Could the Hawthorne Silver Iris be used in a enclosure

I´m just curious since there are several great coaxial speakers of old. For instance here:
Tannoy Speakers

Could one put them inbass reflex, horn enclosures,or or is there something in the Silver Iris construction the prohibits it?

Sterling Silver Iris OB 15" Coaxial Unit
Driver: 15-inch premium full-range coaxial driver with heavy gauge cast basket
Voice Coil: 2-inch
Power Handling: 150 watts RMS
Impedance: 8 Ohms
System Sensitivity: 97.3 dB/W/m
Qt: 0.70
XMax: 3.45mm
Fs: 35.9Hz
Magnet weight: 38ounces
Frequency range: 36Hz to 21kHz
Vas is 243,9 liters. which would be a box of for instance 50x70x70 cm
An aperiodic box might reduce the size a bit.

Here are all the data on the woofer section:

Woofer Specifications: • 15" full-range coaxial • Ideal for full-range, near field and monitoring applications in open baffle configuration • Heavy gauge pressed steel basket • 2" voice coil • Power handling: 150 watts RMS • Impedance: 8 Ohms • System Sensitivity: 95.8 dB 1w/1m • Le: 0.70 • Re: 5.77 Ohms • Qt: 0.91 • Vas: 243.9 liters • Xmax: 3.45mm • Fs: 41.8Hz • Magnet weight: 38ounces • Frequency range: 41.8-18k • Crossover network included • Cut out 13.75" • OD 15.25" 1" throat compression driver
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OK, which model did you have and what were the specific alignments tried?


Sorry, should have been more specific. I had the standard versions on narrow open baffles.

The poor impression I got of the SI's had nothing to do with box or baffle design actually. It was the integration of the compression driver and woofer than was lacking. I had the passive crossovers and I also tried using an active crossover approach, but the two drivers just don't jive well together at all. I didn't do any measurements, but my ears told me the woofer would start to break-up around 1k and the compression driver sounded dreadful under 3k, so there was this painful spot in the middle that just ruined the sound of the whole setup.
I have some of the same experience as theAnonymus on a flat baffle as recommended on the hawthorne forum. However I found that the harshness in the middle, gets better after a longish brake-in, and I have tried two different rooms, and different tube amps.
A small room 2,7x4,4m and a small 1 Watt SET amp sounds best, although the amp lacks a bit at the lowest bass.
......but the two drivers just don't jive well together at all.

Thanks, this is what I was really curious about. Awhile back I auditioned a similar driver and heard the same problem 'in spades' where others didn't seem to either notice and/or at least not mind, but being preconditioned from a technical POV to listen for such things, I can't always be sure of myself anymore due to natural age related losses compounded by decades of periodic hearing abuse.

My experience with the Silver Iris does not support theAnonymous1 and GM's. I find them to be quite mellow sounding. I use them with two Eminence Alpha 15As per side for everything under 160 Hz and think that you really need to do this to get the Irises high enough up from the floor to avoid ripple around 1000 Hz. More than any other driver I've played with the Irises are quite sensitive to baffle size and height.

I know that the passive xover provided with earlier Irises were criticized for similar problems and the xover was updated - did you listen to an earlier version? I haven't tried using an active crossover in place of this passive one but do use an active one to cross from the Alphas to the Iris.
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I didn't say I've auditioned one, just a very similar driver design. Bottom line I guess from decades of preferring life-like reproduction is that while I can't tolerate any peaking that excites my ~life long tinnitus, I don't do 'mellow' except when it's on the recording. :)

Interesting about being finicky WRT OB size/shape. Anyone know what its F3 is when suspended by itself in free air?



Paid Member
2005-08-16 4:21 pm
the first post concerns the expensive Sterling Silver version - I played the standard for awhile and as my previous graph shows, the ASD1001S tweeter is operated strong down to 1K5 - - woofer is a bit rough on top - there may be some tweaks. They sounded typical for Eminence coaxial with multi-rib ~Beta 15 cone and the open baffle has some subjective points of transparency which may not happen if enclosed.

re:finicky = no - to me many speakers will have something which can subjectively tilt their balance from dead - to phat or neutral to dead and includes the vent size and position

if my in-room graph is decent then there's a peak around 3.1Khz for the summed driver which may need attention and could make it rougher sounding. My SI are several years old so I don't know what changes if any have been made in the crossover


here's the effect of reversing SI's tweeter polarity

Si on small baffle - I preferred no wings at all and on this same baffle actually liked the balance of a P-Audio 15" neodymium coax
whose Qts was around 0.37 (!)

I didn't do free air tests but did put Hawthorne Audio's "Silver Iris" coaxial on a 24"x36" canted baffle with one wing and ran basic Woofer Tester Q test to see if anything would show from a compression driver's bucking (or adding) magnetic field

Silver Iris woofer alone - no HF driver, no crossover network

Fms 41.5763 Hz
Zmax 30.1017 ohms
Qes 1.5679
Qms 5.1927
Qts 1.2043
Le 1.1304 mH (at 1 kHz)

Silver Iris add CD8 driver (like PSD2002) screwed flush to woofer magnet. CD8 and PSD2002 have same diameter magnet as Beta 8/10/1215cx/SI magnet assembly.

Fms 41.477 Hz
Zmax 34.708 ohms
Qms 5.301
Qes 1.243
Qts 1.007
Le 1.127 mH @1kHz

Silver Iris - CD8's plate backed off ~0.13 inches from woofer magnet

Fms 41.576 Hz
Zmax 32.894 ohms
Qms 5.246
Qes 1.317
Qts 1.053
Le 1.125 mH @1kHz

Silver Iris woofer with Silver Iris HF driver screwed ~flush to woofer motor

Fms 41.626 Hz
Zmax 33.331 ohms
Qms 5.198
Qes 1.316
Qts 1.050
Le 1.127 mH @1kHz

I like OB - but am a Karlson guy first :^)
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My experience with the Silver Iris does not support theAnonymous1 and GM's. I find them to be quite mellow sounding.

I paid hard earned cash to buy the SI's and lost quite a bit of it when I resold them, so trust me when I say I tried everything I could to make them sound good.

I originally had high hopes for them due to the raving revues, but they unfortunately let me down. I could easily get better sound from some parts-express clearance drivers.