Placement of drivers on front panel. To get the target SPL, place drivers as indicated on the drawing here. Cabinet volume is 10.5 litres and the vent is 46 (ID) x 150 mm, same as 1500/97
What is important here - as always - are the dimensions of the front panel and the placement
of drivers. If you decide to make a cabinet with curved side panels you will have to figure out for yourself the depth and curvature of the cabinet to get a volume of 10.5 litres.

I decided I needed a new pair of test cabs for this set-up, thus a 10.5 litres cab was constructed with the A4 front panel dimensions. The cabinet is 300 x 210 x 280 mm (H x W x D) making a net volume of 10.9 litres. The vent and drivers will reduce volume slightly. Actually an A4 paper is 297 x 210 mm, but no need to be nitpicking!

Impedance and electrical phase of drivers in cabinet.

Frequency response of individual drivers without crossover. Nearfield response of bass driver merged at 350 Hz with 1 metre distance response. Expected system sensitivity is around 83-84 dB/2.8 volts.

Frequency response of individual drivers (red and green), summed response (blue) and response with inverted polarity (purple). Point of crossover = 2300 Hz.

Frequency response with merged nearfield response at 350 Hz of bass driver. An overall balanced response with a more than usual bass extension for a 5" driver. These sliced paper drivers just are good at bass.

So how does this response correspond to LspCAD prediction?

Step response showing positive polarity of both drivers. Note smooth decay of bass driver.

Impedance plot showing vent tuning of 43 Hz. vent = 35 (ID) x 100 mm. I suggest using a larger vent diameter, like 45 x 160 mm.
The combination of a negative 60° phase at 80 Hz and an 10 ohms impedance may draw some current from your amplifier, but I haven't noticed any trouble from my 100 wpc solid state or 50 wpc valve amp.

Vertical dispersion at 1 metre distance. Red = tweeter height. Blue is 20 cm below. The others: Well, doesn't matter much.
This speaker has a remarkable good vertical dispersion and the sound doesn't change much with listening position.

Horizontal dispertion at 1 metre distance. Yellow = 40 deg.

Cumulative spectral decay. Hmm... Maybe these testcabs could do with some bracing. Otherwise a good performance with no severe resonances down to -20dB above 1 kHz.

Hej Troels,   I förrgår blev dom klara och lät bra! Fast efter en stund upptäckte hustrun att det ibland skrapade lite....jag blev riktigt sur! Efter en stunds lyssnande och funderande kom jag fram till att det bara var på vissa frekvenser och bara på höger diskant. DVS troligen någon lödning som inte höll måttet, utan vibrerade vid vissa frekvenser och då slutade leda ström på ett bra sätt. Fram med sexkantsnyckeln och av med elementen för att kunna komma åt filtret. Hmm.. ena lödningen på diskanten ser inget vidare ut....jag börjar med att bara fixa den....OCH DET LÖSTE SIG SÅ ENKELT!   Nu har jag lyssnat lite mer och de låter helt enkelt kanonbra! De gamla HF 90 får stryk vad det gäller bas, transparens, ljudbild, taktkänsla (The LINN faktor!) för att inte tala om utseende! Igår bjöd jag in min granne som har ett förflutet som musiker och studioägare. Han undrade direkt om jag hade kopplat fel polaritet på vinylspelaren eftersom "high hat:en" på Suzanne Vega´s "Luka" låg på vänster sida. De brukar alltid ligga till höger....Vi körde några plattor till och kom fram till att Suzannes trummis var vänsterhänt!   Det känns som om man har fått en massa nya bra skivor - allt (nästan, en del blir tydligt avklädda också) man slänger på låter bra.   Sänder några fler bilder, nu i full upplösning. De är inte riktigt bra, men visar i alla fall den färdiga set-uppen.   MVH   Max

Hi Troels

Enclosed some pics of the A4's I just finished.

These are my third version with these drivers! Originally I used the Dutch A4 x-over. Frankly, I was a little disappointed,
the sound was somehow flat and of a separate bass and treble - as opposed to a coherent one ... Later I tried a three-element (no cap) series x/over . The sound was different, albeit not necessarily better - more bass (a lot more - I guess the L2 inductor was not the happiest choice) and the whole thing sounded too mellow, syrupy.  Anyway, after Papa and Mama Bear, now came the Baby Bear ! The Ellam is just right !

Having listened to it a couple of days (still breaking in, the units were not used for a several months), and confirming the impressions with my audio friend and a cousin (himself a Lowther and tube type), I can say that the system - the crossover first and foremost - is very accurate , coherent and balanced at both ends. The bass is superb (but we all know already about the bass capabilities of the small 15W) , the mids are very smooth ( although not as detailed and of studio-monitor-type class as in 18SP38 ) and the highs are perfect! The metal dome D2800 is really a top driver but it
takes a proper x/over to exploit it.

In short - an excellent small-box system, of a highest caliber . Reminded me very much of an original ProAc Tablette - similar easy presentation , but with a lot more bass.

Regards,
Emil Andreevski