[Hantra]

All:

I discovered something last night that I thought should be shared here.  

I was at BradV's place listening to his system.  At the risk of alienating Brad, I have to say that his system in the past had never really done anything for me.  I mean, it sounded really good, and clear, and clean, and big, but it really didn't grab me and do something special that made me want to listen to it.

So, Brad has made a few changes since last time I was there.  He got a new Sim Audio Moon Nova, and some turntable upgrades that were very significant.  He also discovered that he had a balance problem.  I'll let him explain how he discovered that and all, but he said it was as much 3db off.  I don't know exactly how he fixed it, but I know that last night I went in for another listen, and I was amazed!

The system sounded hundreds of percent better than I remembered it.  It was unreal.  That was the first time I had heard his system where I really liked it a lot.  I could not believe it!

Brad played with the balance control, and showed me what it was like before he fixed it.  And the system just went flatout lifeless again, and sounded almost as I had remembered it.  

I thought it was amazing the difference it made, and I am startled!  You guys REALLY need to check this with a meter if you haven't.  I'm going to check it to just for grins.

Just wanted to stress how important this is!

B

[Brad V]

Hi B,

I'm glad you liked the change. Sometimes we make changes and we are lulled into thinking it is for the better. I guess part of the problem is that I listen to Classical a lot and at some times, there is a lot of info coming out of the left speaker. I've had over 30 people hear my system with this problem and no one said anything until recently. Someone said that they thought they were hearing more info coming out of the left speaker.

So, last week I put in the Rives CD with all those frequency tests and took out my Radio Shack Meter. I measured in the nearfield, like 1/4 inch from the Mid/bass driver, to take the room out of the equation. I was shocked to see a difference of as much as 3db between the left and right speaker. I then switched the speaker connections between the right and left speaker inputs into the amp and the different switched to the other speakers.

I knew that I was having an intermittent problem with my interconnects on the right input on the amp, where I'd have to wiggle the interconnect at the amp end to make a connection. Actually I sent back a pair of Audience AU24's, as I thought there was a short in it. They sent me another pair and I had the same problem. I called Bel Canto and they sent me another Right RCA Connector, which I soldered in yesterday and that problem was solved. Also I noticed that my right Cardas speaker binding post on the Bel Canto was different than the left. I connect my subwoofer with banana plugs and the right banana plug only went in half way. They sent me another Cardas binding post, which I'll solder in tomorrow.

Bel Canto doesn't think that the binding post will make a difference and they think it might be the right transformer causing the problem. I guess I'll find out tomorrow.

I'm able to use my balance control on my preamp to get them the right and left speaker within 1/2 a db, so B will hear even more of an improvement, when I get the Bel Canto resolved. I know it's the Bel Canto SET40, as I've run everything thru my HT Receiver and everything is in perfect balance. I also ran my CD Player directly to the amp and it is still off.

So, I would highly recommend checking the balance on each speaker at regular intervals, especially if you have tube gear.

Have a great day,

Brad

[Sotantar]

Brad, could you tell me approx. where the balance control ended up when you had the volumes near equal?

Thanks much

[DVV]

All:

I discovered something last night that I thought should be shared here.  

I was at BradV's place listening to his system.  At the risk of alienating Brad, I have to say that his system in the past had never really done anything for me.  I mean, it sounded really good, and clear, and clean, and big, but it really didn't grab me and do something special that made me want to listen to it.

So, Brad has made a few changes since last time I was there.  He got a new Sim Audio Moon Nova, and some turn ...

You guys just discovered something I have been raving about ever since the so-called minimalist amps appeared. Not atypically, they threw out the baby with the bath water when they dumped the tone controls by deciding to dump the balance control as well.

If we disregard the volume control as an absolute must, the balance control is hardly any less significant if you only read the specs of the revered volume pots (e.g. Alps Black Beauty, Noble, TDK, Bourns, etc): they are elated when they can claim a 2 dB channel assymmtery. But 2 dB even in voltage terms is +/-26%!!! 3 dB is considered good, and typical mechanical pots in mid-range audio errs by as much as 4 dB.

Yet, for true space, sound stage depth and performance as a whole, balance is of critical imposrtance - err there, and you have a drowned out performance overall. You lose it ALL!

Admittedly, the new digitally controlled volume "pots" are incomparably better, at a typical error of 0.1 dB (just +/-1.15%), a VERY strong argument in their favor.

In my view, anyone serious making a preamp or an integrated, should include a balance control (or, better yet, individual channel gain controls, that way we have even less crosstalk) and a mono switch. This you need to equalize the channels, set the balance and then disconnect it. Usual run-around system is to connect a source with some noise, a tuner, find a channel with no programme, use the noise to set the balance, and then go on listening.

My favorite radio station has a clean 3-4 dB channel imbalance in its transmission, which irritates me no end, and my Karan integrated also has no balance (and yes, I did give him a piece of my mind), but my trusty old Harman/Kardon 680 integrated does. While the H/K is no match for the Karan in any field other than load tolerance, this makes radio listening far more pleasant overall.

Cheers,
DVV

[Brad V]

Brad, could you tell me approx. where the balance control ended up when you had the volumes near equal?

Thanks much

The balance control ended up at approximately the 2 O'Clock position. With it that way, the left speaker is still 1/2 a db louder. If I move it another click to the right, the right speaker will be 1/2 a db louder.

[Sotantar]

Nice to know I wasn't the only one in this club!!

[nathanm]

I wish I had a balance control!  It figures - the car stereo yahoos have too many controls and the hifi guys don't have enough!

Wouldn't it be better to measure the channel SPL at the listening position as well?  That would seem to make more sense as you are trying to get an even balance where your ears are.  I've always done it with the meter pointing straight ahead so that you're getting a reading of a single point in space.  (not that I could do anything about it though)  Measuring it right at the driver would give you each channel's output in isolation, but not necessarily what you hear at your seat with the room interactions taken into the equation.

[Brad V]

I wish I had a balance control!  It figures - the car stereo yahoos have too many controls and the hifi guys don't have enough!

Wouldn't it be better to measure the channel SPL at the listening position as well?  That would seem to make more sense as you are trying to get an even balance where your ears are.  I've always done it with the meter pointing straight ahead so that you're getting a reading of a single point in space.  (not that I could do anything about it though)  Measuring it right  ...

Yes, you definitely want to measure from your listening position. The only reason I measured in the nearfield, was to rule out the room. Once I did that, I knew that I had a problem with some part of my system.

[Brad V]

Hi,

I had to send my SET40 back to Bel Canto to work on it and see what the problem is. This is an email I received from them this morning. I had know idea that the THD was also off and off by a lot.

>>>
Brad, I will start my work on figuring out what you already know. I've tested, and confirmed a gain differential between channels. My testing indicates (with my set of 12AX7's and 845's) that the right channel requires .3725V in to achieve 2.83V (8 Ohm) 1W out. This measurement with 2.4% THD. This is not normal behavior. By comparison, the left channel requires .2965V in to get 1W (2.83V) out. This measurement with .36% THD. This is what it should look like on the bench. I'll keep you updated as I figure out why this is occurring. I may be out of the office for most of today, returning tomorrow.

                                                                              I'll be in touch,
                                                                                             Matt

>>>

I can't wait to get it back now and hear it, the way it was meant to be heard.

Have a great day,

Brad

[mb]

I've had a recent episode along these lines.

One channel of my system seemed to be producing a little more top end (>5kHz), and slightly clearer than the other channel. Swapping the mid-treble units which can be separated from the bass, the problem inverted. To cut a long story short, in my case it was a defective tweeter -- not dead, but attenuated and slightly distorting.

In the process, I've created what I feel is a useful tool:

I recorded a cd-r with a couple of my favourite tracks, in correct L/R channel format, and INVERTED L/R channels. Ie:

Track 1: my fav song (L/R correct)
Track 2: my fav song (L/R channels inverted)
etc, etc

This required the use of some editing software, but AFAIK, the editor does a digitally perfect L/R inversion (actually 100% stereo pan, L->R, R->L).

It feels strange when you hear a familiar track played with L/R inverted, but after getting used to it, this cd allows me to verify balance very well.

As an afterthought, it would probably be very useful to have created a 3rd track for each song -- a mono version, with 50% pan for both channels. This would quickly verify system/room balance.