Post pics of your builds.... - Page 589

Quote:

Originally Posted by b1o2r3i4s5 

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... 

 

---

 

Hi there!

Thanks!

The attenuator is controlled with a single linear pot behind that glorious knob .
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?

Quote:

Originally Posted by earfanatic 

Hi there!

 

Thanks!

The attenuator is controlled with a single linear pot behind that glorious knob .
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...

Quote:

Originally Posted by b1o2r3i4s5 

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.

Quote:

Originally Posted by earfanatic 

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 ?!?! 

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 !!

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%.
 

Quote:

Originally Posted by b1o2r3i4s5 

Very nice! So many heatsinks 

 

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

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! ;)

Quote:

Originally Posted by Twinster 

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

This.

How did I not see something missing....

Quote:

Originally Posted by Fred_com 

Hi all,

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

 

 

 

 

 

 

 

Good job - hows the sound?

Updated Objective stack.  Now it sounds even more transparent! 

Quote:

Originally Posted by FraGGleR 

Updated Objective stack.  Now it sounds even more transparent! 

Haha~ See what you did there 

Is that laser engraved?

Quote:

Originally Posted by b1o2r3i4s5 

Haha~ See what you did there 

 

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.  

Quote:

Originally Posted by FraGGleR 

 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.

Quote:

Originally Posted by FraGGleR 

Updated Objective stack.  Now it sounds even more transparent! 

 

 

 

 

That...is BEAUTIFUL!

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