SB3 Jitter reduction mods

tonyptony · « **Reply #80 on:** 16 Sep 2008, 06:50 pm »

I haven't been here for a while, but have been keeping track via lurker mode.

My vote would be for ditching the 48KHz to add improved jitter reduction, and maybe even regulation.

NewBuyer · « **Reply #81 on:** 16 Sep 2008, 10:42 pm »

Hi Pat,

My vote is for focusing on reclocking with a new clock and improving its supply, and if needed, pulling the 48kHz. You may need to design a purpose-built power supply for the aftermod item as well, to accomplish all that is required.

art · « **Reply #82 on:** 22 Sep 2008, 07:05 am »

OK, the gang has spoken, and I have heard. Mainly because most of you agree with us.

OK, here is the final decision:

I have just ordered some proto PCBs. These will only fit into the Duet.

The features:

44 kHz only. Sorry to all of you that want 48 kHz. It is possible that the doo-hickey will upsample to 44 kHz instead if there is no 48 kHz present. Guys who have played guinea pig have not reported any Internet radio stations that did not work.

Since it is 44 kHz only, it will reclock the output signal.

Since I need a clean clock for it, I have designed a low-jitter discrete clock. (Another reason 48 kHz had to go..........2 clocks on at the same time.........bad for jitter.)

In order to get low jitter out of the clock, I designed in a low-noise supply for + 3.3 V.

And since I found room, I made one almost identical to it for the + 5 V. And guess where it goes.........that's right, the DAC chip.

Of course, the obvious features..............transformer coupled SPDIF w/BNC jack. Etc, blah, blah.

All this assumes that I measured right, and it actually does fit inside. And that I made no mistakes on the layout.

While I am waiting on the PCBs to arrive, I will start work on a dedicated + 9 V supply. Gotta have a clean supply for those low-noise regulators to run properly.

JohnR:

If you want, you can lock the thread. Not sure I would advise sending it to your dustbin, as some may not read it for a while.

When the mods are ready, I will start a new thread. So, this one has served its purpose. Thanks to all who have spoken.

To the unfortunate few still waiting on their SB3s............

I will do something to them. I have a handful of various PCBs that work, but not to my complete satisfaction. Give me some time to decide which option I feel best with, and I will install it for next to nothing. Basically cost of parts, and maybe a few shekels for my time. Thanks for your patience and understanding, and most of all your willingness to participate. None of this would have eve happened without your help. Everyone who will ever benefit owes you their thanks.

Ok, this will be the first night I have gone to sleep before 4 AM. Any one who wants my job..............

Pat

art · « **Reply #83 on:** 9 Oct 2008, 05:59 pm »

Not quite ready to unleash on an unsuspecting public, but........

"When will it happen, bub?", you ask.

When I finish the power supply. Yes, this will happen. And soon.

Back to the lab........

Pat

konut · « **Reply #84 on:** 9 Oct 2008, 07:19 pm »

Quote from: art on 9 Oct 2008, 05:59 pm

Back to the lab........

Say hello to Igor for me!

randytsuch · « **Reply #85 on:** 9 Oct 2008, 09:44 pm »

I thought you would have removed the existing crytals, but I still see one, between your board and the 802.11 board

Randy

art · « **Reply #86 on:** 9 Oct 2008, 09:52 pm »

I did. Just the ones for 44.1 kHz and 48 kHz operation. The ones that you see are for other chips.

The crystal for 44.1 kHz is not visible, as are a whole bunch of other parts.

(On the bottom side.)

Pat

crooner · « **Reply #87 on:** 9 Oct 2008, 11:41 pm »

Looking great!!!

Very neat layout on the PCB. Kudos!

I'm assuming the mod will be available in kit form for us crazy DIY'ers...

art · « **Reply #88 on:** 10 Oct 2008, 12:31 am »

NEIN!!!!!!!!!!!!! Harder to wire in than it would seem to be.

BTW, the position of the +3.3V and +5V will eventually be reversed. The +5V was not part of the original idea. The PCB just kept getting longer, and longer...........and longer. Realised that I had space to work with, so it was added on.

In case anyone is interested, here is what is on the top side, starting from upper right, and going clockwise.

+3.3V for clock/SPDIF
+5V for DAC
Low-jitter oscillator
Buffer
Sine-square converter
Clock distribution
SPDIF reclocker
SPDIF drivers
Transformer (on bottom!)
Some other top secret stuff and output cable. I tried to put the connector on the PCB, and once I got over the problem it created, things moved quickly.

Ok, I'm slow. Or stubborn. Both. Whatever.

Pat

Folsom · « **Reply #89 on:** 10 Oct 2008, 12:47 am »

I have to make a funny comment first. You are upset with other modification service providers, but here is the kicker, you wanted to sell yours to someone who does these!

Anyways I own an SB3, and a Duet is another $400 is way out there considering the pile of other things I need to pull off some good sound. What do you think about making a hole in the SB3 for the stuff? Could you ever offer something like this? It would not be hard to mount a PCB board just off the SB3.

I want good sound and while the price of your re-clocker is cheaper than the Pace-Car for $1100, it is still too much if I have to buy a Duet as well I assume.

I am not seeing it as loosing a market, but more like putting other people out.

tanchiro58 · « **Reply #90 on:** 10 Oct 2008, 12:57 am »

Very nice work!!!

Let us know when you are completely finished.

Thanks,
Tan

ajayrav · « **Reply #91 on:** 10 Oct 2008, 01:59 am »

Looking nice! Do we have a ballpark price for the mod + power supply?

Thanks,
Ajay

dmatt · « **Reply #92 on:** 10 Oct 2008, 02:07 am »

I like where this is going, I'm ready to pack up my Duet.

Is converting a DAC with an RCA SPDIF input to BNC simply a matter of changing the type of connector?

Also, it looks from the picture that a power cable (with a braided cover) is hard wired to the Duet. Are my eyes playing tricks on me, or is that just the prototype that has this cord, or will the final form have an integrated power cord/wall wart/plug thingy (to use the technical term).

Thanks

art · « **Reply #93 on:** 10 Oct 2008, 02:21 am »

We plan to make the "power cord" integral to the Duet. It will plug into an external power supply, which will have a proper IEC inlet on it. We all know how a lot of you guys like to try new power cords. Can't do that with a wall wart. No, it won't have a "Felix-style" doo-hickey inside. It will have another form of RF filtering.

As for your DAC............well, you can. Might help to have a piece of coax (and not twisted pair) to connect to it.

We can sell you a BNC connector, at cost, if you need one afterwards. I'll even throw in a hunk of coax soldered to the BNC gratis. Such a deal.

Of course, there are things that you can do once you are inside, but 'splaining them would be hard for the average DIYer.

OK, the price..........we will know once I finish the power supply.

Goal is $500 for the whole shootin' match.

Or, some of you can still pour more than that into just a power supply. Choice is yours.

Pat

Folsom · « **Reply #94 on:** 10 Oct 2008, 02:35 am »

$500 maybe, but not with a DUET in that price for me. Hmmm

art · « **Reply #95 on:** 10 Oct 2008, 02:45 am »

Quote from: Destroyer of Smiles. on 10 Oct 2008, 12:47 am

I have to make a funny comment first. You are upset with other modification service providers, but here is the kicker, you wanted to sell yours to someone who does these!

Anyways I own an SB3, and a Duet is another $400 is way out there considering the pile of other things I need to pull off some good sound. What do you think about making a hole in the SB3 for the stuff? Could you ever offer something like this? It would not be hard to mount a PCB board just off the SB3.

I want good sound and while the price of your re-clocker is cheaper than the Pace-Car for $1100, it is still too much if I have to buy a Duet as well I assume.

I am not seeing it as loosing a market, but more like putting other people out.

Yes, this did start out as mod for the SB3, and we hoped it could be done for the Duet as well. There is no room inside the SB3 for all of this. As I said, we could do less to make it fit, but it would be less than optimum.

Remember, we were contacted by "other services". Not the other way around. Much the same as every day I get requests from people here, and other forums (I guess), that want this badly. We are responding to what the market asks for. We are not creating it.

The fact that I asked forum members what exactly they wanted should show this is a market-driven product.

We have been building stuff since '86. This is the only instance where we asked the customer what they wanted up front.

As for your other suggestion...........

Yes, we have thought about it. Here are the problems:

It needs a clean +9-12V supply to run it. The SB3 only has +5V, and it is not quiet enough to even consider. As is the Duet supply. But, we can build one supply to do both in a Duet. Can't do that with a SB3.

There are a lot of parts on the bottom side of the pcb. Hanging it on the back isn't the most secure location. Yes, it seems that all it would take is to drill a few holes in the back. If I was a DIYer, yeah, that is exactly what I would do. Selling anything like that does not reflect well on a company. No one here is in favour of that.

I know this won't change your mind any, and it is not intended as such. But many feel that the Duet is a much better platform, and futzing with the SB2/3 is a waste of time for someone like us. Anyone who already owns a Duet knows that they can buy another Duet for $125 or so. Many have more than one. So, we are loosing a small segment of the market, it makes better business sense to move beyond the SB3 and straight to the Duet.

Pat

crooner · « **Reply #96 on:** 10 Oct 2008, 03:31 am »

Pat, I presently have a pulse transformer (yeah the infamous SC) in one coax input of my DAC, along with a BNC connector. The other input is standard factory RCA terminated coax.

In case I want to use your modded Duet, what input is the best?

I figure you'd want to yank out the SC transformer. However, I still have an unmoded standard RCA coax input. Perhaps I should use that one with a BNC or something?

art · « **Reply #97 on:** 10 Oct 2008, 03:57 am »

The one with the BNC and SC transformer. C'mon, just because I hate it is no reason to yank it out. You paid good money for it.

As for that other input...........

You can buy the transformer that I use from Digi-key. I can sell you a BNC at cost, or you can supply your own. Then you can compare the two. I know you guys love to compare stuff.

I know which one will sound better, but it would not hurt for someone totally impartial to say what they think.

Pat

Folsom · « **Reply #98 on:** 10 Oct 2008, 05:20 pm »

I guess the situation is that I am utterly confused on how to have a good transport.

I would consider buying a DUET for the $125 if I could set it up without the controller, and control it via PC, for the time being, and go with your mods.

sts9fan · « **Reply #99 on:** 10 Oct 2008, 06:17 pm »

DOS why can't you do that? What you are really confused about is not HOW to get a good source. Its is how to get a good source while being in school. I could have never bought a $400 anything but books while I was in school.