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

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
I returned to DIY electronics in 2009 after a 20 year pause by building a few kits to get in shape. This blog is for me to keep track of my progress.
Old

Eternally Penultimate Zen - mod #4

Posted 11th May 2013 at 08:32 PM by alexcp (My DIY projects)
Updated 27th April 2015 at 12:29 PM by alexcp (Added pictures, links)

My first solid state amplifier build, in 2009, was The Penultimate Zen, aka Zen Variations Part 4, aka ZV4. It was built with the parts I could find back then, without knowing where to look. It ended up big, heavy with two 400VA toroidal transformers, ugly inside with some electrical tape here and there, without proper grounding, etc., etc. I was as disappointed with the sound as my wife was disappointed with that heavy black metal brick gathering dust.

My first mod on ZV4 came after I turned my disappointment into finding better part suppliers. I returned to my ZV4 and replaced the output caps with something marginally more decent from eBay. The sound improved a notch. Aha!

My second mod was to rebuild the power supply. I threw away one of the toroids, added a softstart circuit from Hypex, and put in a CRC filter with some Mundorf HC caps. One power supply for two single ended channels forced me to learn about grounding and add input transformers and balanced...
Attached Thumbnails
Click image for larger version

Name:	diyaudio46.jpg
Views:	1390
Size:	216.0 KB
ID:	990   Click image for larger version

Name:	diyaudio47.jpg
Views:	932
Size:	224.3 KB
ID:	991   Click image for larger version

Name:	diyaudio48.jpg
Views:	947
Size:	171.6 KB
ID:	992   Click image for larger version

Name:	diyaudio49.jpg
Views:	3387
Size:	239.5 KB
ID:	993   Click image for larger version

Name:	diyaudio50.jpg
Views:	1123
Size:	211.0 KB
ID:	994  

Click image for larger version

Name:	diyaudio51.jpg
Views:	2771
Size:	198.6 KB
ID:	995   Click image for larger version

Name:	diyaudio52.jpg
Views:	1434
Size:	203.8 KB
ID:	996   Click image for larger version

Name:	diyaudio53.jpg
Views:	1142
Size:	152.3 KB
ID:	997   Click image for larger version

Name:	ZV4-JFET 1kHz.png
Views:	741
Size:	116.6 KB
ID:	1620   Click image for larger version

Name:	ZV4-JFET two-tone.png
Views:	540
Size:	115.4 KB
ID:	1621  

alexcp's Avatar
diyAudio Member
Views 2031 Comments 0 alexcp is offline
Old

Ultra Low Distortion Class B Amplifier

Posted 9th April 2013 at 06:40 PM by alexcp (My DIY projects)
Updated 12th May 2013 at 03:49 PM by alexcp (Added better photos)

I built this one a while ago but could not find time to post.

This is a Class B power amplifier that follows the Ultra-LD Mk.3 amplifier design published by the Australian Silicon Chip magazine in 2011, which in turn draws heavily from the concept of a Blameless amplifier devised by Douglas Self. I used a different power supply and speaker protection, and changed the grounding scheme vs what was published.

The distortion at 1 kHz is below my measurement capabilities, and the amplifier does sound very nice, although it seems to give more sibilance than my Class A amplifiers.

The acid test I use is the dual CD "The Very Best of Placido Domingo" album published by EMI Classics. Many amplifiers I have heard cannot deal well with Domingo's tenor, esp. on louder and higher tones. Class A amps, particularly those using simple internal structure like the Zen series, perform well in this test. This amplifier seems to do better than any other...
Attached Thumbnails
Click image for larger version

Name:	diyaudio78.jpg
Views:	1238
Size:	225.7 KB
ID:	1000   Click image for larger version

Name:	diyaudio79.jpg
Views:	2276
Size:	217.7 KB
ID:	1001   Click image for larger version

Name:	diyaudio80.jpg
Views:	768
Size:	167.6 KB
ID:	1002   Click image for larger version

Name:	diyaudio81.jpg
Views:	3538
Size:	252.6 KB
ID:	1003   Click image for larger version

Name:	diyaudio82.jpg
Views:	5067
Size:	230.2 KB
ID:	1004  

Click image for larger version

Name:	diyaudio83.jpg
Views:	772
Size:	215.2 KB
ID:	1005   Click image for larger version

Name:	diyaudio84.jpg
Views:	1910
Size:	163.3 KB
ID:	1006   Click image for larger version

Name:	diyaudio85.jpg
Views:	2072
Size:	120.2 KB
ID:	1007   Click image for larger version

Name:	diyaudio86.jpg
Views:	594
Size:	164.3 KB
ID:	1008   Click image for larger version

Name:	diyaudio87.jpg
Views:	709
Size:	209.6 KB
ID:	1009  

alexcp's Avatar
diyAudio Member
Views 3870 Comments 1 alexcp is offline
Old

Burning Amp BA-3b (Balanced)

Posted 9th April 2013 at 06:10 PM by alexcp (My DIY projects)
Updated 11th April 2016 at 08:24 PM by alexcp (Added better photos)

Big, hot, and heavy! Just completed it and adjusted for distortion, have not had yet a real chance to listen to it. (Update: I have listened to this amp for some time, and it seems to be a keeper, at least for now.) The discussion is here.

The build is in a 4U/400 case from modushop; each side has two 200mm heatsinks, each holding six MOSFETs (three complementary pairs) and a biasing circuit.

The construction is dual mono (separate transformers for each channel) with CRC filtered +/- 18V rails, quiescent current is 3A per channel. Eight Mundorf MLytic® HC High Current Power Caps and two 300VA toroids occupy the most of the chassis, while the actual electronics is mounted on the sides.

Now I need a balanced preamp. I contemplate building some variant of BoSoZ, but am also thinking about a SuperSymmetric balanced preamp using JFETs or tubes...

UPDATE: No- and low-feedback amplifiers have no (or little) control over output errors...
Attached Thumbnails
Click image for larger version

Name:	diyaudio32.jpg
Views:	795
Size:	217.7 KB
ID:	1010   Click image for larger version

Name:	diyaudio33.jpg
Views:	1014
Size:	158.8 KB
ID:	1011   Click image for larger version

Name:	diyaudio34.jpg
Views:	1341
Size:	226.8 KB
ID:	1012   Click image for larger version

Name:	diyaudio35.jpg
Views:	4059
Size:	231.0 KB
ID:	1013   Click image for larger version

Name:	diyaudio36.jpg
Views:	1102
Size:	242.5 KB
ID:	1014  

Click image for larger version

Name:	diyaudio37.jpg
Views:	2372
Size:	242.1 KB
ID:	1015   Click image for larger version

Name:	diyaudio39.jpg
Views:	730
Size:	156.3 KB
ID:	1016   Click image for larger version

Name:	diyaudio41.jpg
Views:	898
Size:	192.2 KB
ID:	1017   Click image for larger version

Name:	diyaudio43.jpg
Views:	1006
Size:	167.0 KB
ID:	1018   Click image for larger version

Name:	diyaudio45.jpg
Views:	4518
Size:	253.2 KB
ID:	1019  

alexcp's Avatar
diyAudio Member
Views 3087 Comments 0 alexcp is offline
Old

My aha! moment - loadline optimization

Posted 9th April 2013 at 11:07 AM by alexcp (My DIY projects)
Updated 9th April 2013 at 11:32 AM by alexcp

I build myself a Millett's Hybrid Headphone amp, originally published in AudioXpress issue 11, 2001.

The amp uses low-voltage 12AE6A tubes for voltage amplification and BUF634 solid state buffers to drive the load. Each tube houses two diodes (unused) and a triode, here loaded with a CCS. The whole thing runs off a 24VDC power brick and consumes maybe 150mA after the tubes heat up.

The DC operating point of the triode can be adjusted with a multiturn trimpot. The original AudioXpress article talks about the influence of the operating point on the sound and suggests to trim for symmetrical clipping, then adjust for the subjectively best sound.

The aha! moment came when I connected the amp to my sound card and looked at the distortion spectrum. On small signals (~300mV output into 300 ohm) the distortion is 2nd harmonic only. The operation point can be trimmed to the point where the the 2nd harmonic goes into the noise floor! I've read about this but...
alexcp's Avatar
diyAudio Member
Posted in Uncategorized
Views 614 Comments 0 alexcp is offline
Old

Adding TentLabs XO2.2 low jitter clock to exposure 2010S CD player

Posted 9th April 2013 at 10:03 AM by alexcp (My DIY projects)
Updated 12th May 2013 at 03:58 PM by alexcp (Added photos, links)

I added a TentLabs XO2.2 low jitter clock and a separate power supply for it to my exposure 2010S CD player. The process was very straightforward - see the pictures.

The exposure 2010S CD player has an easy internal layout, where most of the components sit on a large PCB.

The original clock is based on the 74HC04N chip located in the middle of the PCB, to the left from the three white power connectors connecting the toroidal transformer. A close-up picture shows the crystal resonator wrapped in a black heat-shrink tube, two 33pF capacitors on each side of the resonator (those with black dots on top), and a resistor R75, which also serves in the circuit. The oscillator is built on the single invertor (pins 13 and 12 of the IC).

The original clock is generating 16.9344 MHz at 5V CMOS levels.

To install XO2.2, I removed the resonator and the capacitors, leaving the resistor in place. I connected the signal cable from XO2.2 to the...
Attached Thumbnails
Click image for larger version

Name:	IMG_0111.jpg
Views:	6891
Size:	191.2 KB
ID:	937   Click image for larger version

Name:	IMG_0112.jpg
Views:	1568
Size:	152.7 KB
ID:	938   Click image for larger version

Name:	IMG_0113.jpg
Views:	2413
Size:	151.6 KB
ID:	939   Click image for larger version

Name:	IMG_0114.jpg
Views:	999
Size:	173.4 KB
ID:	940   Click image for larger version

Name:	IMG_0115.jpg
Views:	3098
Size:	220.2 KB
ID:	941  

Click image for larger version

Name:	IMG_0116.jpg
Views:	802
Size:	186.6 KB
ID:	942   Click image for larger version

Name:	diyaudio13.jpg
Views:	1163
Size:	167.1 KB
ID:	1020   Click image for larger version

Name:	diyaudio16.jpg
Views:	950
Size:	219.9 KB
ID:	1021   Click image for larger version

Name:	diyaudio28.jpg
Views:	908
Size:	230.9 KB
ID:	1022   Click image for larger version

Name:	diyaudio30.jpg
Views:	790
Size:	154.8 KB
ID:	1023  

alexcp's Avatar
diyAudio Member
Posted in Digital Sources
Views 3597 Comments 0 alexcp is offline
Old

F5

Posted 28th January 2012 at 05:39 PM by alexcp (My DIY projects)
Updated 11th April 2016 at 08:27 PM by alexcp (Added photos)

Just finished fine tuning my First Watt F5 clone.

I built it about a year ago out of parts that I had on hand back then, including a power supply reused from another project. The resulting sound was rather disappointing. Now I spent time matching transistors and tuning the feedback network. The amplifier now is very close to the performance described in the original service manual.

I am listening to F5 (the music is Tchaikovsky performed by Wiener Philharmoniker and von Karajan) and realizing that it is so good that if this was my first amplifier, I might not be interested in building anything else.

Update: after a year, this is still the best amplifier.

Update: I purchased the official F5 PCBs from the diyAudio store. I will rebuild the amplifier, hopefully with better FETs and other parts.
Attached Thumbnails
Click image for larger version

Name:	diyaudio58.jpg
Views:	645
Size:	210.6 KB
ID:	1024   Click image for larger version

Name:	diyaudio59.jpg
Views:	441
Size:	234.1 KB
ID:	1025   Click image for larger version

Name:	diyaudio60.jpg
Views:	314
Size:	181.3 KB
ID:	1026   Click image for larger version

Name:	diyaudio61.jpg
Views:	524
Size:	232.9 KB
ID:	1027   Click image for larger version

Name:	diyaudio62.jpg
Views:	498
Size:	235.3 KB
ID:	1028  

Click image for larger version

Name:	diyaudio63.jpg
Views:	617
Size:	164.4 KB
ID:	1029   Click image for larger version

Name:	diyaudio64.jpg
Views:	519
Size:	191.1 KB
ID:	1030   Click image for larger version

Name:	diyaudio65.jpg
Views:	519
Size:	180.0 KB
ID:	1031   Click image for larger version

Name:	diyaudio66.jpg
Views:	579
Size:	212.1 KB
ID:	1032   Click image for larger version

Name:	diyaudio67.jpg
Views:	361
Size:	241.6 KB
ID:	1033  

alexcp's Avatar
diyAudio Member
Views 1771 Comments 0 alexcp is offline
Old

How much power is enough for an amp?

Posted 2nd January 2012 at 02:09 AM by alexcp (My DIY projects)

Bruno Putzeys posted:
About power ratings, well... Normal "critical listening" levels hover around a long-term average of 85db SPL at the listening position. If we're assuming uncorrelated signals (rather inaccurate assumption but it'll do for the purpose) that is 82dB SPL for each speaker alone. Crudely calculating back from a 2m listening distance to the 1m standard measuring distance that's 88dBSPL, one speaker, one meter. It's not unusual for speakers to have an efficiency of 88dB/1w/1m so 1W is roughly the required amplifier power.

The current crop of unlistenable hypersquashed pop music has a peak to average range of around 4dB. So all it takes to reproduce pop at a reasonable level without clipping is a 4dBW (2.5W) rated amp.
Before the loudness war got into swing (say until the early 90's) peak-to-average ranges up to 14dB could be found in mainstream music. To play Sultans of Swing at the same average level requires an amp rated at 14dBW
...
alexcp's Avatar
diyAudio Member
Posted in Speakers
Views 1519 Comments 0 alexcp is offline
Old

Zen V4-J

Posted 17th December 2011 at 01:12 PM by alexcp (My DIY projects)
Updated 12th May 2013 at 04:03 PM by alexcp

Now that Nelson Pass published the details of the JFET upgrade to First Watt F2 and that Newark sells power JFETs from Semisouth, there was no excuse not to upgrade my Zen V4 with the new active device.

I replaced Q1 (see the original schematic) with SJEP120R100A; increased R5 to 130 kohm to bias the JFET correctly with Vgs of approx. 1.5V; and reduced R8 to 22 ohm.

The measured result is a nice reduction in THD+N; attached are the graphs for THD+N @ 1W into 8 ohm vs frequency, before and after the upgrade. With IRFP044 as Q1, the distortion was mostly 2nd harmonic (at -65dB), plus some traces of the 3rd harmonic. With the JFET, it is still mostly 2nd harmonic, which is now at -80..85dB, with the 3rd below my measurement floor.

Subjectively, the improvement is remarkable! There is additional detail and depth of the scene.
Attached Thumbnails
Click image for larger version

Name:	ZV4-IRFP044.png
Views:	598
Size:	46.5 KB
ID:	544   Click image for larger version

Name:	ZV4-JFET.png
Views:	609
Size:	45.7 KB
ID:	545   Click image for larger version

Name:	diyaudio51.jpg
Views:	945
Size:	198.6 KB
ID:	1034  
alexcp's Avatar
diyAudio Member
Views 2998 Comments 1 alexcp is offline
Old

Zen V4, updated

Posted 13th December 2011 at 07:20 AM by alexcp (My DIY projects)
Updated 17th December 2011 at 01:41 PM by alexcp

In 2009, Penultimate Zen aka Zen V4 was my first solid state build. I used the parts that were available, did not know much about making it work well, and did not have test instruments beyond a cheap multimeter. Also, I did not have a preamplifier to work with it or speakers sensitive enough to enjoy its 25W. As a result, the amplifier turned out not quite satisfactory and for two years has been gathering dust and my wife's complaints. I was thinking about scrapping it and reusing the enclosure for something more useful. Instead, I reworked it.

I removed one of the two power transformers (moving from dual mono to stereo configuration), replaced my original dodgy Chinese PSU filter caps with Mundorf M-Lytic HC, replaced internal low voltage wiring with thick speaker wire, reconfigured grounding (so it is finally safe!) and installed balanced inputs with input transformers. What a change in sound! With my Exposure CD player, B1 clone preamp and Heresy III speakers, the amp...
alexcp's Avatar
diyAudio Member
Views 1070 Comments 0 alexcp is offline
Old

My systems

Posted 4th December 2011 at 11:41 AM by alexcp (My DIY projects)
Updated 12th May 2013 at 07:41 PM by alexcp

Someone pointed out that it's interesting to see all the components in a system, rather than discuss them individually. I liked the idea - I think it also shows what projects ended up actually useful - so here are my systems (I have four with diy components).

The music I listen to is an eclectic mix of classical music (such as Rachmaninov and Tchaikovsky), opera (mostly arias), jazz (Armstrong) and some pop music.

The first system is the one I listen to the most:
  • exposure 2010S CD player with Tentlabs low-jitter clock
  • B1 clone preamp
  • F5 clone
  • Vintage Celestion DITTON 15XR speakers

The second system is the testbed for whatever project I may be working on:
  • Audio Analogue Crescendo CD player
  • B1 clone preamp
  • Zen V4 with SiC power JFET in the gain stage
  • Klipsch Heresy III speakers

The third is the best sounding so far, has the highest WAF and is likely to stay around for some time:...
alexcp's Avatar
diyAudio Member
Posted in Uncategorized
Views 1217 Comments 3 alexcp is offline
Hide this!Advertise here!

New To Site? Need Help?

All times are GMT. The time now is 02:48 PM.


vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2017 DragonByte Technologies Ltd.
Copyright ©1999-2017 diyAudio

Content Relevant URLs by vBSEO 3.3.2
Wiki