Are Balance Controls Still Necessary?

runeight · 31st October 2003, 10:20 PM

I would be most grateful for your opinions about the need for balance controls.

I have never built any audio equipment without a balance control somewhere, but most of this work was done many years ago.

It seems to me that today, with the consistency of the equipment and so forth, it might be possible to skip balance controls entirely. I know that some manufacturers do this.

I'm working on a tube preamp and I'll be using a stepped attenuator, so the volume control should be very well balanced. It may be that the amp topology is highly relevant. If so, I will post my tentative design.

I have some noble balance controls with M-N tapers that work perfectly, but even so, I'd like to eliminate the extra work and space requirements.

Thanks very much for your help. I searched a bit and didn't find a discussion about this, but if there is, please point me to it.

Brett · 31st October 2003, 10:27 PM

I haven't installed or used one in years, and a bit of channel imbalance doesn't bother me. But then again, I'm not anal about imaging either.

till · 31st October 2003, 10:29 PM

i don´t need one.

fdegrove · 31st October 2003, 11:45 PM

Hi,

Quote:

and a bit of channel imbalance doesn't bother me. But then again, I'm not anal about imaging either.

Oh boy....

I don't need a balance control, it can only degrade the sound but I sure as hell expect equal gain from both channels.

After musicality, imaging means everything to me, otherwise you could just as well built a PA system...

IOW Alex, you don't need to worry...

Quote:

It may be that the amp topology is highly relevant.

Line, phono? What kind of gain are we looking at here?

Cheers,

runeight · 31st October 2003, 11:52 PM

It's a simple line-stage that will convert unbalanced to balanced so that I can drive power amps that take a balanced input. Since many CD players these days can put out more than .5Vp I only need a gain of two to get the 1Vp that I need to drive the power amps. In fact, if it weren't for the balanced requirement, I could possibly even use a simple passive control. OTOH, I want to experiment some with the preamp stage and may build a few different kinds before this is all over.

I know that balanced o/p CD players are available, but none of the ones that I've seen are in my price range.

It uses a simple split load phase inverter and some follwers. Nothing special at all except that I'll probably include a tone control stage that can be completely swithed out.

fdegrove · 1st November 2003, 12:03 AM

Hi,

If you experience balance problems, I doubt you will...you can always adapt the stepped attenuator to closer tolerance steps at the positions you most frequently listen.

Also, it wouldn't be that hard to put a xformer at the CDP output IMHO...

I like to tackle the problem at the source ISO using a bandaid...no offense, just an idea.

Cheers,

dhaen · 1st November 2003, 12:03 AM

Haven't used a "balance control" for a long time. It does seem daft to add something that may degrade performance in any way. However, a preamp that I have, does it in a way that does not:
As well as the volume control, each channel has another attenuator that is detented at 0dB. it is therefore possible to reduce the gain (for testing image position etc), but in normal operation, the signal passes straight through.

fdegrove · 1st November 2003, 12:08 AM

Hi,

Quote:

As well as the volume control, each channel has another attenuator that is detented at 0dB. it is therefore possible to reduce the gain (for testing image position etc), but in normal operation, the signal passes straight through.

Straight through some switch contacts or is it a shunt design?

Cheers,

runeight · 1st November 2003, 12:17 AM

Quote:

I like to tackle the problem at the source ISO using a bandaid...no offense, just an idea.

No offense taken at all. What did you have in mind?

fdegrove · 1st November 2003, 12:26 AM

Hi,

Quote:

What did you have in mind?

Ah...my twisted mind...

Seriously, I'd put a xformer a la Jensen phase splitter, IS xformer, at the CDP's output and go balanced from there.

I.e from CDP out through the preamp ( it's going to cost you extra) to the amp.

Makes a lot more sense to me if that's your main source.

Cheers,

31st October 2003, 10:20 PM	#1
runeight diyAudio Member Join Date: Sep 2003 Location: Texas	Are Balance Controls Still Necessary? I would be most grateful for your opinions about the need for balance controls. I have never built any audio equipment without a balance control somewhere, but most of this work was done many years ago. It seems to me that today, with the consistency of the equipment and so forth, it might be possible to skip balance controls entirely. I know that some manufacturers do this. I'm working on a tube preamp and I'll be using a stepped attenuator, so the volume control should be very well balanced. It may be that the amp topology is highly relevant. If so, I will post my tentative design. I have some noble balance controls with M-N tapers that work perfectly, but even so, I'd like to eliminate the extra work and space requirements. Thanks very much for your help. I searched a bit and didn't find a discussion about this, but if there is, please point me to it.

1st November 2003, 12:03 AM	#6
fdegrove diyAudio Senior Member Join Date: Aug 2002 Location: Belgium	Hi, If you experience balance problems, I doubt you will...you can always adapt the stepped attenuator to closer tolerance steps at the positions you most frequently listen. Also, it wouldn't be that hard to put a xformer at the CDP output IMHO... I like to tackle the problem at the source ISO using a bandaid...no offense, just an idea. Cheers, __________________ Frank

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31st October 2003, 10:27 PM	#2
Brett diyAudio Member Join Date: Jan 2002	I haven't installed or used one in years, and a bit of channel imbalance doesn't bother me. But then again, I'm not anal about imaging either.

31st October 2003, 10:29 PM	#3
till Banned Join Date: Apr 2002 Location: Germany, Clausthal	i don´t need one.

31st October 2003, 11:52 PM	#5
runeight diyAudio Member Join Date: Sep 2003 Location: Texas	It's a simple line-stage that will convert unbalanced to balanced so that I can drive power amps that take a balanced input. Since many CD players these days can put out more than .5Vp I only need a gain of two to get the 1Vp that I need to drive the power amps. In fact, if it weren't for the balanced requirement, I could possibly even use a simple passive control. OTOH, I want to experiment some with the preamp stage and may build a few different kinds before this is all over. I know that balanced o/p CD players are available, but none of the ones that I've seen are in my price range. It uses a simple split load phase inverter and some follwers. Nothing special at all except that I'll probably include a tone control stage that can be completely swithed out.

1st November 2003, 12:03 AM	#7
dhaen diyAudio Moderator Emeritus Join Date: Jun 2002 Location: U.K.	Haven't used a "balance control" for a long time. It does seem daft to add something that may degrade performance in any way. However, a preamp that I have, does it in a way that does not: As well as the volume control, each channel has another attenuator that is detented at 0dB. it is therefore possible to reduce the gain (for testing image position etc), but in normal operation, the signal passes straight through.