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By a "small-ish" imbalance, I mean that the left or right channel is stronger by about (say) 0.3 to 1.5 decibels, and that this results in a shift of the sonic image's center. Once the imbalance gets to 2.0 dB or more, it's pretty egregious to the point that most people can't help but notice it; usually this means you've got a serious setup or component issue. However, smaller cumulative imbalances can arise even with properly functioning, well setup gear.
This is an issue that's driven me nuts for years, and I believe it's quite common in high end setups. Assuming your gear is all within specs, a channel imbalance is most likely caused by:
1) Your phono cartridge - Many high end models are spec'd to only within 1.0dB of perfect L/R balance. Some allow as high as 1.5dB, and the flagship level usually offers 0.5dB, which is still quite audible. I'm ignoring the effects of turntable setup here, which I'll assume has been done properly.
2) Your room setup. Acoustic asymmetries can cause the image to appear off-center, and the effect can easily be perceived as a 0.75dB (or so) imbalance - though the exact amount is going to be frequency-dependent, which is somewhat complicating, whatever happens in the critical midrange region is what you're most likely to perceive.
Electronics and speakers/headphones are a less likely cause, though still a possibility. I've seen an old pair of tube monoblocks, otherwise perfectly functioning, with a 1.2dB imbalance (it wasn't the tubes); they still sounded great. Headphone systems driven from a digital source are free of the two primary causes, though in my experience high end headphones seem less precisely balanced than speakers (for whatever reason), so an imbalance can still be an issue in these systems. Ironically I think the more handmade nature of high-end cans doesn't do them any favors here.
In my 2ch speaker system, an imbalance of 0.5dB is quite noticeable. It corresponds to a perceived shift of roughly 3-5 inches laterally across the soundstage (for reference, my speakers are 7-8 feet apart and I sit 8 feet back). So, a singer that should appear dead-center over my TT spindle now resides over a side of the platter. At that, it's annoying. An imbalance of 1dB is much worse; yet, that's not terribly uncommon even with all properly functioning gear (a cartridge can contribute that alone).
I'm not aware of any good high end solutions, and that surprises me (yes, I know the digital/PC guys can compensate whatever they like in the digital domain). Well, other than perpetually swapping gear to chase the right mix, which admittedly many of us are addicted to. Surely this must also drive other audiophiles up the wall? Yet it's hardly ever discussed.
Solutions? The problem is that as pursuers of sonic bliss, we're paranoid about introducing components into the signal chain that might degrade sound quality; even for such a worthy cause as perfect channel balance. The solutions I've tried include:
1) Get a preamp with a balance pot; these days it's a rare feature. My Rogue Audio Hera surprisingly has one - an Alps Blue type. It can be switched in/out of the Hera's circuit, and this is fortuitous, because it audibly degrades sound quality. Mercifully the the main volume control is a nice (motorized) stepped attenuator. In this case, I'd rather deal with a small imbalance.
2) Swap various L/R interconnects in an attempt to cancel out imbalances. This only works if you've got an even number of roughly equal imbalanced components (including the room), and (sometimes) if you're willing to live with swapped L/R channels. It's unlikely you'll achieve perfect balance with this technique, but sometimes it can reduce the problem "just enough".
3) Build a simple resistor box or cable that attenuates one channel by a small amount. It's a bit of a pain to go "DIY" (I for one have no desire to get into amp building), but this is as easy as projects come in DIY-land. First, you calculate the resistance value needed for a desired attenuation in dB; if the desired attenuation is small then you can get away without a shunt resistor (note that the calculation depends on the input impedance of the component it's feeding into). I'm not very handy so I used a simple plastic box with 2 pairs of RCA connectors. This requires use of an extra set of interconnects, however in my listening, the balance it achieves far outweighs any degrading effects of the extra components. Since I chose to place the box before the phono stage (this can be risky because of the chance to pick up noise), I also added a cartridge loading resistor; in this way I could select a value not offered by my phono stage (I've settled on 230 ohms with my Koetsu cartridge for now, the closest settings on the phono stage were 100 and 1000). In the past week, I've been MUCH happier listening with this box - I can tolerate record crackles/pops, but even a small imbalance just drives me nuts! This is just one of those issues that I have a LOW tolerance for. I can highly recommend the DIY route as a solution, if you've got a small system imbalance that's been eating away at your soul
Ideally, I would want a discrete-step balance control in my preamp (a stepped attenuator balance control). At a minimum it should offer +/- 1.5dB of balance compensation, in 0.5dB increments. This would allow for a balance within 0.25dB - which is vanishingly small - and with a minimum of sonic degradation. An imbalance of more than 1.5dB is getting into "something's wrong that needs fixing" territory, so I think that this range and granularity combination would be effective for most systems. I just can't believe this isn't an ubiquitous feature in quality preamps (along with a mono button/switch, which at least does get some love from manufacturers).
Has anyone else here obsessed over small-ish imbalances like me?
This is an issue that's driven me nuts for years, and I believe it's quite common in high end setups. Assuming your gear is all within specs, a channel imbalance is most likely caused by:
1) Your phono cartridge - Many high end models are spec'd to only within 1.0dB of perfect L/R balance. Some allow as high as 1.5dB, and the flagship level usually offers 0.5dB, which is still quite audible. I'm ignoring the effects of turntable setup here, which I'll assume has been done properly.
2) Your room setup. Acoustic asymmetries can cause the image to appear off-center, and the effect can easily be perceived as a 0.75dB (or so) imbalance - though the exact amount is going to be frequency-dependent, which is somewhat complicating, whatever happens in the critical midrange region is what you're most likely to perceive.
Electronics and speakers/headphones are a less likely cause, though still a possibility. I've seen an old pair of tube monoblocks, otherwise perfectly functioning, with a 1.2dB imbalance (it wasn't the tubes); they still sounded great. Headphone systems driven from a digital source are free of the two primary causes, though in my experience high end headphones seem less precisely balanced than speakers (for whatever reason), so an imbalance can still be an issue in these systems. Ironically I think the more handmade nature of high-end cans doesn't do them any favors here.
In my 2ch speaker system, an imbalance of 0.5dB is quite noticeable. It corresponds to a perceived shift of roughly 3-5 inches laterally across the soundstage (for reference, my speakers are 7-8 feet apart and I sit 8 feet back). So, a singer that should appear dead-center over my TT spindle now resides over a side of the platter. At that, it's annoying. An imbalance of 1dB is much worse; yet, that's not terribly uncommon even with all properly functioning gear (a cartridge can contribute that alone).
I'm not aware of any good high end solutions, and that surprises me (yes, I know the digital/PC guys can compensate whatever they like in the digital domain). Well, other than perpetually swapping gear to chase the right mix, which admittedly many of us are addicted to. Surely this must also drive other audiophiles up the wall? Yet it's hardly ever discussed.
Solutions? The problem is that as pursuers of sonic bliss, we're paranoid about introducing components into the signal chain that might degrade sound quality; even for such a worthy cause as perfect channel balance. The solutions I've tried include:
1) Get a preamp with a balance pot; these days it's a rare feature. My Rogue Audio Hera surprisingly has one - an Alps Blue type. It can be switched in/out of the Hera's circuit, and this is fortuitous, because it audibly degrades sound quality. Mercifully the the main volume control is a nice (motorized) stepped attenuator. In this case, I'd rather deal with a small imbalance.
2) Swap various L/R interconnects in an attempt to cancel out imbalances. This only works if you've got an even number of roughly equal imbalanced components (including the room), and (sometimes) if you're willing to live with swapped L/R channels. It's unlikely you'll achieve perfect balance with this technique, but sometimes it can reduce the problem "just enough".
3) Build a simple resistor box or cable that attenuates one channel by a small amount. It's a bit of a pain to go "DIY" (I for one have no desire to get into amp building), but this is as easy as projects come in DIY-land. First, you calculate the resistance value needed for a desired attenuation in dB; if the desired attenuation is small then you can get away without a shunt resistor (note that the calculation depends on the input impedance of the component it's feeding into). I'm not very handy so I used a simple plastic box with 2 pairs of RCA connectors. This requires use of an extra set of interconnects, however in my listening, the balance it achieves far outweighs any degrading effects of the extra components. Since I chose to place the box before the phono stage (this can be risky because of the chance to pick up noise), I also added a cartridge loading resistor; in this way I could select a value not offered by my phono stage (I've settled on 230 ohms with my Koetsu cartridge for now, the closest settings on the phono stage were 100 and 1000). In the past week, I've been MUCH happier listening with this box - I can tolerate record crackles/pops, but even a small imbalance just drives me nuts! This is just one of those issues that I have a LOW tolerance for. I can highly recommend the DIY route as a solution, if you've got a small system imbalance that's been eating away at your soul
Ideally, I would want a discrete-step balance control in my preamp (a stepped attenuator balance control). At a minimum it should offer +/- 1.5dB of balance compensation, in 0.5dB increments. This would allow for a balance within 0.25dB - which is vanishingly small - and with a minimum of sonic degradation. An imbalance of more than 1.5dB is getting into "something's wrong that needs fixing" territory, so I think that this range and granularity combination would be effective for most systems. I just can't believe this isn't an ubiquitous feature in quality preamps (along with a mono button/switch, which at least does get some love from manufacturers).
Has anyone else here obsessed over small-ish imbalances like me?
