Go Back   Home > Forums > >
Home Forums Rules Articles diyAudio Store Blogs Gallery Wiki Register Donations FAQ Calendar Search Today's Posts Mark Forums Read

PC Based Computer music servers, crossovers, and equalization

IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...
IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...
Please consider donating to help us continue to serve you.

Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving
Reply
 
Thread Tools Search this Thread
Old 13th April 2019, 11:36 AM   #151
diyiggy is offline diyiggy
diyAudio Member
 
Join Date: Jan 2019
For instance this Cornell Dublier FCA cap in 0805 size &16V (for the iancanada smd adaptator on the bottom biggest area which is made for this size)


Cornell Dublier : http://www.cde.com/resources/downloads/fca_mcd.pdf
  Reply With Quote
Old 13th April 2019, 03:56 PM   #152
wlowes is offline wlowes  Canada
diyAudio Member
 
wlowes's Avatar
 
Join Date: Mar 2007
Location: Toronto
Default ceramic vs FCA

Hi diyiggy
I did a little further digging wrt your FCA cap suggestion. Just seeking confirmation of my understanding. Looking at the adapter pcb I believe the 3 ceramic caps are all connecting power to grnd in parallel. They measure .1uF, so it is .3uf in total.

I have a supply of CDE FCA caps that are .68uF but they are the next size up.(1206?) It appears it would be possible to solder one by bridging across a pad. The 3 square pads are +3.3v and the pointed pads are grnd. So it would not be too tough to solder one end to grnd and pick up the 2nd + down the row with a larger sized cap. In some ways it would be an easier smt solder than the 3 tiny caps supplied. Just need to be really careful to not cause a solder bridge resulting in a short. One would end up with .68uf vs the .3 specified. It might actually be a good thing. It appears there are also CDE FCA caps available at digikey in 1206 size that are .33uf. This would produce an almost exact same result as the 3 little 805 caps.

I confess that I am hesitant to do this to working clocks. After messing up several things, it is nice to just have a system that works reliably and the sound is very good now that things are settling in. Probably will try it after a few days when I get the itch to mess with it again.
  Reply With Quote
Old 13th April 2019, 04:43 PM   #153
randytsuch is offline randytsuch
diyAudio Member
 
Join Date: Jan 2003
Location: LA
Quote:
Originally Posted by diyiggy View Post
For instance this Cornell Dublier FCA cap in 0805 size &16V (for the iancanada smd adaptator on the bottom biggest area which is made for this size)


Cornell Dublier : http://www.cde.com/resources/downloads/fca_mcd.pdf
Just a word of warning on surface mount film caps.
I've used them, and found them to be fairly easy to damage with heat. These caps were in the signal path in a ladder dac so it was very obvious if you damaged one.
I got the best results if I heated quickly, and only once. I don't try to touch up solder on SM film caps.
When I used them, I'd buy extra, in case you do damage them.

Randy
__________________
My system is here
http://randytsuch-audio.blogspot.com/2005/10/my-system.html
  Reply With Quote
Old 13th April 2019, 06:03 PM   #154
diyiggy is offline diyiggy
diyAudio Member
 
Join Date: Jan 2019
@ Wolwes : try the 0.68 : it's in between the 0.47 to 1 uF I advised ... at least with the CCHD-957. If you have not 2 others smd adaptators on hand, indeed why to bother ! And I told you the FifoPi having at the bottom an acrylic cap already, you perhaps don't need it... There is a chance iancanada used it cause it readed it somewhere... x7r or tantalum are less expensive. I'd like to know how the FifoPi compares vs the FiFo II board or the MC board.

I really think you should try first: one adaptator with the other unpopulated of any caps the day you try. Notice the difference you will have is also related to how you feed the board and the PCM board with its powersupply cap.

So enjoy first your good dicscover, you're FifoPi is not burned in yet

@ randystuch : that's very true : you need rapid soldering, not too much heat so rapid soldering skill, and most of acrylic references are only 20% precision but the Panasonic PPS which are bigger ! But here the idea is not to use them with a very precise value. I like the CDE more than the Panasonic, but didn't try the Rubycon iancanada uses at the bottom of the FifoPi. However, anyone having a Clock II or a MC Clock and those adaptattors with CCHD-957 should jump on that tip.

Enough said, it's a FifoPi thread here and the Powerboard made of LiFePo4 should maybe changes the game as well (though I really didn't like a123 cell with clocks... certainly because there was a LDO in between)
  Reply With Quote
Old 14th April 2019, 02:35 AM   #155
jacklee is offline jacklee  Hong Kong
diyAudio Member
 
Join Date: Oct 2009
Quote:
Originally Posted by diyiggy View Post
For instance this Cornell Dublier FCA cap in 0805 size &16V (for the iancanada smd adaptator on the bottom biggest area which is made for this size)


Cornell Dublier : http://www.cde.com/resources/downloads/fca_mcd.pdf
Thanks for the link. I'll look into that.
  Reply With Quote
Old 14th April 2019, 08:32 PM   #156
Supersurfer is offline Supersurfer  Netherlands
diyAudio Member
 
Join Date: Feb 2013
I just ordered me some sparkos labs and burson v6 vivid opamps. I can’t wait!

I soldered some 0,47uf black gate NX caps to the power pin of one of the clock positions. The NX series work at their best when paired in anti-parallel configuration, this is the preference by black gate called super-E cap and it will lower the esr considerably.
It is running in now and I will report the outcome later.
  Reply With Quote
Old 15th April 2019, 06:49 AM   #157
ilgavro is offline ilgavro
diyAudio Member
 
Join Date: Sep 2018
My configuration for now. The little cap is polistirene cap 640pf. For me it's the best resultClick the image to open in full size.
  Reply With Quote
Old 15th April 2019, 09:37 AM   #158
Crom is offline Crom  United Kingdom
diyAudio Member
 
Join Date: Oct 2012
Quote:
Originally Posted by wlowes View Post
Crom,
Interesting feedback re sound quality.

Where exactly are you going to place your super caps? Right at the clk?

I have some 5v super caps. I was thinking of putting one right at the input to the +3.3v clean power on the FIFOPi. So it would be right at the output of the 3.3v regulator/input to the FIFO. I need to do some digging and find Greg's suggestion.

Maxwell has modules up to 48v. Probably very expensive. As I understand it, they series connect individual cells and balance the current flow until they get the target voltage.

Interested in your report.
Thanks. I will look for the maxwells. I just put them at the main supply input of each card. Initially one in the 2nd clock board in the DAC (mcFIFO) and then I added 2 more, one on each of the supply inputs to the twisted pear dac boards. Iím not overly enamoured with any of them so I may move them. I do have a longer term plan to replace the avcc regs in each dac board with direct lifepo power and my current on board regulation is pretty good so maybe that part of the system is already optimised. More experimentation needed. I do urge people to try double-reclocking though!!
  Reply With Quote
Old 16th April 2019, 06:53 AM   #159
soundcheck is offline soundcheck  Germany
diyAudio Member
 
Join Date: Mar 2005
Location: DUS
Hi there.

I have a FifoPi Ultimate here for test.

Do you guys think a clock upgrade is a must? The manual somehow implies it. And at least some folks over here seem to confirm it.

From what I understand I would have to order the adapter boards from Ian and the clocks from DigiKey/Mouser. And then I'd have to put it all somehow smd-style together. Sounds very much like a DIY challenge.
And the cost for it will at least be another $80. Almost as much as the board.

I don't understand why Ian is not offering a good set of clocks by default!?!?
Or did I miss something?
DIY activities in the clock department without having top measurement equipment might become a bit tricky. Working with adapters on clocks is probably also not the best of all options. Hmmh!?!?


Are there any measurements (jitter/noise) about The FifoPi Ultimate available btw?
What's the current consumption dirty/clean?
Didn't see anything in the manual. Probably I missed it.

Thx.

Last edited by soundcheck; 16th April 2019 at 06:55 AM.
  Reply With Quote
Old 16th April 2019, 07:50 AM   #160
jacklee is offline jacklee  Hong Kong
diyAudio Member
 
Join Date: Oct 2009
Default Transformer I/V Outputs

@Greg,

I read that you have experimented with various transformer output options. Could you share your latest thoughts on this?

I am now using the transformer output HAT and really likes it. In fact I likes it better than the Std I/V HAT with Sparkos opamps. Thus I want to explore if there are even better transformer choices available.

I tried to read up on current-output DAC and honestly I am not sure I fully understand it. So far my understanding is:

- The optimal load for current-output DAC is a virtual ground but this doesn't work in transformer output as there won't be any voltage generated.

- This is why a resistor (510ohm in the HAT) is used to generate the necessary voltage from the output current. This is not ideal as the voltage generated will interact with the current output source so minimizing the resistance of the load is desired.

- With a line transformer primary in parallel with the resistor part of the output power is then transformed to the transformer secondary. The exact current passing through the primary is then determined by the impedance reflected from the load of the secondary. Given the high input impedance of the next stage (i.e., preamp) this will likely be high so the current passing through the primary will be small compared to the resistor.

- Thus it would be desirable to choose transformer with step-up ratios so that the reflected impedance will be lower. Another benefit is that the step-up will allow smaller value resistor to be used at the primary as the voltage needed can be lower. However, the tradeoff is that the step-up will also multiply the source impedance which could hamper the secondary's output capability, i.e., leading to freq roll off when coupled with the next stage's impedance characteristics. So a balance must be strike here.

- Finally, ideally, if the impedance of the next stage is really high (e.g., input grid of a tube) then perhaps one can use a very small resistor value, e.g., 1 ohm with a very high-gain step-up transformer (e.g., mic or MC). In this case then the DAC can operate in near ideal current output mode. This is just some thoughts I have for now. One will need more precise calculations to determine the operating points or whether this even works or not.

Any comments and thoughts are welcome. Any suggestion for potentially better transformer options are most welcome as well!

Last edited by jacklee; 16th April 2019 at 07:53 AM.
  Reply With Quote

Reply


IanCanada's Latest RPi GB Goodies Impressions... and your tweaks, mods and hints...Hide this!Advertise here!
Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
Detailed specifics, hints and tweaks in designing a sealed sub Squeak Subwoofers 1 17th July 2015 03:27 PM
The latest tweaks :) lowtherdream Everything Else 6 13th January 2009 05:43 PM
S5 K-16LS mods, tweaks? hartze11 Tubes / Valves 3 1st December 2008 05:13 AM
NAD C541i: possible tweaks and mods? Karlosak Digital Source 4 23rd November 2006 06:20 PM
Any mods/tweaks for a Panasonic DVD S-49 mikee55 Digital Source 4 19th March 2006 07:04 AM


New To Site? Need Help?

All times are GMT. The time now is 12:48 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2019 DragonByte Technologies Ltd.
Copyright ©1999-2019 diyAudio
Wiki