515B and 515-8g - magnet design

**jocelys1** · October 27th, 2016, 02:48 AM

Thanks Greg, that puts the topic to rest.

You mentioned the 515 FieldCoil and 803s were different. I have a pair of 803Bs which look similar to the 416s. Is that different to the 515 & 416 we've been discussing ?

**bowtie427ss** · October 27th, 2016, 10:24 AM

I have a pair of 803Bs which look similar to the 416s.

They are one in the same.

The 803B woofer designation was changed to 416A, it was necessary to prevent confusion.

This is also an Altec 803B:

**jocelys1** · October 27th, 2016, 11:33 AM

Thank you. A lot of confusion cleared up.

GM · October 27th, 2016, 12:55 PM

Originally Posted by jocelys1

Thanks Greg, that puts the topic to rest.

You mentioned the 515 FieldCoil and 803s were different. I have a pair of 803Bs which look similar to the 416s. Is that different to the 515 & 416 we've been discussing ?

You're welcome!

Very much so, the former uses an adjustable electromagnet [Qts, i.e. variable electrical damping] Vs the latter's permanent one [~fixed Qts], plus the original 803 has a much weaker one [high Qts], ~20 Hz higher [Fs] and less usable HF BW, major difference. The 803B/416A has a much closer [Fs], ditto [Qts], though still weaker than any of the 515 models I'm personally familiar with due to physically smaller magnets.

GM

**Altec Best** · October 27th, 2016, 04:04 PM

Originally Posted by jocelys1

Phew ! That took four days to appear. Looks like I'm out of 'moderation' as well. Yipeee !

Haven't been online much past few weeks sorry about that !

**jocelys1** · October 27th, 2016, 08:49 PM

All's well. Thanks.

**LICORNE** · October 31st, 2016, 02:52 PM

I didn't read all the answers , With underhung if you go with a wider bigger gap the speaker will cost more and run better than an overhung one at a cheaper price. Evry thing is relative.

**jocelys1** · November 1st, 2016, 01:21 AM

**bowtie427ss** · November 1st, 2016, 07:07 AM

Originally Posted by LICORNE

I didn't read all the answers , With underhung if you go with a wider bigger gap the speaker will cost more and run better than an overhung one at a cheaper price. Evry thing is relative.

I had to read this a couple times, and also consider that English may not be Licorne's first language.

I believe he is talking about the depth of the gap, or in other words it's length corresponding to the linear travel/motion of the coil itself rather than the width of the actual gap. AFAIK, gap width refers to the dimension of airspace between the pole and the ID of the front plate that the voice coil resides in.

**LICORNE** · November 1st, 2016, 12:22 PM

Originally Posted by bowtie427ss

I had to read this a couple times, and also consider that English may not be Licorne's first language.

I believe he is talking about the depth of the gap, or in other words it's length corresponding to the linear travel/motion of the coil itself rather than the width of the actual gap. AFAIK, gap width refers to the dimension of airspace between the pole and the ID of the front plate that the voice coil resides in.

Yes thank's bowtie the word is depth . Somedays I have tons of vocabulary others less .

Short coil deep gap is what I ment .