Before we start: You cannot use any other drivers than those used here
without needing a new crossover and you cannot use any other baffle design (e.g. all flat) without needing a new
crossover, and I can't help you here. Please read
writing. Should you for some reason dislike the ring-radiator you may
use the D2604/830000 by increasing attenuation a little due to 2 dB
This speaker has been on my to-do list for a long time! So long that the ScanSpeak Discovery series wasn't developed yet. What I had in mind was the ScanSpeak Classic series from 22W, 13M and
maybe the 9500 tweeter. However, the
13M drivers are no longer available
and with current range of Discovery midrange drivers I don't miss them.
When I launched the
SEAS 3-Way Classic I never expected this speaker to be built in any
major number due to the classic Seventies design. However, builders
response proved me wrong.
Please DO NOT ask about the sonic differences between
the two. It's been quite some years since I made the SEAS version.
What the ScanSpeak 22W/8534G00 bass driver has the SEAS CA22RNX doesn't,
is a higher mechanical Q due to the fiber glass voice coil former, delivering better low-level detail and
transient response. The 10F/8414G10 is a magnificent midrange driver
bridging the gab between the 22W bass and classic R2604 ring radiator. This
R2604 tweeter is already a classic and I don't see why it shouldn't be
around even longer than some of the ScanSpeak Classic drivers, which are
well into their third decade.
This ScanSpeak 3-way Discovery features an
filter from a stepped baffle and delivers an excellent level of
transparency. The midrange and tweeter levels can be adjusted to
personal taste by attenuation resistors. Small 4" midrange drivers
always sounds different from the common "6+1" set-up due
to better dispersion in upper-mid, thus some adjustments can be
necessary depending on personal taste, your room and not least source of music and amplifiers.
For both midrange and tweeter series capacitor I have used Jantzen Audio Superior Z-caps
due to enhanced transparency and this option and one with Standard
Z-caps will be shown. Superior-Z caps don't come cheap, but if you want
to hear what these Discovery drivers can really do, there's no way
System sensitivity: 88 dB/2.8V, 1 meter. Impedance: 8 Ohms. Minimum
impedance: 5.5 Ohms. Points of crossover: 800 and 3000 Hz, 2nd order LR.
Time-aligned tweeter for improved transient response and phase
Any change to front panel design and you need and new crossover
and I can't help.
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I decided to go for the 8 Ohms version of the 22W driver making a better
partner for tube friends. The 4 Ohms version might have added another 3
dB to system sensitivity, but I reckon impedance more important here.
These Discovery bass drivers feature high mechanical Q, a promise for
dynamic bass that doesn't "die" at low levels. These Discovery 8"
drivers are quite large, actually making some 240 cm^2 membrane area
from my calculation. Some 10% more than the average 8" driver.
The 10F middriver was tested
here. This is one
smooth driver and I'd like to use it also in a small lap-top micro
system with one of the small 3/4" neo domes from ScanSpeak, e.g.
D2004/602000. Some day.
For treble the R2604/832000. I know this tweeter so well having used it
numerous times over the years. Unbeatable for the price to my thinking.
Crossover components values come with kit incl. full parts list and
Just because the 10F can do it all up to 17-18 kHz doesn't mean we can
take the point of crossover between mid and treble up above the main
treble range, e.g. 6-8 kHz. Technically we can, but it doesn't sound as
good as going down to around 3 kHz. Dispersion is the thing here. The
10F cone has a diameter of 68 mm meaning it will start beaming around 5
kHz, thus we go a little below that point. Like the SEAS 3-Way Classic,
this 3-way ScanSpeak features an even simpler crossover due to the
stepped front panel allowing true LR2 filter to be realised (2nd order
to tweeter). It can be revealed that C2021 is 22 uF and C1021 is 8.2 uF
ands I strongly suggest these two caps being Superior-Z caps. These are
the two most critical components in the crossover delivering all he
transparency we can have from these drivers -and there's a lot to be
There were three surprises for me when I first fired up these speakers.
They play classical music very well indeed and female opera singers are
a delight!. Secondly it can seriously rock due to the generous size and
quality of the bas driver. This high-Qm driver does very well indeed and
goes lower than expected. Last, but not least, the mid-tweeter
integration works so well that even seriously sibilant recordings come
through well. I know the R2604 so well but I've never heard a better
match than this 10F middriver. I have a suspicion the smooth roll-off of
the 10F is responsible for this. The 10F is linear way above the point
of crossover and in reality it could play all of the treble range
although dispersion would be an issue if we did so.
Click image to view large
The front panels are screwed into place, ATC style. After seeing Mr.
Wang's interpretation of the SEAS Classic 3-Way, I decided to give this
a try - and for the very good reason that I'm going to make a 2nd pair
of front panels for a SEAS 3-Way Classic mkII, this time featuring the
SEAS CA22RNY driver. Please don't ask when.
Left: Panels piling up, ready for the final cuts. Right: Cutting top,
bottom and sides 45 deg.
The black front panels are made from through-coloured
MDF. This black MDF is really like
HDF, high-density fiberboard, weighing some 0.84 g/cm^3 compared to 0.64
g/cm^3 for the common brown MDF, although it depends on MDF thickness.
Thick MDF sheets often have a rather soft center as producers may cut
production cost by reducing glue content. Black MDF has an almost
ceramic feel to it and comes at approx. twice the cost of standard MDF.
Left: All panels ready for test assembly. Right: For bracings I used
left-overs glued to size.
Left: First time assembly by tape. Right: Fitting in the rear panel.
Left: Cutting the bracing panels. As can be seen I cut 2 mm deep grooves to
guide the brace panels. Makes assembly much easier.
Right: Making the two panels for the midrange cabinet.
Left: Holes to be routed in two upper braces. Right: Braces ready for
Remember to make braces for the two cabinets mirrored!
Left: Lower brace markings. Right: All braces ready for mounting.
Left: Testing braces. Right: Gluing the first cabinet. These cabs are
easy, two straps and a couple of clamps.
Left: Sanding is tedious and the problem with Baltic birch is to avoid
edge ripping. I usually start - by hand - rounding the edges gently with
grade 120 to make the rounding having the radius of the outer veneer
thickness, i.e. less than 1 mm.
Right: I always try to make the rear panel rebates just a fraction of a
mm deeper than necessary. After gluing I remove the surplus by edge
Left: First coarse (grade 80) sanding finished. Later I use grade 120
and 180 before adding lacquer. Time to add all fillets supporting
Right: Fillets in place. Next is routing front panels.
Click images above and below for large view.
A few words on chamfering driver holes. Please first read
The amount of energy coming from the the rear of the driver obviously is
the same as that coming from the front. Thus, we need to make sure we
have as little obstruction to the oscillating air from the rear side of
the cone. The 10F driver has a very small neo magnet, which already helps a
lot. Due to the thickness of the front panel, do as seen on photos. This is the only driver that needs special
attention. Chamfer outer panel 45 deg to a depth of 5 mm from the
rebate. The inner front panel needs some chamfering too. Do as seen on photos
and take care to mark where the middriver cabinet is. The hole in
the lower front panel is the same size as the 10F outer diameter. As can
be seen on the last photo, the 10F driver now has free air flow to its
The hole of the lower front panel for the bass driver is the same
diameter as the driver, 225 mm.
Mounting the front panels
Trying out drivers and port. Port is Ø 68 x 175 mm. Cut the 220 mm
length port to 175 mm.
Left: Small cut-out in fillet to allow tweeter magnet. Right: As can be
seen, lots of rear space for the small middriver.
Left: Hole for vent and cut-out in fillet.
Right: Front panel attached
with M6 umbraco screws into threads made in fillets. Works
excellent! Click right image to view large.
The front panels were sanded with grade 120 and given a single oil
treatment. The cabs had two coats of
I like the rough monitor look!
Making M6 threads. Right: One step back and time to add 4 mm bitumen
pads on all internal panels, even the interior of the midrange cabinet.
Cabinet damping: 8 mm felt on all internal sides incl.
mid cabinet. 30 mm acoustilux at top (image to thet left). 30 mm
acoustilux behind mid cab. Space is limited below port and I placed a
piece of 30 mm acoustilux next to the port as seen on photo. On top of
the crossover (mid section) and half up the sides the final piece of acoustilux.
I cut a thin gasket for the midrange cabinet as seen on photo. See here
never use any gaskets for the drivers. The mid cab must be absolutely
acoustically isolated from the bass driver! Stuff the vent and push the
bass membrane and see if you can make the middriver cone move. If yes,
check the gasket again and make sure you have sealed the wire hole (e.g.
silicone glue). If you glue the front panel you shouldn't encounter any
Note middriver connected with inverted polarity. You can do this on the
driver or at the crossover, but don't forget.
The crossover is mounted on the rear panel behind the bass driver.
This takes a front panel fastened with screws. If glued you may have to
divide the crossover into separate sections, one for bass and tweeter
and one for middriver. The full board is too large to pass through the
bass driver hole.
Before finishing the cabs I just had to set up the speakers and start
modeling the crossover.
These 8" bass drivers are big 8" drivers having some 240 cm^2
membrane area from my measurement - and they can rock! More on sound
here. The actual size of a speaker driver is
controversial. Too many manufacturers claim e.g. 7" midrange drivers
where reality would be more like a small 6". The problem is
that there are no standards for driver size. Based on history a 6"
driver is in the 130-140 cm^2 radiating area range. Some ScanSpeak 6"
drivers with a membrane area of 155 cm^2 are more like 6½" drivers. A
driver should be in the 170-175 cm^2 range and many 8" drivers display
220 cm^2 membrane area. This 8" Discovery is to 240 cm^2. ScanSpeak
conservatively claim 230 cm^2. But big it is and rock it can.
Measurements may give us an idea of tonal balance of a
system, i.e. too much or too little energy in certain areas.
Measurements may tell us about bass extension if far-field measurements
are merged with near-field measurements. In addition to this ports may
contribute to bass extension. Most of us diy'ers do not have access to
an anechoic room for full-range measurements from 20-20000 Hz.
What cannot be seen is what kind of bass performance we get in a given
room. Bass performance is highly dependent on in-room placement of your
speaker and the same speaker can be boomy in one place and lean in
another. Actual SPL level at 1 meter distance and 2.8V input is useful
for en estimate of system sensitivity and combined with the impedance
profile may give an idea of how powerful an amplifier is needed to drive
the speaker to adequate levels.
What measurements do not tell is the very sound of the speaker unless
displaying serious linear distortion. The level of transparency, the
ability to resolve micro-details, the "speed" of the bass, etc., cannot
be derived from these data. Distortion measurements rarely tell anything
unless seriously bad and most modern drivers display low distortion
within their specified operating range.
Many people put way too much into these graphs and my comments here are
only meant as warning against over-interpretation. There are way more to
good sound than what can be extracted from a few graphs. Every graph
needs interpretation in terms of what it means sonically and how it
impacts our choice of mating drivers, cabinet and crossover design.
Left: Let's start with the 22W driver. Now, this is one linear driver
allowing to go as high as diameter (beaming) allows.
Right: Impedance of all drivers. Initially a low port tuning was tested,
thus Fb = 30 Hz. Maybe I'll stay there... Green is the 10F in its small
closed box. Blue = tweeter.
Left: SPL @ 2.8V, 1 meter from final crossover. Measurement merged with
bass near-field response at 200 Hz.
Right: Final impedance of system with port tuning @ 30 Hz. Port 68 x 175
Left: Response of individual drivers driven from crossover and summed
Right: Changing R2041 gives the option of adjusting the important upper
mid/lower treble range. Resistor values and default value incl. in kit.
Left: Just to show the significance of R3012-C3011. Listening to the
bass driver alone driven from crossover the 3 kHz hizz is noticeable.
Right: Tweeter attenuation from 4 resistor values. Lowest value provide
a flat response (too much to my ears but the choice is yours).
values to come with the kit.
You can buy the kit with or without the
drivers - or some of the drivers if you already have some.
Please ask Jantzen Audio
All kit and component prices may be subject to
change and are always to be confirmed by Jantzen Audio Denmark.
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kits, please mail Jantzen Audio at
Connect A to B with wire.