Why do some amplifiers throw a bigger soundstage than others?

I have a pair of Thiel CS6 speakers that dip to around 2 ohms in part of the frequency spectrum. I run them with a Krell KSA 300S that doubles its power down to one ohm (300 watts @ 8 ohms, 2400 watts @ 1 ohm). When I took the amp in for recapping I tried hooking up my Onkyo A/V receiver to the Thiels. The results were laughable. The Onkyo sounded like an AM radio. The soundstage was flat as a pancake. I figured there would be a difference but I had no idea it would be that dramatic.

@8th-note Your conclusion might not be accurate - its very likely that current had nothing to do with it.

To present a sound stage the mids and highs need to be reproduced properly. You usually don't need current for that since most speakers are fairly easy to drive in the mids and highs. Theils tend to have their weird impedance issues in the bass region, which has nothing to do with presenting a sound stage.

If the Onkyo has a power amp input I would run your preamp into that and see if you still say the same thing. Of course by now the issue might be moot since this is an anecdote; my point is that there were a lot more variables going on here than you initially surmised.

Our OTLs are known for a very good soundstage and yet they have a high output impedance so can't deliver the power into lower impedances. Our class D can- but the sound stage of our class D vs our OTLs is nearly identical.

atmasphere

11,504 posts

03-07-2024 at 12:37am

…impedance issues in the bass region, which has nothing to do with presenting a sound stage.

@atmasphere is this statement meant to rule out bass as being important to listener perception of soundstage? That would seem doubtful… query not intended as a challenge for which I have empirical grounds, just interested.

atmasphere

11,504 posts

03-07-2024 at 12:37am

…Our OTLs are known for a very good soundstage and yet they have a high output impedance so can’t deliver the power into lower impedances. Our class D can- but the sound stage of our class D vs our OTLs is nearly identical.

And this would make that potential discrepancy even more interesting.

crustycoot

572 posts

03-06-2024 at 10:50pm

…I also believe the preamp is more instrumental in establishing soundstage than the power amp is in my experience.

Not sure you intended it but, that’s gonna be the pun to beat today.

As a monoral signal has no separation, by the same token, it would seem to me that an amp with better channel separation would throw a wider soundstage than one with poor separation.

BUT, perhaps a bit of out-of-phase channel crosstalk could make the image wider? 

Also, one would want both channels to be/track as identically as possible, to keep the soundstage from shifting about.  If a channel lacks what the other has, it can't really produce mono for a proper center image at that frequency/volume.  This would apply anywhere along the audio chain.

I must admit that it is fun imagining my large deep soundstage emanating from my reference system. So damn good that I suspect it ain’t real - its a repeating simulation.

is this statement meant to rule out bass as being important to listener perception of soundstage?

@benanders Yes. Bass (20Hz to about 150Hz) is important if you want to get the tonality right but it has little to do with imaging and sound stage- the lower the frequency the more this is true. Below 80Hz in most listener's rooms the bass is 100% reverberant (which is why subwoofers don't have to be in the same location as the main speakers if crossed over below 80Hz).

You can try a simple experiment to show how this is so. If you use midrange drivers and tweeters as speakers you'll find they can image nicely, but if you use only woofers that are rolled off at a normal crossover point you'll find the image very indistinct or non-existent, depending on the woofer.