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Old 14th January 2010, 02:19 AM   #121
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cviller: I'm very interested in a pcb for this active crossover. Can you make it flexible enough to be suitable for driving four F5's directly (ie, as a pre-amp/active xo combo)?
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Old 14th January 2010, 02:42 AM   #122
cviller is offline cviller  Denmark
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Since it is basically a B1, I'm sure it can drive a F5, but you may want some gain.
I have a crazy sandwich mother daughter board system in mind, but it might get too complicated.

But this is not my design, not my thread or anything, so I'll leave it to some others to take those decisions.
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Old 14th January 2010, 07:15 AM   #123
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I cannot believe you ever would need more than 0 dB gain in an electronic X-over. I run all my preamps with low gain and -20dB butten active and so on to get to use the volume control over 9 o' !
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Old 14th January 2010, 09:03 AM   #124
njepitt is offline njepitt  United Kingdom
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Quote:
Originally Posted by cviller View Post
I have a crazy sandwich mother daughter board system in mind, but it might get too complicated.
I am putting one of these together for use with an F5, and while I almost certainly won't buy a board I'd like to make a couple of suggestions, if I may.

Why not extend your "mother daughter board" idea to a fully modular approach? I am using small PCBs which slot vertically into a larger board which in my case is p2p, but in yours could be a "mother" pcb. If you follow a modular design, builders can choose from a list of options; whether to use SMD or through the hole devices, final output buffers with gain or without, and how many stages to use, to give 12db/octave or 24, and so forth.

If you'd like to see photos of my approach they are on BF862 Preamp, but I'm sure you'll be able to do better than that. (And avoid the stupid mistakes...)

Cheers

Nigel
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Old 14th January 2010, 11:33 AM   #125
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Quote:
Originally Posted by cviller View Post
I have a crazy sandwich mother daughter board system in mind, but it might get too complicated.
Me too, with the possibility of using input/output buffers capable of both SE and balanced input/output.

My thoughts include one mother board for each output. I'm looking to make both a 2-way and a 4-way.

I have some conceptual work done for this, but not with this actual crossover.
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Old 15th January 2010, 02:39 PM   #126
njepitt is offline njepitt  United Kingdom
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Hi Guys,

I now have a working BF862 preamp, with four output buffers as shown in post #82 here. (At least, two are working - the others probably have something trivial wrong... There are details and photos at BF862 Preamp if you'd like to hear more.) Time has come to plan practical details about the filter section. Following the experience with plugin boards on these buffers, the evident shortage of space, and juma's comments on the other thread about the size of the boards, I am thinking of making the buffers as small boards to plug into DIP-8 sockets. This isn't a new idea, of course, there's a fascinating thread at Pass Discrete Opamp in DIP-8 Package which describes something physically similar, although electrically different. The same idea could be applied to the LP section, using DIP-16 sockets to allow building the buffers as pairs, which is pretty natural given the schematic. My concern is heat; juma will doubtless say I am worried about nothing (again), but there really isn't much space on the top of a DIP-8, and I'm not sure if I fancy the idea of fixing a heatsink on top like EUVL did for his opamp. (I feel it shouldn't be necessary in this case, anyhow...)

If this idea works it might be helpful to cviller with the PCB idea... Use DIP-8 sockets and either plug in a small SMD board, or plug in the 2SK170s directly...

I think I might do a test run with a pair of buffers and wire up a passive buffer with some sort of symmetrical PSU and see how it works, before doing 14 of them...

Anyone have thoughts on this?

Cheers

Nigel
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Old 15th January 2010, 06:20 PM   #127
dviswa is offline dviswa  United States
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Quote:
Originally Posted by udailey View Post
Dinesh,
Look for Dip Trace. Its a very good pcb software and you can use it for free.
Uriah
Uriah,
Thanks a lot. I did not know that, I will check it out.
Just for future reference: DipTrace - Professional Schematic & PCB Design Software
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Old 15th January 2010, 06:42 PM   #128
dviswa is offline dviswa  United States
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Nigel,
Your construction sure looks nice. Hope it all works. Looking at your construction and the comments by cviller, a mother/daughter board setup will be good. The mother board can route output of one as input for the next one. One can always cut traces and jumper it if output from one has to be routed to 2 or 3 stages.
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Old 15th January 2010, 07:59 PM   #129
udailey is offline udailey  United States
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No problem. I found it when looking for a good schematic program. For layout I usually use Layout50 and wish I could link you but the link is so buried in google I cant find it. Illegal copies are abundant but at $40 its pretty nice to be legal. It generates useful gerbers and is super easy to use. Usually have to build your own components if its anything other than the norm, but thats easy to.
Uriah
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Old 15th January 2010, 08:11 PM   #130
Variac is offline Variac  United States
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Somewhere in and about the MOX crossover threads there is a design to make discrete opamps on a pcb board that would plug into a socket. I actually got a PCB boards from the buy- all discrete components, based on Pass opamps, that plug into a socket. If we can find it we could avoid re-inventing the wheel..

I think that Jens Rasmussen was involved.

Mark


Quote:
Originally Posted by njepitt View Post
Hi Guys,

I am thinking of making the buffers as small boards to plug into DIP-8 sockets. This isn't a new idea, of course, there's a fascinating thread at Pass Discrete Opamp in DIP-8 Package which describes something physically similar, although electrically different. The same idea could be applied to the LP section, using DIP-16 sockets to allow building the buffers as pairs, which is pretty natural given the schematic.
If this idea works it might be helpful to cviller with the PCB idea... Use DIP-8 sockets and either plug in a small SMD board, or plug in the 2SK170s directly...

I think I might do a test run with a pair of buffers and wire up a passive buffer with some sort of symmetrical PSU and see how it works, before doing 14 of them...

Anyone have thoughts on this?

Cheers

Nigel
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