Major Noob question about powersupplies. - diyAudio
Go Back   Home > Forums > Amplifiers > Chip Amps

Chip Amps Amplifiers based on integrated circuits

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 27th July 2003, 10:26 AM   #1
diyAudio Member
 
Hybrid fourdoor's Avatar
 
Join Date: May 2003
Location: Ft. Worth, TX
Default Major Noob question about powersupplies.

Lets say you guys recommend a 24V transformer for a GC. At Parts Express they sell a 25V torrid...now heres the question...in order to hook up a stereo pair of GC circuits do I hook them both up to the same output wires, or are there mulitple taps comming off of the transformer that each have 25V?

And also can I power both chips off of one 25V supply, so long as they, collectevly, don't draw more current than the supply can handle (3A or 5A in the case of these torrids).

Also would one of the Velleman PS kits such as the one Parts Express sells that has 1.5-35V @ 1A be suitable to power a GC...using one PS per channel. I don't know how much current a Gain Clone draws so I didn't know if that was a powerfull enough supply.


Sorry for the Noob questions....maybe there are others that watch this forum that don't know this stuff too.
  Reply With Quote
Old 27th July 2003, 10:35 AM   #2
diyAudio Member
 
Hybrid fourdoor's Avatar
 
Join Date: May 2003
Location: Ft. Worth, TX
Ok with the kit mentioned above I would still have to buy a transformer to convert 120V AC down to 24V AC right?

Maybe someone could just point me how to make a PS for these things....it looks like a transformer....some IC's and some caps and thats it.
  Reply With Quote
Old 27th July 2003, 12:55 PM   #3
SY is offline SY  United States
diyAudio Moderator
 
SY's Avatar
 
Join Date: Oct 2002
Location: Chicagoland
Blog Entries: 1
Let me give a somewhat generic answer. Some people will use a transformer with a single secondary (centertapped assumed) to make a single bipolar supply, then use it to drive both channels. Some people will use a transformer with dual secondaries (each ct) to make two sets of bipolar supplies and run one to each channel separately. Or even use two separate transformers to make separate supplies for each channel. All of these schemes will work, at various cost and performance levels.

Is this what you're asking?
__________________
You might be screaming "No, no, no" and all they hear is "Who wants cake?" Let me tell you something: They all do. They all want cake.- Wilford Brimley
  Reply With Quote
Old 27th July 2003, 12:56 PM   #4
Nuuk is offline Nuuk  United Kingdom
diyAudio Member
 
Nuuk's Avatar
 
Join Date: Feb 2003
Location: Somerset, SW England
I think that your questions may be answered HERE

(although I apologise for the 'lack of content'
__________________
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
  Reply With Quote
Old 28th July 2003, 01:06 AM   #5
S.C is offline S.C  United States
diyAudio Member
 
Join Date: Jun 2003
Location: Milpitas
Send a message via ICQ to S.C Send a message via AIM to S.C
What is the effect on sound when we using One PS or Two PSs to power two channels? Will it sound better and louder if we use two separate one with same rating with a Single PS?
  Reply With Quote
Old 28th July 2003, 02:04 AM   #6
diyAudio Member
 
Greg Erskine's Avatar
 
Join Date: Jan 2002
Location: Sydney/Australia
Hybrid fourdoor,

Nuuk site answers the technical side of your questions very nicely, but can I add:

1. I don't think you need the Velleman PS kit. The PS for a GC can be as simple as a transformer and a bridge rectifier or 4 (or 8) diodes. (and fuses ARE required on the primary at least)

2. 25V could be reaching the max recommended voltage. I am currently running my GC from a single 12-0-12 300VA toroid and I was absolutely shocked at the volume generated by these little buggers considering my speakers are very inefficient. (85dB I think)

3. You will find a lot of conflicting opinions, so sometimes it is just better to try it for yourself.
__________________
Greg Erskine
  Reply With Quote
Old 1st August 2003, 03:40 AM   #7
diyAudio Member
 
Join Date: May 2003
Location: SouthEastern Manitoba
I purchased a 25-0-25 toroid in my gainclone project. I decided to go near the top of the documented supply voltage range so I could get the most power out of it...but it was suggested to me that the chips will generate a fair bit of heat when being supplied that high.

I'm going to try it with the modest heatsinks I have. If it runs too hot, I may try dropping the voltage using diodes in series with the power supply. Each one in series with the power supply drops the voltage by about 0.7 volts. Two diodes in series with each rail should bring it down to about the voltage you would get using a 24-0-24 unit. I would locate these diodes in the power supply enclosure, away from the chips.

I'm not sure if adding diodes in series with the power supply rails will cause any sonic degradation. Perhaps someone could comment on that?

If it does end up sounding bad then I will probably build another amp with this transformer and get a lower voltage one for my LM3875 gainclone. I've read about good results with an 18-0-18 tranny.

Good luck!
__________________
-=\Rye/=-
  Reply With Quote
Old 1st August 2003, 04:01 AM   #8
Warp Engineer
On Holiday
 
AudioFreak's Avatar
 
Join Date: Oct 2001
Location: Queensland, Australia
Quote:
Originally posted by S.C
What is the effect on sound when we using One PS or Two PSs to power two channels? Will it sound better and louder if we use two separate one with same rating with a Single PS?

Expect the following advantages by giving each channel it's own power supply...

1) You'll get far less crosstalk / intermodulation between the 2 channels (PSRR with these chips it quite high so that's probably not a major point but it never hurts)

2) Assuming that you dont skimp on power supply rating, you'll get less voltage sag under load by using individual power supplies and so you'll get closer to rated power output for a given rail voltage.

Quote:
Originally posted by grege
The PS for a GC can be as simple as a transformer and a bridge rectifier or 4 (or 8) diodes. (and fuses ARE required on the primary at least)
And of course, dont forget about the filter capacitors.
__________________
- Dan
  Reply With Quote
Old 1st August 2003, 04:37 AM   #9
diyAudio Member
 
JOE DIRT®'s Avatar
 
Join Date: Apr 2003
Location: Brantford, ON
you can also do the math after rectification and capacitance you will get quite a larger voltage
My opinion is to never run a device so close to its S.O.A> in that respect you will benefit to the sonic benefits of its purpose
  Reply With Quote
Old 1st August 2003, 06:03 AM   #10
diyAudio Member
 
Greg Erskine's Avatar
 
Join Date: Jan 2002
Location: Sydney/Australia
Quote:
Originally posted by AudioFreak
And of course, dont forget about the filter capacitors.
The thing with these gainclones is the filter caps are actually on the opamp (usually 1000uF) and not necessarily near the PSU. Although some poeple use additional filter caps at the PSU many don't.
__________________
Greg Erskine
  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
Major Newb Question Nexter Digital Source 0 1st April 2008 05:16 PM
Noob Question USlatin Everything Else 3 13th November 2007 04:01 PM
ZEN noob question MEGA_amp Pass Labs 15 19th September 2006 08:42 PM
noob I2S question p_ete2003 Digital Source 6 19th May 2004 04:51 AM


New To Site? Need Help?

All times are GMT. The time now is 09:20 PM.


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