Ellam Flex
Discontinued from Jantzen Audio. Buy components locally.

Copyright 2020 © Troels Gravesen




Ellam FLEX is just what the name suggests, flexible. The idea is to make a small two-way from the venerable 15W/8530K00 - still the best 5" I know of - as an upgrade/replacement to former Ellam 9800, Ellam XT and W1500/97 constructions. These constructions will disappear from my website as I think I can do better today with all experiences gained over the last eight years, not least the Jenzen speakers.
Finally this construction will be extended with an 8" Revelator bass driver, most likely
22W/4851T00, to make a 3-way system, either run from a new passive 3-way crossover - or run from an electronic crossover with the current 2-way crossover in place. The price for the latter is a final system sensitivity of ~84 dB, where a new 3-way crossover can produce a system sensitivity around 88 dB by using the 4 ohms bass driver.
If an electronic solution is preferred, the 8 ohms bass driver version,
22W/8851T00, can obviously be used. Thus the number of possible 3-way systems can be sixteen depending on tweeter choice, bass driver impedance and passive vs. electronic solutions (4 x 2 x 2).
The 3-way passive will also replace the Jazzman construction as there is no rationale for the inefficient Revelator alu driver,
, although this driver obviously can be used with the Ellam-Flex 2-way - and an electronic crossover. No objection.
As can be seen there are no tweeters from the SS Classic range. I think these tweeters have a hard time being stuck between some really good domes from the Discovery series and the higher priced Revelator/Illuminator ranges.

Ellam FLEX takes advantage of the Jenzen front panel designs and features a stepped baffle allowing proper time alignment of drivers and implementation of true LR2 filters. The 3-way version will be Ellam Flex 3W.

Click images to view large.
Obviously you can turn the speaker upside down to your liking.

The Sound

I could hardly wait after finishing the first crossovers to take the Ellam FLEX to our living room and connect to my GlowMaster KT 88 valve amp. After some tweaking of tonal balance by changing the value of L2011 - and actually completely remodel the tweeter section - time was in for some serious listening. Thus, a wide range of recordings, vinyl and 24 bit were played and I can understand why some people settle with a pair of the 15W Revelator minis. Even in our 25 sqm living room they do deliver a credible soundstage and I'm impressed how the handle a grand piano with proper weight and tonal balance. The 65 watts from the GlowMaster have no trouble swinging the Ellam Flax to their limit.
Tweeter attenuation again was tried out and I finally ended up with R1011 being 2.2 ohm.

Some serious choral works were played and proved mid-treble integration on par with the best of my Jenzen speakers and DTQWT. What they obviously do not is handling the dynamics of larger speakers - but we can't have it all from ~10 litres and a 95 cm^2 cone. I went through all the recordings listed here from the GlowMaster review.

From left: Per Nørgård: Libra and Hymn to The Sun, Works for a chapella choir. William Carter: Fernando Sor Late Works. Jan Garbarek: Rites.

The Ellam FLEX did all of these demanding recordings without ever giving up on resolution or sounding harsh. This indeed promises very well for the 3-way version. Numerous other recordings were on the spinner, from Eva Cassidy and Johnny Cash to Miles Davis and Keith Jarrett. Even Safri Duo, Samb-Adagio, they handle with punch and drama. The 15W Revelator - despite a predicted F3 of 55 Hz - has the ability to at least make us believe it goes much deeper. I guess it's because what it does, it does really well. Remarkable driver.

The Drivers

15W/8530-K00, D3004/660000 and R3004/662000 drivers. Click images to view large.

Download specs here:
15W/8530-K00       D3004/660000      R3004/662000.



*: Most 5" drivers will have a rising response towards higher frequences. When we place these on a narrow baffle we have baffle step loss; for e.g. 20 cm width we will be 3 dB down around 580 Hz. These two things combined often leaves a serious bump around 800-1200 Hz and we need to flatten the response here, otherwise the sound will become much too forward. What is seen over and over again is the use of a large series coil for the bass driver bringing down the upper midrange and the result is a dip in the middle midrange (320-640 Hz) which often makes male vocals thin and anemic; we miss some weight in the overall soundstage as there is a significant amount of energy in almost any music in this range. Thus, a low-value series coil and a linearising circuit can solve the problem. For diy people this doesn't impact cost considerably, but for a commercial designer it's three extra components and they mostly take the easy way.

Crossover simulation targeting a point of crossover in the region of 2 kHz, 2nd order LR topology. Seems manageable.

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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: 6600 and 15W response @ 0.5 meter, 10 deg off axis, normalised for 1 metre 2.8 volts. As we rarely listen strictly on-axis this may display a better starting point for crossover simulation. The dip at 1.3 kHz is due to all too common rubber surround resonance. Not much we can do about it.
Right: ScanSpeak claims Fs = 30 Hz and I have hard time accepting this. Out of the box I measure 47 Hz and after 2 hours 40 Hz massage at +/- 5 mm excursion, I measure 43 Hz. I checked my old files and found 38 Hz from 4 drivers after burn-in, so I think we can assume some 40 Hz +/- 2 Hz. 30 Hz for a small 5" driver does seem exceptionally low considering the light-weight paper cone and that suspensions aren't that loose. I find other measurements on the web suggesting something in the range of 40-45 Hz. Not sure if these drivers were broken in. However, this will rise the driver Qt to something in the range of 0.35-0.40 and makes an F3 = 55 Hz in an 11 litre cabinet.

Left: Dispersion of 15W driver in cabinet at 0, 10, 20, 30 and 40 deg. horizontally.
This driver really does well up to 3 kHz and with a point of crossover around 2.2 kHz we're more than safe in providing an even power response.
Response of 6600 tweeter in cabinet at 10 deg. off axis with (red)/without(green) added bass panel.
The follow-up to this project, a 3-way, looks promising.

Left: Final system response in the critical range of 200-10000 Hz. R1011 = 1.0 ohm providing an almost flat response. What we see is a frequency response around 84 dB +/- 1.5 dB. I would rate this speaker having an on-axis response of 84 dB at 1 meter distance for 2.8V input signal.
R1011 = 1 ohm is a bit too bright to my taste and 2R2 is more like it,
making a balanced upper treble with still a lot of detail due to the 1-4 kHz range almost unchanged.
Right: R1011 = 1.0, 1.5, 2.2, 3.3 and 4.7 ohm. I don't think you'll need 1R0 or 4R7 to find what will suit you best.

Horizontal dispersion at 0, 10, 20, 30, 40 and 50 deg angle. Note the 1-5 kHz range is hardly impacted from this.
Right: Final system impedance, min. 5 ohms at 200-400 Hz. My new GlowMaster KT88 valve amp has no trouble driving this speaker at  all.

Left: Step response for those interested. Tweeter reponse well integrated in midbass response.
Right: Drivers' response and summed response driven from crossover. Point of crossover ~2.1 kHz.

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All technical questions at:

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Tweeter and bass sections

Ellam-FLEX-6600 wiring, click image to view large.

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R3004/662000 version
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Click image to view large. Download specs here.

Ellam FLEX R3004/662000 version crossover.
Compared to D3004/660000 tweeter, C1021 has been changed to 8.2 uF. The rest is only changes to attenuation resistors.


Ellam FLEX 6620 Crossover Kit

All technical questions at:

Ellam FLEX 6620 measurements
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Left: SPL from 6620 version from R1011= 1R5, 2R2, 2R7, 3R3 and 3R9. Right: Point of crossover = 2200 Hz.

Left: Impedance from 6620 version. Right: Far field measurement merged at 200 Hz with midbass near field measurement. Port contribution shown and this demonstrates why having a rear port is sometimes better (peak at 1 kHz). Ports often leak midrange - and not the good part.

Horizontal dispersion shown at 0, 10, 20, 30 and 40 deg. Compare to 6600 dome above.
This is one reason ring radiators sound different from conventional domes.
components needed.