Urei 813 e bay

[LICORNE]

These are from Barclay studios in paris 1600 Euros.


Moniteurs de studio UREI 813 ?quip?s ALTEC 604 8 G JBL en vente sur eBay.fr (fin le 23-mai-09 20:12:02 Paris)

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[wws944]

These are from Barclay studios in paris 1600 Euros......

Was the second woofer used simply to improve the power handling capabilities of the unit? Or was it perhaps tuned differently to complement the 604?

[LICORNE]

Was the second woofer used simply to improve the power handling capabilities of the unit? Or was it perhaps tuned differently to complement the 604?

The Emminence woofer added extra low mid and low bass.



Quote from MIx Magazine

In the mid-’70s, UREI founder Bill Putnam—unhappy with the sound of the Altec 604 monitors in his United Western Studios—worked with UREI’s Dean Austin and Dennis Fink on ways to improve the 604. They replaced Altec’s multicell horn with a wider dispersion design and added a 15-inch Eminence woofer to boost LF output. Ed Long applied his Time-Align™ crossover techniques to achieve time- coherent, true point-source performance.

Engineers and producers mixing on the system were so enthusiastic about its sound that UREI started producing the monitors as a commercial product, with the first UREI 813 debuting in 1977. Typically soffit-mounted, these large, double-15 monitors were ideal for the larger, higher-SPL control rooms of the time.

UREI founder Bill Putnam Sr. tests a very early 813 prototype.
Two years later, Altec replaced its Alnico 604-8H with a ferrite model, requiring modifications to the 813 design, including a foam diffraction buffer, crossover mods and small Helmholtz resonators in the horn flare. This 1979 model was the 813A, followed by the 815A (a 604, plus two extra woofers) and the single-driver 811A, but the 813A was far more popular.

Financial and QC problems at Altec led UREI to find a new driver source, now mating PAS coaxial 15 to a JBL 2425 compression driver. The new 813B version debuted in 1983. Later that year, Putnam sold the business to Harman, with UREI becoming a division of JBL Professional; the 813C, a new model with all JBL drivers, launched in 1984. But in its various incarnations, the UREI 813 was the most successful large-format studio monitor ever made.
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[wws944]

The Emminence woofer added extra low mid and low bass....

Thanks!

I found a pdf with the UREI crossover schematic. It is clearly a 3-way design, with the 604s woofer being used for 'mid-bass', and the Eminence woofer being used for deeper bass.

Were the 604 and Eminence woofers isolated from each other within the enclosure? If not, I wonder how the interaction between the two was taken into account?

[LICORNE]

Thanks!

I found a pdf with the UREI crossover schematic. It is clearly a 3-way design, with the 604s woofer being used for 'mid-bass', and the Eminence woofer being used for deeper bass.

Were the 604 and Eminence woofers isolated from each other within the enclosure? If not, I wonder how the interaction between the two was taken into account?

. The crossover must have been around 150 or 160 Hz.

Here is a quote from Audio Karma UREI 13 owner

The 813s appear to be about 13cu. ft cabinets or so, from my measurments of the internal volume without taking the bracing into account. Interestingly, there's no subwoofer divider in the cabinet - only a 1" thick layer of stiff fiberglass fill.

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[wws944]

. The crossover must have been around 150 or 160 Hz.

Here is a quote from Audio Karma UREI 13 owner

The 813s appear to be about 13cu. ft cabinets or so, from my measurments of the internal volume without taking the bracing into account. Interestingly, there's no subwoofer divider in the cabinet - only a 1" thick layer of stiff fiberglass fill.

Considering all the wood that went into damping the cabinets (176 lbs each!), you'd think they would isolate the two drivers better. Unless it was intentional...

It is interesting to read the service manual for the 813s:

http://www.jblproservice.com/pdf/Vin...s/UREI-813.pdf

The square wave plots comparing their crossover to "brand A" and "brand B" are pretty revealing. I'd like to assume that "brand A" was the stock Altec crossovers of the day, but who would "brand B" be?

Any idea why UREI would have chosen the Eminence woofer instead of something from Altecs stable?

In the background of all these is that I think it would be fun to do some form of project with GPA 604s. (E.g., left+center+right channels for my living room.) So I am trying to pick up some tips from prior art.