Lidstrom improved ZEN - diyAudio
Go Back   Home > Forums > Amplifiers > Pass Labs

Pass Labs This forum is dedicated to Pass Labs discussion.

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 5th April 2001, 08:20 AM   #1
hifi is offline hifi  Sweden
diyAudio Member
 
Join Date: Mar 2001
Location: sweden
http://www.tanker.se/lidstrom/zeni.htm


what do you guys think about it?


/micke
  Reply With Quote
Old 5th April 2001, 04:40 PM   #2
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
hifi,
How 'improved' it might be, I'm not sure. All he did was rearrange the current source to take an N-channel device instead of a P-channel.
It would be slightly cheaper, however, given that N devices are lower cost.
Sound quality? Dunno that I'd expect an audible difference. I once asked Nelson if he'd ever noticed a consistent sound quality difference between equivalent N and P channel MOSFETs. He said he wasn't aware of one. (This was one of those thought experiments I'm prone to whilst driving. The SOZ circuit would provide a convenient test bed for such experiments.)
It wouldn't be particularly difficult to build a Zen with plug-n-play current sources, nor particularly expensive (the heat sink & power supply are the hurtful parts). If you've got the time and inclination, try it and give a report.

Grey
  Reply With Quote
Old 6th April 2001, 05:25 AM   #3
rljones is offline rljones  United States
diyAudio Member
 
Join Date: Mar 2001
Location: california
/micke-

I built one and it works just fine. I prefer using N-channels over P-channels. I truly don't think you'll hear any difference. N-channel devices are less expensive and therefore cheaper to match if you wish to use more than one device.

Robert
  Reply With Quote
Old 1st May 2001, 03:24 AM   #4
diyAudio Member
 
Join Date: Apr 2001
Location: Brisbane Australia
Default Ground missing???

I'm pretty new to all this so please excuse my ignorance. Is there supposed to be a ground connection on the constant current source circuit of the Lidstrom ZENi as shown on the Pass ZEN circuit?
  Reply With Quote
Old 1st May 2001, 04:03 AM   #5
rljones is offline rljones  United States
diyAudio Member
 
Join Date: Mar 2001
Location: california
ding,

I'm assuming you're looking at the schematic at http://www.tanker.se/lidstrom/zeni.gif. The ground connection at the bottom is not the constant current mosfet. The CCS is the upper mosfet. The bottom mosfet is the signal or output mosfet.

The reason it is connected to ground is that, unlike the Aleph series, which uses +/- power supplies with little DC offset and no output capacitors, this design has a single ended power supply. The side opposite the + supply is therefore referenced to ground. This means that the output signal from the Zen amplifier is floating about 2/3 above ground with respect to the + power supply(in this schematic about 2/3 times 34 volts). This in turn is why an ouput capacitor is needed: to prevent putting around 22 V DC into your speaker. Without the cap, 22 V will instantly fry just about any speaker.

Robert
  Reply With Quote
Old 1st May 2001, 04:46 AM   #6
diyAudio Member
 
Join Date: Apr 2001
Location: Brisbane Australia
Question Now I'm really confused

Robert,

Yes I am looking at the same schematic as you. I know the top part of the circuit is the CCS. What I can't figure out is how the earth connection shown on the Pass ZEN schematic (to R6) has been done away with.

Dan
  Reply With Quote
Old 1st May 2001, 02:55 PM   #7
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
Dan,
T'ain't no problem...R6 is still there, and is even labelled R6. What's confusing you, I suspect, is that in using an N-channel device for the current source, all the polarities were reversed (just for the current source). If you turn the schematic upside-down and kinda squint your eyes a bit (pretending that the positive rail is the ground in the original Zen schematic), you'll see that Alice went through the looking glass and brought your Zen back to you.
It's not that R6 needs to go to ground, per se, it's that it needs to go to a reference voltage.

Grey
  Reply With Quote
Old 2nd May 2001, 04:06 AM   #8
diyAudio Member
 
Join Date: Apr 2001
Location: Brisbane Australia
Grey,

I'm a little slow but I'm getting there.
Does this mean that in the original pass circuit that the ground shown is actually a connection to the reference voltage of the circuit at the drain of Q2?
I may have lost the plot here.

Thanks

Dan
  Reply With Quote
Old 2nd May 2001, 09:50 PM   #9
diyAudio Member
 
Join Date: Apr 2001
Location: Brisbane Australia
Default My mistake

I've just looked at the PCB layout at the Pass website and R6 definitely goes to the ground rail. Somebody please explain in simple terms what needs to be done on the Lidstrom ZEN to make it work

Dan
  Reply With Quote
Old 2nd May 2001, 11:30 PM   #10
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
Dan,
Now, I'm the one who's confused...I didn't know it needed fixin' before it would work. Granted, I haven't studied the critter in detail, nor have I built one, but I don't remember seeing anything that looked particularly wonky. I'd say go for it.
If I weren't up to my ears in fiddle-factor here, I'd build one of each and listen to them side-by-side, just to see which sounds which way.

Grey
  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
X.5 series could be improved? mert Pass Labs 9 27th August 2007 09:49 PM
improved opamp I/V ABO Digital Source 7 14th October 2006 07:00 AM
Improved discrete op-amp Mr Evil Solid State 23 8th August 2005 07:13 PM
MC Mods to Lidstrom Phono Stage DrewP Analogue Source 7 21st August 2002 09:08 PM
PCB layout for all N-type ZEN (aka Lidstrom ZENi) ding Pass Labs 9 6th May 2001 11:19 PM


New To Site? Need Help?

All times are GMT. The time now is 04:58 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