FELIX – 2 way small sized desktop/stand/bookshelf Loudspeaker
Cassa acustica a 2 vie di piccole dimenzioni
FELIX – 2 way small sized desktop/stand/bookshelf Loudspeaker project
VALUABLE SOUND QUALITY AVAILABLE TO EVERYONE!
The FELIX is designed to be able to work well in different kinds of installations: on desk, on stands, on a bookshelf and for both near and far field listening. The Speaker has a pleasant natural timbre and it gives us a detailed but not tiresome listening experience. Furthermore it’s capable to reproduce an accurate soundstage that allows us to well perceive the location of the instruments in the three dimensional space. Middle, mid-high and high frequencies are ‘promptly’ reproduced, the extension at the high frequencies is considerable and also gives a significant articulation, in fact the FELIX is able to recreate the finer details of the musical recording, giving us a rather ‘rich’ sound. Surely we cannot rock the house with a 4” driver but considering the physical dimensions of the speaker the low end is surprisingly extended, accurate and fast. (in room placement we can get around 46 hz at -3db). Also with movies this speaker can work well.
Felix speaker is with drivers burn in, individually measured and matched!
Ideal ear height is between Tweeter and Woofer, mainly in near field listening.
The Felix Passive is available as:
- Assembled with Sand Paint Finish (pair): 530,00€ per pair excl. Speaker is with drivers burned in, individually measured and matched.
— Sand Paint Finish is a less sensitive type of coating typically used in Pro Audio Speakers —
- Assembled with Painted Matte Finish (pair): 590,00€ per pair excl. Speaker is with drivers burn in, individually measured and matched.
All kit and component prices may be subject to change.
— Please Note: Crossover components’ values come with the purchase of the DIY Kit —
DETAILS / CARATTERISTICHE:
- 2-way vented speaker system, 4” SB Acoustic mid-bass and 0,75” SB Acoustic soft dome tweeter
- drivers and crossover components are individually measured and matched
- drivers are burned in (There is no need to wait a few months to get them to sound their best)
- 6,4 net liters vented cabinet (virtually ~7,2 liters)
- System sensitivity: ~85.5 db/2.8v, 1 meter
- Frequency resp.: 49/42 – 30.000 Hz (-3db/-6db) – Typical in-room response ~46 Hz (-3db)
- Acoustic point of crossover: 3000 Hz
- Nominal Impedance: 4 Ω
- Minimum Impedance: 3.8 Ω at 220 Hz
- Recommended Amplifier: 30 – 80 W (without clipping)
- Cabinet Dimensions: 17.2 cm wide, 27.2 cm high, 25.3 cm deep
- Rounded edges to reduced Baffle Diffraction
- Internal Bracing to reinforce the structure and to reduce and distribute cabinet vibrations and therefore lower sound coloration
- Chamfered Woofer cut-out inside the Baffle to aid airflow behind the driver and reduce Diffraction
- Drivers and Catchers are Flush-Mounted to avoid unwanted Diffraction
- High quality Crossover components
- Gold Plated Binding Posts
- Friendly and versatile placement in domestic room
- Back firing port to reduce any possible Vent noise to listeners
LEFT: Felix small sized speaker DIY Project in White Matte Finish. (Click to enlarge) RIGHT: Felix small sized speaker DIY Project in White Sanded Finish. 🙂 (Click to enlarge)
LEFT: Felix small sized speaker DIY Project in White Sand Paint Finish. (Click to enlarge) RIGHT: Back view of the Felix small sized speaker DIY Project in White Sand Paint Finish. (Click to enlarge)
The Cabinet is made in collaboration with the Great Team of SafeCase 🙂!
If you want to build the Felix.
High Quality MDF Cabinet as Flat Pack
Rounded Baffle to reduced Baffle edges Diffraction
Internal Bracing to reinforce the structure
Chamfered Woofer cut-out inside the Baffle to aid airflow behind the driver and reduce Diffraction
Drivers and Catchers are Flush-Mounted
(click to enlarge)
The Drivers used are from SB Acoustic and they have an excellent price / quality ratio: Teeter SB-19ST-C000-4, Woofer SB12PFC25-4-R (click on code for Datasheet). They impressed me and matched with the Felix solid and rounded cabinet construction, with high quality crossover components, connectors and cabling they will give you a lovely music listening experience, despite their little dimension and cost! The Tweeter is very well made and has a great dispersion and out of axis behaving. Nice frequency response and very good distortion that stays low also at 95db level from 3000 Hz up (the crossing point I choose). And the most of all it has a very good sound, pleasant middle high and detailed but not tiresome high frequencies, lovely drive. The mid woofer is also very well constructed, it has a plastic basket that greatly makes the job. A powerful magnet that allows this little driver to have a very “fast ” reproduction and a linear +-5mm excursion. The driver is a 30 watt one so don’t aspect to “brake down the house” but with any 4 inch drivers it wouldn’t make any sense. Still in the Felix this drivers will go down to around 49 Hz -3db, and in room you will get even more. The response is linear till 1000 Hz and from 2200 till 8000 Hz. We have a dip at 1800 Hz that “characterizes” a bit the sound of this driver but in room listening this aspect gets less preeminent as you can see in the in Room measures. The overall good construction and this nice “paper” cone brings to a very pleasant sound and natural. And despite the small size of the driver the SB12PFC25-4-R is capable to give us a fair amount of bass information, precisely and with a good punch at “normal” listening levels. From Klang+Ton Magazine Review: “… the SB12PFC25-4 is still a hot candidate for high-class desk sound systems or a near-field monitor”.
LEFT: Measured Impedance and Phase differences between 2 different Tweeter SB-19ST-C000-4 unit, an excellent match that proves the building quality of SB Acoustic! (click to enlarge) RIGHT: Same great match for the mid Woofer SB12PFC25-4-R! Thank you SB Acoustics!🙂 (click to enlarge)
/IT: SINISTRA: Impedenza e Fase misurata su 2 degli esemplari in mio possessol del Tweeter SB Acoustics SB-19ST-C000-4, la differenza tra le due unitá mostra un risultato eccellente! (clicca per ingrandire) DESTRA: Stessa notevole consistenza dei parametri trai i due esemplari del mid Woofer SB12PFC25-4-R! Grazie SB Acoustic!🙂 (clicca per ingrandire)
MEASURES OF THE FELIX SPEAKER SYSTEM
LEFT: Measure at 1m distance with Mic at 3 cm under Tweeter level taken with Arta and shown at 1/24 oct. In Black the response with 1 layer of Foam inside the Vent (recommended!). Fb tuning is at 48.7Hz and we get closer to a SBB4 alignments with good transient response. In Green without the Foam inside the Vent and the Fb tuning is here at 55.4Hz. We get a more “forward” low frequencies reproduction loosing something in terms of transient. RIGHT: In Green the response at 0 deg and in Black at 30 deg. The 30 deg response it gives a better idea of “which response” we will get in a domestic room. (Click to enlarge)
The response is mostly in an average of +/- 1.5 db. The peak and dip around 1300-1800 Hz is given also by a characteristic of the SB Midwoofer and, as tested, will not be noticeable in the Room listening environment. After the pleasant listening results I decided that is not needed to better “control” this part of the frequency with the crossover. Also to avoid a more complicate and expensive crossover. (Click to enlarge)
The acoustic response at low end here is shown with Baffle Diffraction loss that cause a reduction of SPL in the low frequencies (this happens to all speakers). But when a Speaker is placed in the room the lower frequencies will get a „boost” in a quantity that depends on the room sizes, characteristics and on the placement of the speakers.
IN ROOM MEASURES – In different kind of placement at 1/3 Octave!
Despite the different placements we can see how the response from 500/800 Hz and up is always very well controlled and flat!
Everything under 1000/800 Hz is strongly influenced by the Room Characteristics and Resonances!!
40 m2 LIVING ROOM on Stands or next to TV – Room has many furniture, carpet, curtains, books etc.:
LEFT: Felix 2 way small sized Speaker in a 40 m2 LIVING ROOM on Stands: speakers 130 cm from each others, Tweeter and Mic at 95cm high, Mic is 140 cm away, Front Wall 100cm (the one behind the speakers), one Side Wall 70 cm far and the other 250 cm far. 5 deg. toe in. A very well performance! Going more far from the speakers will give us a “more worm” sound.
RIGHT: Speaker placed on the SIDES of TV at 120 cm far from each others in the same 40 m2 LIVING ROOM. Tweeter is at 135 cm height from floor level. Measure is taken at 300 cm far and like if listener is sitting on a sofa. The not acoustically treated room bring to some relatively strong resonances but listening is very pleasant and the reinforcement at the low level gives a nice warm “punch”.
23 m2 LIVING ROOM on Stands – Room is quite empty and no acoustically treated:
The emphasis at 50 and 250 Hz, and the little dips at 60, 300 and 800 Hz are influenced by Room Resonances. Note as at the more far listening distance the Room Resonances increase farther more the low frequencies region.
LEFT: Felix Loudspeaker is in a *quite empty 23 m2 sized room on Stands. Positioned with the Tweeter at about 1.4 meter away from side walls, 88 cm high, 90 cm away from front wall (the one behind the speakers) and 145 cm away between right and left speaker. Measure is taken from a listening position far 177 cm at Tweeter level.
RIGHT: Same but here speakers are 155 cm away from each others and the listening position is at 195 cm.
We can see that the all response is, even in this “difficult” room, between + – 2.5 dB and this is a very nice performance. The frequency response over 1200 Hz is extremely flat!
*quite empty”: no fornitures, no carpet on the floor (wood floating floor) and with just few absorbent material on some part of the walls. This room bring a response boost that is a bit more then the usual from 500 Hz and down.
Placed on Desk in a 16m2 room partially acoustically treated:
LEFT: Felix Speaker placed directly on Desk, no any Tilt or small stand under the cabinet. Here we see a “Near Field” kind of placement: Tweeter axis is at 94 cm height and listening position is at 91 cm height and 106 cm far, going more far we can get an even more linear response. As sad the “ideal” ear listening level is between Tweeter and Woofer. The Front wall (the one behind the speakers) is at 130 cm from Felix Baffle and we are in a 16 m2 room, No any Toe-In for the Speakers. The +3,5 db in the 200 Hz region is a typical increment caused by the Desk under the speakers, the 3,5 db is still a very acceptable value. Also the little increment from 10.000 Hz and up is given by the Desk reflections.
RIGHT: Speaker positioning same as on the Left but with the front Panel lifted of 2 cm that gives a small Tilt. Listening point is a bit higher then before (94 cm) and more far (115 cm). No Toe-In! If you want to recover a bit the high frequencies just give a Toe-In to the speakers in a quantity that matches your needs.
A lot depend on your room dimensions and characteristics and on where you place your Music Production Desk. You need to try and find the best solution! Is not fault of the speakers if you don’t do your best to find the right placement. 🙂
On top of a Wardrobe with Tweeter at 210 cm height from floor level:
Here a quite extreme placement! The Felix Speaker is placed on top of a Wardrobe with Tweeter at 210 cm height and 100 cm from each others. Tweeter is only 52 cm under the ceiling and wall behind the speaker is at 30 cm. Listening position here is 300 cm far and at 140 cm from floor level. I choose this height between sitting and standing as it shows a good approximation of both. We can see that Felix has also a good Vertical Dispersion characteristic.
Measures from 35 Hz and down are influenced by environmental noises.
MORE MEASURES AND VENT TUNING
LEFT: Electrical Impedance and Phase that shows that the Felix is an “easy speaker” to drive for the amplifier, considering that it’s a 4 ohm speaker. We have the maximum negative electrical phase at 102 Hz with -52 Deg and 8.20 Ohm. We should get the maximum load for the amplifier around the 130 Hz where we have 4.8 ohm and -37.5 deg. The lowest impedance is at 220 Hz with 3.8 ohm and a very friendly -11.6 deg. Above 230 Hz the negative Electrical Phase never go under -9.6 Deg. The measure is taken with the 1 layer of Foam inside the Vent. FB 48.7 Hz. (Click to enlarge) RIGHT: Polar Map Directivity, horizontal. (Click to enlarge)
LEFT: Near Field measure of the Woofer SB12PFC25-4-R in the cabinet (no crossover connected). Green is with Foam inside the Vent to get the wanted tuning of Fb 48.7 Hz. With this tuning we get closer to a SBB4 alignments and we get a more precise and better transient response then with no Foam inside the vent. Also we get a less coil excursion around the 45Hz region and under. In Black without the Foam and the Fb tuning is here at 55.4Hz. We get a more “forward” low frequencies reproduction loosing in terms of transient. I recommend the use of the Foam. (Click to enlarge) RIGHT: Measure at 1m distance with Mic at 3 cm under Tweeter Axis. At 0 – 15 – 30 – 40 degrees.
LEFT: Step Response of the Felix, we can see how the Tweeter is very fast and doesn’t show any tales, the Woofer is delayed of only 0,28 ms from the Tweeter. (Click to enlarge) RIGHT: The Impulse Response gets down “nicely” to -45 dB in 0.86 ms, this is a very good performance! Then there is a very shallow peak coming back at 1.13 ms but at a low level of -38.7 dB. The Impulse gets definitely under 50 dB after 1.58 ms. A very nice result! (Click to enlarge)
Group Delay measure of the Felix 2 way small sized desktop/stand/bookshelf speaker. Measure taken with Arta.
LEFT: Cumulative Spectral Decay Waterfall of final speaker set to -35db and not Smoothed. Click to enlarge RIGHT: Same but Sonogram representation. From 1.700 Hz up the -35 db is reached very fast at around 1.7ms or less, a nice result, there are some coming back reflections at 1.700-2.200 Hz (of low entity) that goes again to -35db at around 2.4ms. We can see how middle high frequencies (2.000 to 20.000Hz) are going down to -35db for the first time at already around 1.15ms or less. Over 5500 Hz it’s down to -35db at around 0.6ms. The tale at around 4800 Hz is caused by baffle diffraction, as proven by the off axis responses, and therefore it will not give problems, as proven by the listening tests. Lower middle region is, as usually, slower but performing good, it shows some resonances around 600 and 1200 Hz but they are going down quite soon. Click to enlarge
As the measure is Gated to avoid my room reflections, there are missing data for the middle low and low frequencies. And even with Window Gating set to 4.59ms I still have some room resonances in the measure.
Photos of the crossover plate not yet assembled. The technical drawing of the Plate is available in dwg or pdf format and it can be sent to any Plexiglass company that will cut for you the plate in the right size and with all the cut-outs ready for the components. Then you will just need to assemble the components on the plate. Or you can buy from us the Plexiglass plate ready for assembling for 7.00€ per piece. / Foto della basetta in Plexiglass del crossover. I disegni tecnici della basetta sono disponibili in formato dwg e pdf e possono essere cosí mandati a qualsiasi centro che si occupa della lavorazione di pannelli in Plexiglass, li saranno in grado di tagliarla su misura e con tutti i fori necessari. Dopodiché dovrete solo installarci sopra i componenti ed eseguire le saldature. O potete comprare la Basetta pronta per l’ assemblaggio direttamente da noi per 7.00€ al pezzo.
Here under an example of some of the documents available for who will purchase the DIY Felix project:
Disposition of the components and wiring of them on the crossover plate. All the connections are placed under the plate and except for one all are DIRECTLY connected between the components. The 6 holes with the + sign inside the circles are the holes for the screws used to well fix the plate inside the cabinet.
Vectorial file in dwg or pdf with the plexiglass plate sizes and all cut-outs ready to be used.
Photos of the Crossover assembled. All components are of very good quality and are mostly from Jantzen Audio and 1 coil from Mundorf. You will not find this quality components on similar or well higher priced Industrial Speakers! This is one of the advantages of the DIY speakers, few other advantages are that you can make the final finish of the cabinet as you better like and you can fine tune the Middle High and High Frequency to better meet your listening style and better match with your domestic room. Also you can choose the cable you better like for the internal connections, you know How Is Made your speaker and you probably will have your Unique speaker like nobody else. 🙂
Only the Coil in series of the Midwoofer is a Iron Coil Core and even if I prefer the Air Cores this time I had no doubt about using an Iron one. Always need to consider different aspect and keep a balance between the things. I definitely wanted an extremely low DCR which does not alter driver damping factor or add a loss of efficiency, to do this with an Air Core we need to spend much more and we also need a lot of more space as the Air Core would be much bigger then the Iron Coil.
All coils and capacitors, to try avoid the vibrations coming from the cabinet, are decoupled from the 5mm tick plexiglass with a tick rubber. The resistors are “decoupled” and fixed using Blu tack kind material, that it’s also resistant to heat, though just 1 resistor can get “kind of hot”. Of course you can use also Glue Gun or similar but I don’t. Also I always place a soft material between the cabinet and the crossover plate to reduce vibrations, like Felt or Packaging Foam of about 3/5 mm thickness. – Click to enlarge
THE CROSSOVER SCHEME
Many measuring and listening tests were done and I got to this “final” crossover that I believe is suitable to have a correct sound, a realistic stage reproduction and good general characteristics in the domestic environment.
The measures where made horizontally and vertically from 0 to +– 180 deg., in steps of 10 deg. and in some cases of 5 deg., with some limitations caused by my non Anechoic environment. These many information helped and sad a lot to what we should take care and helped to verify certain acoustical behaviors during the listening sections. Power Response, Directivity Index, Listening Window (+- 30 deg. hor. +- 10 deg. ver.), drivers Acoustic Phase behavior and Impedance Magnitude and Phase were all taken in consideration.
This is a kind of speaker that can be used also on a “desk” (better “a bit” elevated from it) and is suitable also for near listening. It can be perfectly used on stand mounting (that was my main goal) and also with good results it can be placed on a shelf or on a furniture. That is why I also took attention of how the Response and Phase Tracking between the drivers (at 0, 10, 15, 20 deg. horiz.) changes at different listening distances, from 80 to 200 cm, to limit these differences and get a general overall good result. The Tweeter SB Acoustics SB-19ST-C000-4 has a lovely dispersion and this definitely helps a lot to have a more homogeneous high frequencies at different distances and at different angles from the speaker. This is one of the main reason that I choose this Driver.
Phase tracking between Woofer and Tweeter with Mic at 1 meter at Tweeter axis. As you can see the phase tracking is very good 1 octave under and above the 3000 hz crossover point.
Simulated results at 2 meter from Tw axis at 0 deg: SPL, Listening Window (+-30 Hor. +-10 Ver.), Early Reflections per CTA-2034-A (that shows very good results and also how the 1800 Hz dip will be less preeminent in Room. This behavior is confirmed by the Room response measures at 1/3 Octave ), Power Response, Directivity Index (to Listening Window) and Early Reflections Directivity Index per CTA-2034-A, 1/24 oct.
Measures of the drivers mounted on the cabinet where taken horizontally and vertically from 0 to +- 180 deg in steps of 10 deg. (Click to enlarge)
I try first an “usual” Vent of 3,5 cm diameter but, as predicted by the calculations, was too small and the air was moving too fast producing a large quantity of noise around all the 40/50 Hz region! Why I try it!? Cause I see many project out there with this or similar 4 inch drivers (or even 5 inch drivers!) made with a 3,5 cm Vent!! Not enough at all if you have a linear +- 5mm Xmax like in this 4′ nice driver! Now the Felix uses a Vent of 5 cm diameter in the bigger side and of 4,7 cm in the smaller side (Vent has a Conical shape). With this bigger Vent the “noise” given by the fast movement of the air in the port is much better! Ok, most of the time they-we choose a smaller vent as we don’t have enough space inside of the cabinet for a longer Vent but we have to be aware that this is a “problematic” thing and is definitely a compromise…
Felix Powered Speaker Baffle inside view and back panel.
CONTACT ME TO GET ALL DETAILED CONSTRUCTION PLANS AND ACOUSTIC MATERIAL KIND AND SIZES!
Some moments of the first PROTOTIPES CABINET ASSEMBLING with Tibor Szeifert!
LEFT: Before the painting process. RIGHT: After the painting process in white.
/IT: SINISTRA: Prima del processo di pittura. DESTRA: Dopo il processo di pittura bianca
First prorotipes! LEFT: During the painting process, here with a Custom finish (cat drawing) for Liliana. 🙂 RIGHT: Burning in of the drivers.
/IT: Primo assemblaggio per Misure e Test, quí personalizzata con il Gatto per Liliana. 🙂 SINISTRA: Durante la verniciatura. DESTRA: Rodaggio degli altoparlanti.