Twisted Pear Audio - Buffalo32S (ES9018 DAC)

[NeoY2k]

Hi Dustin,
Hi Russ and Brian

Bravo for this new board! It really is neat work, layout is impressive! It should be a killer, no doubt!!!

I'll be happy to hear more about the IVY2. What's inside? What's different? What more/Less? When will IVY II be available (I'd like to get a couple channels).

I'd also like to know why you settled for an integrated THS4131, and not use AD797s as ESS did on their demo boards. Is it better, or just cheaper/more compact. As it's an integrated chip for the two channels, there should be less mismatching between the opposite sides of the signal - thus, less 2nd harmonic distortion. Resistor mismatch remain, but you'll of course use thin film precision resistors, so I feel confident about that.

Well, I just want to know more about your new IVY!!!!

(post modified as requested)

Originally posted by sangram
Can't make out from the top layer, but how does the ESS chip get its VA supply now? Is it tapped off the VA supply from the IVY II supply, separately for each channel or something else?

And, there are a LOT more opamps, but no SE output. Eagerly awaiting more details.

I would bet the 2/3rds of the SO8 you see are for power regulation.

[dusfor99]

Originally posted by NeoY2k
Hi Dustin,
Hi Russ and Brian

Just wanted to say that I get no credit at all for Russ and Brian's endless work on their boards, I just happend to want to get my hands on one like the rest of us!

Dustin

[NeoY2k]

Well, you engineered the chip, so bravo for that part of the work!!!!! xD

Plus, If I understand, you gave some advice to TP guys to have a good layout of your chip. .

[BrianDonegan]

I'd also like to know why you settled for an integrated THS4131, and not use AD797s as ESS did on their demo boards.

Because we think it sounds better, and actually measures better as well. I assumed this is why you copied the design...

[Russ White]

Thanks folks for the kind comments.

1) The Buffalo32S is the stereo version. There is an 8 channel version coming (shortly) as well , but with no integrated I/V .

2) Not everything that looks like an op amp on the board is an op amp.

3) I am now using the OPA1632 not the THS4131 because I found that it actually does perform better.

4) I am using the fully symmetrical op amp in a unique way, at least I have never seen it before. It applies feedback to OCM to make SE output as effective as balanced output. You can use this board SE or balanced with no penalty. You just may need to adjust gain.

I have no problem with the AD797, its just that now that I know how to use it well I prefer the OPA1632 especially because it is so simple to set the common mode voltage. It has a lot going for it.

Some details you can't see in the picture. This is intentional.

AVCC is supplied via the same PS as the I/V stage on each side. And they are separated (unless you choose to use the same supply on both sides).

Cheers!
Russ

[NeoY2k]

Brian:
Well, copied the design...

First, I will probably won't have any spare I/V boards, and if I have any, they will probably go to friends.

Second, I can't tell how it compares before having tested it, simply. I was just curious about your "why", and how you improved it. Sorry for making electronic stuff, not just buying DIY kits.

Third, it's a transconductance amplifier, these are simply opamps with one resistor to the negative feedback. Plus the chip removes DC.

I can't really admit it as a ripoff, components around the chip aren't even exactly the same - if I would have copied your design, I wouldn't have added optional pi filters on input and output - just to test things. I would just have copy/pasted it. And If I wanted to rip off a design, why wouldn't I have simply took ESS's guide schematics? There even is a view of the implementation with smd (as I only work with smd), I wouldn't even had to use my brain to find a layout!

I hope you didn't meant I ripped off your design. Probably I don't have your level and asked some incredibly lame questions on this board, but I completed an electronics degree, that -hopefully! gave me more than enough to understand an inverting amplifier.


Anyway, I'll leave this thread. I always stressed I was not competing with you, I even told people that may want my boards to use them with your boards around them - yes, I even said to use... IVY for output.
If you want me to remove any reference to your work from my thread, just ask a moderator to do so as I can't edit the posts.

Russ: Thanks.

Cheers,
Nicolas

[Russ White]

Nicolas, Don't worry. Everything is fine.

I expected people to start investigating and using some of the ideas I have laid out or I would not have done it in a public forum.

I don't claim to be doing anything that could not be done by spending a few minutes with a datasheet or a book or two.

I am fine with your DIY project and in fact encourage it.

What I think Brian was reacting to was just that you chose to talk about it on our vendor thread. Maybe the more generic ESS thread would have been more appropriate.

In any case I really hope your project works out well for you.

Cheers!
Russ

[BrianDonegan]

Sorry for making electronic stuff, not just buying DIY kits.

Really, let's not go there. My post sounded a little terse as I posted it before my morning coffee. Sorry about that. I assumed it was a copy of the Ivy because you refer to it as "basically the same thing, some slightly different stuff." I can be a little grumpy first thing in the morning, and should know better than to post so early, it always comes out wrong.

Your boards look nice. Honestly, even if it were an exact copy of something we did (it is not), I wouldn't have a problem with it, as you did it for yourself. That's what DIY is all about.

That said, our Vendor thread is probably not the best place to offer your extras for sale, but NO BIG DEAL. Really.

[NeoY2k]

Ok, sorry. I was just replying to Ozone while asking you questions, but forgot I was on your vendor thread.

I really apologize, should me more careful - and not that nervous.

I'll ask moderators to remove my post to Ozone.

Apologies again,
Nicolas

[mravinsky]

Originally posted by BrianDonegan


What Vreg are you referring to?

That of post 1038 from Brian. Thanks