balance

[Pieoftheday]

Does anyone adjust the balance on their amp? Iff so why? Speaker placement? Hearing problems? Owt else? Jim

[awkwardbydesign]

Yes. Room is not balanced.

[Pieoftheday]

Hi Richard,do you mean your room is oddly shaped or your seating position isn't central to your system? Or something else? Cheers jim

[struth]

I do someimes as my seating position is off centre. doesn't always need it. Thats what its for :)

[Pieoftheday]

I do someimes as my seating position is off centre. doesn't always need it. Thats what its for :)

After a couple of opps on my right lug ole, I'm a bit unbalanced hence my question, I couldn't get my set up right and it never occoured to me to use the balance:scratch: I'll start again when I've the time,

[walpurgis]

After a couple of opps on my right lug ole, I'm a bit unbalanced hence my question, I couldn't get my set up right and it never occoured to me to use the balance:scratch: I'll start again when I've the time,

You'll adjust. I've been partly deaf in my right ear since my early teens and don't really notice it much or compensate. I guess the old brain is compensating for me. hopefully your hearing will improve though. Good luck.

[Pieoftheday]

You'll adjust. I've been partly deaf in my right ear since my early teens and don't really notice it much or compensate. I guess the old brain is compensating for me. hopefully your hearing will improve though. Good luck.

Hi Geoff,thanks for your reply , I had a false membrane,in front of the eardrum, stiill have, it grew back!! So won't get better,not huge problem,hinders the low end, sound wise I mean:D

[awkwardbydesign]

Hi Richard,do you mean your room is oddly shaped or your seating position isn't central to your system? Or something else? Cheers jim

The room reflections are different each side. I do sit slightly to the right (and my wife to the left) but I pull the balance to the right for the room acoustics. Not a lot, but I had to add a balance pot to my LDR pre.

[Light Dependant Resistor]

The room reflections are different each side. I do sit slightly to the right (and my wife to the left) but I pull the balance to the right for the room acoustics. Not a lot, but I had to add a balance pot to my LDR pre.

Our LDR boards are now provided with trimpots for both the series and shunt LDR's, and we offer to upgrade prior boards
to similarly include trims at no cost, other than postage each way.

Cheers / Chris

[awkwardbydesign]

Our LDR boards are now provided with trimpots for both the series and shunt LDR's, and we offer to upgrade prior boards
to similarly include trims at no cost, other than postage each way.

Cheers / Chris

But is the overall balance adjustable from the front panel?

[dantheman91]

Interesting guys. My amplifier has no balance control i tried a pair of speakers lately and one speaker seemed louder then the other on other speakers its fine perfectly level. Would would be the option to do with the speakers they work fine other then that is it really important to have equal speaker balance or just a myth really confusing me.

Thanks

[Valvebloke]

If you suspect the speakers then try swapping them over. If the quiet one moves from left to right when you do that then the two speakers are different. The fact that other speakers sound more balanced suggests that the new ones might be iffy. But it could be that the earlier ones had a different dispersion (i.e. they spread the sound out in a wider or narrower cone than the new ones) and that this therefore interacted differently with some asymmetry in the room. In that case the new speakers might not be defective, just not suitable for your particular room layout and geometry.

VB

[awkwardbydesign]

And if the frequency balance is uneven there can be more or less imbalance at different frequencies. So the balance may appear to swing with different music! The variations in dispersion can do the same.
Try angling both speakers sharply in and then out, and see if the imbalance varies. That would suggest a dispersion artifact.

[awkwardbydesign]

is it really important to have equal speaker balance or just a myth really confusing me.

Thanks
I find that if the balance is just right, then the imaging/soundstage is much better than otherwise. So the "realism" is greatly improved.

[walpurgis]

I've not felt the need to try it, but I suppose if you've no balance control and you want to reduce output on one side, you could try something like a Rothwell attenuator in one input or to one side of the power amp if it's separate. Values would have to be experimented with.

[struth]

IMG Stageline 21.2840 Passive Level Attenuator is variable stepped ..10 15 20 db. very useful

[awkwardbydesign]

These are HUGE amounts of attenuation for a balance control! It probably only needs 1 or 2dB.

[walpurgis]

No they aren't.

1 or 2 db would not be really discernable. 3 to 6 db is not very noticeable.

I'd suggest starting at -6db and see how that works.

[Light Dependant Resistor]

But is the overall balance adjustable from the front panel?

Yes, this can be done. it would require a two gang 2k pot for single input, and 4 gang pot for three input
you could then either pass over to a second dual gang for 4 inputs, or use a 6 gang for capability
of balance control for 5 inputs. But better to use 2 balance controls see below, one for the shunt and
the other for series.

2k multiple gang pots are fairly difficult to purchase, in this case use 10k and firstly place a resistor of 2k7
providing 2125 ohms across each gang end to end. Further tailoring suiting each of the series or the shunt pair
could be then done if required, but 2k7 in parallel with 10k would be a good starting point.

Better still would be a balance control on the front panel one single gang 2k arranged as shunt and the other
for the series with as many gangs are required. This would give proper recognition of the circuit as having
shunt and series elements. So 2 balance controls 1 for shunt and one for series - the series having as many gangs
as required. A typical front panel would then contain 4 knobs, namely a volume control, a balance for shunt
a balance for series ( multiple gang ) and a source selector switch originating from the right hand side of the pot legs down
shaft facing you, switching current to the series anodes in this case via gang of 2k pot for each series input LDR pair.

The diagram shows how this is arranged for 2 inputs using 3 gangs, two gangs of which would be physically
be the series pot and one gang of a second physical pot being the shunt. .


A feature of all of our kits has been to allow the LDR cathode to be ground, rather than the pot engaging ground.
Our most recent control boards now require J2 to access the star ground point due to sensing circuitry
The diagram shows the anode and cathode only of the internal led which then couples via light to the variable
resistor, which is the distinct advantage of LDR's vs pots that wipe adding contact problems to the signal path.

14197

[dantheman91]

Interesting guys. I suppose i could use a multimeter to test their output but not sure on how to do this.? i suppose i could be my room but never had a problem with them before. Is it a case of can i live with it or sell them. I think further tests need to be done but not sure which ones to do. It could be the tracks i was playing. I could try a MONO CD as this will be perfectly level i know its not my amplifier because it was freshly serviced last year. Any thoughts chaps any one local to Bournemouth willing to help me on this one.?

Thanks

[struth]

No they aren't.

1 or 2 db would not be really discernable. 3 to 6 db is not very noticeable.

I'd suggest starting at -6db and see how that works.

if you set one to 10 and other to 15 you get a 5 difference ...etc. allows you to get an idea as to whats required. then you can buy the right size

[Pieoftheday]

well i decided to get my ushers out today and have a play,last time i used them it was with a marantz pm8003, now theyre on the end of a 'budget' pioneer a30, there dosnt seem to be any imbalance this time, i wonder if the marantz wasnt quite right:scratch: i was worried the pioneer wouldnt be good enough but it seems a good match for the ushers,im really quite chuffed:cool:

[Light Dependant Resistor]

Interesting guys. I suppose i could use a multimeter to test their output but not sure on how to do this.? i suppose i could be my room but never had a problem with them before. Is it a case of can i live with it or sell them. I think further tests need to be done but not sure which ones to do. It could be the tracks i was playing. I could try a MONO CD as this will be perfectly level i know its not my amplifier because it was freshly serviced last year. Any thoughts chaps any one local to Bournemouth willing to help me on this one.?

Thanks

Hi

With checking or adjusting as can be done with our kits you are confirming resistance of what is called an L pad
formed by LDR's. With a conventional passive pot similarly you can with a multimeter check Left and Right resistance
to ascertain channel balance or imbalance as the case may be. Here with signal leads disconnected volume at half just probe from input to ground for Left and then input to ground for Right then compare the readings, ideally they should be within 1-3% of each other.

In the case of LDR's Viewing one channel this has one LDR called the Shunt which has one signal leg going to star ground
its other leg goes to the output. For stereo this of couse has 2 LDRs as the shunt one being Right and the other Left
As volume decreases the LED internal to the LDR provides more light which causes the resistance on the signal side
of the LDR to decrease, as 2 legs for this stereo pair arranged as Shunt are grounded your volume lessens.

Attached then also to the output, is one leg of a second pair of LDR's. or third pair for two inputs and fourth pair for 3 inputs
these are called the series LDR pairs. The other leg of each of the series pairs connects to each input.The same thing
but the opposite way to the shunt then occurs. As the volume decreases the LED internal for the series pairs
causes the signal side resistance to increase. To switch inputs we simply turn the anode off on the pair just
listened to and ON on the pair required. This causes the resistance on the pair just listened to to go extremely high
approx 10 mega ohms, and on the pair required comparitively low resistance which is accorded to where the
volume control is set.

So checking this with a multimeter you would disconnect RCA's as we do not want the resistance usually fixed
to compete with measurements. with one probe to ground and the other to the input with volume at half you
should obtain a reading across the shunt pair- so from output to ground, then checking
the series from input to output. Then as an aggregate check from input to ground With checking balance
you are asertaining there is close comparison of aggregate resistance ( shunt + series ) from Left input to
ground, and then Right input to ground.

Our kits are provided with trims so you can adjust stereo balance as required. Richard has asked can this be done
from the front panel, and per the earlier reply Yes, ideally with a pot for Shunt that would usually be left in
one position, and another for series suggested as 10k with 2k7 parallel to make approx 2125 ohms using
a multiple gang pot arranged for each input. The balance control of course with LDR's is all done on the LED
side, that then opto couples that change to the signal side

14206

Cheers / Chris

[awkwardbydesign]

No they aren't.

1 or 2 db would not be really discernable. 3 to 6 db is not very noticeable.

I'd suggest starting at -6db and see how that works.
You're talking about relative volume, or level changes here. Shifting a central image by a few degrees is far more sensitive.

[Audio Advent]

In the real world, does the phase change slightly too when the sound moves from left to right? The path of sound from one ear to the other will change so one will be more out or in phase with the other than before. Perhaps that only makes a noticable difference with high frequencies? Remember reading a digital pre changed the phase relationship between channels with the balance control, Meridian I think. Probably did it via a delay. That would be interesting, devising a balance control which also adjusted left/right delay at the same time as level.

Don't know if anyone remembers this but in the 90s some time Tomorrow's World did a simultanious broadcast with Radio 1 to demonstrate a 3D sound emulation via stereo, all done manipulating phase relationships. They played a track by Bomb the Bass, "Winter in July". I taped it (the Radio 1 audio) but have never found the tape at my parent's.. The sound went around the room, perhaps a bit of up and down too? Can't remember now.

Edit: Hey! Here it is on Youtube:

https://www.youtube.com/watch?v=ALJ7_tIm14A

[Light Dependant Resistor]

Hi Sam
A change of phase is not desirable as audio imaging would be compromised when adjusting and finally setting balance

Rather an adjustment of balance may apply to adjust, if the room area in the listeners opinion is compromised
or one experiences hearing loss with one ear vs the other .

What is desirable is the accurate recreation for all audiences then of how the artist(s) if they had
choice when the recording or subsequent mixing occurred, intended the piece of music to sound.
Alan Blumein is credited with patents for stereophonic sound, what he referred as binaural sound.
http://en.wikipedia.org/wiki/Alan_Blumlein

His vision for what then became stereophonic sound was influenced by cinema where he describes
" declared to his wife, that he had found a way to make the sound follow the actor across the screen "

Accurate stereo reproduction with its best clothes on is captured in recordings like those
on the Naim Reference recordings - and its samplers provide wide variety of music. To
Naims credit the sleeeve of the recording gives you a visual colour indication of where
each instrument was placed. The accuracy you can then hear before you.
Simple microphone techniques and excellent recording equipment, usually provide
the best result.

There are many examples of artists playing ( sometimes effortlessly ) with stereo effects,
and at the end of the day ( if they had choice ) what a good stereo system today reproduces
is pretty well what they wanted. Jimi Hendrix adored panning effects and put them to good
use in Axis Bold as Love in Band of Gypsys, and what the became First rays of the
new rising sun, a compilation
from the posthumus albums Rainbow Bridge ( now reissued ) and Cry of Love.
Russell Morris - The Real Thing has similar treatment.

But they are treatments, not portrayal of capturing live sound ( as Blumein intended ) as good engineers
past and present strive for.

Frank Zappa was fastidious with sound, and a listen to his 1969 album Hot Rats is well worth a listen.
and you can hear from what are complex arrangements real effort to preseve an acoustic event.
In Deep Purples Made in Japan effort has been made to really convey what a heavy rock band sounds like.

Other notables Nina Simone, Miles Davis, Prof Johnson Reference recordings

The correct portrayal of stereo with what was recorded is IMO vastly hidden in the
majority of audio systems, in insufficient dynamic range -
which is directly related to increasing bits with digital from the industries first efforts at
digital recording 14 bit ( we are thankful ) to todays 24 bit equipment.
Analog in comparison has a natural boundary for dynamic range
rather than an abrupt cutoff and is why reel to reel recordings
are so good. LP playback also to a degree, but complicated by
RIAA http://en.wikipedia.org/wiki/RIAA_equalization

A read of this ftp://ftp.dbxpro.com/pub/pdfs/WhitePapers/Type%20IV.pdf
will give history & insight into the role dynamic range plays in good audio reproduction.

This is the next step for audiophiles to understand and appreciate how dynamic range can
be captured and stored in recorded sound mediums.

Cheers / Chris