5002 Tweeter vs. Newer Replacement

[Pete B]

I purchased a pair of nice clean, original looking, 5002s some time ago.

Noticed that the plastic tweeter face on one unit was cracked around the

mounting screws. Found a replacement on e-bay that was correctly

stated to be the newer replacement tweeter and looked exactly like the

tweeter that I needed to replace. My understanding was that this was

from one of the current suppliers that are providing copies of the original

driver, but it was not clearly stated in the advertisement.

On closer inspection the replacement tweeter has a much finer textured

finish on the plastic that almost looks smooth. It does not say Advent

Corp, Cambridge Mass on the front, and it has a round magnet as compared

to the original with a square one.

Further observations:

Original 5002 Tweeter:

DC resistance: 5.28 ohms

Lead in wires: solid

Dome is one part with the face plate, no sub assembly that is easily

replaced.

Replacement Tweeter:

DC resistance: 3.99 ohms

Lead in wires: tinsel

Dome is part of a sub assembly that is easily replaced.

The DC resistance alone indicates that the replacement tweeter is signficantly

different. I will measure the T&S parameters when I have some time, but I'm

not going to use this tweeter for the repair.

The tinsel lead in wires and dome sub assembly are pluses for the replacement

tweeter, but I still won't be using it since I want to keep these as originals.

The old tweeter works, and I'll probably just mount it as best as I can

until I find a good replacement.

[Pete B]

T&S Parameters:

Original Advent 5002 1" Black Dome Tweeter PLB#1:

Rvc = 5.28 ohms

Fs = 1326 Hz

Qt of 1.34

Qm = 2.36

Qe = 3.13

Zmax = 10.4 ohms

Zmin (passband) = 6.14 ohms

Z (at 10k) = 7.57 ohms

Lvc = 56.7 uH at 10 kHz

Original Advent 5002 1" Black Dome Tweeter PLB#2:

Rvc = 5.68 ohms

Fs = 1360 Hz

Qt of .99

Qm = 1.63

Qe = 2.50

Zmax = 10.2 ohms

Zmin (passband) = 6.46 ohms

Z (at 10k) = 7.95 ohms

Lvc = 60.3 uH at 10 kHz

Replacement for Advent 1" Black Dome Tweeter:

Rvc = 3.99 ohms

Fs = 1411 Hz

Qt of 1.10

Qm = 2.92

Qe = 1.77

Zmax = 11.6 ohms

Zmin (passband) = 4.75 ohms

Z (at 10k) = 5.63 ohms

Lvc = 33.7 uH at 10 kHz

[Pete B]

All of these tweeters have a fabric pad on top of the pole piece.

The pole is solid without any cavity.

These tweeters all have ferro fluid of the light weight type, however

it has seeped away from the gap onto the top plates and the gaps

are about half empty. Seems that gravity has pulled it mainly in one

direction over the years. Thinking ... The voice coil takes significant

volume in the gap, however I'm not sure if the fluid will displace

evenly during reassembly. Might help to let the tweeter sit in different

vertical orientations so that the fluid can migrate.

Two turns are left off the top layer of the voice coil at the dome end,

only on the replacement tweeter. This is an excellent trick to reduce

distortion. The original tweeters do not have this and are evenly wound.

This replacement tweeter looks very good in many ways, might be

worth testing in system to determine if XO changes are required. I'd

want to get a current pair first.

[Pete B]

A couple more original black dome tweeters from a pair of 5012s which is

the real wood version; these are from November of 1982. These appear to

be original since the face plates have Advent molded into them. The dome/voice

coil assembly is an independent unit for easy replacement and there are

a few turns missing from both ends of the top layer. Lead in wires are tinsel:

================================================

Original Advent 5012/O 1" Black Dome Tweeter PLB-A 5-27-2010

UNIT MARKINGS: 10-995-210 143TND

Rvc = 5.41 ohms

Impedance file: AD5012TA.ZF2

Fs = 1164 Hz

Qt of 1.06

Qm = 2.55

Qe = 1.81

Zmax = 15.3 ohms

Zmin (passband) = 6.19 ohms

Z (at 10k) = 7.70 ohms

================================================

Original Advent 5012/O 1" Black Dome Tweeter PLB-B 5-27-2010

UNIT MARKINGS: 10-995-210 143TND

Rvc = 5.21 ohms

Impedance file: AD5012TB.ZF2

Fs = 1128 Hz

Qt of 1.14

Qm = 2.98

Qe = 1.86

Zmax = 15.6 ohms

Zmin (passband) = 5.75 ohms

Z (at 10k) = 7.36 ohms

Lvc5K = 32.1 uH

Lvc10K = 42.5 uH