[roscoeiii]

Due to what I think is the contribution of my living room (opens on one side to a dining room, so missing a side wall), I have a bit of a channel imbalance in my system. So I am thinking about maybe DIYing a balance control to remedy this situation.

Any recs on the best way to do this?

Seems that I can use a Goldpoint or a DACT attenuator that would give me 0.5 dB steps. For example using this (Goldpoint is also possible, but they don't list this on their webpage, and I'd have to install the resistors myself):

http://www.dact.com/html/balance_controls.html

Or there is a transformer based option:

http://www.sowter.co.uk/cgi-bin/ca000001.pl

Another possibility is grabbing a Wellbourne Labs remote controlled volume control and just use the balance controls on it:

http://www.welbornelabs.com/remote.htm

Any experience with any of these or other suggestions? Obviously looking for the most transparent option.

If it matters, this will be between my Musical Fidelity kW preamp with an output impedance of  <0.5 ohm (!) and my Rogue Stereo 90, which has an input impedance of 200k ohms.

[wakibaki]

The problem is complicated by the fact that you may want to set different balance points at different listening levels.

Perhaps the most straightforward way to implement this is a way of allowing you to turn down one channel by a variable amount.

This will avoid most complications such as increased crosstalk or noise.

Just get a single 20k logarithmic pot and wire it into the side that is too loud. Then you can turn that side down...



I chose the value to fit with your system. This is absolutely the most transparent solution other than using a pair of resistors, which obviously won't be adjustable. You can use a stepped attenuator if you want.

If you use a conventional balance control it will introduce an overall loss, or you'll need some amplification (and a power supply) and it will push up the crosstalk, possibly introduce some noise if not correctly designed.

w

[Folsom]

Currently I'm only interested in Lighternote. Short of that populate a stepped attenuator with $12-17 naked Vishay's. (which may not be nearly as good as LDR's).

[jtwrace]

Take measurements then fix the problem. 

[roscoeiii]

Take measurements then fix the problem.

Measurements? That's crazy talk!   

[roscoeiii]

Currently I'm only interested in Lighternote. Short of that populate a stepped attenuator with $12-17 naked Vishay's. (which may not be nearly as good as LDR's).

Ohhh, LDRs are a nice idea. Off to diyaudio (though the length of some of these LDR threads is a bit scary...)

[wakibaki]

Wouldn't touch 'em with a bargepole, I can always hear them a mile off.

w

[roscoeiii]

Wakibaki,

Is there any particular logarithmic pot or stepped attenuator that you'd recommend based on the output and input impedences I am dealing with, and since I won't need a huge amount of attenuation?

[wakibaki]

Yes. The general rule is that for audio, impedances should be stepped by a factor of 10. Therefore your pre should see 5 ohms minimum and your PA should be driven from 20k maximum.

For these reasons I suggested a 20k pot or switched attenuator. The pre will drive more cleanly into a higher value. You could just choose not to populate the switched attenuator with the greater attenuations.

w 

[roscoeiii]

Aha. Got it. Any brands that you particularly recommend?

[wakibaki]

Alps are good pots. Watch out for fakes. The Blore Edwards Type 72 30-way switch is good.

If you can find somebody to supply one.

http://www.blore-ed.com/products/index.php?title=Type_72

Populate it with 1206 thin-film (metal-film) resistors which fit exactly. Vishay are good, you can get quite a few values off-the-shelf from Farnell.

w

[Folsom]

I don't find Alps pots to be transparent at all. They are very good, but nothing compared to a stepped attenuator.

[howburger]

Scott Endler's attenuators  http://mysite.verizon.net/vze4c5pt/id2.html get audiophile approval in a few forums(fori?) Plug into the back of your amp on the affected channel. Unless I'm missing something.

Harold

[djtw]

Although I use a Goldpoint stepped attenuator in my preamp, these have gotten favorable online reviews, but they are not cheap.

http://www.khozmo.com/

[roscoeiii]

Excellent options. I e-mailed Khozmo, but looks like the attenuation steps are larger than I'd like. Will look at the Endler options in a sec.

Someone on another forum also brought up the idea of adjusting the bias in a tube amp to correct for the imbalance. Of course, I'd check with Rogue before doing that...

[andyr]

Due to what I think is the contribution of my living room (opens on one side to a dining room, so missing a side wall), I have a bit of a channel imbalance in my system. So I am thinking about maybe DIYing a balance control to remedy this situation.

Any recs on the best way to do this?

Seems that I can use a Goldpoint or a DACT attenuator that would give me 0.5 dB steps. For example using this (Goldpoint is also possible, but they don't list this on their webpage, and I'd have to install the resistors myself):

http://www.dact.com/html/balance_controls.html

Or there is a transformer based option:

http://www.sowter.co.uk/cgi-bin/ca000001.pl

Another possibility is grabbing a Wellbourne Labs remote controlled volume control and just use the balance controls on it:

http://www.welbornelabs.com/remote.htm

Any experience with any of these or other suggestions? Obviously looking for the most transparent option.

If it matters, this will be between my Musical Fidelity kW preamp with an output impedance of  <0.5 ohm (!) and my Rogue Stereo 90, which has an input impedance of 200k ohms.

Why not replace the log stereo pot in your MF preamp with 2 x log mono pots of the same value?  TKD plastic log pots are small and sound good ... the TKD stepped attenuator sounds better, but is physically very large.


Regards,

Andy

[roscoeiii]

Why not replace the log stereo pot in your MF preamp with 2 x log mono pots of the same value?  TKD plastic log pots are small and sound good ... the TKD stepped attenuator sounds better, but is physically very large.


Regards,

Andy

That is not going to be possible due to the big ole faceplate and volume knob on the MF, and I want to keep it stock instead of modding it. I'd also lose the ability to use my remote, a necessity due to dog-on-lap commitments.

[wakibaki]

I've got this relay-switched remote/touchsense passive preamp I designed...



...and I'm working on this stepper-motor operated version, which will be a lot more compact.



I'm waiting to take delivery of a CNC mill, which will make it easier to produce, and result in a more professional looking item.   

...but I wasn't going to mention those 

w

[Steve]

I don't find Alps pots to be transparent at all. They are very good, but nothing compared to a stepped attenuator.

+1. I also found the Alps to be wanting. Also, the 10 times rule can be 4 times according to the RCA
Radiotron Designers Handbook. Of course 100 times is complete nonsense.

---------------

Something to remember is that with DC output coupling, 20K May be ok. However, with capacitive output,
the size of the cap is very important to bass response integrity. However, midpoint resistance of 20k
(approx 2 o'clock rotation, 10k ohms) is barely ok as the high frequency response will be minimum at that point.
This is especially important if ICs are directly connected (relatively high capacitance) to the wiper arm.

Thus it is important that the balance control is near maximum or near
minimum rotation for the best high frequency response.

Cheers.

Steve

[roscoeiii]

I've got this relay-switched remote/touchsense passive preamp I designed...



...and I'm working on this stepper-motor operated version, which will be a lot more compact.



I'm waiting to take delivery of a CNC mill, which will make it easier to produce, and result in a more professional looking item.   

...but I wasn't going to mention those 

w

Oh do tell more. What price points to you envision for example?