Homebrewed speakers system

By the end of may 2021 I made a major speakers modification.

The La Scala are my long time favorite, the basis of a powerful and lively restitution. Over the years the Klipsch have been upgraded for a better restitution. The squawkers and tweeters replaced by JBL drivers. Original cast horn by a Bruce Edgar wood tractrix. Despite this I was not completely satisfied, especially in the midrange. I could not get rid of a some harshness that became bothering over time and decided to search a suitable driver compatible with my budget.

It was challenging because there are many good ones on the market. Main difficulty was the impossibly to get a pair for a trial which meant no place for error. I finally stopped on the Altec 288 family. These imposing pieces of iron bear a reputation of excellence among DIYers community.

Unexpected luck, a nice pair of the very desirable 288C model was selling in Germany.

Once collected I was only half my way. What would be the very best horn to go with ? Again, I asked friends, read lots of literature, roamed dedicated forums to search the Grail. It came under Altec 805 reference, a piece of history seldom seen on the second hand market.

At that moment I remembered the very positive comments upon wood replicas by a German guy.

It did not took a long time before I sent a mail to Markus Klug.

I have to say that Markus is the most involved, skilled, friendly guy I had to work with. Three months later I received a huge box containing the extremely well packed horns. Craftsmanship is exceptional and it's not much saying.

Altec 288C, July 1960, close serial numbers and great shape

Markus Klug MK805 multicell horn

I cut the Klipsch cabinet to accommodate the Klughorns. They seat on a dedicated jig built with birch plywood.

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I was a bit anxious after tighting all the parts together but the result exceeded my expectations. Gone harshness, gone beaming effect, gone disturbing hotspot. Music is now more pleasant and relaxed. Soundstage is wider, deeper with a great sens of tempo. Voices are to die for. The big Altec are detailed to the extreme while producing a physical impact on drums or double bass. They blend effortless with the La Scala bass bin to give an homogeneous, rich and lifelike restitution.

Kept the JBL 2402 and Alk Xover, a good match with the other parts. My first attempt was with tweeter atop, but sound was blurred (I think the ceiling is too close). I used raisers to place it between bass cabinet and multicellular horn.




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 June 2020

Bonjour, Hello, Hi, Hallo, Ciao ,привет, もしもし, … to all electronic tube audio enthusiasts.

some pics of my setup in a tiny music room

speakers are modified Klipsch La Scala. Alk crossover, JBL 2470 original phenolic diaphragm, Martinelli's wooden horns, JBL 2402 with 2405 diaphragm and dedicated attenuator. All time aligned
Alk 1st version original schematic

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