Altec 604 Reconing

**HeathKitPat** · May 19th, 2017, 09:01 AM

Looking around the web I can't find any information on re-coning a 604. In my case it's the 604C. Of course I know that GPA offers a wonderful service that is invaluable to the hobby but it would still be nice to learn more about what makes a 604 tick. I have taken apart an EV 12TRX to repair a HF diaphragm, but that is a horse of a different color.

Has anyone here taken one of these beasts apart? OR Does anyone here have a junk or parts duplex speaker they would be willing to take apart for this thread?

For us 604C enthusiasts, if a cone is bad the only real choice we have is to send it off to GPA for an accordian edged cone. While this is a good repair, it will no longer be a 604C (or early D).

There are paper cones offered for sale from time to time that are said to be for the 604C or the 515a Bass speaker. I've been told that the 604C cone is different and has a special shape that enhances the midrange magic and that it differs from the 515a cone. I believe on factory cones the part numbers for the 604C (20598 is a factory C cone part number) and 515a are different.
Anyone that can contribute to this thread to expand on the data base for the duplex speakers would be appreciated.

**LOUDER** · May 20th, 2017, 06:28 AM

As a young man i once took one of my 605's TOTALLY apart. Only to find out it played about a quarter as loud once put back together and reconed. My 605's have been with me going on 40 years now. I've reconed them I think about five times. They were sent to the Altec factory twice for magnet recharging. Think of Johnny Cash's Cadillac. They have black 16 inch frames, green alnico bodys and gray hf magnet covers. (Ya dropped one once, hence the second recharging.) I've had them in countless number of cabinets, settings and vehicles. (They sound really good in a van.) I even played them without the horn for a while for a real boom sizzle sound. y You can change just the cone in any speaker. But it is slow and tedious work to get it perfect. And this would be even harder on a 604\605 since they don't lay flat on there backs. And your right about the cone in the C model. The cone is slightly curvilinear, like the cone in a 803 A.( Try laying a small straight edge on the cone and see if I'm right.) This may give it even a better midrange sound since the cone is even lighter than the standard issue 604 cones. The cone still might be being made. Check out Ted Weber's website. wc15r. Of coarse it would have to be cut and fitted if this is the same cone. y My 605's now are in some 612's and are listened to daily biamped and time aligned. I'll never get rid of them.

**mah** · May 20th, 2017, 06:47 AM

It is inexpensive. Who is game?

WC15R Cone

Mention of 604C improved cone but no details of profile:

http://www.technicalaudio.com/pdf/Du...ex_Speaker.pdf

**HeathKitPat** · May 20th, 2017, 06:07 PM

Mah, the VC on that cone looks a bit small for a 604.

I also really think we are on to something about the shape of the cone for improved midrange. I was told by a few old timers to stay away from a 604C that was reconed using a 515a cone (something that was often done in the past).

Altec 515A, 604 cone paper replacement kit, pair | eBay

As you can see, this kit states that these cones are for both the 515A and the 604

**Elitopus1** · May 20th, 2017, 07:09 PM

Pat,
that is interesting about the 604C and 515A cones being different. I always figured that since the 604 uses basically a 515 for the LF section, that the cones would be the same. Are we talking about the paper hinge cones or cloth accordion surround version?

Very interesting thread BTW.

**LOUDER** · May 20th, 2017, 08:37 PM

[LEFT]HkP and E..... The original 803 was the same cone as the 515 with a smaller magnet, cloth spider grey color and Utah stamped frame. "Early" 803 A cast frame small magnet, cloth spider,gray color and 515 cone. "Later" 803 cast frame, small magnet, cloth spider, green color, and slightly curvilinear cone. This is the same cone in the 604 c. The tell tale "marks" are that the paper hinges on the cone are of equal height. And of coarse the "viscous damped" cone. More important is that the cone received a "cone dip" which strengthened the first two or three inches and that in the A version they started to shorten the x-max to get more excursion and more bass. And all of this before the 803 B the 416's daddy ! ( I have a dead 803 A green frame that I just can't tear apart just yet, to see the voice coil height.)

And yes the WC15R has a different voice coil diameter. But, is it the same cone profile ? The weight seams the same.

**mah** · May 20th, 2017, 08:47 PM

The larger voice coil could be fitted but it may not position correctly in the VC gap. Just one of many factors to be considered by an intrepid DIYer.

**magnarc** · May 21st, 2017, 06:26 AM

I have pictures here of 803A with a 20409 cone (Grey wrinkle and Green), a 20159 cone (Utah Frame), which follow the same run I have seen with a 515, and then an 803A with a 20750 cone, circa 1956.
Alos 604 and 604B with 20159.

The 803B I have pics here with the 21090 accordion edge and then a 20876, with the red surrounds.

Then we go into the 21184.

**LOUDER** · May 21st, 2017, 08:00 AM

Pat, do you have the cone number off of your 604 c ? I just a quick search and came up with a 20598 cone number from '59. Also can you verify if you cone is curvilinear with a straight edge. If so, the 604 c and 803 a would be the only speakers using this cone.

**HeathKitPat** · May 23rd, 2017, 03:49 PM

That is the cone number 20598. The original owner told me my speakers are from 1957. I'll verify the cone with a straight edge tonight and edit this post.. (just have to make sure my nerves are steely! Don't wanna poke a hole in my cone)