Creating a differential signal from a single-ended signal for bridged amps - 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 29th October 2004, 05:15 PM   #1
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Default Creating a differential signal from a single-ended signal for bridged amps

It seems like this subject became pretty popular recently.

The easiest way would be using DRV134, however, I was thinking about something more challenging and less usual.

Combining some schematics I've seen previously (basicaly Pass balanced GC and Borberly preamps), I came up with this. Would it work well in that application?

There is also a possibility of using regular op amps for conversion, and I will post some examples later.
Attached Images
File Type: jpg bridge1.jpg (35.7 KB, 1152 views)
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 29th October 2004, 10:32 PM   #2
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Seems like the subject is challenging indeed, as I only received one comment so far (by e-mail), mixed advice though, and I'm not sure if I could even consider it, especially when it was trying to correct Mr. Borberly's choices. I'm sure more e-mails will come.

In a meantime, we move to ICs, as they are always safer to play with. This is my vision of pretty good, op amp preamp. It is in fact based on an actual, very well sounding preamp design, so no funny e-mails this time please.

I guess, for bridging purposes, the circuit could be used without input buffer (gain stage), but if somebody plans to add volume control, the buffer may be actually preferred. I'm using here OPA627, and it sounds not bad. The phase splitting is done using OPA2604, and in this position they also sound fine, but Carlosfm suggested recently AD815 and I wouldn't mind trying those here, especially when they are described as balanced line drivers.

The two 1k resistors in series, between two op amps, were used like that on purpose and one can add another gain stage for truely balanced preamp operation at the point between them. There is also a switch allowing to change the gain setting.
Attached Images
File Type: jpg ice.jpg (44.4 KB, 975 views)
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 29th October 2004, 11:41 PM   #3
Banned
 
Join Date: Mar 2003
Location: Lisbon, Portugal
Hi Peter,

You have a switch on the input buffer for 3x and 7x gain?
7x gain seams a little high...

As for the AD815, it seams to only be available in SMD version, and it needs a heatsink.
It's not so easy to use this chip, although... it pays.
Sonically I prefer the LM6172 or OPA2132 to the OPA2604.
  Reply With Quote
Old 30th October 2004, 12:25 AM   #4
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Those values can be always played with, whatever preference. My preamp actualy is using those exact values and the gain isn't too high.

I also got some samples of SMD AD815 and I'm quite curious about its sound. After all we usually agree on sonic signatures of various chips.

So far I didn't replace OPA2604 yet, but might do it one day.

For gain setting it's probably advisable to be adding resistor in parallel with 1K (instead of switching resistors), so there woudn't be any switching noise.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 30th October 2004, 01:11 AM   #5
Banned
 
Join Date: Mar 2003
Location: Lisbon, Portugal
Thumbs up Minimalist battery-powered preamp

This is a very good pre too.
Op-amp?
Just an LM6172.
Attached Images
File Type: jpg bat-pre inside.jpg (86.2 KB, 885 views)
  Reply With Quote
Old 30th October 2004, 01:16 AM   #6
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Default Re: Creating a differential signal from a single-ended signal for bridged amps

Quote:
Originally posted by Peter Daniel
The easiest way would be using DRV134, however, I was thinking about something more challenging and less usual.
Well, there's... the 'umble (and purely passive) transformer.

Or wouldn't that quite fit the "challenging and less usual" qualification?

se
  Reply With Quote
Old 30th October 2004, 01:27 AM   #7
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
I've heard good things about LM6172 so it is on my list of chips to try.

As to the transformer, well that is probably most elegant approach, yet not everybody wants to go with it.

I'm considering here a simple circuit to add to the LM4780 board and convert it into bridged amp, as many people asked about it. Transformer, apart form the size restrictions, will not always fit in everybody's budget.

Also, if somebody already has the balanced preamp, they don't really need anything extra and can drive two separate channels in a bridged mode, isn't it? This creates also another possibility; instead of adding a bridging board inside the amp, one might build a balanced output preamp and drive stereo amp in a bridged mode. I might go for that myself, actually.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  Reply With Quote
Old 30th October 2004, 01:39 AM   #8
diyAudio Member
 
Steve Eddy's Avatar
 
Join Date: Sep 2002
Location: Sacramento, CA
Quote:
Originally posted by Peter Daniel
As to the transformer, well that is probably most elegant approach, yet not everybody wants to go with it.
Of course not. But you know I had to mention it.

Quote:
I'm considering here a simple circuit to add to the LM4780 board and convert it into bridged amp, as many people asked about it. Transformer, apart form the size restrictions, will not always fit in everybody's budget.
Quite so. Unless you go with one of the cheapie $10 jobs.

Quote:
Also, if somebody already has the balanced preamp, they don't really need anything extra and can drive two separate channels in a bridged mode, isn't it?
Yup.

Quote:
This creates also another possibility; instead of adding a bridging board inside the amp, one might build a balanced output preamp...
Using transformers?

Ok, ok. I'll put the pom-poms away now.

se
  Reply With Quote
Old 30th October 2004, 01:41 AM   #9
Pedja is offline Pedja  Serbia
diyAudio Member
 
Join Date: Jun 2002
Location: Belgrade
Default Re: Creating a differential signal from a single-ended signal for bridged amps

Quote:
Originally posted by Peter Daniel
The easiest way would be using DRV134, however, I was thinking about something more challenging and less usual.
Quote:
Originally posted by Peter Daniel
I'm considering here a simple circuit to add to the LM4780 board and convert it into bridged amp, as many people asked about it.
For the adequate compensation and % of the $€£(...), I may offer you one such solution.

Pedja
  Reply With Quote
Old 30th October 2004, 01:44 AM   #10
diyAudio Member
 
Peter Daniel's Avatar
 
Join Date: Jul 2002
Location: Toronto, Canada
Send a message via AIM to Peter Daniel
Quote:
Originally posted by Steve Eddy

Using transformers?
I'm presently using S&B 102 TVC and as good as they are, there are certain limitations, like softening of highs in some systems/on certain material. Also dynamics are not always comparable to an active preamp. How would it be to combine transformer with an active line driver, like AD815 for instance (or discreet buffer)? I think there is even an example like that in application notes.
__________________
www.audiosector.com
“Do something really well. See how much time it takes. It might be a product, a work of art, who knows? Then give it away cheaply, just because you feel that it should not cost so much, even if it took a lot of time and expensive materials to make it.” - JC
  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
single-ended to differential? gentlevoice Digital Line Level 16 17th December 2008 06:18 AM
testing a single ended or differential topology Stefanoo Pass Labs 11 26th October 2007 05:59 PM
Converting from single ended parafeed to differential dsavitsk Tubes / Valves 9 12th July 2007 06:46 PM
Volume control + Single Ended -> Differential Amp koolscooby Solid State 2 5th April 2004 11:50 PM
Differential to single ended... Bas Horneman Tubes / Valves 21 2nd April 2003 02:05 PM


New To Site? Need Help?

All times are GMT. The time now is 11:34 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