I've been interested in Dahlquist speakers since I heard the DQ10 s, when they first came out, and liked
their sound. I noticed the Advent looking woofer, Phillips/Norelco lower mid, and the unknown at the time
dome upper mid and tweeter, wasn't impressed with the piezo tweeter. Then about 15-20 years ago I
came across the crossover schematic and was also not impressed with the complexity, but if they sound
good, then enjoy them. I thought about them a lot over the years and my conclusion was that you don't
need anything more than a 3-way, with a better mid and tweeter, vertically aligned, and what do you know
then you have essentially the DQ20, or the i version which can be bi-amped. The DQ20 and i version also
use the Advent woofer, a Vifa 5" paper cone mid with a large magnet, and a .75" Scanspeak tweeter.
I'm often asked how I would build an Advent 3-way and this is pretty close to what I'd do but probably
with a different voicing and a more in-phase crossover. Or I might consider as close as possible to the
DQ20i and an alternate that is not phase linear but with in-phase crossovers - no longer DQ20i inspired.
I was going to build a pair from Advent boxes but then a pair became available from a local friend with
the light oat colored grilles that I like. Also, the woofers had already been refoamed by legendary Miller
Sound. I am in the process of replacing the one NPE cap in the woofer circuit and confirming the schematic
that is online and the inductor values. All the other caps are Solen 400V 5% poly films.
The DQ20, not the i version, was reviewed in Stereo Review June 1988 and is attached as a .pdf.
Also, here's a much more detailed review of the very similar but all in one box M907i, by Don Keele in
Audio from Aug 1990, pg 92 in the .pdf:
https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/90s/Audio-1990-08.pdf
It is VERY interesting that Keele finds the M907i to be fairly linear phase which is what the designer was
trying to achieve. But it uses higher order crossovers, highly damped, with the midrange wired out of
phase - interesting, I'd like to see the math behind this. Note that the M907i uses nearly the same crossover
and drivers. It even has the poor vertical polar response that is expected with a 1st order system with the
main lobe pointing down, rather than up in the M907i. Keele suggests flipping them over for better
standing response.
They look very nice in this room with the light oat colored grilles:
Thread here on Dahlquist history, and at that time he was living in NY:
their sound. I noticed the Advent looking woofer, Phillips/Norelco lower mid, and the unknown at the time
dome upper mid and tweeter, wasn't impressed with the piezo tweeter. Then about 15-20 years ago I
came across the crossover schematic and was also not impressed with the complexity, but if they sound
good, then enjoy them. I thought about them a lot over the years and my conclusion was that you don't
need anything more than a 3-way, with a better mid and tweeter, vertically aligned, and what do you know
then you have essentially the DQ20, or the i version which can be bi-amped. The DQ20 and i version also
use the Advent woofer, a Vifa 5" paper cone mid with a large magnet, and a .75" Scanspeak tweeter.
I'm often asked how I would build an Advent 3-way and this is pretty close to what I'd do but probably
with a different voicing and a more in-phase crossover. Or I might consider as close as possible to the
DQ20i and an alternate that is not phase linear but with in-phase crossovers - no longer DQ20i inspired.
I was going to build a pair from Advent boxes but then a pair became available from a local friend with
the light oat colored grilles that I like. Also, the woofers had already been refoamed by legendary Miller
Sound. I am in the process of replacing the one NPE cap in the woofer circuit and confirming the schematic
that is online and the inductor values. All the other caps are Solen 400V 5% poly films.
The DQ20, not the i version, was reviewed in Stereo Review June 1988 and is attached as a .pdf.
Also, here's a much more detailed review of the very similar but all in one box M907i, by Don Keele in
Audio from Aug 1990, pg 92 in the .pdf:
https://worldradiohistory.com/Archive-All-Audio/Archive-Audio/90s/Audio-1990-08.pdf
It is VERY interesting that Keele finds the M907i to be fairly linear phase which is what the designer was
trying to achieve. But it uses higher order crossovers, highly damped, with the midrange wired out of
phase - interesting, I'd like to see the math behind this. Note that the M907i uses nearly the same crossover
and drivers. It even has the poor vertical polar response that is expected with a 1st order system with the
main lobe pointing down, rather than up in the M907i. Keele suggests flipping them over for better
standing response.
They look very nice in this room with the light oat colored grilles:
Thread here on Dahlquist history, and at that time he was living in NY:
Dahlquist history
I got this off the yahoo Dahlquist group. No idea if its all true but who would lie? Anyway, some interesting tid bits of info in here. About 3 years after Saul Marantz sold his company to Superscope Inc, he discovered another great talent who was obsessed with designing the perfect speaker...
audiokarma.org
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