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

Pass Labs This forum is dedicated to Pass Labs discussion.

"WHAMMY" Pass DIY headphone amp guide
"WHAMMY" Pass DIY headphone amp guide
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 11th July 2018, 10:10 PM   #381
pelayostyle is offline pelayostyle  United States
diyAudio Member
 
Join Date: Jan 2006
Location: los angeles
"WHAMMY" Pass DIY headphone amp guide
Sorry, I meant 0.2 mV.

About the voltage issue. I was a little scared to pop it in at first because of the voltage limit but figured what the heck because I had it lying around and knew I really liked it from other projects. It has survived over 50 hours so far. I've kept on eye on the case temperature and don't see it getting very hot at all.
  Reply With Quote
Old 21st July 2018, 05:38 AM   #382
seanwu is offline seanwu  Taiwan
diyAudio Member
 
Join Date: May 2016
Location: Taipei
I also tried op amp rolling with LM833, MUSES 8920D, AD823 and LME49990.
Listening with 2 headphones: SONY MDR CD900ST and Philips SHP 9500.
Source: iMac with BitPerfect and Schiit Modi 2 Uber DAC.

LM833:
Balanced treble, mid and bass. Bass is punch and assertive. Maybe not sound detail as other op amp but good enough to enjoy the music for me. If you don’t have idea what to use, LM833 definitely worth to try.

MUSES 8920D:
Sounds a little fat and muddy to me. Everything seems bigger and blurry to my ear. I even feel slight echo makes me thought about karaoke. Not my cup of tea.

AD823:
Very detailed sound. Treble is a little bit too sharp to my ear. Bass seems not as punching as LM833. Not a bed choice but I prefer LM833 over AD823.

LME49990:
Sounds balance, detailed and more silent background. Like improved LM833 with more clean and detailed sound quality. My favorite and my final choice op amp for WHAMMY headphone amp.
Attached Images
File Type: jpg AC967495-4DB1-4871-A105-F45578751408.jpg (103.0 KB, 631 views)

Last edited by seanwu; 21st July 2018 at 05:42 AM.
  Reply With Quote
Old 21st July 2018, 03:01 PM   #383
6L6 is online now 6L6  United States
diyAudio Moderator
 
6L6's Avatar
 
Join Date: Oct 2010
Location: Denver, Colorado
"WHAMMY" Pass DIY headphone amp guide
Great observations! Thanks for posting them.

What Mosfet are you using?
  Reply With Quote
Old 21st July 2018, 03:47 PM   #384
jphabc54 is offline jphabc54
diyAudio Member
 
Join Date: Mar 2018
What adapters are you using for the opamps? Itís nice to see they can all fit between the caps.
  Reply With Quote
Old 21st July 2018, 03:58 PM   #385
chiily is offline chiily  United Kingdom
diyAudio Member
 
Join Date: Mar 2003
Location: Malvern
Quote:
Originally Posted by Nisbeth View Post
0.2V offset is quite a lot, are you sure that's not a typo?

AD8620 is a great sounding opamp, but just remember that it's only rated for +/-13V supplies
I have a pair of AD8620s in my Arcam 5 CD player @15v.... they have survived for the last 5 years, and sound fabulous.
__________________
Garf.
  Reply With Quote
Old 22nd July 2018, 07:12 AM   #386
seanwu is offline seanwu  Taiwan
diyAudio Member
 
Join Date: May 2016
Location: Taipei
Quote:
Originally Posted by 6L6 View Post
Great observations! Thanks for posting them.

What Mosfet are you using?
I use FQP3N30 / FQP3P20.
  Reply With Quote
Old 22nd July 2018, 07:27 AM   #387
seanwu is offline seanwu  Taiwan
diyAudio Member
 
Join Date: May 2016
Location: Taipei
Quote:
Originally Posted by jphabc54 View Post
What adapters are you using for the opamps? Itís nice to see they can all fit between the caps.
I bought these adapters online in Taiwan.
The SOIC to DIP8 is less then USD$ 1. The foot print is just slightly bigger than a DIP8 IC.
  Reply With Quote
Old 24th July 2018, 03:38 AM   #388
jhofland is offline jhofland  United States
diyAudio Member
 
Join Date: Apr 2009
Default WHAMMY jr

I've been following the thread for this design with quite a bit of interest. I'm also in the process of building a stepped attenuator for volume control and this seemed to be a fine vehicle to use to test it out. I was also interested in making it a bit smaller. I made the following changes to the design.
Changed the supply voltage for the output MOSFETs to use the unregulated rails. This allows the regulators to be quite a bit smaller and you don't need to heatsink them. The +/- regulated voltage is used on the resistor network driving the gates and for the op amp rails.
I chose to use surface mount parts where it's reasonable to do so to save space.
All of the input and output connectors are board mounted so there isn't any wiring to do.
The power transformer is a Hammond low profile 229 series unit.
There is an added DC/DC converter circuit to provide 3.3V for the attenuator.

The resulting schematic is attached.

When I first turned the board on I had ground loop noise issues. So I hand modified the board a bit to pick a virtual star ground point at the power supply output and reroute the output ground, the power input module common, and the low level stuff to that point. It quieted things down quite a bit.
Pictures of the board with the surface mount components in place before and after the ground changes are attached.
The next picture is of the board with most of the through hole parts loaded.
The last two pictures are of the board fully populated and in the chassis.
The board dimensions are 120mm by 160mm and it fits into the same sized Hammond 1455 series box. That's about half the size of the original WHAMMY.

I did run into an oscillation issue. The first version of the design had some 220pF caps in parallel with the 4.64K feedback resistors. Seemed to be the right thing to do to limit the bandwidth. Both channels oscillated at about 16 MHz, 500mV amplitude. I ran a circuit simulation and discovered some gain peaking well above 1 MHz. The solution turned out to be removal of the 220pF caps. Thanks to Wayne and Jim for suggestions on where to look.

I'm still working on the control firmware for the stepped attenuator so I haven't put a signal through it. It is quiet with no signal input. DC offset is a bit more than 1mV left channel and less than 2mV right channel.
Attached Images
File Type: jpg surface mount populated.jpg (662.3 KB, 505 views)
File Type: jpg surface mount populated post ground update.jpg (822.0 KB, 494 views)
File Type: jpg populated no output transistors.jpg (701.7 KB, 484 views)
File Type: jpg fully populated post ground modification.jpg (690.5 KB, 480 views)
File Type: jpg populated in chassis.jpg (670.1 KB, 202 views)
Attached Files
File Type: pdf whammyJr SchematicRev1_1.pdf (93.9 KB, 55 views)
  Reply With Quote
Old 24th July 2018, 03:39 PM   #389
JamieMcC is offline JamieMcC  United Kingdom
diyAudio Member
 
Join Date: Jul 2014
Location: England (Isle of Wight)
I was taking a look at the Burson V6 discreet op amps interestingly there were a few pics of Whammy builds on their page with them installed combined with some nice output caps.


Would love to get a bit of feed back on how the Burson Vivid and Classic compare in the Whammy if any of you guys who have had the opportunity to compare?

4 DIY Whammy headphone amplifiers (diyaudio.com forum) with Burson V6 Opamp Ė Burson Audio
  Reply With Quote
Old 24th July 2018, 10:15 PM   #390
nano35 is offline nano35  Hong Kong
diyAudio Member
 
Join Date: Oct 2017
Location: HKG
It is our group. To register for warranty, one needed to do a review and to upload some photos.

I compared both classic and vivid V6; I personally favoured the classic one, the vocal came out a bit more and classical is more beautifully rendered. The vivid fits more the modern pops and rocks. My friend also felt about the same.
Yes it is worth the high price, equally good or better than Muses03.

For the boutique capacitors, in general speaking, the more you pay for them, the better they sound. one used a pair of white Evo oil (HKD$300/each) and they sounded a bit better than my vintage Sprague oil capacitors with more clarity. Not much surprise.

Then came the HKD$699/each black color gold/silver oil caps. He love them. I listened to them and wow, all frequencies were there with super clarity, super 3D, breath-taking and very engaging; but heavy bass is something I am not too fond of.

The HKD$1,100/each Jensen paper tube copper foil oil caps was his favourite. I haven't had a chance to borrow them yet. My friend said those were the ones he loved the most: bass is just right, everything is simply natural, neutral, and vocal is very very very......realistic and natural; you can listen to the music all day long without worrying about hearing fatigue. He wondered if the paper tube has anything to do with the SQ-no metal, no interference?

I am fine with my little budget vintage sprague oil capacitors. They are warm and bass is good; I guess it is what others say about "old day SQ" vs "modern day SQ" using oil caps-super crisp and clean sound for the modern oil caps.
  Reply With Quote

Reply


"WHAMMY" Pass DIY headphone amp guideHide 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
FS: Nelson Pass "CSX1/2" "Buffered F6" Front End PCBs luvdunhill Swap Meet 7 10th December 2016 03:03 PM
Small midrange boost with conical "guide" suggestions? Phenoholic Anonymus Multi-Way 11 1st December 2014 01:00 PM
Which Pass Aleph diy board for "no-cost-object" headphone amplifier? Hammerklavier Headphone Systems 43 7th August 2010 04:35 PM
The "Dummies' Guide to getting parts/assembling CarlosFM's chipamp" Spasticteapot Chip Amps 19 18th March 2006 06:17 AM


New To Site? Need Help?

All times are GMT. The time now is 12:00 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 14.29%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki