Q for Jim- Any news on Chime DAC?

hagtech · « **Reply #60 on:** 21 May 2005, 06:06 am »

Got HAGUSB up and running today. Once I fixed the very stupid mistake, it was plug and play. Jamb it into a USB socket on my laptop, other end into the CHIME (HAGDAC), and I was playing CDs off the PC.

Ok, it's just windows media player. I'm sure there are better programs out there. Just glad the thing worked. No drivers, no setup issues, no dialog boxes.

Didn't sound any different than the normal transport feed. I suppose both go through the S/PDIF conversion, so that's why.

Good progress. All I need to do is sort out the PLL reclocking circuit and we're good to go.

jh

flocchini · « **Reply #61 on:** 9 Jun 2005, 04:42 pm »

Jim:

Quote
Didn't sound any different than the normal transport feed. I suppose both go through the S/PDIF conversion, so that's why. End Quote

I know that you have mentioned that direct use of USB interferes with your jitter circuit but I'll still ask - Is it possible to "bypass" the S/PDIF conversion? Or maybe the broader question is the jitter circuit necessary with USB only?

Thanks.

Bob

hagtech · « **Reply #62 on:** 10 Jun 2005, 06:17 am »

It is possible to bypass SPDIF with USB (just not with HAGUSB). One of the other TI chips (PCM2707?) spits out an I2S that should go straight to digital filter. With a decent 12MHz reference on the USB, it might not need the low jitter reclocker (like the Wavelength). On the other hand, that all depends on how that USB chip comes up with the 44.1k rate based on a 12M clock. Fractional PLL?

Anyway, I chose to use a different USB chip, one that spits out SPDIF. I did that so it would be compatible with existing DACs plus easily plug onto the HAGDAC, which was optimized for SPDIF playback.

Also, my listening test was anything but rigorous. A few minutes of non-direct comparison.

jh

hagtech · « **Reply #63 on:** 23 Jun 2005, 10:53 pm »

For the CHIME, I have a switch on front panel to select output phase. Which word (label) do you prefer for this: "PHASE" or "POLARITY"?

Does either make more sense to you? Or does it not matter?

jh

orpheus · « **Reply #64 on:** 23 Jun 2005, 11:37 pm »

Don't know what other people will say, but I think that phase is the term used most often in audio circles. The stereophile test CD's talk call it phase, as well as the Hi Fi News test record. Don't know what other test records call it, but phase makes sense to me.

I think it's a great idea to put that switch in, it will appeal to a lot of people who don't have a phase switch on their preamp or have different sources output in opposite phase. Then there's the recording phase issue...

-Aaron.

hagtech · « **Reply #65 on:** 29 Aug 2005, 01:49 am »

Finally! I can put the CHIME on sale. Looking at this thread, we didn't really start development until March of this year. And now it is done. Six months for a complete development cycle ain't too shabby. Not that it wasn't easy. Went through four proto versions to get here. Started with ECL and LC tank PLL, ended up with VCXO PLL at +5V. So many changes during development, I can't even recall them all. USB on, off, back on. Got rid of PLL meter. Lots of testing and listening and then going back to drawing board. Four revisions each of HAGDAC and CHIME. Nothing goes on sale until it is ready for prime time.

Now if you'll give me just one more day to complete the assembly manual and update the website, I'll be happy to start fullfilling orders.

Thanks again for your patience!

jh

flocchini · « **Reply #66 on:** 2 Sep 2005, 03:04 pm »

Jim:

Great product. Idefinitely see it as a partner to my octal Cornet2.

I am almost embarassed to ask, but given my collection of 6SN7s- Can the 12AU7 be replaced with a 6SN7?

Thanks again for the outstanding project.

Bob

hagtech · « **Reply #67 on:** 2 Sep 2005, 07:29 pm »

Quote

Can the 12AU7 be replaced with a 6SN7

Sure can, with some modifications. Need to double up the current, change resistors in power supply, check heater voltage. I like the idea, so maybe I can build one to find out exact values. This would be a very good combination of tubes.

Might take a little time, busy with production at the moment. Hate to keep anyone waiting for an order. And I need to get me a new 6SN7 from Stu, all out at the moment.

jh