72 replies to this topic

[MartyK]

While other may disagree, I have stacked OLA's on NLA's. The result is quite in impressive. So, although most people probably stack like models, I do not believe it is absolutely necessary.

If you are serious about the advents, you might also find the following thread of interest.

"Advent experiment - mod - much better sound"

Good luck!

Marty

[tysontom]

When stacking Advents are the top units inverted to keep the tweeters fairly close together? If this is not done one would think that the rather distant spacing between the tweeters would cause some odd interference effects. With the top units inverted, the tweeters would form a short, vertical "line" over much of their operating ranges, which would help to reduce vertical radiation in the upper midrange and treble. No telling how the widely spaced woofers would intereact with each other, however.

Howard Ferstler

I believe that the old rule-of-thumb on stacking like-model speakers is to put the tweeters close together in the vertical-stacking arrangement. On the other hand, if the woofers are together -- with the tweeters at the top and bottom -- a phenomenon known as "mutual-radiation" causes the bass response (below the frequency of ultimate-radiation impedance) to rise about 3 dB all the way down to resonance. This is akin to placing single left- and right-channel speakers in the corners. Unfortunately, this rise in this overall low-frequency output does not give added bass extension; the resonance stays the same, but the output (relative to the midrange/treble) gets "heavier" and "punchier" as a result. With the tweeters at the top and bottom, other odd diffraction effects can occur. Using unlike models of a speaker, as in different vintages of the Large Advent, the only real issue might be efficiency, with one set getting more of the amplifier's output than the other set, but otherwise it should work fine.

Stacking mainly gives a system increased power-handling capability and greater "impact," it might also give the sense of a larger sound source with increased spaciousness.

--Tom Tyson

[jackfish]

[Zilch]

When stacking Advents are the top units inverted to keep the tweeters fairly close together? If this is not done one would think that the rather distant spacing between the tweeters would cause some odd interference effects. With the top units inverted, the tweeters would form a short, vertical "line" over much of their operating ranges, which would help to reduce vertical radiation in the upper midrange and treble. No telling how the widely spaced woofers would intereact with each other, however.

They are not mirror-imaged, and there is no vertical line. I have measured stacked Advents here:

http://www.audiokarm...ad.php?t=165025

The rational solution is to disconnect one of the tweeters and lowpass the bottom woofers as subs.

'Nuf said, lest the matter be retired to The Kitchen....

[soundminded]

When stacking Advents are the top units inverted to keep the tweeters fairly close together? If this is not done one would think that the rather distant spacing between the tweeters would cause some odd interference effects. With the top units inverted, the tweeters would form a short, vertical "line" over much of their operating ranges, which would help to reduce vertical radiation in the upper midrange and treble. No telling how the widely spaced woofers would intereact with each other, however.

Howard Ferstler

Why not toe one pair say the top pair in and the bottom pair out? Or better yet, make both bottom pairs and toe the outer pair out and the inner pair in? Then they would be Allisons....well kinda....sorta.....not. What if you did it the other way and toed the inner pair out and the outer pair in, would that give similar results? Or just turn both pairs around to face the front walls at angles, add a front 5" KLH table radio speaker and turn them into Bose 901 and a halfs.

BTW Zilch, your best efforts are lost on me. When I try to access it on AK, I get;

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Guess if you are not a member and can't give the sign, you're not allowed in. Somehow I'll just have to learn to live without it. Don't know if I can but I'll try my best.

[jackfish]

Obviously, the stacked Original Large Advents cannot sound good according to one set of measurements. I think sprucemoose in the AK thread has a good question about how they sound. There is a reason why people are told they must audition loudspeakers, preferably with the components they will use, to find those that sound good to them.

My setup includes stacked New Large Advents in a 11'9"x15'4" room with bass traps in the corners and absorption at wall and ceiling reflection points and behind the listener. The baffles of the speakers are 63" from the front wall and the center of the baffles are 39" from the side walls and 63" from each other. The interface of the cabinets in the stack are at listening ear level which is just outside of the near field (72"). I also have PeteB's 6dB "BSC" in the tape loop.

I think this setup sounds good. I listen to alot of music with it. However, I also know my hearing is compromised. How one's hearing relates to measured frequency response is worth exploring. I have a RS digital SPL meter and would like to put it on a tripod at the listening position and measure the frequency response of the system. What source is recommended to play the frequency spectrum?

[Zilch]

What source is recommended to play the frequency spectrum?

Sinusoidal test tones. The B&K "Ideal Response" chart provides the correction factors to use for each frequency when a dBC meter is used.

You also use EQ, as I recall. Getting this to work requires far more than sticking one speaker atop another, clearly; thank you for clarifying the point. We previously analyzed your setup more comprehensively, as well.

In the end, in the larger sense, stacking violates well-established acoustic principles and therefore, doesn't work. See this quote from The BAS Speaker, 6/77, re: AR "Live vs. Recorded" demo setup, posted in another thread here:

And last but not least, the loudspeakers: a single pair of AR-10's. Two-way speakers do not have the power-handling ability required. Multiple-driver systems, such as the LST, don't work, apparently because of interference effects between drivers covering the same frequency range. The same problem exists when more than one pair of speakers is tried. So: a single pair of three-way systems, located on the wall behind the drummer, about four feet apart.

[Zilch]

Guess if you are not a member and can't give the sign, you're not allowed in. Somehow I'll just have to learn to live without it. Don't know if I can but I'll try my best.

They're trying to tell you something, and thankfully, you got the message....

[dingus]

...In the end, in the larger sense, stacking violates well-established acoustic principles and therefore, doesn't work...

hmm, Large Advents are a decent speaker, they sound quite good and stacking them sounds even better, at least to many owners including myself. if you dont like how they sound that is your prerogative, but in the end this does indeed work for many regardless of acoustic principles, well established or not.

back on topic, the op was asking about matching stacked Advents. i've stacked with matching Large Advents and also with a pair of Large Advents and a pair of Advent 5002's. both trials resulted in similarly outstanding results. as others have found, inverting the top pair gives better results.

[jackfish]

Sinusoidal test tones. The B&K "Ideal Response" chart provides the correction factors to use for each frequency when a dBC meter is used. You also use EQ, as I recall.

Are these test tones available on a CD or must I download a program and run them through a computer? I have NCH Tone Generator. I would much prefer running them through my system from the CD player than from my laptop which has questionable sound card quality. I suppose I could make a CD of test tones using something like the NCH Tone Generator.

[jackfish]

Also, what EQ is available? Will REW do the job?

[Zilch]

Are these test tones available on a CD or must I download a program and run them through a computer? I have NCH Tone Generator. I would much prefer running them through my system from the CD player than from my laptop which has questionable sound card quality. I suppose I could make a CD of test tones using something like the NCH Tone Generator.

http://www.audiokarm...a...8877&page=6

Corrections for dB-C across the top of the B&K "Optimum" curve, below:

Attached Thumbnails

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[justw]

You can find a suitable test cd here:

http://binkster.net/extras.shtml#cd

[dingus]

..Zilch, hey buddy don't diss what you havn't done!

he's done the LA's, he just didnt like how they measured, the sound doesnt matter.