Christmas coming, and DIY 2003 in Tucson, I decided to build some new
small speakers to replace the Onyx. I looked for drivers that would work
well in approximately 7 liters, (440 cu in). This seems like a manageable
size for small living rooms (one requirement) and/or for home theater.
Building all of the boxes at the same time certainly streamlines the construction
and finishing process. It also gave me a chance to compare designs and
test my voicing skills for consistency. I also got an opportunity to use
my new Behringer ECM3000 microphone and UBB802 mixing console.
these at the Tucson DIY 2003. For the most part, people were impressed
with both designs. Some folks were kind enough to offer refinements (like
padding down the Garnet a bit). I've addressed those in the designs posted
wide X 8.0" deep X 11.5" high
MDF baffles, remainder 1/2" Baltic birch
Long, 1.5" Diameter (PE# 260-402)
812978 (Center is 3.5" from top)
55-1855 Aluminum (Center 8" from top)
D27 TG-05-06 (Center 2.75" from top)
850108 CSX (Center 7.75" from top)
812978 (Center is 2.75" from top)
When my brother
asked for a compact monitor for his home in NoCal, I thought I'd
use the last blank boxes from my 7 Liter projects. I liked the high
end from the Sparky and the bottom end from the Garnet.
I always felt the Vifa D27 had a bit too much sizzle for my taste.
I had the woofers on hand, as well as second pair of 812978 tweeters.
(I may be alone, but I like Peerless tweeters). So the
Garnet II combo was born.
Since my bro
has a small bright room for these, I figured he would literally mount
these on a book shelf. So I decided this design should cut back a bit
on baffle step. The big padding resistors on the Garnet look kind of spooky
-- though they sound good. So I tried some new topologies with a lower
crossover for the Garnet II [G2].
still has a notch filter to tame the rising response of 108. However,
I reduced the coil to 1.2 mH for less baffle step.
section adds a bypass cap to control diffraction and impedance effects
of the tweeter. The net effect is a 2100 hz crossover frequency that is
relatively insensitive to tweeter polarity. Padding is now in the 1-2
ohm range and this design appears 1-2 db more efficient than the original
borrowed back the original Garnet pair for comparison. The G2 benefits
more from being closer to the wall. Overall, I prefer the G2 for it's
mids and smoother upper bass. The orginal Garnet has a bit more sizzle
at the top end, but I find the G2 smoother and less fatiguing. The G2
seems to run out of gas at the extreme high end. Overall,
I find the G2 smoother and better balanced across the band. The Garnet
seems a bit punchier, but won't handle higher power levels as gracefully
as the G2.
is my first pass at dark "misson" oak. I made up a water based
dye with Dark Mission Brown & Reddish Brown Transtint. This was sealed
with two spray coats of dewaxed shellac. Next, I mixed black/burnt umber
latex glaze to fill the pores. (You need to work quick!) Finally three
coats of Fuhr 355 waterbased acrylic (gloss). As always, the second one
looks better than the first.
these designs would do well as a standalone monitor for music. Probably
not enough bottom end for hip-hop, techno types, but entirely adequate
for the over 30 crowd.
Sparky - High
Quality Shielded Monitor for about $60
of my friends is blessed with a hypertalented daughter who plays in three
bands and orchestras. His son is interested in movie and sound editing.
As a family project, they are recording the daughters performances and
rendering them to DVD. They needed a set of shielded monitors for mastering.
Since my friend and his wife graduated from Tempe Normal College (now
known as Arizona State), I decided to finish the Sparkies in maroon &
gold. (As a graduate of The University of Arizona, this was aesthetically
difficult, -- but friendship won out)
my driver stash, I found two MCM 55-1855 5" Aluminum cone shielded
woofers. I checked around for folks who measured them. They looked nice
out to about 2400 where they drop like a rock. I needed a good shielded
tweeter with low Fs. After searching a bit I wound up with a Peerless
812978. Under $20 with Fs of about 940.
measured both drivers in the box as is my custom, and got them prepped
in LspCad. I was prepared to use notch filters to tame out resonance at
8000 Hz. With some wild impedance curves, a Zoebel was needed for the
MCM. After tweaking, I tried pulling the notch filter. With the slopes
used, it did not prove necessary. The 25 ohm padding resistor may look
a bit strange, but it's genuine. So is the 1.5 ohm resistor in series
with the tweeter shunt coil. The increased DCR is needed to keep the impedance
of this speaker reasonably level and to tame a slight diffraction peak.
Final crossover frequency is about 2200.
FOR SPARKY MTM MODEL CLICK HERE
is a sweet little monitor with good solid bass down to about 60 hZ. Nice
and smooth, great vocals, piano. I really like the Peerless tweeter. No
sign of "grit". Not as airy as some but not as raspy either.
The slight horn loading gives it a very precise placement. Details are
there when they should be, but quiet otherwise. As much as I like the
Audax TMO25, I think this Peerless is at least as good. Not as airy, but
the extra range and power handling is a real plus. It is a step up from
the little square Peerlesss neo. The MCM is better than expected especially
for $14! Solid throughout it's range, a bit laid back, solid but not overwhelming
bass. Definitely more bottom end than my sealed Topaz in a smaller box.
These could easily serve as music mains in a reasonable room.
was my first experiment with filled pores. I veneered the box in red oak.
After sanding with 180 and blowing everything clean, I prepared a water/alchohol
base for dying. Using Transtint dye concentrates, I mixed up something
I thought would look good. I used my cheapie detail gun to spray the dye.
After drying for a day, I scuffed the surface and shot the boxes with
two coats of 2# cut, pale dewaxed shellac.
is a latex tinted with Transfast pigments. I brushed it on and tried to
work it into the pores. I then wiped it off cross grain. It took a couple
tries to get the right look. I also noted that any place where I got lazy
sanding, or sealing, wound up as a different color. When the glaze was
dry, I shot a coat of shellac to seal everything. Finally three coats
of Fuhr 355 gloss, acrylic, waterbourne lacquer.
Monitor - Serious Thump from a Small Box
Garnet was intended for a "prosumer" friend of mine who retired
and moved into a smaller place. She decided that her old JBL towers were
just too overwhelming (and big) for her new townhouse. The Garnets are supposed
to live on the mantle over the fire place. (We'll see!). She really liked
my sealed Topaz monitors, but wanted something smaller with a bit more thump.
becoming somewhat a fan of Peerless drivers. I really haven't found one
I didn't like. (The aluminum ring dome tweeter is a bit gritty though.)
For this build, I selected the Peerless 850108 5.5" CSX. It modeled
nicely in the 7 liter box, is reasonably priced, and seems to be well
regarded by those who've used it. Since one of my goals is to reduce my
stash, I selected a pair of Vifa D27 TG-05-06. My first kit speakers (ACI
Emeralds) use these. I figured the Peerless would be good for 3000 if
and trying several "conventional" crossover topologies, I couldn't
seem to tame the very gradual rising response of the Peerless in the 2500-3500
range. I thought the original imaging was too forward. So I wound up with
the notch filter shown above to slightly reduce response in that range.
Again the tweeter needed drastic padding down, but the impedance profile
is more benign than the Sparky. Crossover is about 2100, 2nd order --
definitely pushing the bottom end of the Vifa.
quite nice and has huge reverse null. The key tweaking point is the 3.3
ohm resistor. This moves the filter peak. The padding resistor could go
to 25 if you like it a bit more laid back. According to LspCad, 3 ohms
changes tweeter response by about 1 dB.
reactions at DIY, the bass from these is really impressive, (model suggests
F3 of around 50). Most found the sound well balanced with a subdued mid
and clear airy highs. Personally, I prefer the more precise Peerless sound
to the air of the Vifa's. Most at DIY 2003 gave a slight nod to the Vifa.
The bass is definitely "there" on the Garnet. Moved against
a wall, it may be too heavy (for my taste). I estimate the sensitivity
to be in the 85-86 range -- as opposed to the 82-83 for the Sparky.
won't handle huge volume levels (it's only a 5" woofer!) but in reasonably
sized room it produces a very full soundstage, with nice depth detail
and placement. You won't need a sub for reasonable levels. Pushed too
hard, the Vifa gets gritty and the Peerless just works too hard.
is quarter cut Pecan, with three coats of Fuhr 355 gloss. I rubbed it
out with 600, 1200, and 2000 to achieve the satin look.