capacitor at all. The question, of course, is whether one circuit topology is better enough to overcome the handicap of having capacitors in the signal path when compared to a different circuit that doesn't use them. For instance in some tube amps, it's possible that the circuit is outstanding enough that the fact there are capacitors in the signal path is not enough to detract from its performance when compared to other topologies.

 

[netsky3]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Cobaltmute is being diplomatic and I appreciate his efforts. However, netsky3 - remember when I said that hopefully one should find a proportionate increase in sound quality with increase in price? The GrubDAC PCB is twice as expensive as the BantamDAC PCB. I'll leave it at that, except for commenting on capacitors in a general sense - There are good audio capacitors and there are not-so-good audio capacitors. Some might even be called great in their sound. However, considering equal circuits behind them, there is no capacitor that sounds as good as not having a capacitor at all. The question, of course, is whether one circuit topology is better enough to overcome the handicap of having capacitors in the signal path when compared to a different circuit that doesn't use them. For instance in some tube amps, it's possible that the circuit is outstanding enough that the fact there are capacitors in the signal path is not enough to detract from its performance when compared to other topologies.

thanks for your explanation

 

[luvdunhill]

I don't suppose there is a Beezar mailing list?

Auto notification when kits are available would be pretty sweet!

 

[netsky3]

Quote:

Originally Posted by luvdunhill /img/forum/go_quote.gif I don't suppose there is a Beezar mailing list? Auto notification when kits are available would be pretty sweet!

uhm...but in the beezar there isn't a complete kit for a grubdac, right?

I've seen only the pcb

 

[cobaltmute]

Back a few posts...

Quote:

Originally Posted by tomb /img/forum/go_quote.gif The intent is for Beezar to sell kits - in the GrubCableDAC version. However, as you all probably know, the availability of PCM2706/7's is quite bad. I'm working on a solution that will last quite awhile, but it'll be mid-to-late April before I can get a sizable quantity.

 

[rds]

Quote:

Originally Posted by Juaquin /img/forum/go_quote.gif Well no capacitors means you don't have bass roll-off. That's not a problem with the Bantam anyways, though. And of course, if you believe capacitors audibly color sound there's that too.

Keep in mind that a servo using a negative rail created by a charge pump will also "color" the signal. Whether the distortion is audible or better/worse than using output caps is a relative question.

 

[netsky3]

Quote:

Originally Posted by cobaltmute /img/forum/go_quote.gif Back a few posts...

ops...sorry

 

[nullstring]

EDIT: retracted.

This post was me asking cobaltmute if I could get his source files in order to attempt to add the things I need in order to add SPDIF to the design.

Tomb has pointed out that my request was not appropriate, and I will communicate with cobaltmute directly concerning this.

 

[tomb]

Quote:

Originally Posted by nullstring /img/forum/go_quote.gif <snip> In any case, I can't seem to find layouts, schematics.. or anything for the production version.. are you not planning on releasing them?

GrubDAC (grubDAC website)
I can't speak for cobaltmute, but please note the key word, "production." It implies that cobaltmute's extensive prototyping, testing, and modification period is over.

Quote:

Would it be possible for me to get your source files so I can take a gander at making these changes?

Again, not trying to speak for cobaltmute, but please ask yourself - does AMB supply source files to anyone for the B22, Mini3, Gamma 1 or 2? Does Tangent or Runeight or Dsavitsk or cetoole for any of their designs? Beyond that, most of these designers use software that is not free in order to meet the for-profit legal requirements.

Just some things to think about for a bit.

Maybe you should try PM'ng him.

 

[nullstring]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Again, not trying to speak for cobaltmute, but please ask yourself - does AMB supply source files to anyone for the B22, Mini3, Gamma 1 or 2? Does Tangent or Runeight or Dsavitsk or cetoole for any of their designs? Beyond that, most of these designers use software that is not free in order to meet the for-profit legal requirements.

To be honest, I thought that when asked, any of these people wouldn't mind supplying their source files for others who want to take their work in a different direction.

For instance, I was under the assumption that joneeboi had used AMB's mini3 source files in the creation of the carrie.
However, I could be quite wrong about all of this.

I'm not quite sure what the problem would be. It's obvious why one would want to retain copyright over their own design, but I don't see a big issue in allowing another member of the community to make additions to your work under the assumption that the original creator retains full copyright.


On another note, I took the production pictures and put them into photoshop and have found just where everything could be easily added inorder to do what I want to do.
I took the two pictures and layered them ontop of each other, and they the holes were -exactly- matched up. I don't know if it was by design or just luck, but it was pretty cool.

 

[tomb]

Quote:

Originally Posted by nullstring /img/forum/go_quote.gif <snip> For instance, I was under the assumption that joneeboi had used AMB's mini3 source files in the creation of the carrie. However, I could be quite wrong about all of this.

Yes, if I'm not mistaken, Joneeboi's design is completely his. However, because the underlying circuit design was AMB's, that's why AMB gave his permission for a Group Buy (Head-Fi rules - no profit), but not to openly sell the Carrie otherwise.

I could be wrong, too - but that's my memory of the chain of events.

Quote:

I'm not quite sure what the problem would be. It's obvious why one would want to retain copyright over their own design, but I don't see a big issue in allowing another member of the community to make additions to your work under the assumption that the original creator retains full copyright.

Again, you need to contact cobaltmute personally about his opinions regarding this, but there are very few cases in this world where you can take someone's proprietary work and modify it for your own purposes. Pete Millett is one large exception in this community, but he has plenty of his own designs that are not even shared in terms of layouts or schematics (refer to TTVJ for examples).

As for source files, those are the keys to the kingdom, so to speak, and in a digital world are the same as sharing software. In some cases, that's viewed as OK, but in other situations it's viewed as a crime.

I'll stop commenting on it, though, and let you contact him. He may not have an issue with it under certain circumstances. Please don't take offense - I just thought perhaps you should consider more carefully before asking something like this on a public forum.

 

[Billyk]

Hi folks! An email came through showing activity in this thread....
How is the schedule for the 2707 chips? Still on track?
Thanks!!

 

[nullstring]

Quote:

Originally Posted by tomb /img/forum/go_quote.gif Please don't take offense - I just thought perhaps you should consider more carefully before asking something like this on a public forum.

It's quite alright.
I guess that I was under a very different assumption about how the community works. Everyone is so free and easy about posting their layouts, schematics, and even explaining what and why things were done that I didn't think that this would be an issue.

I am an advocate of open source software. When there is a part of an application you would like to see changed and isn't getting added for one reason or another, it's a very appropriate response to just add it yourself.

I was under the assumption that the diy audio community was very similar. It makes sense to not release source files publically and to retain copyright of your work, so that you don't have issues with people trying to make money of it;
I thought that was the reason source files weren't publically available.

Again, it seems I was under a different assumption, and I've made an ass out of you and me (Ok, really just me.)

Thanks Tomb. I will send cobaltmute a more formal message via PM.

 

[Juaquin]

The schematic and layout are both available on the Grub website. Now that the design work is done, it would be relatively simple to copy the schematic in Eagle, make your modifications, and build a board out of it. If cobaltmute supplied the schematic file all it would do is allow you to shortcut a couple hours work, and you're going to have to redo the board layout anyways.

Since the schematic is made freely available I believe you're welcome to do with it what you wish, as long as it's for personal use. If you were to do a group run or post detailed schematics you would probably want to get blessings first, since it wasn't originally your idea.