Kuartlotron Error Correcting Super Buffer

Rega Turntables
Nikhil said:
You may have to try and see in your setup.

I found that the volume control ran out of steam with the CITEC 32K pot that came with the kit i.e. no change in volume after the 10:30 - 11:00 o clock position (with 6:00 o clock being zero). Changed to 10K pot but the bass thinned out and was really not that good.

Currently the 25K pot is working just fine in my setup. Volume tracks the knob turn very nicely. Have not taken it past 12:00 as my amps are pretty loud.
Click to expand...

Are there any difference in sound (volume and quality) when using CITEC 32K pot and 25k pot?
I am planning to use digital pot DS1882 for the volume control which is of 45K ohm total.
 
sarathssca said:
Are there any difference in sound (volume and quality) when using CITEC 32K pot and 25k pot?
I am planning to use digital pot DS1882 for the volume control which is of 45K ohm total.
Click to expand...

I was using the CITEC 32K and an ALPS 25K pot.

The CITEC was more robust but did not track the volume knob turn.
It lost some composure as you turned up the volume but within it's working range it sounded very nice.

The ALPS 25K pot has solved the volume tracking issue and the sound is not too bad at all.
Have been listening to it for a few days and there are really only issues when I do a direct comparison with my AP Preamp.
Listening to it just by itself, I don't think one would complain with the sound.

I don't have any idea about digital pots but looking at impedance alone I suspect it would exhibit the same problem I had with the 32K pot - not tracking the volume knob. If it doesn't bother you and it sounds good I would not really worry further.
 
Digital volume control - how it is implemented? I mean does it control volume using some IC in audio path or some motorized pot or resistance switching arrangement? In case of ic, there is no benefit of buffer as sound signature will be already compromised.
 
I was reading about this, it doesn't control any pot, it controls volume digitally inside chip and needs micro controller help.
 
ya its a digital potentiometer IC and can be controlled by a microcontroller.
More specifically its digitally controlled analog potentiometer. The signal always remains analog and only the control of the potentiometer is digitally controlled from a microcontroller or so. I think internally it would have some resistor network for attenuation.
Unlink other digital pots like PGA23xx it doesnot have internal opamps and require a high impedance stage following its wiper pin, so need to connect it to a high impedance buffer stage after it.
 
The quality of the carbon and corrosion all results in better or worse sq. That is why people opt for stepped attenuator for best results. Downside, they are costly :(
 
sarathssca said:
One more option I am looking at is the relay resister ladder attenuator. There are some threads in diyaudio on this..
Click to expand...
If high quality resistors are used and the ladder is implemented correctly, this will give better results IMHO. Ideally there should not be any signal loss in the attenuator.
 
With vishay dale RN55 resistors and gold plated 4 pole rotary switch, it cost me ?3.5K . But results were stunning.
 
omishra said:
With vishay dale RN55 resistors and gold plated 4 pole rotary switch, it cost me ?3.5K . But results were stunning.
Click to expand...

Outside of transformer based volume controls, I think discrete resistor based pots are some of the best on can buy.
 
I think the best thing is to have a volume control that doesn't fiddle with audio signal eg., LDR based solutions around..

I made one thats based on arduino controller.. look at here

Am quite impressed with the quality of sound (am not expressive interms of mids/highs/lows wide/narro sort of language) but its doing its job superbly.. Its sounding cool to my ears. Now my pre and amps do not have any volume controls :)

Have got this tested at FM Raghu in his chain and is indeed impressive..

Happy to share/help others who is interested to build or listen in their chains as i made it kind of portable with its own IN/OUT RCA Jacks for easy plugin to any chain :) :)

Right now in a temporary house (not pretty though)..

Some pics ::

https://goo.gl/photos/w2ojJSiVLDfy69aE7

https://goo.gl/photos/k24zGoB97S8CwhAa7
 
I received my kit from Sachin last month. Finally I gave it a try to assemble the kit.

Here are the photos:

Dual Rail PSU:

IMG_20160214_100220.jpg


Kuartlotron Error Correcting Super Buffer:

IMG_20160214_161557.jpg



I received 4 pcs of 4.7m resistors in Sachin's kit. As per suggestion by Sachin (in this thread only) I put two of them in parallel to achieve 2.7m (marked in the PCB R9, R20).

IMG_20160214_154245.jpg



Placed order for 12-0-12 1 amp R-Core transformer and waiting for it eagerly now. :)

Please let me know if there is anything wrong with the connection. I will try to rectify it.
 
saikatbiswas82 said:
I received 4 pcs of 4.7m resistors in Sachin's kit. As per suggestion by Sachin (in this thread only) I put two of them in parallel to achieve 2.7m (marked in the PCB R9, R20)
Click to expand...
Two 4.7M resistors in parallel do not get you 2.7M but 2.35M - but I'm nit picking. :D
 
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