[Fred_fred2004]

Quote:

Originally Posted by linuxworks /img/forum/go_quote.gif I am allowing for the tangent pcb in many of my builds. a down side is that you need a lot more gain from the amp. but the crossfeed effect is worth having. note that its also worth being able to bypass/disable it. I use relays (of course)

Your relay idea is clever it cuts down on wiring to dpdt switches which is a pain

 

[linuxworks]

Quote:

Originally Posted by Fred_fred2004 /img/forum/go_quote.gif Your relay idea is clever it cuts down on wiring to dpdt switches which is a pain

thanks

here's the next evolution. TWO relays:

the schematic and layout:

you can turn off both relays, just one, just the other or both. one of those states is 'flat' and the other 3 are diff levels of bass boost. all relay controlled!

I home etched this one (painfully) from toner method. I hate that method, I really do... I must try the photo method some time.

still, it did make an ok board:

it sounds great, btw! I've been listening to it with various relays on and off. the default is both off and that gives a good amount of 'default' boost (as I like it both in my spkrs and phones). one setting is pure flat (one relay on and one off) and the other settings also involve at least 1 relay on. it happened that way because the traces 'told' me to do it that way (lol).

this thing sits on top of the pimeta and I meaured the holes so it fits exactly over the pimeta R4 holes. I used IC socket pins to hold the resistors since they might need to be 'tuned'.

its a hack, but it was a fun and productive hack.

the next part is to create a 2-bit latch to hold the 4 states, some 4 LED driver and more interestingly the interface to the IR receiver/decoder.

 

[vixr]

linuxworks...wow! that is awesome.
here is my gamma1

 

[sandbasser]

linuxworks -

Once again I'm totally blown away by your work (DIY work AND photography); I look forward to your postings. Your latest is totally amazing.

A question: why did you 'socket' the resistors instead of just soldering them directly to the board???

Thanks for the inspiring work!

 

[linuxworks]

Quote:

Originally Posted by sandbasser /img/forum/go_quote.gif A question: why did you 'socket' the resistors instead of just soldering them directly to the board??? Thanks for the inspiring work!

thanks!

I need to be able to change the R's out if I didn't guess or pick the right values.

I wanted to have 3 steps: 1 low R, 1 medium R, both in series (adding to more than either of them) and then both of them out of the circuit.

to 'tune' that means I have to find some low R's that give 'just enough' bass but still when added to the larger R gives another level.

rather than unsolder to tune or change the values, I just decided that a home made pc board won't survive repeated unsolderings so sockets come to the rescue

plus they look nice, those wire-wrap socket pins sticking up high like that (lol). I had a bunch of old wire-wrap sockets and those are actually pretty easy to cut apart and steal their pins from.

I'm using this preamp for both my main spkrs and headphones. a bass setting that is right for my spkrs is too much for my phones, so having settable levels for bass really is a usability feature I'm glad I stumbled on. sitting back in your chair, with a remote, clicking 'bass flat,hi1,hi2,hi3' is a neat thing to have!

 

[ruZZ.il]

hey cool idea there with the relays. you could squeeze more out of it if you hook them up in parallel though (rather than the serial like hookup).. shorter signal path and less interface transitions.. Also, I'm not sure why you'd want to use a state machine.. you'd need to use gates, clocks, flip flops.. unless you program a chip to cut down parts.. not sure its worth the bother with just a few options anyway.. ah.. for a remote.. well.. then you almost may as well program something.. even if just a PLD....

 

[linuxworks]

I'm not sure what you mean by hooking the relays in parallel. do you mean physically next to each other or do you mean *electrically*? I do need to be able to switch each on and off, by itself, of course.

edit: oh, I just realized, you mean programming the total R value by paralleling instead of going in series.

not sure its a win either way; they both could have 2 R's in at a time (causing noise) either in series or parallel. I guess to take one relay R 'out of the path' the relay simply opens and there are no extra contacts to travel thru - that must be what you mean. with my circuit you always go thru TWO sets of relay contacts and you way you would possibly (at times) go thru only 1. you only get 2 golden '1 contact' settings, though (lol).

perhaps if I re-do the circuit I'll try a parallel config. thanks for the idea.

my keyboard mapping is going to be easy because I have a trick in mind

the mapping of the 4 states to either 4 buttons on a remote or maybe just 1 button cycling around to the 4 states. I may run short of buttons and so I might not want to 'waste' 4 on this and maybe only use 1 (cycling) or 2 (direct binary selection via 2 toggles).

 

[thetelevisi0n]

My first DIY project. I probably could have improved the wiring a bit more and the soldering too... But I'm super happy with it!

 

[mattcalf]

Quote:

Originally Posted by thetelevisi0n /img/forum/go_quote.gif My first DIY project. I probably could have improved the wiring a bit more and the soldering too... But I'm super happy with it!

Awesome stuff!
Nice build, I hope my Cmoy turns out that clean.

 

[Fred_fred2004]

Well done, it looks a lot better than my first effort
cheers

 

[-=Germania=-]

I am seriously waiting for digital out from the iPod just to use a gamma1 with a battery pack.

The iPod analog outputs are the limiting factor in my portable setup. It is very irritating when you know its not the files, the amp, cables, or headphone...its the iPod. lame.

Great work AMB!

 

[Fred_fred2004]

OPA2132U
Discrete rail splitter
decoupling caps as suggested (thanks)

just wanted to show somebody

cheers

 

[thetelevisi0n]

Quote:

Originally Posted by Fred_fred2004 /img/forum/go_quote.gif OPA2132U Discrete rail splitter decoupling caps as suggested (thanks) http://i460.photobucket.com/albums/q...4/CIMG2880.jpg http://i460.photobucket.com/albums/q...4/CIMG2875.jpg http://i460.photobucket.com/albums/q...4/CIMG2871.jpg http://i460.photobucket.com/albums/q...icsdiscret.jpg just wanted to show somebody cheers

That looks amazing. Now I'm really ashamed of the wiring in my CMoy.

That interconnect is cool, did you make it yourself? I think that's gonna be my next project.

And a random pic of my CMoy on a breadboard:

 

[Fred_fred2004]

The hardest part of the interconnect is learning how to plait

you'll have no problems

cheers

 

[apatN]

Nice CMoy's in here. Keep them coming!