Model

Altec's original proto-typical 15" Duplex Speaker with field coil magnet structures
Power rating: 25 watts
Response: 60Hz-16kHz
Free Air Resonance: 38Hz
Crossover: 1200 Hz
Network: N-1200-C - series filter network
Network input impedance: 20 ohms
LF voicecoil = 6 ohms
HF voicecoil = 15 ohms
Multicell HF horn: 6x 20° square cells for 60° horizontal and 40° vertical
Frame: 15" stamped steel basket
Magnet(s): field coil(s) standard resistance = 2250 ohms
Field Coil required 300-337 volts at 133-159 mA
Power Supply for Field Coil was Model F-820-B
comment: this is what evolved into 604 and is no relation to the 12" 601A introduced in the mid 50's.

link: 1943 cat pages for 601

Speaker System comprising 601 Duplex Speaker, dividing network and power supply for field coil in a "resonating baffle" or cabinet that is visually similar to and has same dimensions as the 612 utility cabinet

Original Altec 604 (there was no 604"A")
15" Duplex Speaker - with permanent magnets
Magnets: Alnico V
Power Rating: 25 Watts
Free Air Resonance: 38Hz
Response: 60Hz-16kHz
Crossover: 2000Hz
Network: N-2000-A (also N-2000-B) - series filter networks
Network input impedance: 20 ohms
Phase Plug: Circumferential
Multicell HF horn: 6x 20° square cells for 60° horizontal and 40° vertical
Cone: all paper cone
Frame: 15.2" cast frame, rear mount, black finish
Weight less network: 34 pounds

link: 604 introductory lit

Altec 604B
15" Duplex Speaker
Magnets: Alnico V
Power Rating: 30 Watts
Free Air Resonance: 38Hz
Response: 30Hz -16kHz
Crossover: 1000 Hz
Network: N-1000-B crossover - series filter network
Impedance: 16 ohms nominal
Phase Plug: Circumferential
Multicell HF horn: 6x 20° square cells for 60° horizontal and 40° vertical
Cone: all paper cone
Frame: 15.2" cast frame, rear mount, brown wrinkle paint
Weight with network: 40 lb.

link: 1949 cat pages re 604B

Altec 604C
15" Duplex Speaker
Magnets: Alnico V
Power Rating: 35 watts, 50 peak
Free Air Resonance: 38Hz
Response: 30Hz - 22kHz
Crossover: 1600 Hz
Network: N-1600-A - series filter network
Impedance: 16 ohms nominal
HF horn: 6-section sectoral-style horn with divider vanes - 90° horizontal and 40° vertical
Phase Plug: Circumferential
Cone: all paper cone - half-roll surround
Frame: 15.2" cast frame, rear mount - green hammertone
Weight with network: 40 lb.

comment: first to use extended throat 6-section sectoral-style "egg crate" horn with divider vanes - much closer sounding to the newer models than previous versions...

link: 1954 cat pages re 604C

1957
and
available special order as late as 1964

Altec 604D
15" Duplex Speaker
Magnets: Alnico V
Power Rating: 35 watts, 50 peak
Free Air Resonance: 25Hz
Response: 30Hz - 22kHz
Crossover: 1600 Hz
Network: N-1600-B - series filter network (added hf level control)
Impedance: 16 ohms nominal
Phase Plug: Circumferential
HF horn: 6-section sectoral-style horn with divider vanes - 90° horizontal and 40° vertical
Cone: early versions had paper with half-roll surround and later had paper w/ corrugated cloth accordion 'viscous compliance damping and annular spider'
Frame: 15.2" cast frame, rear mount, green hammertone
Weight with network: 40 lb. (?)

comment: 604D was in the 1957 catalog but Altec was trying to shift to 605 Duplex so 604D was "superceded" by 605 in 1959 catalog - 604D continued as a special order item for pro users i.e. recording studios

Altec 605A
15" Duplex Speaker
Magnets: Alnico V (smaller magnet structure than 604D)
Power Rating: 35 watts, 50 peak
Sensitivity was 3dB less than 604D
Free Air Resonance: 25Hz
Response: 20Hz - 22kHz
Crossover: 1600 Hz
Network: N-1600-A (?)
Impedance: 16 ohms nominal
Phase Plug: Tangential - possibly early version of Tangerine?
HF horn: 6-section sectoral-style horn with divider vanes - 90° horizontal and 40° vertical
Cone: paper w/ viscous compliance damping and annular spider (accordion)
Frame: 15-3/16 cast aluminum
Weight with network: 37 lb.

comment: lighter weight magnet - less efficient ... went to B version that continued into 1971 (at least) - this speaker had some good points but recording studios wanted more SPL's and the 3dB efficiency penalty was too much... recording studios paid for non-catalog 604-D's, until 1964 when 604E was introduced as a standard product.

link: 1963 cat pages re 605A

1964
to
1972
or early '73

Altec 604E Super Duplex Speaker
15" Duplex Speaker
Magnets: Alnico V
Power Rating: 35 watts, 50 peak
Sensitivity: 100dBSPL/1W/4ft or 115.4dB w 35 W
Free Air Resonance: 32Hz
Response: 20Hz - 22kHz
Crossover: 1500 Hz
Network: N-1500-A (series filter - first order high pass and second order low pass with h.f. shelving control)
Impedance: "8 to 16 ohms" - nominally 16 ohms
Phase Plug: Circumferential
HF horn: 6-section sectoral-style horn with divider vanes - 90° horizontal and 40° vertical
Cone: paper w/ viscous compliance damping and annular spider (accordion)
Frame: 15.2" cast frame, rear mount, white basket and gray paint on motors
Weight: 34 lb. including network

comment: LF motor moved to a full thickness top plate with a shorter voice coil for more linearity at low frequencies

links: 604E Duplex - 604E Super Duplex - 604E cutsheet and Iconic SuperCrossover for 604E

15" Duplex Speaker
with modified N-1500 crossover, 8 ohms

said to have been a nominal 8 ohm variant of an E that existed before the frame went to 16" with the introduction of the 604-8G but this is likely a phantom model - never seen one and don't know anyone who has.

Altec 604-8G (first 604 with 16" diecast frame, retained 6 cell horn, went to 8 ohm voicecoils)
16" Duplex Speaker
Magnets: Alnico V
Power Rating: 65 watts continuous pink 20Hz-20kHz (AES)
Sensitivity: 100dBSPL/1W/4ft
Free Air Resonance: 30Hz
Response: 20Hz - 22kHz
Crossover: 1500 Hz
Network: matched crossover with parallel filters, 8 ohms, third order high pass and second order low pass
Impedance: 8 ohms
Phase Plug: Circumferential initially - moved to Tangerine phase plug in 1976
HF horn: 6-section sectoral-style horn with divider vanes - 90° horizontal and 40° vertical
Cone: paper cone with an "accordion edge" cloth surround
Frame: 16" die cast aluminum frame dark gray enamel paint
Weight: 34 lb.

comment: there are early G's with Circumferential phase plug and late G's with Tangerine phase plug... transition said to be in 1976 or thereabouts

link: 604-8G Duplex and an Iconic SuperCrossover is available for 604-8G

Audiomarketing
604E2

Altec
604-16G

The Audiomarketing Ltd. 604E2 was a special 16 ohm OEM version 604-8G... essentially a non-catalog 604-16G
16" Duplex Speaker
Magnets: Alnico V
rest of spec assumed to be same as 604G except 16 ohm
Power Rating: 65 watts continuous pink 20Hz-20kHz (AES)
Sensitivity: 100dBSPL/1W/4ft
Free Air Resonance: 30Hz
Response: 20Hz - 22kHz
Crossover: 1500 Hz
Network: used with Mastering Lab 16 ohm crossover as implemented in the Big and Super Reds by Audiomarketing ltd..
Impedance: 16 ohms
Phase Plug: Circumferential initially - moved to Tangerine phase plug in 1976
HF horn: 6-section sectoral-style horn with divider vanes - 90° horizontal and 40° vertical
Cone: paper cone with an "accordion edge" cloth surround
Frame: 16" die cast aluminum frame dark gray paint
Weight: 34 lb.

comment: 604E2 had the new 16" cast basket that came in with G in 1974 - G was 8 ohm nominal - E2 is 16 ohm - the only place these appear as E2's are in Audiomarketing Ltd. "Big Red" speaker systems that used the Mastering Labs Crossover that was nominal 16 ohms. Cabinets for Big Red's were front loading. Since the original Mastering Labs monitors and crossovers were based around a 16 ohm 604E it made marketing sense to call this driver an E2.

Note the 604E2 label is not an Altec label

604-HPLN

The HPLN is another G variant that had 8 ohm LF and 16 ohm HF and was primarily intended for bi-amping - these were first to have the Tangerine phase plug which moved in to later version 604-8G with no change in model designation.

lit: 604-HPLN

Audiomarketing
Big Reds

604 based
Studio Loudspeaker System

Audiomarketing Ltd. (manufacturing for Audio Techniques) a 604-based speaker system called Big Reds.

Big Reds are not to be confused with Tannoy Red's. Audiomarketing's Big Reds were based on a speaker and crossover combination developed in-house at The Mastering Lab, which was in Hollywood (since moved to Ojai California). The Mastering Lab developed (and still do) a lot of their own custom electronics and monitor systems. Among those was system based on 604E's and their own Mastering Labs crossover. The design was licensed to Audiomarketing Ltd., in Stamford, CT, a small audio manufacturer linked by common partners to Audio Techniques, a large pro-audio dealer in NYC (the MCI dealer in town among other things).

The Mastering Labs Crossover is a 16 ohm Network designed originally for the 15" 604E. Altec was producing Duplex speakers with a new 16" cast aluminum frame that was better suited to front loading but the stock 604-8G was an 8 ohm speaker. It is said that Big Reds used 604-E speakers but in fact the 604 variant found in these cabinets is a 16" front loadable frame, Alnico magnet Duplex with a six cell horn. That would be a "G"

Big Red's were very popular and still in use i.e. a pair hangs to this day in the control room of Studio A at Avatar Studios (formerly Power Station)

For a short time Audiomarketing made a thing called a Super Red, probably to compete with the UREi 813 that came out a few years after Big Reds hit the market but people preferred 813's so very few Super Reds were produced and sold.

If you have a pair of Big Reds and/or a Mastering Crossover - make sure your speakers have not been re-coned or re-diaphragmed with 8 ohm parts - this is very very common and your crossover will not work properly if this is the case... so send your speakers the GPA, have the magnets re-magnetized and 16 ohm parts installed to match to the crossover.

pics front, back, Mastering Labs crossovers, 604E2 pair, 604E2 label

UREi 813
UREi 813A
UREi 813B
UREi 813C

Control Room Monitor Speaker System developed by Bill Putnam (UREi) with Time-Align crossover designed by Ed Long (CSI) starting in 1976... first official 813 as a product rolled out in 1978. The 813 had an additional 15" "helper" woofer - this was an Eminence part dubbed the 800W. The sectoral horn of the 604-8G was replaced by a blue one piece exponential horn. Other models in the series were the 811 which had a single 604 in a box with no additional woofer and the 815 which was a single 604 in a huge box with two additional woofers.

The 3-way 838 Time-Align network for the 813 was designed around the 604-8G. Over the time period when the 813 was being developed Ed Long designed and UREi manufactured Time-Align (TA) networks for sale for both 604-8G and 604E Duplex Speakers. The original 813's used late 604-8G and 604-8H Duplex Speakers - replacing the different horns with their own.

811 - single woofer coaxial with Model 828 2-way TA network
813 - dual woofer coaxial with Model 838 3-way TA network
815 - triple woofer coaxial with Model 848 3-way TA network

Model 824 2-way TA network designed for 604E
Model 834 3-way TA network designed for 604E with additional UREi 800W L.F. driver
UREi also offered the blue 800F horn as a retrofit to 604E and 604-8G

"A" series. When 604's went from Alnico to ferrite ceramic magnets the geometries changed so the Time-Align networks needed to change - other changes and improvements came in with the "A" series in 1981 - still 604 based but using an 8K - the blue horn was modified with a foam surround to reduce "shadow effect" - a BNC connector was added to the back of the cabinet to provide feedback to UREi 6500 series power amplifiers as a way to compensate for conductor loss.
811A - single woofer coaxial with Model 829 2-way TA network
813A - dual woofer coaxial with Model 839 3-way TA network
815A - triple woofer coaxial with Model 849 3-way TA network

"B" series. Due to poor quality control and high rejection rates in the 604's that UREi was getting from Altec and the need for higher power handling and more SPL's UREI moved to a compound speaker that used a PAS coaxial woofer and a JBL compression driver. There was some additional tinkering with the horn. The 813B was probably the best of the series.The system was 3dB more efficient and could handle twice the power (150 Watts vs 75 as in previous versions) - a 6dB improvement in overall output level
811B - single woofer coaxial with Model 830 2-way TA network
813B - dual woofer coaxial with Model 840 3-way TA network
815B - triple woofer coaxial with Model 850 3-way TA network

"C" series. When JBL bought UREi they went to all JBL drivers... they sounded nothing like previous models

604-8H

1979 or
1980 to
1981

Altec 604-8H (last 604 with Alnico magnets and first with Mantaray horn)
16" Duplex Speaker
Magnets: Alnico V
Power Rating: 65 watts continuous pink 20Hz-20kHz (AES)
Sensitivity: 100dBSPL/1W/4ft
Free Air Resonance: 30Hz
Response: 20Hz - 22kHz
Crossover: 1500 Hz
Network: matched crossover with parallel filters, 8 ohms, added mid-frequency EQ
Impedance: 8 ohms
Phase Plug: Tangential "Tangerine" phase plug
HF horn: Mantaray constant directivity horn 60° horizontal x 40° vertical
Cone: paper cone with an "accordion edge" cloth surround
Frame: 16" die cast aluminum frame dark gray paint
Weight: 34 lb.

comment: Last, and some say best, model of Alnico 604 series from Altec, and the H introduced the newer Mantaray horn - these and 604-8G's were used in original UREi 813 using UREi's blue horn and Ed Long designed Time-Align crossover

link: 604-8H Duplex - Iconic SuperCrossover available for 604-8H

604-8K

also
604-16x
604-168x

Altec 604-8K (first 604 with Ferrite Ceramic magnets)
16" Duplex Speaker
Magnets: Ferrite Ceramic
Power Rating: 75 Watts continuous pink 60Hz - 20kHz AES
Sensitivity: 98.5dB SPL/1W@1m or 116.8dB SPL at 75W
Free Air Resonance: 28Hz
Response: 60Hz - 20kHz
Crossover: 1500Hz
Network: matched crossover with parallel filters, 8 ohms
Impedance: 8 ohms
902 HF driver with Mantaray constant directivity horn 60° horizontal x 40° vertical
Cone: paper cone with an "accordion edge" cloth surround
Frame: 16" die cast aluminum frame dark gray paint
Weight: 34 lb.

Note: 604-16x has 16 ohm voicecoils, 604-168x has 8 ohm LF and 16 ohm HF

comment: more sensitive "SPL" ratings than previous model 604's - smoother HF dispersion due to the CD "Mantaray" horn and improved crossover networks. UREi adapted with introduction of 800"A" series (811A, 813A, 815A)

Altec started marketing the 604K as a "ceiling speaker" and introduced various impedance combinations for OEM and direct bi-amping. New high power Duplex speakers were introduced. All these were discontinued with rest of Altec line in 1998.

link: 604-8K Duplex - 604-16x and 604-168x - and Iconic SuperCrossover for 604-8K

High Power (150 Watt) version of 604 otherwise similar to 604-8K

New version listed in the early 2000's by Altec Lansing Pro.
Essentially a late K, not highly regarded.
...
Altec 604-8L
comment: a K with a higher power LF voice coil
902 HF driver used Pascolite Aluminum H.F. Diaphragm

link: 604-8L

Great Plains 604-8H-II
HF horn: 60h40v "Manta Ray"
crossover: 1500 Hz
Power: 100 watts continuous pink noise 60Hz-20kHz (AES method)
Sensitivity: 99dB SPL 1Watt (1 meter?)
Impedance: 8 ohms
Weight: 34 lb.
Magnet: Ferrite V magnet
Phase Plug: Tangerine phase plug
Response: 30Hz - 20kHz
Free Air Resonance: 30Hz
Frame: cast frame gray powder coat
Cone: paper cone with an "accordion edge" cloth surround

comment: Great Plains Audio services vintage 604's. Their standard service includes re-magnetizing the magnet structures... this is mandatory if you want your 604's to sound right. They have all the parts and original factory expertise. They also build and sell improved crossover networks for these speakers.

link: 604-8H-II and 604-8H-III (III is new and has exponential horn)

Iconic
704-8A

Iconic 704-8A
HF horn: 60h40v "Manta Ray"
crossover: 1500 Hz
Power: 140 watts continuous pink noise 60Hz-20kHz (AES method)
Sensitivity: 99dB SPL 1Watt (1 meter?)
Impedance: 8 ohms
Weight: 34 lb.
Magnet: Ferrite V
Response: 30Hz - 20kHz
Free Air Resonance: 30Hz
Frame: cast frame gray powder coat
Cone: paper cone with an "accordion edge" cloth surround
Tangerine phase plug
Mantaray horn

links: Iconic 704-8A and Iconic Super Crossovers

Parts and Service - vintage Altec speakers

Great Plains Audio
7127 N. W. 3rd Street
Oklahoma City, OK 73127 USA

405-789-0221
www.greatplainsaudio.com

Parts and Service - vintage Altec electronics

Iratec Pro Audio Repair
Oklahoma City, OK
U.S.A.

405-324-5311
www.iratec.50megs.com

Parts and Service - vintage Altec mics

MicroMike Laboratories
1537 West Cris Place
Anaheim, California 92802
Telephone: (714) 774-0342
Attention: Mr. Bill Hayes