Illuminator-7R
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DRIVERS CROSSOVER CABINET WORKSHOP PICS MEASUREMENTS SPEAKER-KIT CROSSOVER LAYOUT
Fortunately Viawave is back in business from Slovakia! Very pleased so, as I've long
wanted to make use of the ScanSpeak 18WU/4741T00 in combination with the
Viawave GRT-145W-4. I've had a pair of GRT-145W-4 in stock for a long
time and have tried it out in a mockup and it did very well. At
least as good as the Be dome tweeter - if not even better.
Should I point to my two favourite midbass drivers it would be the
Ellipticor 18WE and the Illuminator 18WU. The 18WE has the advantage of
the elliptical voice coil and the Illuminator the advantage of a
magnificent sandwich cone and underhung voice coil, both delivering
great midrange. The Illuminator further has the advantage of being able
to play some decent bass.
My
Illuminator-71s are among my few keepers as an example of what can
be done from a simple crossover and state of the art drivers, and the
Illuminator-7R here is likely to replace it - or maybe I'll just keep
both. And for sure the GRT-145W-4 delivers some of the best - if not
the best treble I've ever heard. Period! I used Amber-Z for the
tweeter section in my prototype crossovers. The basic kit will have
Alumen-Z as the Amber-Z is seriously expensive, but should you want
Amber-Z, please ask Jantzen Audio if possible.
Basics:
2-driver speaker.
Dimensions: 24 x 33 x 50.5 cm, WxDxH.
System sensitivity: 86 dB/2.8V/1 meter.
Impedance: 4-8 Ohms, minimum 4.7 Ohms.
Power requirement: 30+ watts/channel. Depends on how loud you play. If
you play it loud - and this speakers can handle it - use 50+ wpc. This
speaker works well with my 400 wpc
Parasound A21+.
Useful links (Please
follow all links before e-mailing!):
http://www.troelsgravesen.dk/tips.htm
http://www.troelsgravesen.dk/tips.htm#CONSTRUCTION_OF_CROSSOVERS
http://www.troelsgravesen.dk/crossovers.htm
http://www.troelsgravesen.dk/LCR-RC.htm
http://www.troelsgravesen.dk/Inverted-Polarity.htm
http://www.troelsgravesen.dk/choices.htm
http://www.troelsgravesen.dk/Placement-of-ports.htm
Download specs here:
Viawave GRT-145W-4 ScanSpeak 18WU/4741T00
The crossover features a simple LR2 crossover.
Cabinets were made from 20 mm Baltic birch. More about cabinet materials
here.
My mockups had a flat front panel and measuring
dZ revealed a value of around 10 mm with the microphone at a height
close to between the two drivers. Tilting a cabinets a little could
overcome this, but I'd like the ribbon to be at listening height, thus a
small step of ~10 mm to avoid tilting the cabinets or having a too high
stand. See workshop images how to accomplish this.
The dimensions are based on exactly 20 mm panel thickness, adjust to
local properties. Usually the Baltic birch I buy is 20.5 mm.
All things start with a mockup to measure if
this idea has any future. Here to determine the
dZ of the drivers. Measured at a height between the two drivers, dZ
is about zero, so this will be the optimal listening height. If placed
on a low stand you may tilt the speaker lightly.
Eventually I decided to retract the ribbon 10 mm giving a better
response at ribbon height. See below.
The ribbon comes close to the to panel.
Chamfering the front panel sides are optional.
Bitumen pads on all side panels. No bitumen on rear panel.
Cut the 3 sheets in half and use 25 cm heights for the sides.
It does not have to cover the entire available surface.
Routing for ribbon.
Left: It fits nicely!
Right: Adding felt to all sides except bottom.
Behind midbass driver, add two layers of felt.
Fasten with
vinyl glue.
Right: Gluing front panel.
Left: Bottom panel. Right: Middle compartment behind port straight tube.
Acoustilux:
Fold 1 pcs 17x50 cm and place at bottom on top of crossover.
Cut 1 pcs 18x50 cm and place behind port tube on rear panel and up the
sides.
Cut 1 pcs 25 x 25 cm and stuff behind ribbon tweeter towards rear panel
(below, left picture)
Cut 2 pcs 15x25 cm and place to the sides of the ribbon tweeter (below,
right picture)
Left: Upper compartment, behind ribbon tweeter. Right: Stuffing next to
ribbon tweeter.
Prototype crossover...auditory memory is short lived, and initially I thought I'd forgotten to connect the tweeter. I hadn't, just didn't remember how utterly neutral these ribbons are. Whatever treble you may have from your vinyl, tape or high-res streaming will be presented to you in the most neutral possible way. Not sterile, not lush, not anything but neutral. You may miss the distortion you're used to but give it time and you will appreciate true treble. And seamless integration with the 18WU woofer. I ran these prototypes from my Parasound A21+ amp, 2 x 400 watts (according to Stereophile) and together with this 18WU it defies its size and make us think we have a larger 3-way system. My EAR-861 (32 wpc) did equally well, but for sure a solid state powerhouse has a more firm grip on the bass driver. For the crossover I tried Cross-Coil, Wax-coil and Litze-coil for the bass, not much difference - if any. For tweeter I tried Alumen-Z for C1 and later Amber-Z too. Not much difference either, but the kit will come with wax-coil for bass and Alumen-Z/wax-coil for the ribbon as standard. Should you want Amber-Z for the ribbon, please ask Jantzen Audio.
A few comments on
MEASUREMENTS before you start interpreting the readings below.
First of all, if we think measurements will
tell us how a speaker sounds, we're wrong. The perception of sound is
way too subjective to be reflected in any measurements we can perform. A
loudspeaker system is meant to give us a satisfying idea of an acoustic
event and for some people a pair of 5 USD ear-plugs are enough, others
spend 200 kUSD on a truly full-range pair of speakers - and the latter
may not be happier than the former.
Measurements may give us an idea of tonal balance of a system, i.e. too
much or too little energy in certain areas, although dispersion
characteristics play a vital role here. A two-way 7+1 and a three-way
7+4+1 may display similar horizontal dispersion, yet sound very
different. 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 we 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 much
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 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.
What measurements certainly do not tell is the sonic signature of the
speaker, because speaker cones made from polypropylene, aluminum,
Kevlar, paper, glass fiber, carbon fiber, magnesium, ceramics or even
diamonds all have their way of adding spices to the stew. Nor do
measurements tell what impact the quality of the crossover components
add to the sound, from state of the art components to the cheapest of
coils and caps, they all measure the same if values are correct, yet
sound very different.
Frequency response.
Horizontal dispersion @ 0, 10, 20 and 30 deg. off-axis
(red/green/yellow/orange).
Final system impedance. Minimum 4.2 Ohms @ 35 Hz.
To configure a DIY kit and get a
written offer including shipping cost, please use the DIY kit
configurator in the Jantzen Audio website:
https://jantzen-audio.com/diy-kits/
All technical questions to troels.gravesen@hotmail.com
CROSSOVER-LAYOUT
BACK TO INDEX
Check this out before start making crossovers:
http://www.troelsgravesen.dk/tips.htm#CONSTRUCTION_OF_CROSSOVERS
Also please read this:
http://www.troelsgravesen.dk/LCR-RC.htm
Read here:
http://www.troelsgravesen.dk/tips.htm#Heavy_foil_coils
Mounting the crossover at bottom secured with screws and covered with
double layer of acoustilux.
Don't forget to connect ribbon with inverted polarity! Plus goes to
minus.
Speaker wiring:
