Kegger
R.I.P. 1/12/1966 - 6/1/2017
Here's a little light reading I found interesting while trying to find out what the L100's
xover points are. Note the part about the mid and tweeter producing from 3k on up,
the same as the 60 and 100.
" The Marantz Imperial 6 was the first speaker Dawson had designed after Bart Locanthi had completed the lab/listening room set-up along with teaching his speaker design methodology to Dawson. We speaker novices would listen to the Imperial 6 all day long in between setting up other tests. It was a paper-cone 10” two-way with a phenolic ring (edge) cone tweeter. The woofer had a doped cloth surround and all cabinet parts where of ¾” veneered particleboard. In the lab the Imperial 6 measured ± 1.5 dB, 60Hz to 17,000Hz. It had a real walnut cabinet and retailed for $129.00 each. Guess what? It didn’t sell worth beans.
What did sell at that time was the Marantz Imperial 7. The 7 was a marketing-driven design all the way. A 12” 3-way, in the same size box as the Imperial 6. The Imperial 7 was Marantz’s answer to the hottest speaker of its day, the JBL L100 Century. Marantz marketing asked us to give them a design which would “jump out” from the L100 on the sales floor. And, oh yea, they wanted it to retail for $299 each versus the L100’s $399 each.
The L100 measured fairly flat and had a die cast 12” basket. We knew our stamped steel framed woofer had more sensitivity than the JBL plus it was considerably cheaper. And putting it in the same size box as the Imperial 6’s 10” meant that the Imperial 7’s 12” would roll off starting at 80 Hz. Fortunately for us, a ported 12” pumping out lots of 80Hz air sounded to most consumers at the time like a whole truckload of bass!
The answer to making the midrange and tweeter drivers “jump” was even easier. Don’t use any crossover component to roll off the midrange. That way both the mid and tweeter would be working in the same 3KHz – 10KHz region and we’d get a huge bump. (Never mind the cancellation effects which would limit the Imperial 7’s ultimate high frequency response to a pathetic 12KHz before it headed straight down.) (which just happens to be where the HPM kicks in!)
In the end Marantz’ marketing ploy was very successful. The Imperial 7 sold in huge numbers and the Imperial 6 sort of faded back in the model line-up. For a short time, my Locanthi-Hadley basic precepts of technically correct speaker design were a bit tarnished. Here I was at the beginning of what I had hoped would be a wonderfully challenging and enjoyable engineering career. And I had to look forward to speakers pre-designed by marketing?
Fortunately that situation was short lived. A well-known early audio pioneer named Henry Kloss was starting a new speaker company. In 1972, Kloss was so certain that he had designed the best price/performance speaker of its day that he started his company with only one product. The speaker was The Large Advent, a 10” two-way design.
Henry was not only a great speaker designer, he was a better marketing man. The Large Advent received glowing reviews from the enthusiast magazines of the time. The same magazines who had given our Imperial 6 a rather tepid “it’s a pretty good speaker” review a year earlier.
So we bought a pair of Advents. We measured them. They were good. They measured almost as well as the Imperial 6s. The main frequency discrepancy with the Advents was at their 1800Hz crossover frequency.
Henry had custom designed a cloth dome tweeter which had a 1” dome in its center but with a huge 1” cloth annulus surrounding (and part of) the dome. So to get down to 1800 Hz what the audio pioneer had designed was a 3” cloth-dome tweeter! In measuring the system it graphed out showing two very narrow, high Q peaks then dips on either side of the 1800Hz crossover. Other than that Henry’s system had about the same smooth and flat frequency response characteristic as the Imperial 6.
We listened to both the Imperial 6 and The Large Advent in mono (the Model 32 preamp has a an L + R setting) on the 8” riser in our lab. Only by A-B’ing both speakers, and knowing exactly where to listen, could we pick up the very slight smearing effect that the Large Advent had at the crossover frequency. But when we listened above 8KHz and into the high extreme-treble region it was Henry’s soft dome all the way. Was it ever smooth!"
xover points are. Note the part about the mid and tweeter producing from 3k on up,
the same as the 60 and 100.
" The Marantz Imperial 6 was the first speaker Dawson had designed after Bart Locanthi had completed the lab/listening room set-up along with teaching his speaker design methodology to Dawson. We speaker novices would listen to the Imperial 6 all day long in between setting up other tests. It was a paper-cone 10” two-way with a phenolic ring (edge) cone tweeter. The woofer had a doped cloth surround and all cabinet parts where of ¾” veneered particleboard. In the lab the Imperial 6 measured ± 1.5 dB, 60Hz to 17,000Hz. It had a real walnut cabinet and retailed for $129.00 each. Guess what? It didn’t sell worth beans.
What did sell at that time was the Marantz Imperial 7. The 7 was a marketing-driven design all the way. A 12” 3-way, in the same size box as the Imperial 6. The Imperial 7 was Marantz’s answer to the hottest speaker of its day, the JBL L100 Century. Marantz marketing asked us to give them a design which would “jump out” from the L100 on the sales floor. And, oh yea, they wanted it to retail for $299 each versus the L100’s $399 each.
The L100 measured fairly flat and had a die cast 12” basket. We knew our stamped steel framed woofer had more sensitivity than the JBL plus it was considerably cheaper. And putting it in the same size box as the Imperial 6’s 10” meant that the Imperial 7’s 12” would roll off starting at 80 Hz. Fortunately for us, a ported 12” pumping out lots of 80Hz air sounded to most consumers at the time like a whole truckload of bass!
The answer to making the midrange and tweeter drivers “jump” was even easier. Don’t use any crossover component to roll off the midrange. That way both the mid and tweeter would be working in the same 3KHz – 10KHz region and we’d get a huge bump. (Never mind the cancellation effects which would limit the Imperial 7’s ultimate high frequency response to a pathetic 12KHz before it headed straight down.) (which just happens to be where the HPM kicks in!)
In the end Marantz’ marketing ploy was very successful. The Imperial 7 sold in huge numbers and the Imperial 6 sort of faded back in the model line-up. For a short time, my Locanthi-Hadley basic precepts of technically correct speaker design were a bit tarnished. Here I was at the beginning of what I had hoped would be a wonderfully challenging and enjoyable engineering career. And I had to look forward to speakers pre-designed by marketing?
Fortunately that situation was short lived. A well-known early audio pioneer named Henry Kloss was starting a new speaker company. In 1972, Kloss was so certain that he had designed the best price/performance speaker of its day that he started his company with only one product. The speaker was The Large Advent, a 10” two-way design.
Henry was not only a great speaker designer, he was a better marketing man. The Large Advent received glowing reviews from the enthusiast magazines of the time. The same magazines who had given our Imperial 6 a rather tepid “it’s a pretty good speaker” review a year earlier.
So we bought a pair of Advents. We measured them. They were good. They measured almost as well as the Imperial 6s. The main frequency discrepancy with the Advents was at their 1800Hz crossover frequency.
Henry had custom designed a cloth dome tweeter which had a 1” dome in its center but with a huge 1” cloth annulus surrounding (and part of) the dome. So to get down to 1800 Hz what the audio pioneer had designed was a 3” cloth-dome tweeter! In measuring the system it graphed out showing two very narrow, high Q peaks then dips on either side of the 1800Hz crossover. Other than that Henry’s system had about the same smooth and flat frequency response characteristic as the Imperial 6.
We listened to both the Imperial 6 and The Large Advent in mono (the Model 32 preamp has a an L + R setting) on the 8” riser in our lab. Only by A-B’ing both speakers, and knowing exactly where to listen, could we pick up the very slight smearing effect that the Large Advent had at the crossover frequency. But when we listened above 8KHz and into the high extreme-treble region it was Henry’s soft dome all the way. Was it ever smooth!"
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