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GB for R-2R Volume Controller with 4 inputs

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danzup

danzup

Member
Joined 2007
Firmware v3.14 with issue solved.
Please use the version suitable for you :
- ATM16_R2R_LCD_Vicol_v3_14 = firmware vicol audio for board with all transistors on board
- ATM16_R2R_LCD_Vicol_v3_14_fara_tr = firmware vicol audio for board without all transistors on board , the one without Q1...Q6 on board
- ATM16_R2R_LCD_Vicol_v3_14_fara_tr_diy_audio = firmware diyaudio / vicol audio for board without all transistors on board , the one without Q1...Q6 on board
Please test and share if you find some bug .
 

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  • ATM16_R2R_LCD_Vicol_v3_14.zip
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  • ATM16_R2R_LCD_Vicol_v3_14_fara_tr.zip
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  • ATM16_R2R_LCD_Vicol_v3_14_fara_tr_diy_audio.zip
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R

ristar

Member
Joined 2013
danzup said:
Firmware v3.14 with issue solved.
Please use the version suitable for you :
- ATM16_R2R_LCD_Vicol_v3_14 = firmware vicol audio for board with all transistors on board
- ATM16_R2R_LCD_Vicol_v3_14_fara_tr = firmware vicol audio for board without all transistors on board , the one without Q1...Q6 on board
- ATM16_R2R_LCD_Vicol_v3_14_fara_tr_diy_audio = firmware diyaudio / vicol audio for board without all transistors on board , the one without Q1...Q6 on board
Please test and share if you find some bug .
Click to expand...


Perfect!

Thanks Danzup and Tibi for the quick responses to bug reports!
 
R

ristar

Member
Joined 2013
Thanks for the ever quick response Tibi. It is less than 5mV for the source... I tried an empty input as well and the plop in those two distinct positions plop, too. What is interesting is the plop is still there but it has reduced in loudness when i measured all those points? i have left this in standby all the time, could a charge have built up somehow?
 
iTiberius

iTiberius

Member
Joined 2005
ristar said:
Thanks for the ever quick response Tibi. It is less than 5mV for the source... I tried an empty input as well and the plop in those two distinct positions plop, too. What is interesting is the plop is still there but it has reduced in loudness when i measured all those points? i have left this in standby all the time, could a charge have built up somehow?
Click to expand...

You have huge leakage current. Any signal source should have DC in microVolt, better in nV.

Regrads,
Tibi
 
R

ristar

Member
Joined 2013
Hi Tibi,

I'm using the DAM1021 and just remeasured things it is pretty much at 0mV except for when i first put the probes. I don't know if that is really the problem... I have also tried with no source connected.

What is clear is it is always at -32 to -31 and -16 to -15.
 
iTiberius

iTiberius

Member
Joined 2005
OK, I have a DAM1021 as well but not tested yet. Anyhow 5mV is far too much and a capacitor must be used. Try a 100uF cap and see if clicks are attenuated.
5mV with amplifier gain will be translated in hundred mVolts, or near to 1Volt range, generating huge plops and clicks. Even more, if you are using a high impedance input amplifier DC coupled, this may damage your speakers.

Regards,
Tibi
 
Last edited by a moderator:
R

ristar

Member
Joined 2013
Hi Tibi,

Thanks for the advice.

I changed the inputs between the two boards (DAM is used SE unbuffered) the board on top (with AC connector) have loud plops... The lower board has considerably softer plops.

Measuring the inputs at the attenuator as 0mV but at the outputs i get 18mV... Very weird?

There is a capacitor at the output of the DAM from what i know so i'm not certain what the issue is.

I hope you don't get the wrong idea that i don't like the R2R attenuator becuase i really do. Sounds very transparent! i'm just trying to make it perfect here ;)
 
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R

ristar

Member
Joined 2013
ristar said:
Thanks Tibi I will troubleshoot the pumpkin preamp that i have paired with your r2r attenuator at the moment.
Click to expand...

Hi Tibi,

Just an update that I have largely sorted this with your help. Everything is rigged on a plastic table at the moment... So the pumpkin was affected by the change in temp/airflow. Re calibrated the set up and now I only get a soft plop at the 32 to 31 transition... It is silent at 16 to 15. This will do for now until i get everything cased up.

I wanted to extend my thanks for furthering my knowledge and for a great product!

Best,
 
L

lemon

Member
Joined 2009
ristar said:
I'm not sure if it is because of the firmware update but i'm hearing pretty loud pops when changing the volume from -32 to -31 as well as -16 to -15. Anyone else getting that?
Click to expand...

tvicol said:
Any DC component on you source or input ?
Measure with a millivoltmeter.

Regards,
Tibi
Click to expand...

tvicol said:
Than DC component is coming from the amplifier. Any DC current is transformed in Volts by R-2R resistors.

Regards,
Tibi
Click to expand...

Hi to all.

I have the same issue with all fw that I have tried.

From my little experience it seems to be a glitch relay issue or some delay from how to combine the fw the relays at this points.

If you carefully listen the time that happened this, you hear a little different noise on relay crackling, every time at the same points.

I have used a 0mV source->R2R->DCB1 Buffer with -0.08/0.02 dc offset -> final amplifier with a capacitor on input and I had the exactly same issue.

I don't understand how the "ristar" decreased this issue!
 
R

ristar

Member
Joined 2013
lemon said:
I don't understand how the "ristar" decreased this issue!
Click to expand...

Person... not thing here :)

This thread discusses some of the stuff (http://www.diyaudio.com/forums/pass-labs/215210-pop-noise-relay-volume-control.html) and suggests some workarounds including firmware tweaks to reduce the intensity of the transition points we pointed out. I found this after while trying to troubleshoot. Jan also explains why it happens at the 16 to 15 transition point.

I never thought the succeeding stage could cause problems really... but after Tibi told me about it, I went to check and recalibrate my preamp (Pumpkin) and it reduced the loudness of the plop/pops. I didn't bother to try to eliminate it because the pumpkin isn't cased up and airflow/temp fluctuates making it next to impossible to zero it for now. That said, I was able to reduce the DC at the r2r's output from 18mV to 6-7mV... I'm thinking it should be possible for me to do better when it's all cased up.

I guess this explains why an unused input channel has pops as well. That said, the board (balanced config) that doesn't have the AC input is definitely quieter. I'm wondering if there may be some leakage current as well...
 
L

lemon

Member
Joined 2009
@ ristar = sorry, wrong syntax!
Thanks for the link.
@ tvicol = mV

First, I can't make any fw code change...
What is the specific relay position (parallel to coil) to put a capacitor for a trial?

I haven't final connections yet and I have used the direct input only.
 
iTiberius

iTiberius

Member
Joined 2005
lemon said:
@ ristar = sorry, wrong syntax!
Thanks for the link.
@ tvicol = mV

First, I can't make any fw code change...
What is the specific relay position (parallel to coil) to put a capacitor for a trial?

I haven't final connections yet and I have used the direct input only.
Click to expand...

It is not clear for me where you want to put a capacitor. Relay coils are already decoupled with a 100nF MLC and diode.

regards,
Tibi
 
iTiberius

iTiberius

Member
Joined 2005
On other hand this VC is our main volume controller in Quasar amplifiers.
I'm using this in various configurations:
- dac with trafo output - no audible clicks
- subbu dac - no audible clicks
- tube output DAC with output PIO caps 0.1mV DC - no audible clicks
- Accuphase DP-550 - no audible clicks
- Naim CD5Si - no audible clicks

If you have no DC component across VC, I'm very interested to understand what cause this in your system.

Regards,
Tibi
 
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