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post #8821 of 9591
Quote:
Originally Posted by b1o2r3i4s5 View Post

Lookin' good!

Just a few questions....

how many steps does it have?

does it use a logarithmic resistor ladder? or just something like rotary stepped-attenuator with relays instead?

what relays are you using? (that thing looks really small....)

what are you using to control the relays? standard logic or microcontroller?

it that a pot or rotary encoder behind that gold knob?

Thanks! because I'm thinking of building one too... biggrin.gif

 



 

Hi there!

 

Thanks!

The attenuator is controlled with a single linear pot behind that glorious knob biggrin.gif.
The pot is then read by the microcontroller's ADC to control the relays. The resistor set is logarithmic.

There are 128 steps and two input channels. So I used 7 relays for the ladder and one more relay for channel selector.

The relays are indeed small. The one I used are made by American Zettler.

 

What do you want to use your attenuator with? Any plans yet?


Edited by earfanatic - 10/26/12 at 3:06am
post #8822 of 9591
Quote:
Originally Posted by earfanatic View Post

Hi there!

 

Thanks!

The attenuator is controlled with a single linear pot behind that glorious knob biggrin.gif.
The pot is then read by the microcontroller's ADC to control the relays. The resistor set is logarithmic.

There are 128 steps and two input channels. So I used 7 relays for the ladder and one more relay for channel selector.

The relays are indeed small. The one I used are made by American Zettler.

 

What do you want to use your attenuator with? Any plans yet?

Thanks! 

I was thinking of building one with a similar archetechture to yours, but still deciding weather to go with a 8-bit ADC chip or a microcontroller

and also to use relays or analog switches. 

 

I'll probably go with the relays because good analog switches don't come cheap and relays will not distort the sound.

Few concern though, does it make lots of clicking noises as you turn the knob?

and I was worried the the relay at the LSB may die very quickly because of all the switches it'll make...

post #8823 of 9591
Quote:
Originally Posted by b1o2r3i4s5 View Post

Thanks! 

I was thinking of building one with a similar archetechture to yours, but still deciding weather to go with a 8-bit ADC chip or a microcontroller

and also to use relays or analog switches. 

 

I'll probably go with the relays because good analog switches don't come cheap and relays will not distort the sound.

Few concern though, does it make lots of clicking noises as you turn the knob?

and I was worried the the relay at the LSB may die very quickly because of all the switches it'll make...


Well, I think it is a challenge either with a microcontroller or without. But you are facing issues easier to solve with a microcontroller like switching order.

Actually all relay attenuators make clicking noise. Relays are not silent in this way. But you put it in an enclosure and play some music... it wont bother you much.

The relay at LSB makes a lots of clicks, yes. Actually there are dip compatible relays. You can put them into dip ic socket if you like. But these relays are good for 10^8 times switching so I did not worry.


Edited by earfanatic - 10/26/12 at 6:37am
post #8824 of 9591
Quote:
Originally Posted by earfanatic View Post


Well, I think it is a challenge either with a microcontroller or without. But you are facing issues easier to solve with a microcontroller like switching order.

Actually all relay attenuators make clicking noise. Relays are not silent in this way. But you put it in an enclosure and play some music... it wont bother you much.

The relay at LSB makes a lots of clicks, yes. Actually there are dip compatible relays. You can put them into dip ic socket if you like. But these relays are good for 10^8 times switching so I did not worry.

That's why I was thinking of using analog switches instead of relays, since they're solid state.

 

Wow! 10^8 times ?!?! eek.gif

Your average pot only has 10^4 cycles.

In your setup each cycle has 128 steps so in the life time of your pot, the LSB relay would only have switched 1.28 x 10^6 times.

So the pot dies before your LSB relay does !!

post #8825 of 9591

Yes, these relays are very durable, and has gold plated silver-palladium contacts.

I had read somewhere about a mosfet switcher circuit but as I remember not many liked it in real world.

Consider that the relays are ultra fast... sealed with very high grade contacts, and you can use even Nasa approved resistors if you can pay it.

In my design I tried to make the shortest patches that possible with following manufacturer directions, and the resistors have 0.1% tolerance. Even the fancy Alps RK50 ($$$$) has total resistance tolerance of ±20%.
 


Edited by earfanatic - 10/26/12 at 11:04am
post #8826 of 9591
Quote:
Originally Posted by b1o2r3i4s5 View Post

Very nice! So many heatsinks eek.gif

 

btw, why's the power switch in a seperate box? 

or it the transformer in there as well?

 

and what happened with the pot?

 

lol I'm a curious person biggrin.gif

 

 

hehe, cheers.

 

yeah, the b22 has it's own power supply. the regulator board is in the main box w/ the 2 channels, but the toroidal transformer is in the blac box and i chose to mount the switch there... this normally goes in a little shelf under my desk, with the main amp on the desk... the black box is outta sight and well outside range in which it can cause noise interference thru the amp... it;s also convenient to reach down and flick it on or off...

 

the pot? i dunno... when i built the amp, i tried to wire it in and it screwed up... so i wired it out until i built the box. first time i tried to wire the pot back in, it worked... so i must have just been cross eyed after the lengthy build i guess...

 

nice pcbs... sure would have come in handy for a clutz like me! ;)

post #8827 of 9591
Quote:
Originally Posted by madcap386 View Post

Finally after many many builds of the the crystal Cmoy, here is my most satisfied version:










Simple component setup: Vishay resistors, Nichicon FG caps,  OPA2134..
But it sounds excellent.. redface.gif

Just pure ART. Very beautiful. Sorry for asking but where is the volume pot? rolleyes.gif
post #8828 of 9591
Quote:
Originally Posted by Twinster View Post

Just pure ART. Very beautiful. Sorry for asking but where is the volume pot? rolleyes.gif

This.

How did I not see something missing....

post #8829 of 9591
Quote:
Originally Posted by Fred_com View Post

Hi all,

here's my balanced Bijou (not really great casework, but considerably better than my previous attempts):

 

 

 

 

 

 

 

 

 

 

Good job - hows the sound?

post #8830 of 9591

Updated Objective stack.  Now it sounds even more transparent! tongue_smile.gif

 

 

 

700

 

700

post #8831 of 9591
Quote:
Originally Posted by FraGGleR View Post

Updated Objective stack.  Now it sounds even more transparent! tongue_smile.gif

Haha~ See what you did there biggrin.gif

 

Is that laser engraved?

post #8832 of 9591
Quote:
Originally Posted by b1o2r3i4s5 View Post

Haha~ See what you did there biggrin.gif

 

Is that laser engraved?

 Yep.  I am lucky to have access to a laser cutter at a local community lab.  It cuts and etches acrylic with no problems.  

post #8833 of 9591
Quote:
Originally Posted by FraGGleR View Post

 Yep.  I am lucky to have access to a laser cutter at a local community lab.  It cuts and etches acrylic with no problems.  

Nice, I've had my share of experience with a laser cutter too.

It's part of my middle school curriculum to do CAD / CAM.

post #8834 of 9591
Quote:
Originally Posted by FraGGleR View Post

Updated Objective stack.  Now it sounds even more transparent! tongue_smile.gif

 

 

 

700

 

700

That...is BEAUTIFUL! basshead.gif

post #8835 of 9591

nice... an o2 with jacks in front and back =)

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