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

Class D Switching Power Amplifiers and Power D/A conversion

Why isn't this system LOUDER?
Why isn't this system LOUDER?
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 17th August 2016, 11:13 PM   #11
easp is offline easp
diyAudio Member
 
Join Date: May 2016
Anandtech measured the iPhone6 full-voulme output at ~1v RMS.

You are going to need to get closer to 24v one way or another. Two fully SLA batteries in series may exceed the operating range of the TPA3116, and/or the caps on your board.
  Reply With Quote
Old 18th August 2016, 07:23 AM   #12
Jerms is offline Jerms  United Kingdom
diyAudio Member
 
Join Date: Jun 2015
Location: High Wycombe, Bucks, UK.
DC-DC boost converter time then.....
  Reply With Quote
Old 18th August 2016, 03:51 PM   #13
Gnobuddy is offline Gnobuddy  Canada
diyAudio Member
 
Join Date: Mar 2016
Quote:
Originally Posted by easp View Post
Two fully SLA batteries in series may exceed the operating range of the TPA3116, and/or the caps on your board.
Not to mention, add up to a lot of weight. Lead is heavy!

This is a good application for A123 Systems and similar (LiFePO4) batteries, if you can find them at a manageable price.

The ones I've encountered came off the charger at 3.6 volts per cell, quickly settling down to about 3.3 volts per cell. Six cells in series would add up to just under 22V hot off the charger, so should be safe for your electronics. (You do need a charger specifically designed to cope with this cell chemistry.)

Please keep in mind that other types of lithium batteries are quite unsuitable, and many pose a severe fire hazard.

-Gnobuddy
  Reply With Quote
Old 19th August 2016, 04:27 AM   #14
jhaneyzz is offline jhaneyzz
diyAudio Member
 
Join Date: Nov 2010
Default Making progress

Just got back from a business trip with all of your input dancing in my head.

I wired the DVC Sub in parallel and things got MUCH louder. Given that it is midnight here I canít really crank it up, or hook up a tape deck etc. until tomorrow.


Jerms
You may find that you need a preamp. Output levels from mobile devices tend to be lower... Or install a Chromecast audio or a bluetooth board or similar with a DC-DC converter to feed them 5V. Beware of ground loops/noise if you do this. At the least a GLI is likely to be required.

Iíve been doing some research on available pre-amp boards. You mentioned a Bluetooth board. Are you implying that such a board would have a pre-amp in it?

Looking for suggestions on good boards.

You also have something of an imbalance in the sub. It's 89dB, the coaxs are 93dB. It's a dual voice coil design nominally 4ohm. Running it at 2 is unlikely to suit the amp whilst running it at 8ohms you will have to crank the amp up even higher to keep level with the Polks.

One of the nice things about this amp is that is has a pot for modifying the crossover frequency (I donít know how electrically kosher that is, but it seems to do what it is advertised to do.) As well there are separate volume controls for the stereo channels and the Sub. Plus a ďMaster volume control."


Anandtech measured the iPhone6 full-voulme output at ~1v RMS.

You are going to need to get closer to 24v one way or another. Two fully SLA batteries in series may exceed the operating range of the TPA3116, and/or the caps on your board.

I havenít checked the caps out yet, but this is directly from the TI spec sheet.
(TPA3116D2)
2 ◊ 50 W Into a 4-Ω BTL Load at 21 V

I am loading the left and right at 4 Ω
The sub is at 2 Ω
There are two (TPA3116D2) chips on the amp.
So I donít really know how to determine the draw or the voltage ceiling.


Jerms
What do you mean by:

DC-DC boost converter time thenÖ..


Gnobuddy

I will definitely look into that battery option.

I have a previous build in a big Samsonite suitcase that I haul around with a luggage cart because it is so heavy.
  Reply With Quote
Old 19th August 2016, 12:52 PM   #15
jhaneyzz is offline jhaneyzz
diyAudio Member
 
Join Date: Nov 2010
Some of the Preamps I am looking at are dual rail and need V-0-V input.

Sorry about the Newbie question, but how do you go about supplying that if your power source is a battery?

James
  Reply With Quote
Old 19th August 2016, 12:57 PM   #16
jhaneyzz is offline jhaneyzz
diyAudio Member
 
Join Date: Nov 2010
Are Boost converters an option for audio use? I always thought that there had to be a catch somewhere.
  Reply With Quote
Old 19th August 2016, 10:30 PM   #17
Gnobuddy is offline Gnobuddy  Canada
diyAudio Member
 
Join Date: Mar 2016
Quote:
Originally Posted by jhaneyzz View Post
...how do you go about supplying that if your power source is a battery?
The simplest way is to use two batteries of the appropriate voltage in series, with the centre-tap being your zero-volt rail.

Other than that, there are switch-mode supplies that can turn a positive rail into a negative rail.

If you're rolling your own, many old (pre-opamp) discrete preamp circuits will run happily off a single supply rail. Performance will not be as good as an opamp, but might be just fine for a portable, battery-operated boombox application.

-Gnobuddy
  Reply With Quote
Old 19th August 2016, 10:50 PM   #18
Gnobuddy is offline Gnobuddy  Canada
diyAudio Member
 
Join Date: Mar 2016
Quote:
Originally Posted by jhaneyzz View Post
Are Boost converters an option for audio use? I always thought that there had to be a catch somewhere.
Well, they've been in a lot of car audio power amps for many, many, years. Anything above about 12 watts RMS per channel requires more than a 12 volt rail, so some kind of switch-mode supply is mandatory, and it has to boost the nominal 12V rail from the car battery up to higher voltage.

-Gnobuddy
  Reply With Quote
Old 20th August 2016, 12:42 AM   #19
jhaneyzz is offline jhaneyzz
diyAudio Member
 
Join Date: Nov 2010
The simplest way is to use two batteries of the appropriate voltage in series, with the centre-tap being your zero-volt rail.

I am such a noob! Err.... What's a center tap and a zero volt rail?
  Reply With Quote
Old 20th August 2016, 05:20 AM   #20
Gnobuddy is offline Gnobuddy  Canada
diyAudio Member
 
Join Date: Mar 2016
Quote:
Originally Posted by jhaneyzz View Post
Err.... What's a center tap and a zero volt rail?
Sorry for the confusion!

Zero volts is another way to say "ground", so "zero volt rail" is just the ground rail. When you said "V-0-V" in your post, the "0" is the zero volt rail.

Let's suppose your dual-rail requirement is (+9 volts), 0 volts, (-9 volts). You can get this by connecting two 9 volt batteries in series, + end of one to the (-) end of the other.

You will now have one (+) end free; that's your +9 volt rail. You will also have one (-) end free; that's your (-9 volt) rail.

And the connection between the (+) of one battery and the (-) of the other - that becomes your zero volt rail, or ground.

The advantage of this approach is that it's very simple. Unfortunately, there are also disadvantages - you need two batteries, so that doubles the battery cost, weight, and bulk you have to deal with.

-Gnobuddy
  Reply With Quote

Reply


Why isn't this system LOUDER?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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
My Profile Isn't Me JR_W Forum Problems 12 22nd January 2014 09:26 PM
Isn't this like...wrong? EchoWars Solid State 11 5th January 2007 11:15 PM
This isn't damaging my system is it? Prismatic Subwoofers 5 3rd July 2006 08:34 AM
Quiet here, isn't it? pinkmouse The Lounge 24 8th February 2005 08:29 PM


New To Site? Need Help?

All times are GMT. The time now is 05:15 AM.


Search Engine Optimisation provided by DragonByte SEO (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Resources saved on this page: MySQL 15.00%
vBulletin Optimisation provided by vB Optimise (Pro) - vBulletin Mods & Addons Copyright © 2018 DragonByte Technologies Ltd.
Copyright ©1999-2018 diyAudio
Wiki