Balance Control Needed - Speakers

[Deleted]

I have a problem trying to get the listening position right from a chair that can't be moved. I need the left speaker to get a bit more power than the right. My setup is a pre to biamp arrangement and I'm thinking of an attenuator at the preamp before the interconnects to nip the right channel back a bit.

Can anyone suggest a good quality small-box way of doing this please?

Thanks, Syd

[PinkFloyd]

Dec 6, 2009 14:34:23 GMT @juke said:

I have a problem trying to get the listening position right from a chair that can't be moved. I need the left speaker to get a bit more power than the right. My setup is a pre to biamp arrangement and I'm thinking of an attenuator at the preamp before the interconnects to nip the right channel back a bit.

Can anyone suggest a good quality small-box way of doing this please?

Thanks, Syd

This is Rick's department.... hopefully he will see this thread Syd

[rickcr42]

a balance MAY work but more likely it will come down to a combination of speaker shifting AND a slight nudge of either the left or right channel.

Think distance from center-your distance to the center to speaker A and your distance to the center of speaker B,then plane as in does one speaker aim at YOU and the other in an entirely different direction ?

If yes then the fix is easy.

Pull the speaker furthest away out a bit then adjust the toe until the CENTER of the drivers is as the exact same distance and the exact same angle in relationship to your chair.

This "fix" is free other than if you don't own a measuring tape.


Oh yeah.The secret to a good STEREO image is exactness of the two channels so if for instance your left side is surrounded by soft goods and your right side all hard surfaces your image will wander so do make the atempt to passively eualize the two using plants,bookcases,CD/Records i boxes,furnuture,toss pillow,wall hangins,etc

Hope this helps

[Deleted]

Thanks for the replies.

Miguel, err, no that's why I need..... ;D (Mind you, I quickly double checked)

Rick - I've got little room to manoeuvre on position as I'm keenly aware of how little makes a difference. This a fairly bulky system in a well-filled living room. I've made all the adjustments that I can of the type you have suggested and I have great soundstage height wise but its biased too far to the right, caused precisely by a soft armchair that we can't move or remove.

I had a rethink after I posted and I think what will be best is an attenuator on the output from the right output of the source rather than the preamp. What I don't know is how to decide a value and if just an attenuator will do or do I need other components around it.

Thanks again Rick, I find it amazing that with all you're going through you have the energy to help out.

Syd

[Deleted]

had a rethink after I posted and I think what will be best is an attenuator on the output from the right output of the source rather than the preamp. What I don't know is how to decide a value and if just an attenuator will do or do I need other components around it.

Syd
You could try a resistor between the wiper (centre) and the earth side of the right channel to see what happens. Measure the resistance across those 2 points at a typical listening level setting, and let all of us know what the resistance reading is. Sometimes the attenuation needed is far less than you would expect.Yes, I know, it's not the ideal way to do it, but try it with the pot set at around your usual listening setting.
It may be enough to get you out of trouble
Alex.

[Deleted]

Alex

I'll get the reading to try this tomorrow evening. It'll be nice if it does the job.

Thanks, Syd

[rickcr42]

another "possible" fix,one that won't break the bank OR butcher your SQ in any significant way would be to use a simple "Pot In A Box" on the louder channel.

In this device you would hook up the pot as a "Rheostat" rather than the typical "voltage divider" of volume/balance controls.This "pot" then becomes a variable PAD ans as such has no influence over impedances as any add on divider would it being in reality a single inline resistor

Add the other channel jacks and interconnects even though they do nothing if you want to keep "harmonic" balance and do add in a $4 defeat switch to totally short out the pot when you need to (maybe recording ?",again just to have left right consistancy-is how I would do it anyway.

to be honest though ? I avoid ANYTHING added to the signal path unless I must and that mostly due to the added cost and complexity (not to mention point of unreliability) of the additional intercoonects every single one of which is a bottleneck right at every single jack/plug connection point

so what would be your options if not an "electronic" fix ?

Well since you asked..............................................

Option 1-sell the big mamma honking monitors and look to near field monitors as replacements

Option 2-put trolleys on you speakers so when listening you can roll them into a better position and when not ?

Back to the problem area they go !

Again,hope this helps

[cyteen]

More complicated but would give balance, volume, the option of remote and eliminate the need for a potentiometer in the signal path:

www.diyaudio.com/forums/analog-line-level/80194-lightspeed-attenuator-new-passive-preamp-137.html#post1966790

Paul Hynes has pcbs available.

[rickcr42]

Why complicate the simple ?


we are looking to pad down the signal level of a SINGLE channel which screams single resistor in the louder channel (fixed pad) or single pot as a rheostat,i.e. variable resistor,for fine tuning NOT add an entire active section to the signal path which even the best of add their own distortion,noise and sonic footprint (not to mention the power supply SQ).

not me bubba.This is about as "overkill" as I personallly would go

www.tubecad.com/2008/02/blog0134.htm




.

[rickcr42]

www.marchandelec.com/att.html

scroll to "AT12"

[Deleted]

I have temporarily held off on the resistor idea Alex. The reason is that the top of the CD player is held on with an unfamiliar recessed screw head type that I have no driver for and they are quite visible so I don't want to destroy it. After Christmas I'm sending it back for the upgrade boards that are already in the new DAC so I'll reconsider when it comes back, hopefully I'll get the right blade by then. It would be a neat solution though.

Last night I spent a few hours with Sterophile test CDs and a couple of well recorded SACDs and CDs and sitting central to the speakers the left and right test signals sound evenly matched, the left to right moving sound follows perfectly. Yet when I play music its often as if there was little information recorded to the left 'side'. So I thought of Miguel and his balance control <G> and substituted an old Marantz amp that has one . About three minutes to twelve on the balance knob is all that's needed to make it very acceptable. The room has definite acoustic issues but I have moved the speakers as much as I can and this is as good as it will get.

I see your latest post Rick and I'm going to see if anything similar is available over this side. If not I'll send to there.

Thanks for all your help, Syd

[rickcr42]

The room has definite acoustic issues but I have moved the speakers as much as I can and this is as good as it will get.

if you refer to my earlier post it was explained how left side/right side acoustics have a real and sometimes,as in your case TOO real effect on what is heard at the listening position and part of the reason why nearfield listening is becoming more popular (along with more desktop based high end systems)-takes the room acoustics mostly out of the equation.

So in your particular case it sounds more like one side is far too absorptive (the missing notes and lower apparent level) while the other speaker is sitting in a more reflective environment which means the fix could be as simple as either removing something (large throw pillow for instasnce) from one side to make it more "live !" or if you prefer your sound more reticent,more layed back,by adding that same pillow to the reflective or live side.

LOOK at your system in the context of hard and soft then make subtle corrctions until you get a good left/right match thus a more stable stereo image with music.

I see your latest post Rick and I'm going to see if anything similar is available over this side. If not I'll send to there

DIY ?

The links are more "guides" on how it is done with the ONLY reason for the PCBs (both the Marchand and the Tube CAD) being they are kits meant for easy assembly by any knucklehead but that are in reality a poorer choice purely on the merits of both the objective and subjective than hard wiring each resiastor directly to the rotary switch so if you or someone you know can solder then the plans for a single channel,12 step,stepped attenuator are here :

www.marchandelec.com/ftp/at12man.pdf


hope this helps

[Deleted]

Rick

Your posts certainly have helped. I take your point about hard/soft and their effects. A large part of the problem is this room has a fairly large and tall bookcase in the area where the speakers have to go. When I say I moved the speakers around I also did what I could with other items. One change that helped was to move the 'louder' speaker more in the 'wrong' direction which also brought it nearer to a large soft leather armchair yet things improved! So I'm fairly convinced I've done the physical things and the 10k attenuator should complete things.
Should say I also agree with near field findings. I have a small setup upstairs that has some decent small speakers on stands only 4 feet apart. When I move my seat up close the sound is amazing.

I'll report back when I get the attenuator set up. Thanks again,

Syd

[rickcr42]

Funny thing is Syd,is that your EYES are just as important when setting up a loudspeaker room as your ears,and in some cases moreso.

Think "hard and soft" then "peaks and valleys" and finaally the listening triangle.

First,when doing the initial set up you always want that "stretched" trainagle where the apex is your seat and the base the left right spread which ideally should be no less than seven feet or you begin to lose stere "width".

Next is the room/wall speaker relationship where in all cases unless the speakers are specifically designed to be placed right at the wall or corners (K-Horns for instance) you want to make them as uninfluencel as possible and this means out of the corners,away from the walls.This is the ONLY way the first note you here will be the intended one without the early reflections mixed in.Any other way and it is not the speaker but a mix of both room and speaker you hear and though rooms always influence we really want the initial attack to be pure then hopefully tune the room for a pleasant decay.

Next is mentioned earlier but is where your EYES really come in and where the first reflection point (the 1/3 of the way to your seat) can be SEEN for what it is-hard, soft,reflective,absorptive,diffuse,etc.


You WANT symmetrical but what you DON'T want is "one note reinforcement or subtraction" which translated into "anyspeak" means:

not ALL hard and not ALL soft and not at all one dimensional but two so for instance tossing an overstuffed pillow to the "stark/loud/reflective/reverberant" side may balance the ying/yang of the two sides on one front youb STILL want to make that 1/3 mark "confused".

Confused ?

Yes.Again.while symmetrical is a goal in one aspect you want to " busy up" the reflections so they are no longer DEFINED but DIFFUSE so think angles and think mountain ridges (high- low) which taken to your stuffed bookshelf would mean UNSTUFF THE BITCH thn restuff with a plan that has shelf 1 having books to the 1/4 mark on the left side then leave a space,then fill the remaining 1/2 (1/4 books,1/4 open space or hard surface staue,1/2 books which even better are on their sides)

Shel two goes similiar but with the pening in a different spot and the books/items different enough as to portray an entirely differnt acoustic pattern


I can go on but you get the gist:

Get the two sides the same then set about confusing the reflections

[rickcr42]

JEEZ !


i hope that last post is somewhat lucid because man,I couldn't make head or tails of it !

blame it on the Morphine

[matt7941]

Good evening folks.

I'm having a similar issue to Juke, in as much as balance has wandered. I've checked the 50k ALPS pot at approximate listening levels and the tracks are imbalanced by approximately 1.8kohm, not much different to when it is at full attenuation.

Can anyone advise as per Alex's suggestion as a temporary measure what value resistor could I run from centre to ground on the channel with lowest resistance to balance it up, or is it a case of just as simple as using a 1.8kohm resistor? Pardon the ignorance but I am presuming this is the issue as I've checked for cold joints etc and can't find any other reason for imbalance, I've even repositioned the furniture to have as balanced a room as I can.

I should mention the balance is only just to the left of centre but just enough to be irritating.

Cheers

Matt

[Deleted]

matt
It isn't so much the actual resistance values, but the ratio of the resistances from centre tap to earth , and centre tap to the top (input) of the potentiometer. You could as an experiment , try fitting a parallel resistor of many times the measured value from centre tap to earth of the louder channel, across it's CT and earth tags. The resistor value needed may be surprisingly high.You could temporarily have up a setup where you have say, a 100K pot or trimpot connected there, and adjust for the best results with typical listening volume. Then remove the trimpot and measure it's value at the position you got best results, and fit a MF resistor of the closest preferred value to that measured, across the CT and earth of the louder channel. Another option is a MUCH higher value in parallel with CT and top of the lower level channel.
Alex

[matt7941]

Thanks Alex. I knew there would be something more to it.

I have, after some brain straining worked out a way of accommodating a stepped attenuator using a universal joint, bracket and a sunroof modification. Otherwise, housing a stepped attenuator in a separate enclosure with a separate volume control is feasible.

One question, what is the longest the leads can really be from the board to the attenuator without it seriously compromising sound/accuracy. I know as short as possible is best but the wire length almost dictates the mounting position.

Sorry for all the questions. I must get myself booked in on a microelectronics course!

Thanks

Matt

[Deleted]

Matt
Just use some low capacitance screened cable. e.g. The red and white inners from SVHS cable are hard to work with, but if you get a metre length and carefully remove the inners, you can practice on a short length first. Also go easy on the soldering iron heat. You can also cut short lengths of the red and white outer cover, and slip over the shield wires after twisting, and also the thin inners to give it a little more protection.It is VERY easy to cut the stuff right through when stripping the outer !!!
You can of course also use lengths of quality screened audio cable.
Alex

[Deleted]

My 10k attenuator arrived from China today and was quickly wired up. I used a good quality phono socket and plug with teflon silver plated wire. It works great with one problem - there is some hum from the amp and 'static?' from the right speaker which is the line fitted with the attenuator. The attenuator is not cased up but neither it nor the wires are touching anything.

Any suggestions please?

When a track is playing this not audible to me in the listening seat.

Thanks, Syd