[f] AMB on Facebook

Relays in the audio signal

delta1

Moderator: linux-works

Relays in the audio signal

Postby willsw » November 17th, 2017, 1:20 pm

I haven't gotten the δ1 yet, but I've been playing with some other designs I got my hands on and have run into the problem of the relays being directly present in the audio signal. As in, every relay is heard clearly through headphones. At very loud volumes, I have heard less consistent noise from the relay that sounds more like some kind of bounce. Anyone know what this would be?
willsw
 
Posts: 2
Likes: 1 post
Liked in: 0 post
Joined: November 17th, 2017, 1:02 pm
Location: Washington, DC
Country: United States (us)

Re: Relays in the audio signal

Postby amb » November 18th, 2017, 1:25 am

In the δ1 (and pretty much any other relay-based attenuator), the relays change state as you change the volume (either by turning the volume potentiometer connected to the LCDuino-1, or using the remote control). But they do so without regard to the signal passing through, i.e., it can happen when the signal is not at zero crossing. This means a potential "kink" in the waveform as the steps are changing, which is perceived as a small click in the audio (not the mechanical click of the relay). Fortunately one does not do critical listening while changing the volume, so it's a minor issue.

As for contact bounce, the relay could have a little, but that's short in duration and probably not audible. The only other possibility of clicks while changing volume is if there is a significant DC offset in the audio signal.

willsw likes this post.
User avatar
amb
Site Admin
 
Posts: 10379
Likes: 175 posts
Liked in: 482 posts
Joined: March 29th, 2010, 9:49 pm
Location: Sunnyvale, CA
Country: United States (us)

Re: Relays in the audio signal

Postby willsw » November 18th, 2017, 11:35 am

amb wrote:if there is a significant DC offset in the audio signal.


I'll check for this. I've heard other relay-based attenuators and the associated nosie, including with this same design, but what I'm experiencing is entirely different from what I've heard before. Thank you very much.
willsw
 
Posts: 2
Likes: 1 post
Liked in: 0 post
Joined: November 17th, 2017, 1:02 pm
Location: Washington, DC
Country: United States (us)

Re: Relays in the audio signal

Postby Garrard301 » November 20th, 2017, 5:03 pm

I've found that the clicks are just about noticeable if you listen for them, but really no big deal provided your signal source doesn't have massive DC offset as Ti says. With speakers the noise of the relays themselves inside the preamp is a lot louder. The benefit of the R-2R attenuation is more than worth it.

The audio clicks can be a little more noticeable at certain points e.g. at -64dB, that's when several of the relays are switching over at once I think.
Garrard301
 
Posts: 23
Likes: 0 post
Liked in: 5 posts
Joined: November 1st, 2015, 5:42 am
Location: Derbyshire
Country: United Kingdom (uk)

Re: Relays in the audio signal

Postby dashpuppy » November 14th, 2019, 9:57 pm

I to have never liked Relay Attenuators :( they are so noisy. I have listened & used alot of the DIY units on the market and they all have noise issues, and I'm not talking about actual relay noise. I'm referring to clicks and pops in the audio path when increasing the volume.

IMO a good ol ALPS or TDK pot is best.
dashpuppy
 
Posts: 11
Likes: 2 posts
Liked in: 0 post
Joined: November 14th, 2019, 9:47 pm
Location: Nanaimo
Country: Canada (ca)

Re: Relays in the audio signal

Postby amb » November 14th, 2019, 11:16 pm

Point taken abot the small clicks, but δ1 is quite good in this regard. You're never going to achieve the range and precision tracking in a simple pot compared to δ1, not to mention the many bonus features that the LCDuino-1 system gives you (see the LCDuino-1 website for details).
User avatar
amb
Site Admin
 
Posts: 10379
Likes: 175 posts
Liked in: 482 posts
Joined: March 29th, 2010, 9:49 pm
Location: Sunnyvale, CA
Country: United States (us)

Re: Relays in the audio signal

Postby dashpuppy » November 15th, 2019, 8:24 am

amb wrote:Point taken abot the small clicks, but δ1 is quite good in this regard. You're never going to achieve the range and precision tracking in a simple pot compared to δ1, not to mention the many bonus features that the LCDuino-1 system gives you (see the LCDuino-1 website for details).

Any pics of what you are talking about or links ?

Is it a relay ladder ? or something else ?
dashpuppy
 
Posts: 11
Likes: 2 posts
Liked in: 0 post
Joined: November 14th, 2019, 9:47 pm
Location: Nanaimo
Country: Canada (ca)

Re: Relays in the audio signal

Postby amb » November 15th, 2019, 12:03 pm


dashpuppy likes this post.
User avatar
amb
Site Admin
 
Posts: 10379
Likes: 175 posts
Liked in: 482 posts
Joined: March 29th, 2010, 9:49 pm
Location: Sunnyvale, CA
Country: United States (us)

Re: Relays in the audio signal

Postby dashpuppy » November 15th, 2019, 12:57 pm




Some interesting things on there, Might have to buy a few pcb's !
dashpuppy
 
Posts: 11
Likes: 2 posts
Liked in: 0 post
Joined: November 14th, 2019, 9:47 pm
Location: Nanaimo
Country: Canada (ca)


Return to δ1 relay-based R-2R stereo attenuator

Who is online

Users browsing this forum: No registered users and 0 guests

Quick Links

AMB audio DIY resources
AMB audio shop

cron