Another ONKEN finished

[DUC985]

Hi, i just want to share some pictures about the finished Mini Onken. Thanks to GM who convinced me to look for Altec 414 drivers.
They sound great in the cabinet.
I started with Altec 806A on 811 Horns. They sound great for the money. Very smooth, but lacking some detail and HF extension.
I ended up now with TAD 2002 and a simple 6dB crossover at about 900Hz with Autoformer -12dB. This driver is simply amazing with a very simple crossover.

[DUC985]

TAD TD-2002 with Altec 811

[Tim Moorman]

DUC985,

I built something similar some years ago for the big brother 416 woofer and 511 horn. Tons of fun, and a big wall of sound. While the bass was slightly better with the larger woofer, the 414 has an addictive midrange when paired up well with a horn.

Feel free to experiment, as that's part of the fun. I used both the TAD 2001 and the Altec 901 drivers crossed at around 900 Hz. Not a big difference, really, on that horn. The 414 will easily go higher, and may even match up better in directivity at 1200 Hz or so. Your call.
I did use 2nd order on the crossover, and added a small cap/resistor to the HF circuit to raise the response a bit at higher frequencies. Not a massive change, either.

What size is the Onken enclosure?

It's hard to imagine using a "bookshelf" speaker after something like this, eh?

Nice work.

Tim

[vuki]

Nice work DUC985! I started with something very similar (511 instead of 811) few years ago, but gradually it transformed in two loudseakers
Just as Tim says: there is no going back now!



altec 2way 1

altec 2way 2

[Brett]

Originally posted by Tim Moorman
It's hard to imagine using a "bookshelf" speaker after something like this, eh?

That is a bookshelf speaker.

Nice.

[Tim Moorman]

Brett,

Hehe. Bookshelf. Right! Just a shift in perspective.

Vuki,

I see you too are still at it. Nice tannoy cabs.

Tim

[chops]

Excellent work! Those look great.

So how do the 806A's compare to the TAD's throughout the range (minus the very top end of course)?

If theyr'e a major improvement (however I have 902-8B's), I might try to spring for a pair of TAD's eventually for myself.

[Pano]

Nice looking box - congrats! I've always like the sound of Altec woofers in an Onken box, very nice indeed.

If you care to share dimensions and other details, we'd love to know.

[DUC985]

i have attached the drawing i used for the for the bass cabinet.
I'm still fiddeling around with the crossover. First i just compared the Altec's with the TAD's using the same simple 6dB crossover.

1.5H on the woofer and 12uF for the TAD or 22uF on the 16Ohm Altec. Simple L-Pad to adjust the levels.

The whole setup is fired through a 300B direct reactance AMP and a DIY CD-Player with PCM1704 NOS Dac usind a Pass D1 output stage. Just to give you an idea what overall sound i like.

I did not want to use a very low crossover point because i like the mid's of the 414 very much. So around 900 - 1000Hz will be the final XO point.

In comparison the TAD's are not lightyears ahead of the Altecs. The overall character of both drivers is pretty close. The TAD's sound super fast and super revealing but still smooth. Never harsh, like some people claim here in the forum. This is exactly what i was looking for.The Altec's keep a more romatic sound and i'm missing some details. It is like comparing vinyl with a CD sound. With the Altec's i would for sure add a supertweeter.
I also tried BMS 4590 drivers and listened to the Orphean horns. That is what i do not like ! You need a hell of a crossover to get this drivers sound nice and smooth. If you have a huge listening room there are advantages to use a very low crossover point around 300Hz with a huge horn and you can do that with the BMS They only integrate well if you sit at least 5 - 10 meters away. I do not have that distance.

So far i owned the following compression drivers i can compare the TAD's with :

- JBL 2420 drivers as midrange with a Klipschorn
- BMS 4590 with a Klipschorn
- B&C DE25 as tweeter (very very nice sounding mylar driver) would be my first choice as tweeter driver

I now moved to a 12dB crossover with 1.5H, 10uF as lowpass and 12uF,3H as Highpass. I compared resistors against my auto transformer, both set at -12dB. What is strange is, that the resistors simple kill the sound of the Horn. It sounds like **** compared to the auto trafo ....

I'm not sure wether i should test also a 18db Le'Cleac type crossover or not ? Usually the more complex the crossover gets the sound gets worse ...

One question would also be if the Altec 811 is working weel with the TAD, maybe at some point in time i will also test a tractrix horn ....

Currently i'm happy with 12dB crossover and the 811 ...

[Tim Moorman]

DUC985

I like the autotransformer idea. Something I intend to try...

As far as differences in the 1" drivers, I had the same experience. I believe the horn dominates the sound to the extent that it masks the qualities of each driver, to some extent.

I tried other 90 degree dispersion horns, both wood and a fiberglass DDS horn, and the sound changed dramatically. I think you would be pleased with a tractrix or similar flare. Vuci fiberglassed up his own pair of round horns.

Anyway, your right about the Altec being softer on top, which effects the overall tonal qualities - a warmer, less detailed sound . The TAD 2001 I used rolled off about 16K Hz with a slightly ragged break-up on the larger Altec horn, but could load down to 500 Hz. I actually liked it crossed higher.

Glad that your enjoying this older design. It may not be cutting edge, but it IS fun.

And thanks for the information on the various drivers you've tried.
Much as I thought, but it is nice to have it confirmed.

Tim