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

AKSA Builders of market proven kits and modules at sound quality to rival the best in high end

Reply
 
Thread Tools Search this Thread
Old 26th September 2009, 12:38 AM   #101
iko is offline iko  Canada
diyAudio Moderator
 
iko's Avatar
 
Join Date: May 2008
Location: Toronto
Aspen Headphone Amp
Does anyone know first hand how it sounds? Has anyone built a prototype, or, is anyone planning to do it before the group buy?
  Reply With Quote
Old 26th September 2009, 12:46 AM   #102
keantoken is offline keantoken  United States
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Quote:
Originally Posted by forr View Post
Hi Keantoken,

---Also, how about you try bootstrapping to Q7's emitter instead of to the output? This will make the bootstrap much more accurate. One transistor works more, but this should theoretically encourage even harmonics.---

Would doubling this with a second electrolytic connected to Q10 emitter be worth for linearity ?
I just checked in the simulator. I found very little affect (slightly positive) from changing between bootstraps to Q7 and/or Q10's emitter. In other amp simulations, I have noted that the harmonic spectrum changes significantly depending on whether you bootstrap to Q10 or Q7's emitter. I think this is worth experimenting with.

Also, the circuit has begun uncontrollably oscillating after I added series inductance to the caps and decreased the timestep. Increasing the miller cap didn't help, so it seems the problem is in the C-multiplier. I get the same oscillation whether or not I use the CFP c-multiplier. Just added some smaller bypass caps...

Okay, now look at this. The new bootstrap reference helps! 3rd harmonic is about 25db below the 2nd, whereas with normal bootstrapping it was 20db (I measured this at 20KHz since it gave a better FFT). (THD itself actually increases, but I prefer this because the spectrum is, by Hugh's logic, more benign). (I added a .four command to the schematic, results of which you can see in the error log)

Attached are old and new FFT's, and the .asc file used.

PS. I know the Jfet is funny and it can be done without (I agree with Hugh about bias decoupling). Also, the Vout node is before the output cap, since this gives better FFT. And for the record, the CFP C-multiplier can be done without, because the capacitors take care of PSU impedance in the audio range much better (CFP output impedance is about .078 ohms). I selected the caps by clicking "select capacitor" in the cap menu and then edited in my own estimated inductance values.

- keantoken
Attached Images
File Type: png OldFFT.PNG (14.7 KB, 309 views)
File Type: png NewFFT.PNG (17.4 KB, 292 views)
Attached Files
File Type: txt Aspen_hdph_withCM_2.txt (10.2 KB, 32 views)
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer!
Need something built, repaired or modded? PM me and ask what I can do!

Last edited by keantoken; 26th September 2009 at 12:51 AM.
  Reply With Quote
Old 26th September 2009, 02:10 AM   #103
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Location: Waterloo, ON or Herefordshire UK
Aspen Headphone Amp
Hugh,

I like the extra diode, from my thermal sims this is a safer option and ensures that the bias current will have a -ve thermal coefficient.

Good addition of the discharge resistor to the output cap - I was just about to suggest this (I remember it from NPs Zen amp) and of course as usual you are a leap ahead...

keantoken,

I'm disturbed by the problems with the cap multiplier. We should discard this if there is a risk. The psu needs to be clean and without regulators we need to ensure that channel-channel x-talk is kept low so that may mean dual supplies with passive filtering.

I need to look at those FFTs....
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 26th September 2009, 02:30 AM   #104
keantoken is offline keantoken  United States
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Well, we need to test the multiplier in real life. I think I'm doing this ESL thing wrong. Is it standard for capacitance multipliers to oscillate!? (by definition they should not, because they have no NFB. Of course, ESL adds a whole new dynamic to this)

I think we only need regulators to keep hum out, otherwise we can't get much better than the caps for load rejection. Why not power both channels from the same supply but with separate LC filters?

We could try boostrapping the LTP source in order to increase PSRR if we go without regulators.

- keantoken
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer!
Need something built, repaired or modded? PM me and ask what I can do!
  Reply With Quote
Old 26th September 2009, 02:33 AM   #105
tessier is offline tessier  Canada
diyAudio Member
 
Join Date: May 2008
Hi keantoken

You've got a PM

Thanx

Paul
  Reply With Quote
Old 26th September 2009, 02:36 AM   #106
keantoken is offline keantoken  United States
diyAudio Member
 
keantoken's Avatar
 
Join Date: Aug 2006
Location: Texas
Hey Tess, sorry for being late. I have actually been putting together a reply. I had to reset my computer too, because the space bar was doing weird things...

- keantoken
__________________
The Kmultiplier rail filter! -=- The Simple Kuartlotron Superbuffer!
Need something built, repaired or modded? PM me and ask what I can do!
  Reply With Quote
Old 26th September 2009, 02:36 AM   #107
MJL21193 is offline MJL21193  Canada
Account disabled at member's request
 
MJL21193's Avatar
 
Join Date: Mar 2007
Quote:
Originally Posted by Bigun View Post
Hugh,


I need to look at those FFTs....

Here's what I get for Hugh's single supply model:
Attached Images
File Type: png 117.PNG (29.5 KB, 288 views)
  Reply With Quote
Old 26th September 2009, 02:37 AM   #108
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Location: Waterloo, ON or Herefordshire UK
Aspen Headphone Amp
I like the change in bootstrap, it keeps a bit H2 in there even at lower frequencies. This is something it would be nice to prototype, but my vote is in favour of your change.

Took me a second to remember you'd moved the OUTPUT to the 'wrong' side of the output cap - frequency response was great at 10Hz compared with my original sim

I've read headphones are pretty good at low frequencies, we should revisit the cap values.

For the cap multiplier, if we want to work that angle further, perhaps we should stick with the non compound version, keep it simple ?

Single supply still preferred. For my last project I used soft recovery diodes instead of the usual one-piece rectifier and CLC filters. No complaints about the results so far!
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote
Old 26th September 2009, 02:39 AM   #109
tessier is offline tessier  Canada
diyAudio Member
 
Join Date: May 2008
Quote:
Originally Posted by keantoken View Post
Hey Tess, sorry for being late. I have actually been putting together a reply. I had to reset my computer too, because the space bar was doing weird things...

- keantoken
Hi

No problem, I was just not sure that you've readed your PM messages.

Thanx

Paul
  Reply With Quote
Old 26th September 2009, 02:39 AM   #110
Bigun is offline Bigun  Canada
diyAudio Member
 
Bigun's Avatar
 
Join Date: Jan 2009
Location: Waterloo, ON or Herefordshire UK
Aspen Headphone Amp
Quote:
Originally Posted by MJL21193 View Post
Here's what I get for Hugh's single supply model:
Looks to me like the THD is too low, we don't want this to sound like an opamp do we !? - let's get that H2 up...
__________________
"The test of the machine is the satisfaction it gives you. There isn't any other test. If the machine produces tranquility it's right. If it disturbs you it's wrong until either the machine or your mind is changed." Robert M Pirsig.
  Reply With Quote

Reply


Aspen Headphone AmpHide 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
Another DAC + Headphone amp ghetto Digital Source 14 10th July 2008 05:02 PM
ESL Headphone X-former bjackson Planars & Exotics 5 19th September 2005 04:45 AM
Headphone amp audioPT Headphone Systems 5 28th September 2004 09:03 PM
Zen v4 headphone amp Rob M Headphone Systems 11 21st May 2003 01:58 AM
Aspen Amplifiers - the ASKA 100 WATT griff Solid State 25 13th April 2002 04:15 PM


New To Site? Need Help?

All times are GMT. The time now is 06:35 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