As usual it is all in the implementation. The top end of the DD tables got it right, the next level and down not quite so much.
What's gotten better, what's gotten worse, what's about the same.
- Thread starter JohnVF
- Start date
Even my Kenwood, the totl for Kenwood in the US in 1978, if not a TOTL table per se, taught me a lot about what DD tables could be.
Sad to think that lovely table sits unused right now. Time to get that listed!
Oh. And my sweet ginger of a daughter has reminded me that I cannot sell the HH Scott gear. She has claimed them as her own and I do not have her permission to sell them. So there goes that.......
That's easy then. And she has excellent taste.
There are VERY few pieces of audio gear I wish I hadn't sold. One definite one is my NOS valves restored 299D. What a sweetheart that was.
I'm still kicking myself for having chosen the Fisher integrated instead of the Scott receiver that was sitting right beside it, when I dove into vintage tubes for the first time. I'm not really that enthralled with the Fisher stuff. But the Scott stuff? Yeah. That's some class act gear all the way.
It’s mine she says.
That just warms the heart, delightful photo. And she has good taste.
My daughter is the only one of my squad that shares my hobby. Though she doesn’t really like Vinyl that much. Loves the digital and CD rigs. Notes that the Esoteric CD player and Dac will nicely match up with the Scott gear. The girl has a good eye and ear indeed!
JimPA
Junior Member
Let me bring the conversation around to me.
So why am I spending a lot of money on a pair of @Pat McGinty 's speakers? It's not just because he is a brilliant speaker designer. He is that. Undoubtedly. But I would never have planned on going in this direction with my system. However, what he had done is remove a couple of the very bad things from my in home music reproduction.
1) Passive crossovers - Passive crossovers are just bad things. While they are a necessary evil, crossover design is all about minimizing the terrible damage they are doing to the music. All of them. There isn't a passive crossover that doesn't screw up the signal. Sure, there are some brilliant designers out there, guys like Pat, Alan Shaw, etc who spend months or years tweaking the crossover to minimize the damage. But they all screw things up. By moving to DSP, all if that goes away. Sure, that creates other problems, but they are minor compared to what they fix.
2) Speaker/Room interface - As folks who have spent ages tweaking speaker placement know, the room, and placement within the room, can screw up the sound of the best equipment. With DSP, that goes away.
3) Amp/Speaker match - No more mixing and matching amps and speakers. Half of that is caused by the crap in the speaker (ie the crossover). Plus, the amp finally has total control of the woofer. Direct connection with nothing in between. Brilliant.
There is fun to be had with the DSP in other ways too. More on that later.
This is all 2019 technology. None of these things were possible before. And what it does is removes whole layers of crap from between me and the recording. And that, to me, is very cool.
Very good observations on the pros and cons of loudspeaker crossovers.
After reading many off the AES papers of the years I would like to add a few things.
John K. Hilliard, J. Robert Ashley, Allan Kaminsky and Richard Small did a lot of the ground breaking research into passive and active crossovers.
Otto Zobel was the first to point out the differences between parallel and series crossovers circuits with his work at Bell Labs.
The main argument for active crossovers was the cost back then.
Active crossovers only required caps and resistors
It was less expensive to use separate amps for each driver compared to the cost of large value inductors required for passive crossovers.
Inductors using iron cores caused so many problems unlike their air core more expensive counterparts.
Brian Cheney of VMPS before his death patented many of his active speaker designs.
Brian also stated on Audio Circle somewhere that a properly designed series crossover performed as well as an active crossover.
Bud Fried also came to the same conclusion with his experience using series crossovers.
I am surprised that so many people don't grasp the understanding of the differences between a series vs parallel circuit.
blog0402.htm
Many of those who argue parallel is better have not done enough research.
Francesco Maffioli's AES paper from 2001 really sums up what Fried and Cheney found out by his extensive research without naming either of them.
Maffioli expanded on the works of the others I have previously stated.
Maffioli proved that if the woofer and and tweeter have the same impedance at the crossover frequency with a first order series circuit it becomes a quasi 2nd order crossover.
You got two crossover slopes for both drivers by using just a cap and inductor.
The AES papers are a wealth of knowledge and copyright protected so I can't post them on the forum.
You're not alone in that assessment (in case you felt the need for any affirmation
).
If we are talking groundbreaking research into crossovers I think Harry Kimball of Bell Labs and later MGM is worth a mention. He more or less invented the crossover in around 1930. I don’t know if he wrote papers for the AES, but he contributed several chapters to the 1938 book ”Motion Picture Sound Engineering”. According to John K. Hilliard ”Kimball should be given the credit for initiating this whole filter and dividing network business”.
JimPA
Junior Member
Actually Harry Kimball as well as John K. Hilliard both authored Dividing Networks for Loudspeaker Networks from the AES journals.
This work was originally printed in the Academy Research Council Technical Bulletin March 3. 1936.
JimPA
Junior Member
I bet your old pal Tom, one of the greatest boiler makers from Chicago could give you quite a history lesson
.He is one of the few people on any audio forum I have ever found that recognizes the names of these audio pioneers.
Every aspect of crossover design has it's basis from the AES journals.
Each contributor expanded on the works of others.
I have learned more about crossover design from the AES journals than from any of the books I have read.
Many people buy PC speaker design software but don't understand electrical engineering.
I find it quite interesting that Maffiioli found that a 2nd order 3 way speaker series crossover performs the same as a 6th order electrical filter.
One of These Days I will elaborate more about these designs when time permits.
Oh I'm sure Tom could. I've never met a person with a better recall of names and dates than him. Fascinating fellow and far from an audio tribalist...he was open to anything as long as it sounded good.I bet your old pal Tom, one of the greatest boiler makers from Chicago could give you quite a history lesson
He is one of the few people on any audio forum I have ever found that recognizes the names of these audio pioneers.
Every aspect of crossover design has it's basis from the AES journals.
Each contributor expanded on the works of others.
I have learned more about crossover design from the AES journals than from any of the books I have read.
Many people buy PC speaker design software but don't understand electrical engineering.
I find it quite interesting that Maffiioli found that a 2nd order 3 way speaker series crossover performs the same as a 6th order electrical filter.
One of These Days I will elaborate more about these designs when time permits.
I know that Hilliard had his name on the 1936 Dividing Networks for Loudspeaker Systems (sic) paper, but the reason for this may well have been that Hilliard was Kimballs boss at the time. When the paper was included in Motion Picture Sound Engineering (as Chapter XX) in 1938 only Kimball was credited as author.
The motion picture industry really was a driving force for a lot of the research, wasn't it?
It certainly was. And the stuff that Western Electric, Lansing Manufacturing Co. and Altec Lansing produced hasn’t been bettered since, in MNSHO. Big and bulky and much of it very expensive, but if it is natural and lifelike sound reproduction you want, that’s where it’s at.
kirk57
Junior Member
At that time it was an industry full of opportunity and as such drew the brightest minds to solve problems. Much like the bicycle industry around the turn of the last century drew people like the Wright Brothers.
