unbal-balanced driver with opamp

lumanauw · 5th June 2004, 03:17 AM

What is the best possible unbalance-balance converter using opamp? In RodE's site he's using a cross feedback between 2 opamps (like C). Is this giving better performance than stand alone (B)?
I saw (A) in here. Is (A) possible to make unbalance-balance converter?
Maybe I draw (C) wrongly. RodE using 3 opamp. I saw these kind of configuration with 2 opamps, in PDF somewhere in here, but forgot how it looks like, feedback crossing with only 2 opamps. Anyone can help, which opamp pdf datasheet have drawings like (C)?

theChris · 5th June 2004, 04:04 AM

A has positive feedback, so i'd say not to use it.
B has a lot of resistors. they must be chosen such that the resistors on the bottom opamp are 2x the resistors on the top.
C doens't look like it works.

jleaman · 5th June 2004, 04:43 AM

What about just useing a balanced chip ? I ordered a few samples they go from rca to balanced and there pretty cheap.

mandat · 5th June 2004, 05:22 AM

Look at Texas Instrument home page and search Burr-Brown's OPA1632.
The OPA1632 is a fully-differential amplifier from input stage to output stage. It is dedicated to driving high-performance ADCs.
FEATURES:
Distortion: 0.000022%, Noise: 1.3nV/SQRT Hz, SR: 50V/µs, GBW: 180MHz
Supply: ±2.5V to ±16V, Power Shutdown option.

The OPA1632 is available in an SO-8 package and a MSOP-8 PowerPAD package.

mikeks · 5th June 2004, 07:26 AM

try this

http://diyaudio.com/forums/showthrea...726&highlight=

djk · 5th June 2004, 02:46 PM

This circuit is best:

http://focus.ti.com/lit/ds/symlink/drv135.pdf

It mimics a transformer.

mandat · 5th June 2004, 03:38 PM

This a copy from a THS4130 datasheet, an older brother of OPA1632. In this case you use one opamp, only.

djk · 5th June 2004, 09:56 PM

To the unwashed, the 1632 circuit looks similar to the 135 circuit, but close examination shows that it is not.

If you actually intend to send audio any distance down a balanced line, the circuit must mimic a transformer.

If you actually intend to receive audio any distance down a balanced line, the receiver must be a transformer. The receiver chips, despite their 0.001% matching of resistors, are up to 50dB worse than a transformer.

Those that have been to the balanced line seminar at CEDIA will be familiar with these ideas.

markp · 5th June 2004, 10:07 PM

Take a look at these http://www.analog.com/Analog_Root/pr...2142%2C00.html
They work really well in everything I've used them for. Low noise and the ability to drive very long cables. Its an easy one chip solution.

djk · 6th June 2004, 02:50 AM

While the SSM2142 mimics the performance of fully balanced
transformer-based solution for line driving, the previously linked to TI/BB DRV135 is an IMPROVED REPLACEMENT FOR SSM2142.

The SSM2142/2141 is the SPECIFIC CHIP SET used in the CEDIA seminar showing that this solution can be up to 50dB worse than using a transformer for the receiver.

5th June 2004, 04:04 AM	#2
theChris diyAudio Member Join Date: Dec 2001 Location: SIUE, Illinois, USA	A has positive feedback, so i'd say not to use it. B has a lot of resistors. they must be chosen such that the resistors on the bottom opamp are 2x the resistors on the top. C doens't look like it works. __________________ if only it could be used for good, not evil...

5th June 2004, 10:07 PM	#9
markp diyAudio Member Join Date: Oct 2003 Location: L.A., CA	Take a look at these http://www.analog.com/Analog_Root/pr...2142%2C00.html They work really well in everything I've used them for. Low noise and the ability to drive very long cables. Its an easy one chip solution. __________________ If it sounds good... it is good!

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Balanced Driver / Receiver	arigy	Solid State	11	14th June 2010 09:26 AM
Fully balanced Opamp	rkn	Pass Labs	21	29th August 2008 06:21 PM
opamp driver stage	Acoustat	Solid State	11	22nd February 2005 10:09 PM
Balanced Line Driver	Jerry Parker	Everything Else	1	1st April 2003 05:32 PM
rod's balanced driver & receiver	hugobross	Solid State	2	19th March 2003 08:36 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	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

5th June 2004, 04:43 AM	#3
jleaman Banned Join Date: Apr 2002	What about just useing a balanced chip ? I ordered a few samples they go from rca to balanced and there pretty cheap.

5th June 2004, 05:22 AM	#4
mandat diyAudio Member Join Date: Oct 2003 Location: Gliwice	Look at Texas Instrument home page and search Burr-Brown's OPA1632. The OPA1632 is a fully-differential amplifier from input stage to output stage. It is dedicated to driving high-performance ADCs. FEATURES: Distortion: 0.000022%, Noise: 1.3nV/SQRT Hz, SR: 50V/µs, GBW: 180MHz Supply: ±2.5V to ±16V, Power Shutdown option. The OPA1632 is available in an SO-8 package and a MSOP-8 PowerPAD package.

5th June 2004, 07:26 AM	#5
mikeks Account Disabled Join Date: Jun 2004 Location: Animal farm	try this http://diyaudio.com/forums/showthrea...726&highlight=

5th June 2004, 02:46 PM	#6
djk diyAudio Member Join Date: Feb 2001 Location: USA	This circuit is best: http://focus.ti.com/lit/ds/symlink/drv135.pdf It mimics a transformer.

5th June 2004, 09:56 PM	#8
djk diyAudio Member Join Date: Feb 2001 Location: USA	To the unwashed, the 1632 circuit looks similar to the 135 circuit, but close examination shows that it is not. If you actually intend to send audio any distance down a balanced line, the circuit must mimic a transformer. If you actually intend to receive audio any distance down a balanced line, the receiver must be a transformer. The receiver chips, despite their 0.001% matching of resistors, are up to 50dB worse than a transformer. Those that have been to the balanced line seminar at CEDIA will be familiar with these ideas.

6th June 2004, 02:50 AM	#10
djk diyAudio Member Join Date: Feb 2001 Location: USA	While the SSM2142 mimics the performance of fully balanced transformer-based solution for line driving, the previously linked to TI/BB DRV135 is an IMPROVED REPLACEMENT FOR SSM2142. The SSM2142/2141 is the SPECIFIC CHIP SET used in the CEDIA seminar showing that this solution can be up to 50dB worse than using a transformer for the receiver.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)