A New Take on the Classic Pass Labs D1 with an ESS Dac - Page 20 - diyAudio
Go Back   Home > Forums > Source & Line > Digital Line Level

Digital Line Level DACs, Digital Crossovers, Equalizers, etc.

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 22nd June 2010, 05:34 PM   #191
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
Owen, can you please reply with the values for the caps you have in those pics? what scema are you using for that, it seems different to the no cap one. I have the resistors (the power ones, sorted) I know what fets, but need to know the cap values for hirez and the small through hole ones you have used there.

can you point me to the schema if you already posted that one. has been a few and without knowing what those caps are its difficult to tell if you made any changes for the higher voltage and using the PCB from pierre. I need to build it up this weekend as the sydney headfi meet is coming up next week and i'm running out of time. i'll be right once I know those, its straight forward to build and I have every possible combination of values pretty much

thanks mate
  Reply With Quote
Old 22nd June 2010, 05:38 PM   #192
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
i'm assuming 0.01uf, but is that really a 22uf film the big blue ones? and the small resistors are? soldering iron at the ready!! I have like 10 days to assemble and test the ackodac, most parts arrived today, but if I cant get that done, I would at least like to install the mosfet IV in my buffalo II for the meet.
  Reply With Quote
Old 22nd June 2010, 07:04 PM   #193
opc is offline opc  Canada
diyAudio Member
 
opc's Avatar
 
Join Date: Oct 2004
Location: Ottawa, Ontario, Canada
Hi qusp,

I see you're under the gun! I know the feeling... we had a meet here in Ottawa last week and I spent all night trying to finish up a pair of line arrays to bring along with me. I even enlisted my wife to help with the gaskets and driver installation! I got them done, but just barely.

I've attached a PDF with the final schematic, and all the values that were used to get everything just right. This is exactly the way I have Pierre's PCB's setup right now. You can use this schematic at a variety of of voltages, by simply adjusting the value of the resistor feeding the gate of the fets. In this schematic you're looking at R16, 17, 24, 27 with a value of 30k9 which works perfectly for around 50V rails. If you drop down to say 18V rails, then you'll want something more like 10k in place of the 30k9. All other values stay the same.

For the output coupling caps, I would suggest going larger than the 6.8uF listed on the schematic. You can use anything from 4.7uF to well over 100uF, but you'll probably get some low frequency roll-off with values less than 10uF, depending on the input impedance of the following stage. In my case, I know that the next stage has an impedance of 22k, which gets me a LF corner frequency of 1Hz.

Here are the parts I used:

200R = Caddock MP930
400R = Ohmite TN15P400RFE (Thin Film)
FET = FQA32N20C
10uF Caps = TDK 10uF ceramic 50V Y5V (I like to live on the edge)
Output caps = Epcos 6.8uF Polyester
Other resistors = 1% metal film

For the four caps that set the HF filter, I still don't have the correct values, but I've been using the DAC without them and I can't hear or measure a problem with that setup. If you're running the DAC at 96 or 192kHz then I'd suggest leaving them out completely. If you're always running at 44.1 then it might be beneficial to have them, but certainly not necessary. I'll get the values sorted out soon for those who really want them.

Let me know if you have any problems with your build, and I'll be sure to help out.

Cheers,
Owen
Attached Files
File Type: pdf D1 Final SCH.pdf (83.1 KB, 645 views)
  Reply With Quote
Old 22nd June 2010, 07:42 PM   #194
diyAudio Member
 
Join Date: Jul 2007
Send a message via Yahoo to narkissos
Anyone tried this one with the IRF610 yet?
  Reply With Quote
Old 22nd June 2010, 09:34 PM   #195
opc is offline opc  Canada
diyAudio Member
 
opc's Avatar
 
Join Date: Oct 2004
Location: Ottawa, Ontario, Canada
Hi Guys,

Just thought I'd let you all know that I finally got around to testing the IRF610 after Pierre kindly supplied me with a few at the Ottawa DIY meet last weekend.

For the same values as the other fets (Vds=25V Id=130mA) the transconductance is 0.360S (average of two devices tested).

It's neither good nor bad, so if you have it, you can use it, but you'll get better results with the suggested FQA32N20C. As for the sound, you'll have to try it yourself to find that out.

Cheers,
Owen
  Reply With Quote
Old 23rd June 2010, 04:44 PM   #196
qusp is offline qusp  Australia
diyAudio Member
 
qusp's Avatar
 
Join Date: Oct 2009
Location: Brisbane, Australia
also owen, I dont have a pot on my QRV08 dual mono headamps, which are in the same case as headphone amp and buffer/line driver (defeat-able) i'm using the sabres internal digital pot and the headamps have a buffer (4 discrete diamond buffers a channel in my case) with or without gain as the first stage. so the input impedance is massively high, I could probably get away with 0.1uf, on the input there is an optional DC removal 0.1uf SMD PPS film cap, which since the amps have servos and output offset will be very low if I leave a cap on the output of the D1, I could omit the cap, then there is a 470k R on the way to the regulator and another 100k to ground directly after (pull up, pul down) and the effective input impedance of the amp is 1MO haha, so either way the cap value can be very low indeed. only reason to think about a larger cap there would be to allow for the option of using the dac without the headamps inline (IE not using its unity gain mode as a buffer by installing a switch or separate set of outputs), but i will see how it all sounds before I make those sort of tweaks.

so really I could look at buying another 2 x mundorf silver in oil 0.68uf or another 2 x VCAP CUTF 0.1uf to go with the 2 I have and using those . so I dont think I have to worry about 10uf, I will have another look at the input impedance of my active monitors, but I think if I did work it so the QRV08s arent in the line out, I would work out some sort of switching arangement, or simply put the output caps inline with the output wiring connected directly to the XLRs
  Reply With Quote
Old 30th June 2010, 12:41 AM   #197
diyAudio Member
 
PierreQuiRoule's Avatar
 
Join Date: Feb 2004
Location: Ottawa
Owen

Thank you very much for measuring the IRF610s. So their transconductance is in the ball park of other small MOSFETS, and a bit less than half that of the bigger brothers. This is useful to know.

Pierre
  Reply With Quote
Old 3rd July 2010, 08:29 PM   #198
Sandor is offline Sandor  Italy
diyAudio Member
 
Join Date: Mar 2004
Location: Milan
Default Balanced to unbalanced

How can I connect this D1 circuit to the unbalanced input of my preamplifier?
Using a transformer do I need a center tap on the primary to be connected to ground? Which transformer would be best suited? And are the output capacitors necessary?
Regards.
Paul.
  Reply With Quote
Old 4th July 2010, 08:32 PM   #199
opc is offline opc  Canada
diyAudio Member
 
opc's Avatar
 
Join Date: Oct 2004
Location: Ottawa, Ontario, Canada
Hi Paul,

You can just use a 1:1 transformer, no need for center taps. If you do go that route, then you shouldn't need to use any coupling caps since both outputs are at the same potential in a well adjusted circuit, and that should mean no DC across the transformer.

I might actually try it out with a small signal transformer I have kicking around here, and I'll let you know how it works. There seems to be a lot of people interested in using SE output.

Cheers,
Owen
  Reply With Quote
Old 6th July 2010, 11:47 AM   #200
diyAudio Member
 
merlin el mago's Avatar
 
Join Date: Sep 2009
Location: Catalonia - Europe
Default pcb

I'm interested to compare vs Erno Borbely I/V, It's possible to buy pcbs or exist a GB?
  Reply With Quote

Reply


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
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Pass Labs S/Ns ? dejanm Pass Labs 8 26th January 2007 07:35 AM
My opinion on Pass Labs and Mr. Pass (Nelson) himself b_online Pass Labs 11 21st May 2003 12:39 AM


New To Site? Need Help?

All times are GMT. The time now is 12:53 AM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2014 DragonByte Technologies Ltd.
Copyright 1999-2014 diyAudio

Content Relevant URLs by vBSEO 3.3.2