Replaced my Field Coil Speaker...

[icr]

I went to great lengths to repair the fragile little 1" voice coil that is in my Gibson EH125 amplifier's speaker. This was a few years ago, but the old and brittle voice coil finally came apart. I thought long and hard about trying to re-cone the speaker, but decided to replace the speaker with a ceramic magnet speaker, and save all the parts.
I wound up removing the field coil from the frame of the old speaker and attaching it to the back of the new speaker.

Stealth installation, no one can tell there is a ceramic magnet speaker in there.

[icr]

I also took the opportunity to replace the 500K volume pot, as it was shot.

[vintagelove]

She's a real beauty.

[ruger9]

Very nice! So how does the ceramic magnet change the sound, if at all? I've seen some people say the field coil was the "magic" in these old amps, and that modern speakers completely change it, but I have suspected those are just the vintage snobs, LOL. "If it ain't ORIGINAL, then it CAN'T sound as good"...

[6v6ster]

Wow, inspiring work!

[icr]

Very nice! So how does the ceramic magnet change the sound, if at all? I've seen some people say the field coil was the "magic" in these old amps, and that modern speakers completely change it, but I have suspected those are just the vintage snobs, LOL. "If it ain't ORIGINAL, then it CAN'T sound as good"...

Quite a change in the character of the amp. I figured this, that is why 5 or so years ago, I repaired the voice coil and re-attached it to the existing cone and spider.

This issue now is the field coil is not on any support, the wires are wound only around a cardboard tube, and as that deteriorated, it touched and damaged the voice coil. I cleaned out the channel of the field coil but it still is so, so close to the moving voice coil, I don't know if it would be stable and not touch a new voice coil. Also, the only new voice coils 1" I found were double wound, so the new one will be even thicker than the original.

I do have recordings of the amp 24hours apart with the old speaker and new. Will post them.

[icr]

Also, I do have many vintage amps with all the original capacitors and nice original field coil speaker and everything still in tact for my 'collection.' This Gibson AH125 has had nearly everything REPLACED already.

Also, along those same lines, I made a 5e3 "Tweed Deluxe" will all new parts but wound up giving it to my brother...it just sounded like a new amp.

[icr]

Here is an example of another reason NOT to rebuild this field coil speaker. As you see in this schematic, the field coil cannot interfere with the voice coil.

In my speaker, the field coil extends the entire length, so the voice coil has to go down inside the field coil. I don't think it is a good design in the first place.

[sgosnell]

There were excellent reasons why field coil speakers haven't been manufactured in many decades.

[Herbie]

Quite a change in the character of the amp. I figured this, that is why 5 or so years ago, I repaired the voice coil and re-attached it to the existing cone and spider.
(…)
I do have recordings of the amp 24hours apart with the old speaker and new. Will post them.

I think that many of us are interested in these recordings too.

[darkwaters]

I recently replaced the old 8” Rola speaker in my ‘59 Supro Super. The speaker still worked, but it sounded very “papery” and uninspiring. I went with an Eminence 820H and I’m glad I did. It’s breathed new life into the amp. With all the great speakers available these days it seems a shame not to give one a try.

[icr]

[Simon1234]

Fantastic tone! Wow! I'd love to know how to sound like that.