604-8K or 604-8L in M600 Maestro?

[gearfreak]

I now have a pair of 604-?? in M600 Maestro units, questions at bottom.

My observations:
++++++++++++++++++++++++++++++++++++++++++
- Rear Label:
ALTEC LANSING THE MAESTRO SERIES
Loudspeaker System M600 8 Ohms
ALTEC LANSING CORP., OLKA. CITY, OK MADE IN U.S.A.

- No rear HF cover. I am not sure what to call the plastic housing otherwise, but it holds the diaphragm to the mag with 3 screws.

- HF Diaphragm marked with:
26420 (so we assume it's a 26420 pascolite)
32980
91 31

- Xover: MODEL N604-8A (stamped: 8167 ?)
- on woofer cones: 035400
- on woofer frame: Instead of the expected green (e.g.) "AL 70" in-a-square QA symbol, I see what appears to be: (green) "PI 15" in a circle.

- From a copy of an M600 spec sheet, it spec's :
R604-8L recone kit
16" coaxial loudspeaker 50-03-026768
N604-8A
++++++++++++++++++++++++++++++++++++++++++



...direct or tangentially related quotes from Altec forum posts RE 604-8L:
##########################################

01)
"The M-600 uses the 604-8L. It is a K with a higher LF power voice coil and uses the Pascolite Alluminum H.F. Diaphragm. That ought to be confusing enough fo now, Jim."

02)
"Incidentally, these improvements and T/S's are exclusive to the ICONIC Model 704-8A - the 604-8L off by ALPro is NOT the same speaker, nor does it share these characteristics (and it's more expensive)."

03)
Altec 604-8L
HF horn: 60h40v "Manta Ray"
X-over:
Power:
Impedance: 8 ohms
Weight:
Magnet: Ferrite Ceramic
Response:
Frame: cast frame dark grey paint
Cone: paper cone with an "accordian edge" cloth surround
comment: a K with a higher LF power voice coil
uses Pascolite Alluminum H.F. Diaphragm

04) from: http://www.altecpro.com/pdfs/vintage...%20Summary.pdf
"604-8K" (K)
N1500-8A (L)
LF = 12 dB/oct
HF = 18 dB/oct

604-8L = Same as K with new crossover network, hand-built for Altec Lansing Professional by Great Plains Audio, USA

05) "ALPro is (or already has) dropped the 604-8L from their product line. They have always been made by GPA in OKC, but they are different than the 604-8H-II he makes now."

06) The "L" was nothing but a late "K" with all of it's flaws and is no longer being made.
ALPro has dropped everything from it's line that is not made in China, including the 604.
The 604-8H-II is a redesign of the 604, taking it back to what it was, yet making it better in several ways.
##########################################




My questions are:

a) do I have a 604-8k, or a 604-8L ?

b) What are the flaws mentioned in (06) ?


thanks for any input!



*Small pics should be posted in a moment...

[GM]

The plastic rear cover is called a loading cap. It's used to reduce the rear cavity volume (Vb) causing it to be somewhat under-damped, so it can handle more power. Should be replaced with a standard felt lined cap for HIFI/HT apps for smoothest response: Altec Compression Driver Rear Loading Caps

No personal experience with them, though here it lists the 8K in M600 and in a later doc it states that the 8K, 8L are identical, so this implies that at some point they became the same except for the 8K's consumer cosmetics Vs the 8L's stripped for action 'look' as yours do: http://www.lansingheritage.org/image...ro/1993-35.JPG

GM

[whitebroncoii]

The information below was pulled off a document that I have updated a few times over the years;

604's Forever!
The first production 604 appeared in 1944 and quickly became the industry standard. The 604 is a "Duplex?" or coaxial loudspeaker utilizing a 15" woofer and a 1" throat HF compression driver (1.75" voice-coil). The HF magnet mounts directly to the back of the woofer magnet and the throat of the HF driver extends through the center of the woofer to a small horn. This basic configuration has remained unchanged for 50 years . . .

604 B,C,D,E
16 ohm, Alnico, Circumferential Phase Plug, Multicellular Horn, 15.2” rear-mount woofer frame, network = N-1000-B (B), N-1600-A (C, D, E), crossover frequency = 1000Hz (B), 1600Hz (C, D, E), 30W (B) and 35W (C, D, E)

604-8G
8 ohm, Alnico, Circumferential Phase Plug, Multicellular Horn, 16” front or rear mount woofer frame, network = “604-8G” with LF 12db/oct and HF 18dB/oct, crossover frequency = 1500Hz, 65W Pink Noise

604-8H
8 ohm, Alnico, Tangerine? Phase Plug, Mantaray? Horn, 16” front or rear mount woofer frame, network = “604-8H” with LF 12db/oct and HF 18dB/oct, crossover frequency = 1500Hz, 65W Pink Noise


604-8K, L
8 ohm, Ferrite, Tangerine? Phase Plug, Mantaray? Horn, 16” front or rear mount woofer frame, network = “604-8K” (K), N1500-8A (L) with LF 12db/oct and HF 18dB/oct, crossover frequency = 1500Hz, 75W Pink Noise


Notes:
604 B,C,D,E = Only small differences in construction. The B/C used a true multi-cell horn and the D/E used a sectoral-style horn with divider vanes.

604-8G = New crossover and diaphragm assembly improved power handling, delivered smoother mid-range, and exhibited lower distortion

604-8H = New Tangerine? phase plug and Mantaray? horn improved high frequency coverage. New crossover network offered HF and MF controls.

604-8K = New magnet offered same flux density as Alnico. Improved adhesives resulted in higher power handling.

604-8L = Same as K with new crossover network, Duplex? component hand-built for Altec Lansing Professional by Great Plains Audio, USA

[gearfreak]

Thanks GM and whitebroncoii


Ahh, so that's the loading cap. I didn't realize it'd be mechanically fastened to the magnet, figured it sat in the back of the cover instead.

I'll have to give GPA a call and see if and at what cost they will sell me a pair of covers w/felt.

[gearfreak]

Finally was able to scan the M600 spec-sheet (only 1 page) that I happen to have.
Created an HB 'album' which thus seems to offer some extra space for pics.
Had to split into top/bottom to meet pixel reqs. Severely cropped and slightly edited to make smaller.

Res is low on the posted copies, but perhaps you can zoom in and still glean something from it.

+++++

* Update: Scans removed. For some reason, they were replaced with someone else's pics of a makeshift XO on a kitchen table, and mine deleted... (during hostboard upgrade?). Oh well.

+++++


...came back to this post, and added the transcription, alas, the post app has removed all of my pretty aligned spacing. oh well, we will all live.

SPECIFICATIONS FOR THE M600 MAESTRO MONITOR LOUDSPEAKER SYSTEM

System Type: Two-way coaxial, vented, full range loudspeaker system.

Pressure Sensativity: 98.5 dB SPL (1W, 500 Hz - 3kHz,
re: 20?Pa, see Note 1)

Frequency Response: 60 Hz-20kHz (see Figure 1, Note 2)
Power Handling: 150 Watts, 60hz - 20 kHz, AES method
(see Note 3)

Maximum Long-Term Output: 119.8 dB SPL (150 watts input, 1m,
re: 20?Pa, see Note 4)

Impedance: 8.5 ohms minimum, maximum inductive phase angle = 65? @ 8 Hz,
maximum capacitive phase angle =
68? @ 78Hz, (see Figures 3 and 4,
Note 5)

Distribution Pattern: 60? horizontally by 40? vertically
(See Figure 8)

Components: 16" coaxial loudspeaker, part number
50-03-026768.

Crossover Network: Part Number N604-8A, at 1.5kHz, with
choice of high frequency attenuation.

Enclosure: Vented type for optimum response
built of 3/4" (1.9 cm) black stained
birch plywood, lined with glass wool,
includes 5/16" tee-nut mounting points
on each side and a removable grille.

Input Connection: Red and black five-way binding posts.

Replacement H.F.
Diaphragm: Model 26420

Replacement L.F.
Recone Kit: Model R604-8L

Replacement Grille: RG-M600

Dimensions: 26" (66.0 cm) high
22" (55.9 cm) wide
17" (43.2 cm) deep

Net Weight: 67 lbs. (30.5 kg)

Shipping Weight: 81 lbs (36.8 kg)

Finish: Black stained birch veneer, black
grille cloth.

[Panomaniac]

Gearfreak - thanks for posting the scams. Great info.

My buddy John, who lent me the 604-8Ks I have now, says that there where some early versions that used EV magnets and are not very good. EV was forcing Altec to use what they had in the way of ferrite magnets. A little later Altec went back to using their own magnets which were much better. That's what I have.

At this point that is just rumor, but someone here might know more about it.

[gearfreak]

Interesting differences noted for posterity...

Mine came with handles on the side (which I never questioned as non-original, but noting also that they are not shown in the spec sheet pic) perhaps they were an option or aftermarket.

As well, mine do not have the 4 (felt pads?) shown on the bottom of those.

[bowtie427ss]

As well, mine do not have the 4 (felt pads?) shown on the bottom of those.

pretty sure those are flypoints, just T nutted holes in this case.

[oface1]

Wow,, talk about up charging...

He had this posted on Craig's about a year ago for $2.5k or less, & I thought this was a bit excessive... now he is asking $5k... they might not be that common, but man this much?


-chris