SB3 Jitter reduction mods

jhm731 · « **Reply #20 on:** 19 Mar 2008, 04:55 pm »

Pat-

SD's CEO posted lower jitter measurements with the 12.2880 crystal lifted. See:

http://forums.slimdevices.com/showthread.php?t=15882&highlight=sean+jitter+measurements

rajacat · « **Reply #21 on:** 19 Mar 2008, 05:20 pm »

Why not have two SB3s in your system? One for audio file playback with maximum mods and the other for internet radio.

-Roy

art · « **Reply #22 on:** 19 Mar 2008, 06:37 pm »

Interesting.........resampling 32 kHz to 48 kHz.

Oh, well............you're knackered, Tony.

Even if I didn't need the room, I would take out the 12.whatever crystal. Two clocks, on at the same time.........not a good idea.

(OK, if I did have the room, I would make a special version for Tony, that would enable the 48 kHz if you really needed it. Then you would have to come up with a way to switch clock frequencies on the reclocker..............no, you know what.....Internet radio isn't worth the hassle. Sorry!)

OK, 2 of 3 plumbing problems solved. Last one may be the worst. 30+ years of calcification to deal with........

Back to plumbing.

Pat

posternutbag2000 · « **Reply #23 on:** 20 Mar 2008, 11:38 pm »

Sorry for everyone for being a lurker over the past few months/years and not chiming in with my 2 cents earlier...I have the SB3 with the dual transformers (Newava & SC) and dual outputs from the original thread in which Dan kindly sent Pat his SB3 to mess around with...Yup, I bought that SB3 from Dan a few weeks back...Anyway, its been in my system for the past few weeks and imo is an improvement over the stock SB3 and stock Duet feeding an outboard DAC (in my case a modded (Burson discrete op-amps) Promitheus non-OS SS Dac)...In fact, it was readily apparent to even my wife. Better PRAT, drive, cleaner background, more "pluck" and sustain on guitar strings and piano notes...

So my point is that Pat is using measurements as his criteria for an improvement while I'm using my ears...In the end, I'm a fan and only wish I'd paid more attention in my undergarduate engineering days (

) to understand the technical side of this stuff better...Alas, I pursued the biological sciences instead

again just my 2 cents...anxious to hear what Pat has done this time to perhaps better improve things...

tonyptony · « **Reply #24 on:** 21 Mar 2008, 12:49 am »

Quote from: art on 19 Mar 2008, 06:37 pm

(OK, if I did have the room, I would make a special version for Tony, that would enable the 48 kHz if you really needed it. Then you would have to come up with a way to switch clock frequencies on the reclocker..............no, you know what.....Internet radio isn't worth the hassle. Sorry!)

D@mn engineers!

Hey, wait a minute...

art · « **Reply #25 on:** 21 Mar 2008, 10:14 pm »

Quote from: mgalusha on 19 Mar 2008, 02:21 pm

Pat, any plans to offer your board/technology to intrepid DIY types? Granted there are not that many who should be hacking away at SMT parts but for those of us who can...

mike

OK, if I was brazen enough to sell a DIY version, what would you want:

Assembled tested version? (It does have lots of 0805 parts on it.)
Blank PCB? With or without parts?

How much is either worth? Parts, sans PCB would be around $30, including BNC and transformer. All, except BNC, can be sourced from Digikey.

How much can I gouge you guys for warehousing all the parts, that you can buy on your own? (You aren't likely to find the BNC. You may find something close. Maybe.)

What happens when you can't make it work?

Pat

art · « **Reply #26 on:** 23 Mar 2008, 06:13 pm »

http://www.audiocircle.com/index.php?topic=52394.msg470101#msg470101

I knew the stock SMPS couldn't be good, but now that I realise how truly pathetic it is, this may have an impact on the jitter reduction mod.

We will probably have to design a linear +5 V PSU to go with the mod, and that will probably alter who we would team up with.

Pat

tonyptony · « **Reply #27 on:** 23 Mar 2008, 06:31 pm »

Quote from: art on 21 Mar 2008, 10:14 pm

OK, if I was brazen enough to sell a DIY version, what would you want:

Assembled tested version? (It does have lots of 0805 parts on it.)
Blank PCB? With or without parts?

How much is either worth? Parts, sans PCB would be around $30, including BNC and transformer. All, except BNC, can be sourced from Digikey.

How much can I gouge you guys for warehousing all the parts, that you can buy on your own? (You aren't likely to find the BNC. You may find something close. Maybe.)

What happens when you can't make it work?

Pat

Pat, my vote would be for blank PCB + parts + instructions. Opens up a real Pandora's box for the level of support you'd be willing to provide, I know. But my vote would be for stipulating a very limited range of support - suitable to what you believe to be anticipated. Buyers would have to acknowledge the Ts & Cs before purchase. Anybody else - if you're not smart enough to play in the sandbox then don't walk into the playground!

Anyone who doesn't have the requisite assembly skills could have an option to pay extra to have the work done for them.

mgalusha · « **Reply #28 on:** 23 Mar 2008, 10:23 pm »

Quote from: art on 21 Mar 2008, 10:14 pm

OK, if I was brazen enough to sell a DIY version, what would you want:

Assembled tested version? (It does have lots of 0805 parts on it.)
Blank PCB? With or without parts?

How much is either worth? Parts, sans PCB would be around $30, including BNC and transformer. All, except BNC, can be sourced from Digikey.

How much can I gouge you guys for warehousing all the parts, that you can buy on your own? (You aren't likely to find the BNC. You may find something close. Maybe.)

What happens when you can't make it work?

Pat,

From my perspective I would be fine with either a board/parts or a built/tested version. I figure if I can do a QFP48 chip the 0805 parts aren't too bad.

However, as you say, what if the person can't make it work. For your own sanity and to hopefully reduce the headaches I'd say offer it as an assembled and tested board. Provide some photos and instructions and if the folks can't make it work then refer them to whoever you partner with to have them make a proper job of it. Hopefully that would keep you out of the support business.

Mike

mgalusha · « **Reply #29 on:** 23 Mar 2008, 10:25 pm »

And yea, the stock SMPS is really really bad.

Bob in St. Louis · « **Reply #30 on:** 25 Mar 2008, 03:50 pm »

Quote from: mgalusha on 23 Mar 2008, 10:25 pm

And yea, the stock SMPS is really really bad.

Personally Mike, I'd recommend more emphasis on the word "really".

Bob

art · « **Reply #31 on:** 28 Mar 2008, 05:43 pm »

Someone donated a Duet to work on. Same problems inside, but nowhere as bad.

The same PCB won't fit in both............grrrr............have to make 2 different ones.

Pat

art · « **Reply #32 on:** 25 Apr 2008, 06:29 pm »

Well, I now have a good idea what the final design will be. Still don't know how I am going to shove it all on the PCB that I have room for.

This turned out to be much more challenging than I would have imagined. No, I am not giving out hints on what needs to be done or how. But I doubt that the "competition" (if there is any for this sort of mod) will have spent the time and energy required to do it right.

OK, to actually do it right, I would need a much larger PCB. It would have been a lot easier to design this in as part of the original circuit, but such was not the case.

As part of the process, we have plans to make a dual-voltage linear supply for the SB3. One will obviously be +5 V, to run the unit. And a smaller, yet independent + 12 V for the clock.

Also, we are nearing completion of an agreement with a new firm, to collaborate on these projects.

Stay tuned.

Pat

art · « **Reply #33 on:** 17 May 2008, 04:55 pm »

I think that I have a PCB design that will work for both the SB3 and the Duet. Waiting on samples of a specialised part that is essential to its performance. I have the part in a TO-92 package, but other than the fact it is no longer made, period, I have to source a SMT version from a second-source. Hope to have that in hand this week.

Because of all the hassle and design tricks involved, I doubt there will be a DIY version. I could make some of the simpler versions available. Performance won't be as good, but a substantial improvement over stock.

Your thoughts?

Pat

art · « **Reply #34 on:** 17 May 2008, 05:15 pm »

Here is how all DIYers (and most engineers, unfortunately) go about fixing oscillator jitter by selecting low-noise regulators:

http://www.diyaudio.com/forums/showthread.php?postid=1511080#post1511080

And in the post right below it:

http://www.diyaudio.com/forums/showthread.php?postid=1511420#post1511420

Well, he has problems............and he ain't gonna fix'em that way.

Pat

JoshK · « **Reply #35 on:** 17 May 2008, 05:15 pm »

Quote from: art on 21 Mar 2008, 10:14 pm

Quote from: mgalusha on 19 Mar 2008, 02:21 pm
Pat, any plans to offer your board/technology to intrepid DIY types? Granted there are not that many who should be hacking away at SMT parts but for those of us who can...

mike

OK, if I was brazen enough to sell a DIY version, what would you want:

Assembled tested version? (It does have lots of 0805 parts on it.)
Blank PCB? With or without parts?

How much is either worth? Parts, sans PCB would be around $30, including BNC and transformer. All, except BNC, can be sourced from Digikey.

How much can I gouge you guys for warehousing all the parts, that you can buy on your own? (You aren't likely to find the BNC. You may find something close. Maybe.)

What happens when you can't make it work?

Pat

I'd be one of the intrepid DIY types, I wouldn't need or assume support. I would personally like a stuffed and tested PCB that i install. This way you don't have to worry about some daft DIY'er like myself botching the stuff job and taking up your time trouble shooting it. I'd be willing to pay a premium over parts/pcb for such a solution. Can't think of a price off the top of my head, but $100 is easy, $150 would be ok too. Its just more convenient to order a board than have to send my SB to you to mod it for me when I am comfortable doing it myself (that is squeezing a board into an existing SB).

art · « **Reply #36 on:** 17 May 2008, 11:31 pm »

I would think that $100 would be top price. Parts would probably be $30-40, depending on how large of a quantity we order for some of the more pricey parts.

I'm trying to make the Duet version where the BNC solders onto the PCB, without going through a piece of coax. That would make the install easier.

The tough part of the install will be running a ribbon cable (supplied) from the output/clock chip on the SB3/Duet PCB. Might not be as hard on the Duet (have not tried one yet), but it is tricky on the SB3.

Pat

mgalusha · « **Reply #37 on:** 18 May 2008, 12:50 am »

Pat,

Per our previous discussion I'm still game to have a go at this as well.

Mike

art · « **Reply #38 on:** 18 May 2008, 02:21 am »

Don't worry............I didn't forget about you.

Pat

art · « **Reply #39 on:** 3 Aug 2008, 07:00 am »

Some of you are aware that I have been out of the office a great deal lately. I don't see this trend reversing any time soon.

However, when I am in the office:

I am working on the SB3 mod. Long story short, we had to come up with a bit more exotic regulator than we had initially hoped for. There isn't room for it inside.

(For those of you who think that a 3-terminal regulator will work: no I think I have already told you that it won't. Nor can you make one without any capacitors. Problem is that they take up lots of room. And you can't stick them any ol' place and expect it to work in this application.)

It has to go inside, as the amount of wire used would increase the output impedance substantially above the impedance of the regulator. Normally, this would not be the case. However, since they are using the same chip as the clock and SPDIF output, the solution is a bit trickier.

The ultimate solution would be to make better clocks (which could be disabled so that the one not being used would not corrupt things), have all the SPDIF stuff separate, with nice linear regulators for each one.

Probably easier to do for a Duet, as making a new case would not be that much of a hassle. The SB3: more of a challenge.

So for all of you who are either about to turn blue from holding your breath or thought that we had vanished......

Nope, still here. Just doesn't seem like it. Hang in there a bit longer. I'm sure the cavalry is riding to the rescue. Can't hear 'em charging yet, but I'm sure they are out there.

Pat