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Jambo DAC - Page 3

post #31 of 219
Thread Starter 
Thanks everyone for the interest.

Quote:
Originally Posted by bearmann View Post
hey there! I'm definitely interested in ~2 boards of the next/new charge... as I've seen on the wolfson website, you can order samples online. So probably this could become a decent and (relatively) low-priced DAC!
Cool. We'll see how cheap it'll be, group buying components will definitely help. If I make up build kits (which there does seem to be demand for?), I aim to provide two options, a no expense spared one and a more budget one. An idea I'm having just now is to use OPA134s instead of AD797s - saving there is £14 per board and the specs on the 134 look pretty decent. Anyone have any comments, I've never used the 134? It seems to be pin compatible apart from it lacks the compensation pin that the 797 has but that's easy to deal with.

Quote:
Originally Posted by bearmann View Post
How do you power it up at this time? Don't know how important the power supply on DACs is...

best regards and keep up that good work!
bearmann
The power supply is pretty important, for prototyping just now I'm using a bench supply that I designed which takes a 12V wall wart supply and using LM317s provides 3.3V and 5V and then a small switcher provides +/-12V. I haven't checked but I'm pretty sure that the TREADS will also work.
post #32 of 219
I don't think this is practical, but I'd love a DAC that had multiple outputs that were switchable - I don't suppose there's any demand for that?
post #33 of 219
Quote:
Originally Posted by rustbucket View Post
I don't think this is practical, but I'd love a DAC that had multiple outputs that were switchable - I don't suppose there's any demand for that?
YOu just need to connect the output of the DAC to a rotary switch or a relay based selector like the darwin from twistedpearaudio.com

No need for this to be in the DAC board.


Jambo, don't forget that if you go ahead with your idea of selling kits, don't forget to post a mall-fi. They're cheap, you'll get much more attention and salles and still support head-fi! good luck and keep us posted.
post #34 of 219
How does it sound? is it comparable to Opus DAC?
If yes, I'd like somebody to build me one(depending on the price, of course)
post #35 of 219
I'm interested in two boards. Looks great!
post #36 of 219
Thread Starter 
Quote:
Originally Posted by Cankin View Post
How does it sound? is it comparable to Opus DAC?
If yes, I'd like somebody to build me one(depending on the price, of course)
I've never heard the Opus, but I'd be surprised if it were siginificanlty different.

Comparing it to my cheap (single CMEDIA chip) PC sound card is night and day, very very clear, the stereo sounds very wide, bass is tight and there is no background hiss at all when the amp is turned right up. Sorry, I'm not particularly good at hifi speak, but I'm really pleased with it. Compared with my Wharfedale CD player which has a reasonably decent DAC from Burr Brown the differences aren't as great, but it is still better. Obivously this isn't just a DAC though - it has the advantages of multiple source selection and USB input so it's a pretty useful bit of kit.

Edit: Re building, cool, I will probably offer to solder the ICs for a modest fee if people want, then you could probably manage the rest yourself.
post #37 of 219
damn wrong thread.

sorry for not getting back to you. but i decided i'd rather wait for the full thing. Any idea on rough pricing?
post #38 of 219
Thread Starter 
Quote:
Originally Posted by lordmozilla View Post
Hey, i was just looking into this product then came across what you said. How do you change the inputs? This is really interesting to me, in fact this feature will probably mean i'm going to buy one. Please explain how it is done and how easy it is to do. Thanks!
If you look on the second page of this thread where I posted the block diagram, that might help you follow what I'm saying here - picture says a thousand words and all that. The WM8805 is an SPDIF transceiver but it has 8 inputs, I've used 4 of them - USB, Optical x2 and coaxial. The microcontroller (shown as an FPGA on that diagram) receives inputs from momentary switches and then tells the WM8805 which input to choose. I've created the code for this, so it's easy for you! Depending on your idea of what is fun, I could supply the board with the micro soldered and flashed.

There are headers/solder holes on the PCB for attaching the switches to so that it can be mounted in a case nicely, rather than having the switches on the board and there is a similar header which will drive LEDs to show the current input source.

I hope that answered your question but if not let me know.

While I'm here, power supply requirements are +3.3V, +5V and +/- 12V, although I dare say that you could run the analogue stages of the DACs off +3.3V as well thus doing away with the 5V supply, but then there wouldn't be much isolation between analogue and digital supplies.
post #39 of 219
sorry changed my question since i got the wrong thread. I thought this was about the 707 dac and got really exited since i disregarded it because you couldn't change the inputs. Your product sounds like a winner though :-)
post #40 of 219
Sorry guys, noob question. What is I2C? Based on your block diagram I'm guessing that's just a control signal from the FPGA to the Wolfson for switching inputs?
post #41 of 219
Thread Starter 
Yup exactly, stands for inter integrated circuit if i remember correctly. It's a two wire interface, devised by Phillips I think. It's quite cool because each device has a unique address, so you don't need chip select wires.
post #42 of 219
Looks very nice.
At the moment I am looking for a inexpensive USB DAC and this looks very interesting.
If there ist a group buy I am definatly interested in a board.
post #43 of 219
Thread Starter 
Quote:
Originally Posted by lordmozilla View Post
damn wrong thread.

sorry for not getting back to you. but i decided i'd rather wait for the full thing. Any idea on rough pricing?
The full thing will be rather cool

I've just been doing some rough pricing. If ten people will commit and my Excel sheet is correct, kit prices should be no more than £70 (~$140). 25 kits and it gets close to £60 (~$120). That's parts and PCB, however I decided not to include LEDs or switches in the pricing as I thought people would probably want to do their own thing - how's that sound?

I'd be prepared to solder all of the ICs and flash the micro for around £10, assembling the whole thing could be negotiated too, but that takes a lot of the fun out of it...
post #44 of 219
If you can keep the price equal to the DAC super pro 707 shipped with IC's soldered and micro flashed, then you got my money ;-) (its £70 shipped to the UK)

Are you in the uk? Also will this thing need an external power source or will usb be feeding it +5V ?

lastly, when do you reckon you'll get the first kits ready?

Thanks
Brendan
post #45 of 219
Thread Starter 
I am in the UK yes, and I have no intention to profit from postage charges, they will not be above cost.

I should point out that that price above was using OPA134s in the output stage, not the AD797s. I think they're just going to be too expensive, but I'll offer both options or people can buy their own amps.

RE the DAC Super Pro 707... I just had a quick read of a web page about it and can't figure out if the Optical/Coaxials are inputs or outputs? Anyhoo, my DAC has much much better components in it than that does, so it sounds better (I hope) and as such costs me more so unless we get into serious volumes I can't see that target being met. I'm confident it'll be worth the extra cash.

USB power doesn't cover this unfortunately. You'll need to make/buy/rip out of an old cd player... a +3.3V, +5V, +/-12V supply. Depending on the success of this I might design a power supply next...

I hope to get a couple of prototype revised boards here within the next fortnight. Once they're tested I'll make any corrections necessary and order a larger number which should be here within a fortnight of then. So, around a month I hope.
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