CUSTOM LOUDSPEAKER DESIGN
One of the major activities at Humble Homemade Hifi is designing and building extremely high quality, tailor made loudspeakers. With nearly 35 years of experience in loudspeaker design, acoustics and interior architecture, Humble Homemade Hifi is able to offer solutions for those who are looking for something unique, something tailor-made to your specifications and that can compete with the absolute best in high-end audio. We work closely together with experienced furniture craftsmen and suppliers of very high-grade components to realise an end product that meets the highest quality level in sound that is possible - exactly as you want it. Humble Homemade Hifi creates custom solutions for the discerning music lover.
A testimonial from one of our many clients: "Hello Tony, For 3 years, the Eves have delivered a coherent, natural, spacious, and mature sound that I have come to love. The Andromeda Mk-III energizes my 52m^2 room effortlessly such that the sonic virtues of the Eves can now be suited to a smaller room. This no-compromise design is the closest to a visceral live performance, surpassing anything I've witnessed in a home setting. From top to bottom, the music is balanced, coherent, uncolored, and detailed. I couldn't ask for anything more. Bass impact can be heard and felt in the gut - deep, tight, and well articulated. Compared to the Scan-Speak Classic based Eves, the Illuminator drivers have more dynamics, clarity, openness, and low level detail. The level of transparency allows for better micro-details and finer nuances. The separation of instruments is discernable in orchestral music with better edge delineation than my Eves. Full maturity settled in after 200 hrs of use. The Jantzen Audio Superior Z-Cap + Mundorf EVO Oil large value mid cap create a well balanced, wonderfully spacious, and tonally rich midrange with an image depth and width that extend beyond the speakers. The Mundorf Supreme Silver Oil + Audyn Reference for the tweeter produce a refined, open, and airy top end with excellent micro detailing that's never fatiguing. The fluid and smooth nature imparts an analog smoothness to harsh and edgy digital music making extended periods of listening a joy. No one region of the spectrum is highlighted. Vocals and acoustic instruments are exquisitely refined and airy. Piano music comes through very realistically, with wide dynamic range, full-bodied, and open. The recent addition of the Duelund Silver Bypass Caps on the mid and tweeter were noticeable in enhancing transparency and immediacy even more. Many thanks, Tony, for your patience, expertise, and sharing your vast experience. Having heard the B&W 801, Snell Illusions, this custom designed Andromeda Mk-III easily competes with world class speakers above $35k+. I'm forever discovering new nuances, instruments, and detail in my music collection. Wow! Best Regards, George Vosgerichian, USA."
Below an couple of examples of loudspeakers based on the Soup Ceramique built to the client's specifications. On the left with an Accuton 8-inch ceramic woofer, a 5-inch ceramic mid woofer and a 3/4-inch ceramic tweeter with cabinets made from 30mm thick (baffle 60mm) Marine Grade Baltic Birch plywood finished with book-matched and mirrored American Walnut veneer. On the right with two Audax 7-inch Aerogel woofers, a 4-inch ceramic midrange and a 3/4-inch ceramic tweeter with cabinets made from 30mm thick (baffle 60mm) mdf finished with book-matched ash veneer. Further high-lights: huge, custom wound and impregnated Mundorf VT-390 transformer type inductor with 6x2mm flat-wire, Intertechnik Audyn True Copper capacitors, Finite Elemente Cerabase Classic and Soundcare Super Spike component feet, WBT Nextgen binding-posts, cryogenically treated Furutech Alpha S-14 internal wiring, etc.
A subwoofer for hifi and home-cinema use with two 18-inch woofers, mounted back to back on each side of the cabinet. The woofers work in a so called impulse compensated configuration. Big drivers are capable of moving huge amounts of air however, at the same time the mechanical forces involved can cause unwanted side effects. These two woofers work back-to-back so the opposite forces compensate each other and unwanted vibrations are cancelled. The heavily braced cabinet is made from 18mm thick / 13 layer and 40mm thick / 28 layer Marine Grade Baltic Birch plywood, epoxy coated and then finished with several coats of semi-gloss deep black spray-paint. The total weight is 140 kg's and the subwoofer is powered by an efficient 500 watt BASH plate amplifier with parametric EQ. Bandwidth +/-1dB is 14Hz to 37Hz with a usable bandwidth of -3dB from 13,2Hz to 39Hz or -6dB from 12,4Hz to 42Hz. Notice the cd for size reference!
The following is an example of a three-way loudspeaker system built to the client's specifications (shape, size and driver configuration) with two 7-inch Nomex Kevlar woofers per side, a 5-inch ceramic midrange and a 3/4-inch ceramic tweeter. The heavily braced cabinets are made from a combination of 18mm and 30mm thick Marine Grade Baltic Birch plywood with an extra top layer of book-matched birch veneer. This system is a completely active set-up with DEQX digital crossovers and room correction, all driven by no less than six Pass Laboratories monoblock amplifiers. The details show some of the the CNC-machined internal bracing elements from which the cabinets are assembled and the rear of one of the loudspeakers with multiple Furutech binding-posts and Furutech internal wiring to connect the individual amplifiers to.
Another example of a three-way loudspeaker system built to the client's specifications with four 11-inch woofers per side (two on the front and two on the rear), a 7-inch ceramic midrange with custom wound voice-coil impedance and a 1-inch diamond tweeter. The heavily braced cabinets are made from 40mm thick / 28 layer Marine Grade Baltic Birch plywood with a top layer of book-matched American walnut veneer. Tastefully finished with 10 coats of high-gloss clear varnish. Eye for detail: the woofer section of the crossover of the loudspeakers. Note the paralleling of many small capacitors and the bypass capacitor to obtain the large main value of several hundreds of microfarads of a low frequency correction-network. On the right, the matched pair of ceramic midrange drivers with user-specified voice-coil impedance.
LOUDSPEAKER CROSSOVER DESIGN
The crossover is the heart and soul of any loudspeaker. Even the best drivers in the world mounted in a well built cabinet can sound terrible if the crossover typology and quality of the crossover components used are not well designed and implemented. A loudspeaker filter has several functions, the main one being to divide the frequency spectrum into pieces that the corresponding drivers can cope with. The woofer must be attenuated before it starts beaming at high frequencies, the tweeter must have protection from low frequencies so you don't blow it up! Now this may seem easy, you just look at the datasheets of each driver, see in which region they overlap, choose a crossover-point somewhere in the middle of that region, feed the data into one of the many online crossover calculators - and bingo! Unfortunately, as with most things in life, it is nowhere near that simple.
First of all loudspeaker drivers don't have ruler flat frequency and impedance curves. The load that a driver presents to an amplifier consists of a complex electrical impedance, a combination of resistance and both capacitive and inductive reactance. A loudspeaker driver does not have a constant resistance over its frequency range but a resistance that varys depending on the frequency. The voice coil's inductivity rises towards higher frequencies, the driver has mechanical resonances, the enclosure changes the driver's electrical and mechanical characteristics, etc. (source: http://en.wikipedia.org/wiki/Loudspeaker). For example a nominal 8 ohm impedance midwoofer can have a peak of over 100 ohms and a dip down to 6 ohms. So that makes all static charts, tables and online calculators completely useless. They are based on constant values. So the only way to design a loudspeaker crossover correctly is to take very accurate measurements of each of the driver's frequency and impedance curves with their corresponding acoustic and electrical phase response, in their final enclosures and after they are fully burnt-in. Also waterfall plots must be made to see if there are any parts of the frequency spectrum that take a little too long to decay. And add in a few off-axis frequency measurements to check baffle edge diffraction problems and some distortion measurements for spotting any other nasties. And don't forget to measure the output from the port either - especially with a two-way system, there can be quite some midrange energy radiating from the bass reflex port!
After thorough interpretation of all this data, the relevant sections are fed into accurate and versatile simulation software and several crossover typologies and options are modelled. This is where over 35 years of experience comes in handy to know what has potential and what is a complete waste of time. This modelling results in about 5 or 6 different crossover schematics that all seem to produce a more or less flat summed frequency plot, an amplifier friendly impedance curve and are kind enough to the driver / cabinet combination used. They may vary in steepness of the slopes, crossover-point, have lots of additional correction correction-networks or be relatively simple, etc, etc. Each of these 5 or 6 different crossovers are then built in real-life with standard quality components and listened to extensively. This part of the crossover design is quite interesting as it lets you hear how the various driver / crossover combinations work (or don't work) together. Some combinations "harmonise" better than others but they all have their own sonic signatures. After this lengthly period of evaluation you are left with about half the amount of crossover schematics that still seem to sound okay. Then it is time to measure again. These measurements will show any potential "problem area's" and together with their sonic characters help narrow down the options. Just to keep things simple: say you are left with two filter possibilties that both sound quite good. With the recent measurements in the back of your head, further modelling of these crossovers and even more listening sessions, you try to "tune" the two options until you have the feeling that you can "squeeze" them no further. Let them both compete with each other, like a sort of speaker "shoot-out". When crossover A seems to be the winner soundwise and concerning measurements, then "tune" crossover B even more until it seems to be on top. Keep this process going on as long as possible, combining constant measuring with listening to all types of music, from string quartet to big-band, from electronic dance to large orchestrial and choir works (see my Music Page for inspiration). Don't make the mistake of only listening to those so called audiophile recordings of jazz-trio's that you often hear at hifi-shows. They always sound good, even on a crappy system. Give them something healthy to eat like a nice helping of Johann Sebastian Bach's Weihnachtsoratorium. This part of crossover design has nothing to do with personal taste nor is it part of any "voicing" stage. The only things that should be on your mind during this stage are things like balance, neutrality, sound-stage and coherence.
After a while you should be left with a crossover schematic that measures very well and sounds very good. This one will serve as the basis for the final design stage. Now it's time for fine-tweaking, system matching and a little bit of personal taste. The crossover is next built with high-grade crossover components on the more critical positions. This can get a bit tricky because you have to take into account the signature of the loudspeaker drivers, etc and the signature of the crossover components. They all have to blend together well to form a synergy that takes the system to a much higher level. There is no point in just buying "the best" components money can buy, the chance that you will get a perfect "match" that way is rather remote. What I usually do first with (for example) a two-way system, is to start with the midwoofers low-pass inductor because the choise here is limited: air-core's of various wire diameters, round wire, flat wire, hexagonal wire, litze wire, copper foil with polypropylene or copper foil with impregnated paper - that's just about it! When you have decided on your favourite inductor then it's time for the tweeters main high-pass capacitor. I often mix "flavours" in various ratio's to obtain the taste I like. From experience I know what types / brand's go together well like salt & pepper, peanut butter and jelly, fish & chips, gin & tonic, etc, etc. Another sonically critical component is the resistor that is directly in the tweeters signal path. This substituting process is repeated for all the components throughout the crossover. For example, to obtain a maximum in coherency, I often choose the same brand and type of inductor as used for the woofer (just a smaller gauge) for the high-pass inductor parallel to the tweeter.
The final icing on the cake are the bypasses. These are components with a very small capacitance compared to the main value. With normal simulation software you don't see any difference when they are in place, but they do make small audible enhancements in things like smoothness, micro-detail and spatial information. These parts are so cheap that you can use them in most positions and blend multiple types untill you obtain your favourite taste.
Like many things, the loudspeaker world hasn't stood still. Due to increasingly better measuring techniques and insight, new materials and applications, more refined products appear on the market. Humble Homemade Hifi continuously follows these developments and offers you the possibility to make use of them in your existing loudspeakers. An upgrade or modification can consist of the strategic and careful replacement of electrical components such as resistors, inductors or capacitors. But also alterations to the dampingplan and the mechanical properties of the loudspeaker cabinet can result in less colouration and better integration with the room acoustics. The end result is better definition, a more spacious image, more fine detail and a calmer presentation of the musical content. You also have the possibilty to fine-tune an existing loudspeaker to the rest of the hifi-system and to your own personal taste. So, if you're not completely satisfied with your current loudspeakers but you find it a pity to get rid of them or the purchase of a set of new loudspeakers is too costly, consider a loudspeaker upgrade.
What customers say:
"The initial set of values you sent worked out to be the best. When I say that this was a good thing that you did is an absolute understatement!! The speakers are so natural, transparent, detailed without edge, and the sound stage is staggering: depth, width and height. The depth in a large choir or orchestra is sensational. I have recently purchased an SE 845 amp and the synergy is quite simply ... Breathtaking. Thanks you for giving me this experience, one which I have never had in my listening room." (Brian, East Greenbush, United States of America - filter upgrade Swans Speaker Systems Allure)
No part of this website may be reproduced in any form without written or e-mail consent from the author. The designs are free to use for private DIY-purposes only, commercial use is strictly prohibited. Humble Homemade Hifi is a subsidiary of tg-acoustics - Chamber of Commerce 37138402 - The Netherlands
Last updated 3.8.2016