Skip to main content

Altec 2-way XO Redux

This is an update on crossovers I use for the Altec 2-way speakers.

JEL N1600 Crossover

JEL N1600C + HF EQ
optimized for the 802 driver fitted with the original
16 ohm 20275 diaphragm

The above crossover circuit, as discussed in this previous post, was optimized for my cherished pair of green Hammertone Altec 802Ds fitted with the original aluminum 20275 diaphragm, which has an aluminum wound voice coil. To my ears, this diaphragm has a more prominent midrange response which necessitates rolling off the upper midrange/lower high frequencies of the 414A woofer for flatter response.

JEL Universal Altec 2-way XO

For the Altec 802 driver equipped with the 34852 (16 ohm) or 34647 (8 ohm) diaphragms, which have copper wound voice coils, I recommend the 6dB/octave crossover circuit below which is hinged at around 2500 Hz + high frequency EQ boost. This aluminum diaphragm has less energy in the upper midrange giving a tonal balance that sounds more extended in the high frequencies compared to its 20275 predecessor. In this implementation the Altec 414A woofer is connected as a full-range driver inspired by Joe Roberts. 

JEL Universal Altec 2-way XO with HF EQ circuit

Altec 414A + 32A/802/GPA 34852
+
JEL Universal Altec 2-way XO

I've also used this crossover successfully with the Altec 802 driver fitted with the Symbiotik diaphragm, Emilar EA/EC175 and Renkus-Heinz SSD1800/1400. Please take note of the different capacitor values for 16 or 8 ohm drivers.

Simplest Crossover



If you want the simplest crossover, my buddy Joe Roberts listens to his Altec 414A/802/32 set-up with the woofer in full-range mode + a 1.5uf paper in oil cap for the compression driver, no L-pad or HF peaking EQ circuit. See his Audiokarma post for more details.

Comments

  1. Just wanted to say that based on this post by you I changed my crossover to your recommendation last night. I'm running 909A-16s with the 34852 'frams and 414-16Bs in 614 cabinets. I'm liking what I'm hearing so far. The midrange seems much improved - vocal presence is smoother and more beguiling, and the bass seems a little more defined. I also like the fact that the physical crossover is simpler. Thanks for continuing to lead me astray.:-)

    ReplyDelete
    Replies
    1. I'm glad you found this useful. Happy listening and tinkering!

      JE

      Delete

Post a Comment

Popular posts from this blog

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…