Converting balance to unbalanced input

diyman · 5th March 2004, 03:34 PM

I have built a new preamp with balanced output but my power amp only have an unbalanced input. Can I install an input transformer in the power amp to accept balanced inputs? If yes, how do I go about doing it?

diyman

azira · 5th March 2004, 03:50 PM

This isn't exactly DIY, but they actually sell those things in music shops. They are used for mixing boards (like a mackie 1202) which only has unbalanced outputs when you want to run the signal to a balanced PA (like a powered monitor). I'm not totally positive if it is a true balun converter though.

The key device is an audio isolation transformer. It's typically 1:1 transformer that'll isolate the signals. On one side you connect it across the +/- of the balanced signal, on the other side you connect it GND/+ (watch out for the phase) for your input.

6th March 2004, 05:01 PM

Two possibilities:

1. Of cause you can use an input transformer to benefit from the advantages of symmetric cabling and galvanic isolation.
The better ones have their price:
http://www.experience-electronics.de...ebertrager.htm

2. To just get things work, it is adequate to take one (the "+"-)signal of the symmetric source and the ground as an unsymmetric input-signal for the poweramp. "-"-signal remains unused.
If your preamp uses an output transformer (-> signal not referenced to ground), it would then be necessary to connect the "-"-output to ground.

Regards

ChocoHolic · 7th March 2004, 09:13 PM

Hi DIYman!
I do not know exactly the internal structure of your preamp....

But normally you could simply use one half of the balanced
output and ground in order to drive an unbalanced input.
Depending on the topology of your preamp, you should put
a dummy load btw ground and the unused half of the preamp.
This dummy load should be similar as the input impedance of your
power amp.

May be my proposal sound a little bit blasphemic to you....
And it is.... setting up an symmetrical preamp and then using
only half of it.
But putting an additional unbalancing transformer would be
even more blasphemic for me.....

Have fun
Markus

ChocoHolic · 7th March 2004, 09:16 PM

...uhps, now I see the second proposal of Vek....
He already proposed the same as I did.

5th March 2004, 03:34 PM	#1
diyman diyAudio Member Join Date: Nov 2001 Location: Malaysia	Converting balance to unbalanced input I have built a new preamp with balanced output but my power amp only have an unbalanced input. Can I install an input transformer in the power amp to accept balanced inputs? If yes, how do I go about doing it? diyman

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
About the NAD s200 bal-input not balance?	Wizard	Solid State	0	12th May 2007 07:11 PM
converting and unbalanced in into a balanced input	joyfulstudios	Parts	2	12th June 2005 12:41 AM
Balance Input For Aleph-X	thomasfw	Pass Labs	2	26th January 2005 04:35 PM
Converting unbalanced AF signal to balanced	bostjancek	Solid State	5	23rd January 2004 09:29 AM
Unbalanced input SOZ?	paulb	Pass Labs	5	27th September 2001 05:01 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 March 2004, 03:50 PM	#2
azira diyAudio Member Join Date: Dec 2003 Location: Near Seattle	This isn't exactly DIY, but they actually sell those things in music shops. They are used for mixing boards (like a mackie 1202) which only has unbalanced outputs when you want to run the signal to a balanced PA (like a powered monitor). I'm not totally positive if it is a true balun converter though. The key device is an audio isolation transformer. It's typically 1:1 transformer that'll isolate the signals. On one side you connect it across the +/- of the balanced signal, on the other side you connect it GND/+ (watch out for the phase) for your input.

6th March 2004, 05:01 PM	#3
Vek Guest	Two possibilities: 1. Of cause you can use an input transformer to benefit from the advantages of symmetric cabling and galvanic isolation. The better ones have their price: http://www.experience-electronics.de...ebertrager.htm 2. To just get things work, it is adequate to take one (the "+"-)signal of the symmetric source and the ground as an unsymmetric input-signal for the poweramp. "-"-signal remains unused. If your preamp uses an output transformer (-> signal not referenced to ground), it would then be necessary to connect the "-"-output to ground. Regards

7th March 2004, 09:13 PM	#4
ChocoHolic diyAudio Member Join Date: Dec 2003 Location: Munich	Hi DIYman! I do not know exactly the internal structure of your preamp.... But normally you could simply use one half of the balanced output and ground in order to drive an unbalanced input. Depending on the topology of your preamp, you should put a dummy load btw ground and the unused half of the preamp. This dummy load should be similar as the input impedance of your power amp. May be my proposal sound a little bit blasphemic to you.... And it is.... setting up an symmetrical preamp and then using only half of it. But putting an additional unbalancing transformer would be even more blasphemic for me..... Have fun Markus

7th March 2004, 09:16 PM	#5
ChocoHolic diyAudio Member Join Date: Dec 2003 Location: Munich	...uhps, now I see the second proposal of Vek.... He already proposed the same as I did.

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