Altec 604 D Enclosures

**charly1944** · January 17th, 2012, 07:05 PM

Hi everybody,
I received from GPA my pair of 604 D.They remag. them and changed the LF cones.I also bought from them their N1600-16 crossover.After a pretty long breaking in period,i tried them at a friend's place.He has got a pair of 604 E with original cones ,a pair of "interesting" enclosures.So we could compare the two pairs of speakers in the same room and the same enclosures using the GPA crossover.The first conclusion is that the 604 D reconed by GPA sounded much better than the 604E with their original cones.Our best guess is his speakers probably need a remag.and may be a change of surround to perform optimally.The second obvious conclusion is that GPA did a very good job and that people should not hesitate sending their Altec to GPA for reconing.
Now come my questions regarding the enclosures.My friend has a pair of BR enclosures with the following external dimensions in feet :Height 3.05;Width 2.13;Depth 1.48.
Internal volume is about 11,3 cubic ft (from which one has probably to deduct the volume of the driver).The cabinets are bottom vented and the vents are actually two rectangles(1.0x1.5 feet) cut in the bottom of the enclosures and facing the floor.The 4 feet are 2 inches high.The walls are made of pretty thin(O.6 inch) and light plywood(Density about 0.5 when Baltic plywood is 0.7).No braces.The only internal damping consist of thin felt covering the internal walls. Those speakers are driven by high quality SE 300 B amplifiers.I was expecting from those speakers a lot of disturbing vibrations but actually they sounded pretty good and the only limit i could find was that i would have preferred the bass to go lower.So should i simply copy those light,inexpensive ,easy to built enclosures for my 604 D or should i try to improve them and in this case how?Charly 1944

GM · January 17th, 2012, 07:44 PM

For real?! That puts the tuning up around 72 Hz whereas a typical Altec tuning would be around 40-42 Hz.

GM

**cradeldorf** · January 18th, 2012, 03:02 AM

I had an E and a C, the C was way better sounding than the E, It dawned on me that the E crossover is supposed to be 1500 and I was running it with the same GPA N-1600 crossover your using. Not sure if that's why it didn't sound as good, but it could have been. The cabinet you described reminds me of my ex brother in laws Klipsch Cornwalls. When I saw the insides of them all I remember saying is they look like wooden bird cages. they were very light in weight. I was about 14 at the time so....yeah.
I'm glad to hear you got them back and that they sound great. I can't wait to see what cabinet design you go with but there are some real beauties out there.
These are my favorite for looks.
http://www.jacmusic.com/Yamamoto/Spe...604/YS-604.htm
These seem pretty cool too.
http://www.audiocircle.com/index.php?topic=54147.0

**charly1944** · January 18th, 2012, 05:53 PM

Hi sorry i did get back to earlier and thanks for the pictures.I like the OB very much but i am wondering how big they are and how do they perform,specially when it comes to low freq.Regarding the difference of performance of your 604 E vs C,they are indeed different drivers with different surround and i doubt that the the GPA crossover is equally adapted to both of them.There is also a distinct possibility that your E and your C are not in the same"shape".Did you check the surrounds,the spiders and the level of magnetisation of both pairs?
Charles;

**David Yost** · January 18th, 2012, 06:39 PM

Hi, GM

I didn't have any idea that Fisher had shared your design and PMs without permission, otherwise I never would have referred the OP to the sites. That really wasn't kosher for those boys to do that, and I hope it hasn't discouraged you from sharing your ideas with us DIY folk.

Best wishes,
David

GM · January 18th, 2012, 07:33 PM

Greets!

No biggie, it's old news and no, for the most part it hasn't, though I now limit most help to on-line Qs.

GM

**omodo** · January 18th, 2012, 06:03 AM

Originally Posted by GM

For real?! That puts the tuning up around 72 Hz whereas a typical Altec tuning would be around 40-42 Hz.

GM

GM, how does floor loading, especially in this case being only 2"/50mm off the floor, have an effect on port calcs/sizing?

**charly1944** · January 18th, 2012, 06:42 AM

Originally Posted by GM

For real?! That puts the tuning up around 72 Hz whereas a typical Altec tuning would be around 40-42 Hz.

GM

Thanks GM,
Pretty high tuning indeed.No wonder that i found it could have gone lower in the bass.What options would you recommend to go for.I dont mind wether it is an OB (provided it is not too big) or a BR solution.Thanks.
Charles.

**David Yost** · January 18th, 2012, 11:53 AM

I think GM has posted a MLTL box design for 604s on this site or perhaps AA High Efficiency, but it should be easy to find. I don't know if anyone has built it.

Here's another one: 6moons audio reviews: Steph?n's Altec 604 Dream Speaker

GM · January 18th, 2012, 02:40 PM

Originally Posted by charly1944

Thanks GM,

What options would you recommend to go for.

You?re welcome!

While OB, IB are theoretical ideals, there?s nothing intrinsically wrong with the existing cabs that maybe some additional damping, adding bracing and reducing vent area to lower tuning can?t solve and large enough to allow for an adequate amount of EQ/tuning options, though ideally we need their new GPA specs, especially since I seriously doubt they?re even remotely close to OEM.

Otherwise, at least as large an internal volume [Vb], though taller to make them an offset driver MLTL tuned around/at Fs and use some form of EQ to ?fill up? the cabs as required to tonally balance them in-room. This assumes of course the re-cones aren?t as ?weak? [high Qts] as some other recent GPA re-cones I?m aware of.

GM