January 2006 - Joe's Loudspeaker Dream Comes True

Everything started with our attendance in early December 2004 at the European Triode Festival (ETF) in Langenargen at Lake Constance. This venue, which was launched by tube & music enthusiasts years ago in Denmark, is a wonderful opportunity to meet some of the most outstanding designers of the DIY tube amplifier/ loudspeaker scene from all around the world.

When Joe and I  drove to Langenargen to be part of the festival in 2004, one of Joe's friends, tube amp designer Thomas Mayer from Germany, installed an incredible loudspeaker system into the big show room at ETF in Langenargen. It looked like this:

Thomas' system sounded extremely impressive and lively with its two Altec 15" 515B and two Altec 15" 416A (i.e. 16 ohms version) mid bass / bass units and Technical Audio Devices' (TAD) TD4001 with TD horns for the mids plus super tweeter for each channel; Joe was hooked immediately and decided to go for his 'ultimate' dream loudspeaker system. Thomas Mayer's system at ETF 2004 was great fun to hear; despite some audible problems, it was obvious what capabilities such a big LS system can have  (on Saturday night we had definitely the best disco sound ever in Langenargen).

By the way, at ETF 2005, the same system, this time with fitting electronics designed by Thomas, was a music lover's dream. I've never heard music so real and lively and with such impact - this was an awesome experience. (Hmm, the dimensions of such a system are too big for my dedicated music room, but one day there will be a horn-loaded system playing music for me, I think...)

After the initial impression in 2004, Joe went on faith and decided to use Thomas' system as a starting point. Since he had neither the space nor the will to separate parts of his living room, a solution had to be found. Starting from an infinite/open baffle speaker, one can either go for a sealed enclosure (if one bends the baffle backwards) or to a horn (bending the baffle forward).

One of Joe's real strengths is his admirable capability of rapidly realizing his projects. Once he had acquired 10 Altec bass chassis, it took him about one year from the various prototypes to the finished speakers. OK, he's fortunate enough that one of his friends, Christian (www.zendron.at), is a carpenter and Joe could get his advice, use his machinery and part of his work space, but man, regarding this project no time was wasted.

It is always said that horn loudspeakers have such an impressive bass, but it is mostly second hand (you know, "I read it in a magazine," "I have a friend who has a friend and he heard it somewhere," and so on). But what is the truth? As Joe says "the proof of the pudding is in the eating", so a prototype horn was built.

(Photo courtesy of Joe)

Hmm, impressive but the phase problems between bass and midrange were impressive too. So, Joe gave it a second try.

(Photo courtesy of Joe)

Damn, these horns were not only really good sounding and powerful, but they also could fill up a 40m living room.

So, what can be done to preserve the power and the glory of these monoliths yet wrap them up in some less demanding enclosure? After some discussion with our friend David, Joe finally decided  that his 'ultimate' LS system would consist of the following: two Altec 515B and two Altec 15" 416A mid bass / bass units loaded with wave guides developed by David, whose simulations indicated that this arrangement would preserve the slam and ease, but with one octave bass more, and allow a far more handsome appearance.

The rest of the system should consist of the elliptical horn system for the mid and treble sections Joe had used in his LS system (also designed by David) driven by a TD4002Z driver (this is the Neodym version of the TD4001 without horn adaptor), plus a JBL 2405 super tweeter (16 ohm Alnico version) for each channel. Overall efficiency of this system should be close to 100 dB (that's what all the great low powered directly-heated SE triode amplifiers out there need to really shine...).

To give you a glimpse of how it was done...

The wave guides are made of concrete, so what you need for the speaker is...

(Photo courtesy of Joe)

do this...

(Photo courtesy of Joe)

and get that:

(Photo courtesy of Joe)

If you have two of these, simply sand, glue and polish them and you get one wave guide front of the project. Have I said that you need 4 double-wave guides?

On Saturday, January 14, 2006 Christian, his friend Florian and I met at Joe's apartment to help him install his dream speakers (nicknamed Big Otto's after a famous Austrian wrestler "Big Otto Wanz," who in fact only weighs 160kg). Here are some pics of the installation process:

The waveguides for the lower left and right speaker. We had to
glue slotted grub screws into the ready drilled holes of each waveguide
to later on be able to fix the 15" Altecs via their mounting holes. To achieve
the correct position of the grub screws for an easier assembling process, we
put the Altec chassis in place during the hardening process of the gluing.


Left cabinet skeleton; you can see the lower and upper chambers for each pair of Altec bass- / midbass-units as well as the space in between for the mid/treble horn section

Lower left bass chamber with mounted waveguide and Altec 515B in place. The weight of one waveguide is approx. 85 kg (about 187 lb), so the finished speakersystem will weigh approx. 260 kg (about 575 lb) - awesome!

Ok, both Altecs are mounted in the lower left cabinet. Let's have a coffee break..


Right cabinet skeleton with lower waveguide mounted - we're making progress;
 on the right side you can see Joe's Platine Verdier, and on the left, the power amp armada, which will drive the speakers in the near future.

Upper waveguide and bass chassis mounted. To lift up and fit the 85 kg
(187 lb) waveguide into the upper cabinet was quite a job, but Christian is a strong guy and the price was an excellent apple strudel - so, worth all the effort...


Internal view of the upper cabinet. Both
chambers are sealed cabinets, the one for the
515B has a volume of 150 l, the one for 
the 416B on top has 250 l volume. (The same
goes for the lower cabinet).

Finally, we finished the assembling work and here's the result plus a proud owner Joe (on the left) and his friend Christian:

Aren't they gorgeous. Sorry, I'm talking about the speakers...

It was definitely a great Saturday afternoon and I can't emphasize strongly enough, that I'm more than curious to listen to these babies. So, dear Joe, please finish the cabling, remaining cabinet work, active crossover and the remaining power amps as soon as possible, cause it's torture to wait much longer for a listening session.

I promise, I'll keep you informed about our first musical impressions...


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