One piece cone vs seam cone...

[e_fortier]

Hi,

I'm about to buy a pair of vintage full range drivers from the late 50'
Both drivers are 8 ohm and were connected in parallel on a push-pull 6BQ5 mono amp. in a console with a turn table.

What I'm wondering is that the unit (Zenith console) is using 2 drivers which have differente cone construction even though they were both manufacturered the same year and by the same manufacturer.

One cone has a radial seam and the other cone is a one piece cone, no seam.

I have seem in many occasion this configuration in Zenith console, using 2 full range drivers located close to each other but with different cone construction…

Both drivers have the same basket, frame material, magnet type and size..

Why go to the trouble of using 2 slightly different drivers ? Any idea why would a manufacturer would do this ? I have some ideas but would like to hear yours first.

I'm probably making too much out of this but I keep wondering the reason for doing such a thing.

If there is sonic differences between the 2 cones, I would prefer to know now before moving ahead with this purchase.

Thanks,
Eric

 

[Galu]

This is interesting, Eric, but I can't find or offer any helpful information.

So, I'll simply give your thread a bump.

Is the Zenith driver in the attached image the "radial seam" type to which you refer?

(The seller describes the cone as having "no cuts or tears".)

 

[e_fortier]

Hi Galu,

Yes, this is the Radial seam except that mine doesn’t have that ring in the middle, see pic.


BR
Eric

 

[planet10]

A seemless cone will be formed and can have curve built-in.

A seamed cone is formed from a flat peice of paper, and will be straight sided.

The first likely has more ectended top if curved, the second does not require a big expensive cone press andwould have been cheaper to build at the time.

dave

 

[Galu]

Here are the fruits of my research, Eric!

Seaming is a way of making paper cones from a flat sheet of paper instead of the alternative, which is forming the paper pulp with cone shaped moulds.

The area where the two edges of the cone overlap is glued to keep the cone's shape.

Seamed cones have a very particular sound and have been used mostly for guitar speakers.

They offer a sound which is different from moulded cones. I presume the presence of the seam alters the modes of vibration of the cone compared to one without a seam.

 

[planet10]

Seamed cones have a very particular sound and have been used mostly for guitar speakers.

Lowthers. ACR.

dave

 

[e_fortier]

Thanks for all this valuable info

Kinda wonder if they will sound different for a stereo setup. One seamed and one seamless?

I guess I’ll let you know next week

BR
Eric

 

[Galu]

I also read that the felted paper sheet is further compressed between heavy rollers, resulting in a density greater than achievable by moulding.

Changing that property alone would result in different sound.

If you do go ahead with your purchase, Eric, then just flick each of the two cones with your fingernail.

That should expose any difference in sound!

 

[boswald]

Go to the Misco site, and read the story of their reproducing a particular Yamaha driver.


They got very close in spec, but could not get the tone right until they used the original seamed construction.


Using yours might involve your room, i.e. one in a brighter or softer part of the room. You'll fig it out, crossover and box needs should be the same.

 

[e_fortier]

Well just an update...I received the drivers today.

The seamless cone (49CZ861) is warmer sounding vs the seam one (49cZ860) which is slightly brighter. I prefer the 861.

I still don’t know why Zenith would use 2 different drivers in a mono setup. From 10 feet away they sound almost identical...

BR
Eric

 

[Galu]

Thanks for the update, Eric.

That brighter sound you describe was no doubt the reason that seamed cones were popular as guitar speakers.

Perhaps the intent of Zenith was to brighten up the sound of the mono speaker combo a tad.

 

[as_audio]

If you use two speakers in a table top radio or in a mono console it is a good
idea to make them slightly different in order to avoid mutual resonances.

 

[e_fortier]

Very good info. Looks like the engineers from Zenith knew what they were doing.

Thanks everyone
Eric

 

[e_fortier]

Thanks for the update, Eric.

That brighter sound you describe was no doubt the reason that seamed cones were popular as guitar speakers.

Perhaps the intent of Zenith was to brighten up the sound of the mono speaker combo a tad.

The mono setup also had 1 mid and 1 tweeter although you really don’t need them...

 

[midrange]

A seemless cone will be formed and can have curve built-in.

A seamed cone is formed from a flat peice of paper, and will be straight sided.

The first likely has more ectended top if curved, the second does not require a big expensive cone press andwould have been cheaper to build at the time.

dave

Ah, that's how Lowther keep their prices so low.🙂

 

[Mattes]

Ah, that's how Lowther keep their prices so low.

Hi,

Exactly. And many other cheap offers like Voxativ, Cube, or Feastrex use their straight cones in order to maintain their low prices...

The problem is generally to buy or to produce curved cones in small numbers, should you feel the need for a curved cone in your design. Buying is relatively easy - Dr. Kurt Müller is well recognized - but you may not get exactly the specifications you want if you buy only a few.
Segmenting the cone and glueing the paper back in shape is an option, Ken from songeraudio does it that way.

Making a one-piece curved cone is easily done in a mold if you work with plastic, carbon, foam sandwich or whatever. But all this is much too heavy for a widerange driver.
The challenge is to make a curved, light paper cone in small numbers. This is possible, but very time-consuming and expensive. In fact, you could easily buy a SB Sartori 6", rip off the cone, use it and still be a lot cheaper...

All the best

Mattes