I will have a new layout Monday or Tuesday. I am getting close to finishing this amp. Thanks for the E-mails. You guys have helped a lot.
John do you like this layout better?
John do you like this layout better?
I would like to make a few prototypes to prove out the board. If there is a lot of interest I can have more made. If someone wants to run more boards I can send them the gerber files when I get them.
Sig, it certainly looks to be in the 'ballpark'. I should get the original unit out of storage and measure it sometime. In 1974, when we first made this design, it was specifically used with an Electrovoice T350 tweeter that had a sensitivity of 108dB/W or so. So, even at 1W, it was really, really, loud. It was designed for 8 ohms originally and modified (like you have) to also be OK at 4 ohms. That is about as low in impedance as we ever thought it would be used.
I am glad that you added the series resistors in the bases of the devices. Originally, we only used 4 MHz devices or less, and the series resistor did not seem necessary. Later, when we switched to ring emitter transistors, we added base resistors out of necessity, given the advice to me by the 'late' Jon Iverson.
I am glad that you added the series resistors in the bases of the devices. Originally, we only used 4 MHz devices or less, and the series resistor did not seem necessary. Later, when we switched to ring emitter transistors, we added base resistors out of necessity, given the advice to me by the 'late' Jon Iverson.
Mike,
Sorry I haven't been much help to you on the PCB thing, but I'm hip-deep in doing my own artwork here and there's only so much of that I can do in a day before my eyes go buggy. I've got a front end board, output boards, rectifier & first cap bank boards, regulator boards for both front end and outputs (are you regulating your rails?) which will be combined if I can manage it, and as if that wasn't enough, I'm on my third or fourth iteration for the front end board as I keep trying different variations on the basic topology.
Best of luck.
Grey
Sorry I haven't been much help to you on the PCB thing, but I'm hip-deep in doing my own artwork here and there's only so much of that I can do in a day before my eyes go buggy. I've got a front end board, output boards, rectifier & first cap bank boards, regulator boards for both front end and outputs (are you regulating your rails?) which will be combined if I can manage it, and as if that wasn't enough, I'm on my third or fourth iteration for the front end board as I keep trying different variations on the basic topology.
Best of luck.
Grey
A-40
I am going to have to take apart my A-40 mosfet amp. The housing will be used for the JC amp. If any of you guys want a couple of working A-40 boards let me know. I also have a couple of SYM amp boards.
If you have a couple of IRFP 9140 or 9240's I could use them. I still have a F4 board to build. Thanks, Mike.
I am going to have to take apart my A-40 mosfet amp. The housing will be used for the JC amp. If any of you guys want a couple of working A-40 boards let me know. I also have a couple of SYM amp boards.
If you have a couple of IRFP 9140 or 9240's I could use them. I still have a F4 board to build. Thanks, Mike.
Hi Mike,
Are they complete with the original output devices? I believe they were made by Lambda. I never got around to build this amp. I have as many 240 and 9240 as you can use.
Roar
Are they complete with the original output devices? I believe they were made by Lambda. I never got around to build this amp. I have as many 240 and 9240 as you can use.
Roar
The original JC-3 design had a simple regulated power supply. Mark Levinson's later version was much more complex.
Hi Mike,
Mea culpa. I can see how you not understood me. I took your mentioning of the A40 to mean Nelson Pass classic amp from -78. This utilized a pair of Darlington output devices made by Lambda Corp. I could use a couple of boards for this amp.
Clarifying?
Regards
Roar
Mea culpa. I can see how you not understood me. I took your mentioning of the A40 to mean Nelson Pass classic amp from -78. This utilized a pair of Darlington output devices made by Lambda Corp. I could use a couple of boards for this amp.
Clarifying?
Regards
Roar
Mike,
I would talk to the people at www.4pcb.com .
If you are a first time user, you will get a discount.
If I remember correctly, Ayre uses them.
Sigurd
I would talk to the people at www.4pcb.com .
If you are a first time user, you will get a discount.
If I remember correctly, Ayre uses them.
Sigurd