NEWBIE: OPEN BAFFLE solution - for Altec Duplex 604 E.

**omodo** · November 22nd, 2012, 08:24 AM

The "tube kingdom" baffle as described in the following article would be a better place to start, IMHO.

JE Labs Arkiv: Open Baffle

**cradeldorf** · November 22nd, 2012, 12:47 PM

Originally Posted by omodo

The "tube kingdom" baffle as described in the following article would be a better place to start, IMHO.

JE Labs Arkiv: Open Baffle

Yep this is a much better design, your 612 open baffle concept is a great thought but OB's need more width.

**Tralalalala** · November 22nd, 2012, 01:20 PM

thanks again for generous suggestions.

infact I have a pair of ESL57?s so since this open baffle design has the same dimensions as them this will suit me quite well

just have to drop my idea about making a hybrid front .. dropping this is maybe not such a dumb idea after all....

- tralalalala

**gortnipper** · November 22nd, 2012, 03:38 PM

I had a pair of GPA 604-IIIs in the JE Labs OB for a couple of years, and they sounded quite nice in them as an "interim" solution. However, they sound much, much, much nicer in proper big cabs.

It certainly is different (better) having the drivers at ear level vs shin level as they were in the OBs. The upper mids are definitely better - more detailed/articulated. Snare brushes are coming through with a lot more clarity and expression now. Much better control and imaging than the having them in the JE Labs OB.

**Panomaniac** · November 22nd, 2012, 10:25 PM

I have not tried the JE Labs baffle with a 15", but with smaller baffles it has no bass, none. Just the harmonicas, no fundamentals.
In Dallas I showed a 605 on OB with an 18" helper sub. Worked great. For many tracks the 18 isn't even needed - but when it is, it makes a world of difference.
The speaker belonged to my friend John. I'll dig up a photo, if I can.

**Cal Weldon** · November 23rd, 2012, 11:51 AM

I'm with Pano. The Qts of the 604's is far too low for an open baffle arrangement without reinforcement.

I tried - then I cried.

Use a tuned box. It was designed for that. The 612 or variant is a good starting point

**Cal Weldon** · November 23rd, 2012, 11:53 AM

Originally Posted by Panomaniac

Just the harmonicas

That's it? No other instruments or vocals?

**Tralalalala** · November 23rd, 2012, 01:00 PM

Thanks people !

I?ve now decided what to do ... got my 604 E?s today.

I?ll make a DIY enclosure of the 612 C and Iconic cab.

the main reason is because I will not put money into a sub right now - have understood that people disagree on this subject about OB?s....

**Panomaniac** · November 23rd, 2012, 04:30 PM

Originally Posted by Cal Weldon

That's it? No other instruments or vocals?

LOL! Yes, mouth harp was all that came thru!

(Thank you spell-check).

Tralalala, people disagree about a lot of audio stuff, it's par for the course. You can make the 604 or 605 work on a large open baffle, but you have to sacrifice efficiency to get the tonal balance right. The crossover is very important here - the woofer section has to be crossed much lower than normal to fight the rising response an OB give you. Done like that, it will mate up to the horn about where it should. A powered OB sub will help fill in the very bottom when needed. It's not hard to do.

You can see the 605s on OB in the first photo here:
http://www.hifizine.com/2010/06/lone-star-audio-fest/