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

Group Buys Members group buys

Simple High Performance DC Coupled Class A HPA with sub PPM THD
Simple High Performance DC Coupled Class A HPA with sub PPM THD
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 24th March 2019, 06:27 AM   #421
yourownbuzz is offline yourownbuzz  Australia
diyAudio Member
 
Join Date: Mar 2017
A 19V 2A ASUS laptop brick
  Reply With Quote
Old 24th March 2019, 08:00 AM   #422
xrk971 is online now xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Simple High Performance DC Coupled Class A HPA with sub PPM THD
Quote:
Originally Posted by yourownbuzz View Post
I've really been liking the sound of this amp, more than the DCA or the AKSA HPA!
Glad itís working out for you - there is something to be said for a DC-coupled design. It passes everything through clearly. The other amps are AC coupled single rail, single ended Class A designs, which will sound different due to the topology and the fact that they are capacitively coupled. The DCA is dead simple compared to this one though.
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio
  Reply With Quote
Old 4th April 2019, 03:05 AM   #423
avtech23 is offline avtech23  Australia
Certifiably addicted to DIY.
diyAudio Member
 
avtech23's Avatar
 
Join Date: Dec 2017
Location: South 'straya
Simple High Performance DC Coupled Class A HPA with sub PPM THD
Just to follow up, I realised that I had missed the two 1uF film caps (C137 etc). It seems this was causing some instability and part of the sensitivity when I put my hands near the other film caps.

I installed those and disconnected the loop breaker to test and the noise dropped to a tolerable level, but still getting capacitive coupling with the chassis.

With the loop breaker in place, the amp is silent and happy.

I'll still try and hunt down where the grounds are getting mixed (engineer OCD) but regardless, this amp sounds great.

Thanks for all the work in bringing this to us, XRK et al.
__________________
The ever growing project list.. :NAP140 Clone, NAD 3020i & 3225PE, JLH1969, TDA2050, Fender 5F2A Princeton, NE5532 Pre, SHPA, B1 Korg. : VSQC Phunk Style, Retro 50W, Filmosound 601. : Apex AX-14, TGM-10, TDA7265, LM4780 (Last in line)...maybe

Last edited by avtech23; 4th April 2019 at 03:07 AM.
  Reply With Quote
Old 4th April 2019, 02:46 PM   #424
xrk971 is online now xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Simple High Performance DC Coupled Class A HPA with sub PPM THD
Glad to hear that it’s working out. You have some sort of capacitive coupling between your board ground and the case it seems. Keep the GLB between the signal GND and case and maybe use larger 51R resistor even plus 100nF film cap in parallel.
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio
  Reply With Quote
Old 5th April 2019, 03:44 AM   #425
avtech23 is offline avtech23  Australia
Certifiably addicted to DIY.
diyAudio Member
 
avtech23's Avatar
 
Join Date: Dec 2017
Location: South 'straya
Simple High Performance DC Coupled Class A HPA with sub PPM THD
Thanks X. I'll have a play around again when I get a chance. Too many projects to dwell too long! (Got all the bits for a Korg B1 that won't assemble itself!).

In the meantime, I'm pretty happy with the finish on this build.
Attached Images
File Type: jpg SherpaFinished1_DxOFPr.jpg (670.1 KB, 241 views)
File Type: jpg SherpaFinished2_DxOFPr.jpg (916.9 KB, 353 views)
__________________
The ever growing project list.. :NAP140 Clone, NAD 3020i & 3225PE, JLH1969, TDA2050, Fender 5F2A Princeton, NE5532 Pre, SHPA, B1 Korg. : VSQC Phunk Style, Retro 50W, Filmosound 601. : Apex AX-14, TGM-10, TDA7265, LM4780 (Last in line)...maybe
  Reply With Quote
Old 6th April 2019, 12:46 AM   #426
xrk971 is online now xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Simple High Performance DC Coupled Class A HPA with sub PPM THD
That’s beautiful work! Bravo!
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio
  Reply With Quote
Old 13th April 2019, 02:16 AM   #427
stellarelephant is offline stellarelephant  United States
diyAudio Member
 
stellarelephant's Avatar
 
Join Date: Jan 2017
Location: Western NC
Avtech, I really like what you did with the wiring in your amp! I have been experimenting with mumetal shielding and ferrite beads lately, so definitely interested in preventing stray EMF pickup.

Let me see if I have your process figured out...So you twist up the wire pairs, then slip on that braided shielding sleeve along with two bits of heat shrink OVER the sleeve (that looks like it was hard). Solder wires. Then finish by slipping the heat shrink down to the ends, to cover the joints and secure the ends of the shielding sleeve in place. Man, that is cool.

Did I get it right? Where do you get that shielding material?
  Reply With Quote
Old 13th April 2019, 06:04 AM   #428
xrk971 is online now xrk971  United States
Got Foam?
diyAudio Member
 
xrk971's Avatar
 
Join Date: Oct 2012
Location: Metro DC area
Simple High Performance DC Coupled Class A HPA with sub PPM THD
I think that’s just silver colored decorative nylon braid to tidy things up. To make shielding you would tie just one end to GND. Twisting pairs of wires does help reduce stray noise pickup.
__________________
XRKaudio https://www.etsy.com/shop/XRKAudio
  Reply With Quote
Old 16th April 2019, 10:30 AM   #429
avtech23 is offline avtech23  Australia
Certifiably addicted to DIY.
diyAudio Member
 
avtech23's Avatar
 
Join Date: Dec 2017
Location: South 'straya
Simple High Performance DC Coupled Class A HPA with sub PPM THD
Thanks Stellar,

For this particular build I just used the nylon braid, as X correctly identified, to tidy up the cables and make it a bit neater. The cables themselves were multicore sheilded already so I didn't need the extra shielding.

I've used similar products to this a fair bit at work and it seems to do the job: 30508 | Wurth Elektronik Expandable Fibreglass, Nickel Plated Copper Grey Cable Sleeve, 8mm Diameter, 1m Length | RS Components

For this build, I attached the JST connectors to the wires at both ends. Then using a plastic tube, compressed the sleeve to open it up, slip onto the tube then feed the wire through the tube. Heatshrink (unshrunk) on one end, withdraw the tube most of the way, laying the sleeve on the wire, then pop the second heatshrink on the sleeve. Hit it with a hot air gun and ready to go!
__________________
The ever growing project list.. :NAP140 Clone, NAD 3020i & 3225PE, JLH1969, TDA2050, Fender 5F2A Princeton, NE5532 Pre, SHPA, B1 Korg. : VSQC Phunk Style, Retro 50W, Filmosound 601. : Apex AX-14, TGM-10, TDA7265, LM4780 (Last in line)...maybe
  Reply With Quote
Old 16th April 2019, 10:32 AM   #430
avtech23 is offline avtech23  Australia
Certifiably addicted to DIY.
diyAudio Member
 
avtech23's Avatar
 
Join Date: Dec 2017
Location: South 'straya
Simple High Performance DC Coupled Class A HPA with sub PPM THD
Quote:
Originally Posted by xrk971 View Post
Thatís beautiful work! Bravo!
Thanks
__________________
The ever growing project list.. :NAP140 Clone, NAD 3020i & 3225PE, JLH1969, TDA2050, Fender 5F2A Princeton, NE5532 Pre, SHPA, B1 Korg. : VSQC Phunk Style, Retro 50W, Filmosound 601. : Apex AX-14, TGM-10, TDA7265, LM4780 (Last in line)...maybe
  Reply With Quote

Reply


Simple High Performance DC Coupled Class A HPA with sub PPM THDHide 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
Ultra-high performance, yet rather simple - hybrid and more! vzaichenko Solid State 998 13th June 2018 11:12 AM
High Performance Class A Current Feeback Headphone Amplifier monty78pig Headphone Systems 14 12th November 2015 01:01 PM
Simple High-Performance DAC psk Digital Line Level 17 8th September 2014 04:41 AM
simple, high performance amp using DRV134? Fast Eddie D Headphone Systems 6 6th May 2014 05:17 AM
Huginn, High performance, Class A, Lateral FET headphone amplifier Neutrality Headphone Systems 11 7th November 2013 07:29 PM


New To Site? Need Help?

All times are GMT. The time now is 03:40 PM.


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