Since around 1977, I've been DIY with ESLs, mostly bits and pieces from Mike Wright and ticknpop. But now time to move on, and "down-sizing" is my path.
I hope somebody can parse for me the rules about parting with stuff on this website and what kind of work-arounds are feasible within the rules.
Ben
Bathurst / St Clair West
I hope somebody can parse for me the rules about parting with stuff on this website and what kind of work-arounds are feasible within the rules.
Ben
Bathurst / St Clair West
The panels I am now offering are something like the ones in the picture, but just the bottom 6 cells. The cells are different and set up as a curved panel, 3 cells across and 2 cells high. With the big spacing of DW cells, they go to maybe 100 Hz in free air, 55 Hz in Mike Wright's gas box, if you have the bias and drive voltage for them. The DW transformers at 1:100 and weigh 32 lb each (on eBay).
I don't have a need just now and my impression is there's only the most specialized market for those exceptional one-of-a-kind transformers. I'm cryin' to think they might end up ship anchors or landfill.. the copper is valuable.
DW pre-amps have an enduring appeal. He used MIL-spec construction and aimed for simplicity consistent with high-end performance. I think there's a DW moving-coil pre-pre-amp out there.
Hi Dave,
Yes. The uA749 was a very good op amp. Marantz used them as well. Loaded with a current sink, they performed extremely well, especially for the time. The uA739 had an internal 5K load resistor, the uA749 was open.
Back then the 301A was probably the best choice, it wasn't slew rate limited compared to the 741. THe LM308 I believe had "super beta" transistors in the input and was low noise, but also low slew rate if memory serves. I'd have to look them up. I remember designing with them.
I may have a new case for one of those EQ units Dave.
Yes. The uA749 was a very good op amp. Marantz used them as well. Loaded with a current sink, they performed extremely well, especially for the time. The uA739 had an internal 5K load resistor, the uA749 was open.
Back then the 301A was probably the best choice, it wasn't slew rate limited compared to the 741. THe LM308 I believe had "super beta" transistors in the input and was low noise, but also low slew rate if memory serves. I'd have to look them up. I remember designing with them.
I may have a new case for one of those EQ units Dave.
I think Mike Wright told me the 301 was configured in a feed forward circuit to get a higher slew rate
How did you end up with a EQ case? !! They stopped building them in 76 when Leigh took over.
What boards do you have? I remember seeing some unstuffed boards when I visited Leigh when they were clearing out DW parts.
How did you end up with a EQ case? !! They stopped building them in 76 when Leigh took over.
What boards do you have? I remember seeing some unstuffed boards when I visited Leigh when they were clearing out DW parts.
Mike worked for Leigh, then went out on his own. I used to buy Marsland loudspeakers from Leigh Instruments.
The LM301 was a normal decompensated op amp. The LM318 could be used in feedforward to increase slew rate from 50V/uS to 70V/uS. Deadly fast for a voltage feedback op amp even today. Keeping them stable could be an issue.
I have a few boards I picked up recently, they are moving. I got the case at the same time.
The LM301 was a normal decompensated op amp. The LM318 could be used in feedforward to increase slew rate from 50V/uS to 70V/uS. Deadly fast for a voltage feedback op amp even today. Keeping them stable could be an issue.
I have a few boards I picked up recently, they are moving. I got the case at the same time.
Leigh Instruments along with Spar Aerospace, Bell-Northern Research and one or two others were the great heroes of Can. tech in those days. I think Leigh did stuff like mail sorting consoles.
But Leigh started buying all kinds of businesses but flopped with a loud quite unexpected thud (OK, many a great fortune started with the same phase) .
Leigh bought the remnants of Dayton-Wright and ran with it for a few years. Much dispute with Mike about agreements. Anybody who knows Mike might not be surprised to hear that (is Mike still with us?). And Mike seemed to get back some of his remnants although not fully happy about that either.
My good buddy, Paul Young, was the brains behind speakers at Leigh Instruments. He worked on sorting-out issues with the DW brand and created a wonderful small two-way speaker that looked like a large wooden dinosaur laid an egg. I have two pair. Very fine speakers with complex xo like the Rogers BBC box. As they were about start selling The Egg, good-bye Leigh.
Maybe we need a history file - like tales of the many years of Toole at NRC (BTW, I found him to be quite a nice fellow, we both had great love for our Lotus Elan+2 cars... but wonder if he misses Canada).