I am soon taking delivery of a pair of stacked quads, recently rebuilt by Electrostatic Solutions and with custom Sound Anchor stands (steel stands, with speakers set between aluminum side panels). The aluminum side panels place the two speakers on a vertical plane with the transformers back-to-back in the middle, and no middle surface to which a tweeter could be mounted. I can also get custom side panels made that would accommodate other configurations (convex or concave speaker positioning, a middle panel in which tweeters can be inserted, etc.). I have had single quads before (Wayne Piquet rebuilds), and I have the following ancillary equipment that worked well with the single quad 57's: a Bedini 25/25 solid state amp, a pair of VTL Tiny Triode TT25 EL84 monoblocks (most recent build), a pair of Cary SLM70 EL34 monoblocks (35 watts), a pair of Townshend super tweeters, and a pair of Magnan signature speaker cables.
My questions, in order of priority, include:
1) There are 3 ways to wire these speakers: a single amp driving a stacked quad wired in parallel, or in series, or two amps (or two channels) each driving a single quad in the stacked pair. What are the advantages and disadvantages of these three options? Does choosing one of these options disqualify any of my current amplifiers? Note that I don't have four channels of the same amplification for the third option, and would prefer to use my current amplifier arsenal, so I would have to mix and match amps for each stacked pair, which might require a means to balance output.
2) Electrostatic Solutions (Kent) prefers the geometry of this mounting (2 speakers on a flat plane) to convex or concave configuration. He places the speakers kind of high in order to deal with the limited vertical dispersion of the tweeter (beaming), so that the midpoint of the bottom quad is at seated ear level. The stand is fully height adjustable, so there is plenty of flexibility there. Any other thoughts about the mounting geometries?
3) I know that the Mark Levinson HQD stacked quad systems used supplemental tweeters. I have the Townshend super tweeters, which claim to " accurately reveal high frequency detail above 6kHz" but seem to emphasize frequencies above 20kHz. I also have nowhere to mount the supertweeters - I would have to strap them to one leg of the stand. I know that Kent doesn't believe that stacked quads need additional tweeters. What is your experience? I could change the panel configuration so there is a middle surface for tweeter mounting. Is it necessary to use expensive types of ribbon tweeters (e.g. the Deccas used by Mark Levinson), or are there more affordable and excellent ribbon tweeters now available? How does one wire the tweeters - in parallel with the stacked quads with a simple capacitor/resistor as a passive Xover?
Thanks in advance for any insight you can provide! Peter
