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For want of a better name: the HackerNAP board

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As with several others I'd be interested in 2 rising to 4 if the price were low enough.

Carl,

will you be doing another run of the power amp PSU boards to meet the demand created here?

malcolm
 
Carl

Jumping the gun a bit:

I currently have 4 power amps based on an older Neil McBride NAP 135 design which use MJL3281A output transistors which are TO-247. I am Interested to know what you were thinking of using for output transistors?
 
Wow! I guess there's sufficient interest to warrant a GB.

flashgo: 6
stackowax: ?
benzp: ?
olpplo: 4
Bemused: 4
Pete MB&D: 4
Uzinusa: 4
Yank: 2
sam_cat: 2
John Luckins: 4
chiily: 2
paulski: 2
TonyK: 4
misterc6: 2
keithsnaim: 2
hacker: 6

Total so far: 48

Where someone put "X boards, possibly Y depending on price", I went for the lower figure. Let me know if you change your mind once prices are in. I think we might get a price break at 50 boards - shouldn't be a problem given the initial interest!

Seeing as this appears to be taking off I'll work on putting up a schematic and BOM as soon as possible.

Is there interest in doing another run of the power amp PCB boards? If so I'll make sure to adjust the diode spacing to avoid the possibility of them touching. As far as I know that's the only design defect, although I do have one slight tweak I'd like to make. More later.

Cheers,
Carl
 
benzp said:
Carl

Jumping the gun a bit:

I currently have 4 power amps based on an older Neil McBride NAP 135 design which use MJL3281A output transistors which are TO-247. I am Interested to know what you were thinking of using for output transistors?
Click to expand...

I currently use MJW21194G in my monoblocks and they seem pretty good.

Cheers,
Carl
 
I am afraid I might miss out !
Put me down for two HackerNAP boards and 4 if the price is low enough.

If you are going to do a re run of the power amp PSU boards I will obviously be requiring 4 or 8 of these too! I will obviously need them eventually anyway. Could do with some PSU boards for my pre amp too - can I use the power amp ones or do I need to wait for an additional buy?

Dave
 
I've moved the running total of interested parties to the first post to make it easier to track. I'll also add schematics and price information into that post once I have them.

I think it would be a good idea to start a separate thread for a new group buy of the power amp rectifier PCBs. Watch this space.

Cheers,
Carl
 
Daft question and I will probably get torpedoed for this:rolleyes:
I understand the need for a quieter supply for the 1st stage
But why do you need a completely separate power supply to achieve that as it only takes a Milli amps and I thought it was better if it was a constant current source. So why not just split the output of the Cap6 and regulate the feed to the front end?, I understand also that this will only get say 45V after regulation but why would it need to be exactly 50V?
If this could be achieved it would save a trannie and cap 6 for each channel

Alan
 
Well, the front end needs to be higher voltage than the business end. Nonetheless, it does seem to be overkill to have separate HackerMiniCAPs for the front ends. I'm thinking of building a 6 channel amp in one case, so I was thinking of doing one 100VA transformer + one MiniCAP for the front ends of all 6 channels. Carl, is that anathema to you?
 
337alant said:
why not just split the output of the Cap6 and regulate the feed to the front end?, I understand also that this will only get say 45V after regulation but why would it need to be exactly 50V?
Click to expand...

That would work just fine (the NCC200 has the front end running at slightly lower voltage than the output stage due to the 220R/100uF R/C filter). However, "fine" is not necessarily "better".

For example, running the front end off the same PSU as the output stage will (especially at high volumes) subject the very sensitive front-end supply to modulations on transients. This has an effect on supply quality, something that can be avoided by having a dedicated front end supply. Note that this PCB of mine doesn't do any regulation, instead it just uses passive noise filtering in the form of a VBE so it's important to have a steady PSU for the front end.

PD once noted that you can use one transformer and two sets of rectification as a form of compromise between performance and complexity/cost.

flashgo said:
Well, the front end needs to be higher voltage than the business end. Nonetheless, it does seem to be overkill to have separate HackerMiniCAPs for the front ends. I'm thinking of building a 6 channel amp in one case, so I was thinking of doing one 100VA transformer + one MiniCAP for the front ends of all 6 channels. Carl, is that anathema to you?
Click to expand...

Yup, the higher voltage is apparently quite important. As for running the front ends from one supply... hrm, dunno! It would get quite complex with regard to grounding, but I'm sure it could be done. Why not?

Carl
 
Hi Carl

Looking to put together 3 amps ...... so looks like 12 PSUs plus 6 Amp Boards + 4 & 2 to get started and iron out "errors"!!!!!

Looks like you have a goer ...... however need to be mindful of costs ...... so lets see the final pricing ...... seen this earlier today and waited until "logic" kicked in????

Regards

John
 
If there's that much demand some custom trafos might be in order too, say 2 CT secondaries, 30v-0-30v for the back and and 35v-35v for the front - it may save expense and space in the case...
 
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