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Altec 2-way horn system redux

Truth be told, I was never fully satisfied with the performance of the Altec 2-way which is why I never uploaded the old article in the Arkiv.
Let's recap how the 2-way horn system evolved...


The project was conceived in mid 1998 because I needed a monitor system that was more efficient than the OB/755 so I could listen to SE amps with 2 watts output and below.
I commissioned my cabinet maker neighbor to build 614 bass reflex cabinets and loaded them with Altec 419A 12" drivers + 811 horns (early version/heavy sand cast) and 804A compression drivers gathered from hamfests and radio shows. Crossover was a textbook 1st order/6dB/octave hinged at 900 hz and the horn padded down to match the sensitivity of the low frequency driver.

Eventually I acquired proper 12" woofers - Altec 414As, which lack the upper midrange nasties of the 419As. The 414As have great midrange quality even if they lack the bass end of their larger 416/515 brethren.

802D compression drivers replaced t…

2017 Update: Hi-Fi Room

One year progress report

Stereo
Garrard 301 + Ortofon RMG 309/SPU GME or SME 3012 + Denon DL103 Altec 4722 MC step-up
Digital line level sources processed  through UTC A20 transformers

JEL Stereo Preamp DX
JEL Stereo SE2A3 DX amp with Tango NY15S OPTs
Altec 2-way Altec 414As in 3.5 cf bass reflex enclosures + Altec 32A horns with 802D compression drivers
or
Mono Neat P58H 4 speed idler turntable + Velvet Touch viscous damped tonearm with Denon DL102 or GE RPX cartridges

je2a3 mono integrated amp

Stereo > Mono Line Level Mixer

Mixing line level stereophonic signals into full dimensional monophonic ;)
Here's a DIY project for mono aficionados that's so basic, I should have uploaded it many years ago. But other things got in the way.

Just like an MC step-up, these are entirely passive devices. 

The simplest way to convert stereo to mono is to connect left and right channels via a Y connector. But there's a more elegant way than just shorting two channels.

Resistors can blend two signals into one better by...

...using Allen-Bradley carbon composition for warmer sound ;)
We can end the mixing quest here but...

...the most elegant way of mixing two channels as was done in the studios by audio pros of yesteryears was through transformers.


This single UTC A-20 transformer was in a box lot of tubes and parts I picked up at a radio show. It's a high quality transformer designed for mic, mixer or line matching applications. Instead of trying to find a mate for MC step-up duty, I repurposed it for a g…