Nelson has too much going for him, to worry about a bunch of "groupies" like us
Imagine having such a prolific mind that you can open your bag of tricks whenever you get bored? This sounds like the world of Nelson Pass. He strikes me as a genius who will never run out of ideas. If someone were to take advantage of Nelson, that poor fellow would probably be run out of town on a rail by the rest of us......
Concerning a mass purchase:
I'm not at all opposed to waiting for the beta rev.1 pcb if it doesn't take too long. The idea with my layout is expediency; a treat for some of us to enjoy while waiting for the best of the best from our brightest minds in this forum.
John Inlow
Imagine having such a prolific mind that you can open your bag of tricks whenever you get bored? This sounds like the world of Nelson Pass. He strikes me as a genius who will never run out of ideas. If someone were to take advantage of Nelson, that poor fellow would probably be run out of town on a rail by the rest of us......
Concerning a mass purchase:
I'm not at all opposed to waiting for the beta rev.1 pcb if it doesn't take too long. The idea with my layout is expediency; a treat for some of us to enjoy while waiting for the best of the best from our brightest minds in this forum.
John Inlow
OK, we're up over 50 now for the main order. Beta order is going out ASAP, so please contact me ASAP about getting in on it if you haven't already done so...
A reminder: rev. Beta boards are the prototype, and while every attemp will be made to ensure correctness (these boards have passed three sets of eyes now), there is no guarantee they will function flawlessly. Secondly, they will not be the same production quality as the main run described in my initial post (they are being run at expresspcb.com). However, they will be available much sooner than the main production boards.
A reminder: rev. Beta boards are the prototype, and while every attemp will be made to ensure correctness (these boards have passed three sets of eyes now), there is no guarantee they will function flawlessly. Secondly, they will not be the same production quality as the main run described in my initial post (they are being run at expresspcb.com). However, they will be available much sooner than the main production boards.
I will send a confirmation email to all those who have requested Beta version boards, so please keep your eyes peeled for this in the next day or two, and reply quickly to confirm your exact order quantity and the price.
order update
Updated order totals are:
rev. Beta: 22
rev. 1.0: 88
Looks like the production boards are going to be very cheap!!
I'll get some new price estimates made for higher volumes.
Also, I'm sending out the confirmation email today for those who are ordering the Beta boards. We'd like to submit the order ASAP, so please watch for this email, and reply promptly.
Updated order totals are:
rev. Beta: 22
rev. 1.0: 88
Looks like the production boards are going to be very cheap!!
I'll get some new price estimates made for higher volumes.Also, I'm sending out the confirmation email today for those who are ordering the Beta boards. We'd like to submit the order ASAP, so please watch for this email, and reply promptly.
Notice!
We are now freezing the order for Beta PCBs, so that our pricing information and order count will be accurate. From now on, I'll only be accepting requests for rev 1.0 boards.
If you have <i>already</i> requested Beta boards from me, but don't receive the confirmation email in the next 24 hours, please let me know ASAP so you don't get left out!
We are now freezing the order for Beta PCBs, so that our pricing information and order count will be accurate. From now on, I'll only be accepting requests for rev 1.0 boards.
If you have <i>already</i> requested Beta boards from me, but don't receive the confirmation email in the next 24 hours, please let me know ASAP so you don't get left out!
OK, confirmation email has NOT gone out yet... I'm still discussing some things with grataku. I'll post again when I've sent it. Sorry for the confusion here...
Confirmation email has been sent. Keep your eyes peeled!
OK, Beta order confirmation email just went out with payment details etc. If you don't get this email, that means I haven't got you on my list, so you should contact me ASAP. In case your email isn't getting through, it's best to post here.
Beta boards should arrive in about a week, and then we're moving right on to revision 1.0 boards by Christmas!
I'll have the final Beta schematic and board layout preview posted here soon.
OK, Beta order confirmation email just went out with payment details etc. If you don't get this email, that means I haven't got you on my list, so you should contact me ASAP. In case your email isn't getting through, it's best to post here.
Beta boards should arrive in about a week, and then we're moving right on to revision 1.0 boards by Christmas!
I'll have the final Beta schematic and board layout preview posted here soon.
Schematic
C9 and C10 are 0.001uF. I would absolutely have the provision for AC coupling the inputs and jumpering the caps if DC coupling is desired. A couple of 47uF Black Gates or other good 25V radial electrolytics would not require much room on the layout and nice big pads for off PCB film caps would be cool too. Some big pads to mount off PCB source resistors would be nice too. I have to admit that think you are about there and schematic is beautifully drawn and thought out. You may have seduced me into being a beta tester.........
Impressed as hell and no hanging chad on my ballot,
Fred
C9 and C10 are 0.001uF. I would absolutely have the provision for AC coupling the inputs and jumpering the caps if DC coupling is desired. A couple of 47uF Black Gates or other good 25V radial electrolytics would not require much room on the layout and nice big pads for off PCB film caps would be cool too. Some big pads to mount off PCB source resistors would be nice too. I have to admit that think you are about there and schematic is beautifully drawn and thought out. You may have seduced me into being a beta tester.........
Impressed as hell and no hanging chad on my ballot,
Fred
Thanks Fred, and since you are such a good sport I may allow you on board.
The board is pretty tigthly packed. So AC coupling at this point is going to be a pain. Lets leave that for version1. Unless Chad wants to make radical changes in the gerber-izing process.
Input was spaced for a phoenix contact blue terminal like in the real AX.
Outs and PS can be hooked up with brass of cu screws 4-40 or M3 and a ring wire terminal.
The board can be fastened with up to #6 screws and stand-offs.
thanks for listening
PS
For all others besides Chad, Fred, and I.
The options are:
Grey ccs
D1a, Q6a, and r17 1.5k to J1 to ground, bypass r48,
Fred ccs
D2b, Q6b, Q12a or Q12b, r17 15-20k, r48=10
The gate of J501 is connected internally to the cathode.
The board is pretty tigthly packed. So AC coupling at this point is going to be a pain. Lets leave that for version1. Unless Chad wants to make radical changes in the gerber-izing process.
Input was spaced for a phoenix contact blue terminal like in the real AX.
Outs and PS can be hooked up with brass of cu screws 4-40 or M3 and a ring wire terminal.
The board can be fastened with up to #6 screws and stand-offs.
thanks for listening
PS
For all others besides Chad, Fred, and I.
The options are:
Grey ccs
D1a, Q6a, and r17 1.5k to J1 to ground, bypass r48,
Fred ccs
D2b, Q6b, Q12a or Q12b, r17 15-20k, r48=10
The gate of J501 is connected internally to the cathode.
So AC coupling at this point is going to be a pain
Not a big deal as caps can be easily mounted on input jacks.
There are even more current source options within the existing schematic/PCB layout with component value changes.
1. Use of D1b with Q6a or D1a with Q6b with appropriate change R24 and R26 values.
2. Use of R17 with D1b with a value change to 7.5K ohms and J1 installed.
3. Use of D1a with 3.9K resistor in place of Q12a, short for R17 and no install for J1
4. Use of D1a with 5mA current source like the J511 installed for Q12a. J1 would be a no install and R17 as 1K for current monitoring and increased HF power supply noise rejection.
This is offered, not to confuse, but to show the flexibility in implementation and parts purchasing. I still feel that the Grey CS zener diode bias offers poor rejection of supply noise for the zener diode CS voltage reference. This should be easy to measure and I think a lot of people will concur if they go make the measurements. It will be interesting to hear about any sonic differences as a result of these changes.
Watching and waiting,
Fred
Not a big deal as caps can be easily mounted on input jacks.
There are even more current source options within the existing schematic/PCB layout with component value changes.
1. Use of D1b with Q6a or D1a with Q6b with appropriate change R24 and R26 values.
2. Use of R17 with D1b with a value change to 7.5K ohms and J1 installed.
3. Use of D1a with 3.9K resistor in place of Q12a, short for R17 and no install for J1
4. Use of D1a with 5mA current source like the J511 installed for Q12a. J1 would be a no install and R17 as 1K for current monitoring and increased HF power supply noise rejection.
This is offered, not to confuse, but to show the flexibility in implementation and parts purchasing. I still feel that the Grey CS zener diode bias offers poor rejection of supply noise for the zener diode CS voltage reference. This should be easy to measure and I think a lot of people will concur if they go make the measurements. It will be interesting to hear about any sonic differences as a result of these changes.
Watching and waiting,
Fred
Yep, that was my reasoning. Coupling caps can get physically large, and people always seem to have their own preference for type x or y, so there are too many footprint possibilities and they would take up too much space on the PCB. Good thing resistors and mosfets come in standard pakcage types...
Additional pads for off-board expansion will be added tonight too, for source resistors and parallel output devices. Adding small rail decoupling caps on the board would be rather nice, and there is probably space to do it, but running a trace to the star ground could be a bit of a trick. One little mod I might do is move J1 down beneath the Q12s, and add J1b to the negative rail. That way, all current current source options can run to either negative rail or ground. For resistor-only solution, a jumper would be needed across Q12a.
Fred: How did you arrive at 1nF for C9 and C10? Is this from your own testing, or a standard value pulled from Aleph designs?
You want to be flexible with compensation cap values.
As I indicated before, we are running XA200's without any
small caps and no "Zobel" network at the output. This leaves
us with 4 electrolytics required for the Aleph current sources,
plus of course the power supply caps. I recommend having
the holes there, but don't be too eager to fill them...
As I indicated before, we are running XA200's without any
small caps and no "Zobel" network at the output. This leaves
us with 4 electrolytics required for the Aleph current sources,
plus of course the power supply caps. I recommend having
the holes there, but don't be too eager to fill them...
I recommend havingthe holes there, but don't be too eager to fill them
That narrows it down...........
I would think that the larger number of output devices for the AX200 might also be a mitigating factor in the choice to not use these caps. Could smaller output stages warrent thier possible usage?
Waiting for the lightning bolt,
Fred
That narrows it down...........
I would think that the larger number of output devices for the AX200 might also be a mitigating factor in the choice to not use these caps. Could smaller output stages warrent thier possible usage?
Waiting for the lightning bolt,
Fred
Countdown to order...
OK, folks. The order for Beta boards will go out within the next 24 hours or so. If you want to secure your order, now's the time act! Remember, I can't take a big financial risk here, so I'm looking for assured payment before I place an order on your behalf.
<b>Get in while you still can!</b>
OK, folks. The order for Beta boards will go out within the next 24 hours or so. If you want to secure your order, now's the time act! Remember, I can't take a big financial risk here, so I'm looking for assured payment before I place an order on your behalf.
<b>Get in while you still can!</b>
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