PSU of class A amps - diyAudio
Go Back   Home > Forums > Amplifiers > Solid State

Solid State Talk all about solid state amplification.

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 7th August 2004, 10:24 PM   #1
GKU is offline GKU  Switzerland
diyAudio Member
 
Join Date: Jul 2004
Location: South West Germany
Default PSU of class A amps

Hi everybody,

I'm new in this forum but this is already my second post in one day. It seems today I'm very productive!

Some threads have attracted my interest:
There are 943 replies on JLH 10W class A amp and 51 on Hiraga 30W vs Le Monstre. Seems to be very interesting for many forum members.

At the JLH most people use a regulated PSU. But at the Hiraga nobody use a regulated PSU but very big passive PSU.

Questions:
1. Why?

2. Did anybody of the JLH builders have compared a big passive PSU with the mentioned regulated ones?

3. Did anybody of the Hiraga builders have compared regulated PSU like those from JLH, with the big passive PSU?

4. Have some of the Hiraga builders used and compared the regulated PSU proposed from Pierre Johannet for the 100W Kaneda power amp at the Hiraga 20/30W with the big passive PSU?

I'm not an electronic engineer, perhaps I'm missing something else, but for me it seems not logic that the JLH use reg. PSU and Hiraga passive.

Any explanation from the electronic guru's?

Rgds

GKU
  Reply With Quote
Old 8th August 2004, 09:40 AM   #2
JohanH is online now JohanH  Netherlands
diyAudio Member
 
Join Date: Dec 2003
Location: Noord Brabant
Default Just a quick reply

Q. #2

http://www.xs4all.nl/~cfw/amp/p02_comp.htm

Cheers,
Johan
  Reply With Quote
Old 8th August 2004, 10:36 AM   #3
diyAudio Member
 
Join Date: Feb 2004
Location: Queensland Australia
The original JLH (1969) PSU was regulated and the following year (Dec 1970 ) he published a postscript where he showed an unregulated supply (a 5,000uF cap). There was no subjective comment but he said that distortion worsened below 100Hz. In his subsequent writings and Class B designs he regularly made the comment that regulated supplies "gave a tighter bass". I recall that he said that regulation allowed a lower output impedence from the supply in a physically smaller package. There was also the point made that channel separation was improved. I am inclined to take him seriously about PSU units. The many designs of JLH were characterised by elegance and economy. He disliked elaborate circuits and was conscious of the cost of extra components, the inconvenience of constrution and the greater likelyhood of failure with additional components. In one Class B design he used a PSU that was able to close down under fault conditions. To my knowledge this is one of the very few cicuits that give protection to speakers without fuses or relays in the signal path. Now, given his desire for simplicity he must have felt fairly strongly about the audible benefits of regulation to so consitently advoctate their use. You will find a wealth of info' at Geoff Moss's site www.tcaas.btinternet.co.uk/index.htm#index Recently he's put up an English translation of the original Hiraga article for his 20 watt class A design. I haven't read it yet but there may be an explanation of Hiraga's philosophy of PSUs and why his are unregulated.
__________________
"It was the Springtime of the year when aunt is calling to aunt like mastodons bellowing across primeval swamps." P.G. Wodehouse.
  Reply With Quote
Old 8th August 2004, 02:39 PM   #4
GKU is offline GKU  Switzerland
diyAudio Member
 
Join Date: Jul 2004
Location: South West Germany
Default PSU of class A amp

Hi Johan, Jonathan,

Johan:
Thanks a lot for the comparison of reg. and passive PSU of JLH amps.
Questions:
1. What type of pre-amp Rudi has used during this comparison? Solid State or Tube?
2. What type of speaker you used?

Jonathan:
I have all issues of the journal L'Audiophile and all articles written by Jean Hiraga.

Jean Hiraga with his Japanese roots has very long and good relation ships to Japanese Audio DIY freaks. In addition he is a fan of Prof. Kaneda, who principally use regulated PSU's for his designs. Unfortunately these designs are very difficult to build by amateurs and the used transistors with very thight data are very difficult to find on the free market, especially outside of Japan.
In addition other Japanese freaks are using hugh passive PSU's with C up to 1F even for pre-amps achieving - according to him and some Japanese audio journals ( Radio Experimenters Magazine) - extremely good results especially in the deep bass region as well as at the heights. In addition these PSU's are much easier to build than the most regulated ones, but with the limitations of their high cost.

Hiraga and the team of the journal L'Audiophile has re-designed in 1988 a Kaneda 50W class A amp using easy to procure Japanes transistors including the ones already used in his 20/30W class A design. The predriver part use a regulated PSU designed by Guy Marec and the power part use passive PSU with C= 0.6F. I have build this amp, which has been becoming very populare in France and which I use in my active powered speaker-system for the bass < 200 Hz. A very musical amp.
In 1992, a 100W version has been published by Pierre Johannet using a regulated PSU with MOS-FET's (2SJ50/2SK135).
I have used this PSU with my 50W Kaneda replacing the passive PSU and achieved more punch in the deep bass region as well as more transparency and drive in the upper bass.
Now I'm thinking to modify this PSU for the application with my Hiraga 30W amp, the reason for this post.
Perhaps some other forum members have already get experienced with such PSU and are willing to share their experience. I will try to scan the hand-designed circuitry and will post it with my next post.

Gerd
  Reply With Quote
Old 8th August 2004, 08:18 PM   #5
JohanH is online now JohanH  Netherlands
diyAudio Member
 
Join Date: Dec 2003
Location: Noord Brabant
Hello Gerd,

Unfortunately, I was not present at the comparison. IIRC I found this link in the "building JLH amp" thread. I do know that Rudy contributed to the JLH thread and to Geoffs website. A bit of searching might reveal his thoughts on the how and why of unregulated PSU for the JLH.

(BTW I'm planning to build a JLH too and will use unregulated PSU, just because I liked it on my Hiraga 30W)

Looking forward to your design,

Johan
  Reply With Quote
Old 8th August 2004, 10:04 PM   #6
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
People don't get quite as passionate about regulated vs. unregulated power supplies as they do about tubes vs. solid state, but sometimes it's a near thing.
The ideal power supply would supply a constant voltage no matter what current demands were made on it. In the real world, after a certain point, the voltage begins to 'sag' or 'droop' depending on who you're talking to. Ripple will increase as well. How much of a problem this is depends on the circuit design. A circuit with good common mode rejection will not react as badly to ripple, but not all circuit topologies are able to reject ripple.
Note that this is part of the reason that people disagree about power supply design. Their circuits react differently to the power supply. If they use the same amplifier circuitry, they might agree more readily. Sometimes. Maybe. Of course, the sun might rise in the west tomorrow, too.
A power supply that supplies any required current on demand without a change in voltage is also a good definition of a voltage regulator (not to be confused with a current regulator). Aside from the heat, cost, and complexity of adding a regulator, it's really pretty much an ideal situation. As though that wasn't enough to stop most people in their tracks...
A large enough passive power supply will begin to approximate a regulated power supply, simply because the capacitor bank will give up the current on demand without too much of a drop in voltage.
Other points of disagreement include:
--What type of caps to use. Many people these days use film caps as bypasses, or in extreme cases as the entire cap bank. Others claim that oil & paper sound better, or perhaps electrolytics.
--Feedback vs. non-feedback regulators. Some claim that non-feedback regulators sound better. Others point out that they don't regulate as well.
--The ever-popular argument between those who want to use series regulators and those who prefer shunt regulators. I've seen at least one person argue for shunt regulators for circuits whose current draw is constant or nearly so; series regulators for all other circuits. His reasoning seemed sound.
--Tube regulators or solid state?
--How much capacitance to put after the regulator. Some people put massive banks of caps, other put virtually nothing (or in the case of some low level circuitry, none at all).
--A related issue is the stability of the regulator. Some oscillate if there isn't capacitance after the regulator, some oscillate if there is.
Any one of these points can be spun out into a thread lasting for weeks if people get riled up enough. Me? I like regulators, film caps, and lots of capacitance. That's enough to start arguments right there.

Grey
  Reply With Quote
Old 9th August 2004, 03:04 AM   #7
paulb is offline paulb  Canada
diyAudio Member
 
Join Date: Jun 2001
Location: Calgary
Well...
The possibilities could be categorized as:
0. passive filtered supply
1. capacitance multiplier or smoothed supply (not regulated in a strict sense, but closer to Grey's definition than a passive)
2. no feedback regulator - adds regulation of input voltage changes (could be as simple as adding a zener to #1)
3. feedback regulator - regulates input & output voltage changes

You can rank the 'idealness' of the supply types in this order, but their efficiency goes down as their idealness goes up. Many JLH builders have reported good results with #1, and I personally think that's all you need.

Paul
  Reply With Quote
Old 10th August 2004, 05:17 AM   #8
diyAudio Member
 
Join Date: Feb 2001
Location: Columbia, SC
Oops...Paul's right...I forgot capacitance multipliers.

Grey
  Reply With Quote
Old 22nd August 2004, 06:43 PM   #9
GKU is offline GKU  Switzerland
diyAudio Member
 
Join Date: Jul 2004
Location: South West Germany
Thank you guys for your interesting contribution.

Please aplogize the late reply, but I'm traveling a lot, which hinder to be frequently online for the hobbies.

I have attached an actualized scheme of Pierre Johannet's proposal puplished in the issue 19/1992 of the French journal L'Audiophile for a hybrid PSU, which I successfully use at my 50W Kaneda power amp.
This one I intend to try with my Hiraga 30W, in comparison with my actually used passive PSU version with a total C of 1.4 F.
May I have your comments and input please.

I will keep you updated with the results (subjective comparison) on my front loaded ORIS 150 hornspeaker of BD-Design/NL.

Regards

Gerd
Attached Files
File Type: zip reg. pow.supply hiraga 30w.zip (8.0 KB, 416 views)
  Reply With Quote
Old 22nd August 2004, 07:00 PM   #10
Bricolo is offline Bricolo  France
diyAudio Member
 
Bricolo's Avatar
 
Join Date: Nov 2002
Location: Grenoble, FR
Hi Gerd,

Could you please also post an image file (a screen capture), we don't all use the same schematic editor here
__________________
Just remember: in theory there's no difference between theory and practice. But in practice it usually is quite a bit difference... Bob Pease
  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
For Sale: Tube Amps, Class-A Amps, BG Ribbons, Chassis and Other Goodies! opc Swap Meet 23 2nd November 2009 06:04 PM
How about a round-up of Class A kit power amps, or collectable vintage class A? Brisso57 Solid State 4 14th February 2007 11:30 AM
Amps Class G,H,T,Z Gold_xyz Solid State 1 14th December 2005 01:39 AM
Has anyone compared the Chip amps against Class T amps? soongsc Chip Amps 3 24th July 2005 12:50 PM


New To Site? Need Help?

All times are GMT. The time now is 08:45 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