y1 gamma-1 DAC - Page 27

Make sure you have the correct chip installed for U2U. What does the marking on it say?

hi there guys; been a while since I dropped in here. My gamma1 kit (full build) has been sitting around waiting for me to decide what to do with it. I have decided on a larger hammond 1455.....201 (cant remember the middle. so i've decided to add battery power if I can. Wondering what the best way to implement this is. the idea being that I could use it with an iRiver via optical similar to EFN's, so i'm excited what it should sound like with my lisa. In this situation of course so no usb power would be supplied. unless I tap into the same USB circuit and supply exactly 5v with the right resistor value and battery combo?? would this be a viable option? or would I then have auto sensing issues to contend with, or is that just on the audio inputs?. I assume I can use the DC power supply also. Been wondering what else I could do with the touch extra space too. obviously that means I can use a nicer RCA,, and caps?? hehe anyone else put one of these in another case yet?? roll call!!

....anyone??

I appologize for my continuing noobness with some of this stuff, I ordered some books last week to get me on the right track, but i've had so little time of late that I havent even had the time to get this littly baby running. a whole new world of portable rigs is starting to open up; cant wait

thanks

I 'embedded' a gamma1 into an existing amp/preamp box.

for me, one key was to ignore the usb board and use only the spdif/dac board. for the cost of 1 jewelbox CD you can get a usb-spdif dongle and so having that take up a full board, imho, isn't the best use of internal space. I can easily get usb to convert to spdif outside the box with, say, a turtle beach cmedia dongle like this:




that does bit perfect output up to 48k, just like the PCM chip does.

and so by having that part outside my box, I get to 'eliminate' one board and that can make mounting the receiver/dac gamma1 board a lot easier.

of course, when you remove usb, you now have to solve the +5v power issue on your own

the cirrus receiver chip does (I would guess) as good as job as dejittering as the PCM TI chip would. so I opted to build my 'embedded' gamma1 without that PCM board.

an early photo of a one attempt at embedding the gamma1 (and pimeta) into a preamp 1U box:



living with 'just' the receiver/dac board was just fine with me

My parts are on the way from farnell, is there any audiable diffrence using USB, rather then using my motherboards optical out ?

I had a hard time telling the difference.. in fact, I couldn't. Maybe if I were using a more revealing system at the time, but I was satisfied with what I was using.. for now

What did you end up using? USB?

Hi qusp,

I explored this for a while and ended up with a 6-pack of NiMH AAs connected to the 5V version of one of these:

NewClassD UWB Regulator

I put the regulator on a tiny heatsink and stuffed it in an mint tin and soldered connectors to it so I can snap it all together in different ways (I also had in mind powering it from a 12V car cigarette lighter plug -- but quickly found driving with headphones and hi-def audio hilariously irresponsible and stopped).

It works great -- I'm off the grid with a RockBoxed iRiver containing lossless audio sending bit-perfect data > optical cable > Gamma1 > Mini3 > headphone of choice. I need to carry around a small camera bag for all of it, but no laptop, which was the goal.

There are doubtless more elegant Li battery solutions that stuff a much smaller battery pack and the reg board and maybe even the DAC into a single container -- I almost went down that route but decided not to spend the $ on the batteries and charger. Let me know if you want some pointers on where I got exploring that, with help from the kids at work who use Li power for remote-control airplanes.

I'll try post a picture later.

I'd also enjoy trading info with others on this kind of project -- perhaps in a new thread...

__Roy

its my understanding that both 'receivers' do a fine job (fine enough) on getting clock and data from the stream that it doesn't matter if you 'come in' via spdif or via the usb path.

usb goes to a burr brown pcm chip then an i2s stream is created and sent to the dac.

if you go via spdif, the burr brown chip is not used and a crystal/cirrus chip is used. it does basically the same functional thing and creates an i2s that is sent to the dac.

I don't really think the dac 'cares' and it generates the same output regardless of WHO creates the i2s stream.

that's my thinking.

that looks like a great product.

but the price - what a shocker. way too much, I think. looks good on paper, though.

I agree they are expensive, but for me it was the missing link in a rig that cost probably 10x the cost of that board.

I'd welcome a pointer to a cheaper alternative with anything like those specs in that approximate size; remember that I had thought I'd be trying to get clean power from a car with it, too, which provides terrible DC. I don't have the skills to design one myself.

Or you could have built a portable usb to spdif converter using the left over usb board. It might have cost more, but also might have been higher quality and offered both coax and optical.

It says A08G.

/edit: I also tried another USB cable and tried it on Vista laptop and a Windows XP laptop. Still says USB device not recognized.

I do plan to use my leftover board for that.

but its really hard to beat the size of that turtle beach thing. for my money, usb to spdif is commodity, at this point, and not really 'hard' anymore. the cmedia chip does its job well enough.

I'm thinking of taking that usb board half and not only getting spdif-outs from it but also analog-outs. the pcm chip DOES do audio-out just like it can do i2s out. its just that the analog-outs are left dangling and that seems wasteful to me

The Hammond 1455C1201 won't give you enough extra space to implement a good battery-power solution. The current consumption of the γ1 full configuration could be as high as ~90mA, so you'll need fairly substantial battery mAH to have usable run-time. It also needs 5V with a fairly tight tolerance, and no battery is going to give you that unless you use at least four or five NiMH cells and add additional voltage regulation (no, a resistor won't cut it). In addition, γ1's connectors and switches are PCB-mount and are designed for the 1455C801 case. If you use a longer case, you'd have to change to panel-mount pieces on one end. The front panel has only a switch and a jack, so it's less items to air-wire, but the NKK illuminated switch is not panel-mountable, so you'd have to use a different switch and a dual-color LED instead. Similarly, you'd have to change to a panel-mount output jack. Since they are off-board, they will eat up internal space in the case, so there will be little left for your batteries and voltage regulator.

A much better battery-power solution would be to buy or build an external rechargeable battery pack that puts out 5V, and plug it into γ1's DC power jack. There are commercial battery packs, designed for portable media players and cell phones, that would work.

OK, it's the correct chip. Looks like you've eliminated the cable as a possible problem, or the computer, and the supply voltages measured fine. So, if you're absolutely sure the solder joints are all ok elsewhere, then the only remaining culprit might be a bad U1U or U2U.

Yes, the PCM2707 has an onboard DAC that we're not using. It is inferior to the WM8501, but if you want to use it, not only must you connect the VOUTL and VOUTR pins to an output jack, you'll also need to provide analog supply voltage to the VCCL and VCCR pins, and add a decoupling cap from the VCOM pin to PGND (See the PCM2707 datasheet for details). Given the close pin-spacing and small PCB pads, this will be messy.

hmm - I think this is a ploy to get me to TRY to connect to it (LOL!)

I didn't realize how much was missing to get analog 'working' but I'm still a little curious how much of a dac-in-stein (lol) it would end up being. do you have any photos of protos that you might have tried like this?

the pcm chip on the bantam sounds 'ok' to me and I'm curious if they both are really the same internal engine (I am guessing so) on the analog side, this pcm and the bantam pcm.