"Power Tracking" in supply, ever heard, DIY ideas? - Page 2 - 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 31st May 2003, 05:41 PM   #11
diyAudio Member
 
jeffreyj's Avatar
 
Join Date: May 2003
Location: Tampa, FL
Default Re: Re: Re: "Power Tracking" in supply, ever heard, DIY ide

Quote:
Originally posted by Circlotron
The bitstream that is coming out of your CD player and into the dac, have it first go into a cheap-and-nasty dac, the output of which controls the supply rail voltage with a fast attack slow decay setup. The bitstream then gets clocked through a delay line (say a static ram or whatever) and gets delayed for 1 second then finally gets to the proper dac that makes the music.
....
That means the power supply doesn't have to respond so terribly quickly. Heck, you could use triacs to switch taps on the power tranny secondary if you really wanted to go low tech. Lower noise than a switchmode supply. Easy for diy too.
This is almost a very good idea... A seductively good one, I'd say, but it does not eliminate the problems incurred trying to yank the output voltage of a SMPS all over the place! To wit: you will need just as fast response time whether you delay the bitstream or not because you still have to be synchronized to said stream! So, whether the SMPS must vary its output now or 1 second from now is irrelevant, its the fact that it must vary it up to 20,000 times per second which is important!

There are many problems in doing this, and most of them are tradeoffs; e.g. - increasing the loop bandwidth demands that the switching frequency be proportionally increased.

The one thing you wouldn't have to worry about, though, is noise. A SMPS operating at the necessary 400kHz or higher fs will not affect audio circuits (unless there are those among you who claim they can hear up to 400kHz!) This is not to say that stray magnetic fields transformers or chokes could not cause problems! I am only speaking of the inevitably higher ripple SMPS exhibit compared to their linear counterparts.
__________________
Before you make that audacious claim, check this site out:QAudio Myths
  Reply With Quote
Old 31st May 2003, 09:20 PM   #12
diyAudio Member
 
Join Date: Feb 2001
Location: Mars
Instead of speculating on good/bad,
go audition the Bob Carver Sunfire
amplifiers..

Do you like the sonics?
  Reply With Quote
Old 1st June 2003, 08:52 AM   #13
djk is online now djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
A Schottky diode solves the noise problem, 200V types are common now.

Carver's Amazing Subwoofer uses a bridge amplifier with a tracking regulator for 2.7KW output with no line tansformer.

Here is a bridge amplifier combined with a tracking circuit to form a Class H amplifier, note that all you need is an ordinary 30-0-30 transformer to get the voltages required.

http://164.195.100.11/netacgi/nph-Pa...&RS=PN/6304138

Go to figure 5 in 'Images', D1 is a power Schottky type.

Any amplifier may be substituted for the 3886, although with two pair of TIP35C/36C driven by the power supply pins and a suitable supply, 800W/4R is possible.
  Reply With Quote
Old 1st June 2003, 11:19 AM   #14
diyAudio Member
 
Circlotron's Avatar
 
Join Date: Jun 2002
Location: Melbourne, Australia
Default Great minds not thinking alike ;-)

Quote:
Originally posted by jeffreyj
This is almost a very good idea... A seductively good one, I'd say, but it does not eliminate the problems incurred trying to yank the output voltage of a SMPS all over the place! To wit: you will need just as fast response time whether you delay the bitstream or not because you still have to be synchronized to said stream! So, whether the SMPS must vary its output now or 1 second from now is irrelevant, its the fact that it must vary it up to 20,000 times per second which is important!
What I was envisaging was a setup that simply makes the supply rails jump up to slightly more than what the peaks of the signal require, about 1 second before the output stage actually makes that signal. The supply rail is then allowed to reduce of it's own accord over several second perhaps, and tough luck about the excess dissipation for a few moments. Not quite as fancy as yours jeffreyj, but maybe a bit easier to do.
__________________
Best-ever T/S parameter spreadsheet.
http://www.diyaudio.com/forums/multi...tml#post353269
  Reply With Quote
Old 1st June 2003, 02:36 PM   #15
ted is offline ted
diyAudio Member
 
Join Date: Dec 2002
Location: Chicago, Il
I am also one of those people that are intrigued by the Carver power supply design, but what to do about that custom transformer [multitap & a 60Hz-SMPS)? (Actually never seen the schematic of a m400).

One interesting solution was what the tda1562 did. The idea was to use a single supply voltage and then temporarily, during peaks, raise the voltage above the rail-voltage with a capacitor voltage reservoir. I am sure that inside that chip there are more transistors then you can shake a stick at to accomplish this task. But, it's one way to not have to use a multitap transformer.
  Reply With Quote
Old 2nd June 2003, 03:28 AM   #16
djk is online now djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
"One interesting solution was what the tda1562 did. The idea was to use a single supply voltage and then temporarily, during peaks, raise the voltage above the rail-voltage with a capacitor voltage reservoir. I am sure that inside that chip there are more transistors then you can shake a stick at to accomplish this task. But, it's one way to not have to use a multitap transformer."

The TDA chip is a bridge amp with a high voltage tier. The high voltage tier comes from two bootstrap caps on either end of the speaker outputs. This is a non-inverter solution to getting high voltage for a car stereo amplifier.

Any regular center tapped transformer will work fine to provide the tiers for a bridge design.

You do not need a special transformer.
  Reply With Quote
Old 2nd June 2003, 07:38 AM   #17
diyAudio Member
 
Join Date: May 2002
Location: Switzerland
The newer designs by Bob Carver are indeed VOLTAGE-tracking downconverters (like the one used in the sunfire sub).

The old cube was somewhat different by using a circuit like it is used for dimmers (don't know the English expression, in German it is "Phasenanschnittsteuerung").

An alternative hybrid method would be the use of PARALLEL linear and switching power stages.


Regards

Charles
  Reply With Quote
Old 2nd June 2003, 02:27 PM   #18
diyAudio Member
 
jeffreyj's Avatar
 
Join Date: May 2003
Location: Tampa, FL
Default Re: Great minds not thinking alike ;-)

Quote:
Originally posted by Circlotron

What I was envisaging was a setup that simply makes the supply rails jump up to slightly more than what the peaks of the signal require, about 1 second before the output stage actually makes that signal. The supply rail is then allowed to reduce of it's own accord over several second perhaps, and tough luck about the excess dissipation for a few moments. Not quite as fancy as yours jeffreyj, but maybe a bit easier to do.
Love that subject line, btw

Let's see if I am now following your line of thinking, as it occurred to me that perhaps I wasn't.

Ok - because we aren't going to worry about decay time, we can dismiss the time constant of the output caps. What we want the SMPS' error amplifier to look at, then, is not the absolute output voltage, per se, but the voltage across any one output device. Monitoring this differential would be fairly easily as long as the common mode input limits of the differential (instrumentation?) amp were respected!

Integration of this voltage to limit its bandwidth will be necessary, of course, but I would estimate 2kHz to be a reasonable upper limit for the error amp's response. I propose this because with so little energy present in the upper octaves of any signal except white noise, there is clearly a diminishing return from making the SMPS slew faster!

All that remains, then, is whether a delay stage would be necessary. I still say that it wouldn't because the speed at which the SMPS must respond is dictated by the dv/dt of the signal and delaying the signal by any amount of time does not affect its instantaneous rate of change.

Getting closer?
__________________
Before you make that audacious claim, check this site out:QAudio Myths
  Reply With Quote
Old 3rd June 2003, 12:33 AM   #19
mbroker is offline mbroker  United States
diyAudio Member
 
mbroker's Avatar
 
Join Date: Mar 2002
Location: Fox Valley area in WI
Default Re: Re: Great minds not thinking alike ;-)

Quote:
Originally posted by phase_accurate
The old cube was somewhat different by using a circuit like it is used for dimmers (don't know the English expression, in German it is "Phasenanschnittsteuerung&quot.
"Phase control" is the literal english translation. Yes, this is how a typical light dimmer functions: ZVS


Quote:
Originally posted by jeffreyj
Integration of this voltage to limit its bandwidth will be necessary, of course, but I would estimate 2kHz to be a reasonable upper limit for the error amp's response. I propose this because with so little energy present in the upper octaves of any signal except white noise, there is clearly a diminishing return from making the SMPS slew faster!
Yep As I recall from the whitepaper (that I can no longer find online ), the original Sunfire amp used a limit of 6 or 7kHz as the power supply response. I have no idea if it has been upgraded or not in the newer models.

I don't think I have ever seen the results of a listening comparison from a source I trust between any of the Sunfire products featuring the Tracking Downconverter and some other manufacturers' similarly priced models.

Regards,

Mark Broker
  Reply With Quote
Old 4th June 2003, 10:02 AM   #20
djk is online now djk
diyAudio Member
 
djk's Avatar
 
Join Date: Feb 2001
Location: USA
"Yep As I recall from the whitepaper (that I can no longer find online ), the original Sunfire amp used a limit of 6 or 7kHz as the power supply response. I have no idea if it has been upgraded or not in the newer models."

Doesn't really matter, the tracking supply is fed by the audio, the audio is then fed into an all-pass delay line before amplification.

The end result is the change in supply voltage is always ahead of amplifier demand.
  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
power supply schematic with a 6080 used as a "pass tube" jarthel Tubes / Valves 4 9th July 2012 03:25 AM
High Voltage Power Supply PCB "oopsie" Sale Geek Swap Meet 1 2nd January 2009 06:06 AM
"rule of thumb" used to determine xxVA for a power supply's transformer? CopyofAudiófilo Chip Amps 11 22nd July 2008 01:01 PM
help in adjusting Vout in the power supply of the "Brute force in a line stage" by Er jarthel Tubes / Valves 9 30th May 2006 08:47 AM
Audio Crafters Guild "Super Symmetric Power Supply" raincheck Digital Source 16 22nd April 2002 09:06 AM


New To Site? Need Help?

All times are GMT. The time now is 02:19 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