Kuartlotron Error Correcting Super Buffer

[sachu888]

Joshua is correct. You have to use two 4.7M parallel. Raghu has soldered another resister from underside as this is a double sided PCB.

Regards
Sachin

 

[jls001]

@manniraj: there are two rows of holes - three holes in top row, and three in bottom row.

Start with top row, the hole just above the word "quad" is hole for CCW, middle hole is for Wiper, and right most home for CW. Top row is for first channel.

Row 2 is repeat for second channel. The hole just below the word quad is CCW, etc.

 

[quad]

I have put both source selection switch and potentiometer inside the cabinet, as close to the board as possible to avoid longer run of signal wires.

I guess you plan to use some kind of shaft coupler and extension for
the source selection switch and pot.

You can use the brass insert from a 60A electrical connector which is cheap
and easily available at any large electrical shop -

shaft coupler


6mm rod is also available very cheap in mill stores or metal rods shops

 

[omishra]

+1 to quad.
I used that 60A connector for shaft connectors and I procured 6mm rod from Robotics shop for 25Rs. Then I realized same rod could be cut to exact length from Kitchen Trolley makers workshop in 5 Rs.

 

[jls001]

Thanks Quad for the idea. I was thinking of getting the insert machined. Will try your idea first. Luckily brass rods are available easily and cheaply.

 

[omishra]

Hmm from the build of Raghu that Sachin posted from the pictures I see that he has used a single M value for R9 & R20 and I believe he also build it from the kit supplied by Sachin. So I am not sure whether Sachin marked it correctly. Will check it out.
Thanks for the CCW part but the closest to "quad" there are 2 holes, one from R23 and the other from 25k. So which is the one goes to what and also what about the other 2 holes for each of the R23 and 25K. I believe one of these holes is a -ve value but not sure its either the centre one or the last one as their is a "-" marked in between.

Parallel the two 4.7M and place at location of 2.7M.
for potentiometer - there are 3+3 pads for each channel. Two pads each one above and below letter quad are CCW. pads near R23 25K are input CW. center are wiper W. the white dash '-' means you can short those W and CW if no volume control required. Then inputs directly go to buffer.

 

[jls001]

I'm listening to Bloaty the Bass and Muddie the Treble on my Kuart

I think it needs many more hours to start sounding good.

 

[omishra]

Sachin has provided authentic ON semiconductor transistors. I swear by its origin. You have mixed, yours with locally purchased. Raghu didn't mention anything regarding this burn in. His worked from day 1.

 

[manniraj]

I finished my build yesterday very late into the night but heard it only in the morning with my NAD tuner. I did not feel anything missing compared to the DCB1 but have not heard the entire setup over my DAC and PC. Thanks to Joshua and Raghu for the same. Not to forget Sachin :clapping:

 

[jls001]

Completed the shaft extenders for volume pot and source selector using 60A electrical tag block. The hole of the tag block is about 7 mm diameter while pot shaft is 6 mm. Even the hole on the front panel knobs I have are exactly 6 mm. So I rolled up a piece of plastic cut from a restaurant takeaway plastic container, and the shaft is a snug fit now.

But both extensions are slightly skewed, testament to my less than sterling precision mechanical skills Will try and refine for a smoother rotation. The volume pot is very nearly acceptable but the source selector is wobbles bad.

 

[manniraj]

Heard the buffer with my DAC and yes its clearly ahead of DCB1 with very nice highs and deep base :clapping:. The female vocals too good and now I am loving the sound of Madonna and Shania Twain.

 

[keith_correa]

But both extensions are slightly skewed, testament to my less than sterling precision mechanical skills

Will welding rods work? Out of the box they are very straight!!!

 

[jls001]

Will welding rods work? Out of the box they are very straight!!!

Hope they don't start sparkinghyeah:

 

[keith_correa]

Hope they don't start sparkinghyeah:

You save money on LED's

 

[quad]

Will welding rods work? Out of the box they are very straight!!!

The ones I have seen are probably 2 or 3mm in dia. Pot shafts
are usually 6mm or 1/4". These dia rods are easy to find - you
could even scavenge a 6mm tower bolt from your nearest hardware shop!!!

 

[jls001]

Sachin has provided authentic ON semiconductor transistors. I swear by its origin. You have mixed, yours with locally purchased. Raghu didn't mention anything regarding this burn in. His worked from day 1.

Both bass bloat and muddiness in treble resolved by removing the thick Hilton foam sheet on which my speakers were resting, thanks to two visiting audiophile friends who experimented with my equipment support.

 

[jls001]

Some more cheap experiment has improved the sound. Replaced the brass cone below speakers with 8 mm bearing ball. Bass is tight and controlled. One of the negatives of using the Bug Head player was the slightly bloated bass (compared to what I was used to hearing with foobar playback). I repositioned my speakers just like I do when I make changes to my system, but this time I just couldn't tune it right. Till I discarded the thick foam layer below the speakers, that is. So I rested the brass cone support directly on the speaker stand's platform, and much of the unpleasantness in the bass went away. Replacing the brass cone with bearing ball refined it further. The balls are placed on the brass "shoes" on which the brass cones were resting. I would have loved if the ball could rest directly on the platform, but it is not stable when placed directly. So one needs some conical indentation on which the ball must rest.

Cost: Rs 2 per ball (x6). I said it is cheap

For those who need bigger balls, 12 mm costs Rs 5 per piece

Also, did detailed comparison between the DCB1 and the Kuart with two visiting audiophile friends.The general consensus amongst the three of us seems to be that DCB1 has nice midrange weight, while the Kuart is airier in the mids and highs. It is difficult to choose an outright favourite as their differences are very narrow, and it boils down to a difference in presentation. The Kuart is slightly more resolving due to cleaner mids and highs, but only slightly. If one values a lighter presentation in general, the Kuart is the one for you. Denser, choose DCB1.

Addendum: one major difference in the way I've built the DCB1 and the Kuart is the difference in internal wiring. DCB1 uses Helusound AES DMX balanced cabling with shields grounded at source ends, whereas the Kuart uses 20 gauge solid core copper with Teflon insulation. I may change (later) the solid core wire to the DMX to understand if it improves the sonics.

 

[keith_correa]

Brass cone? Bearing ball? In the singular????????

Also, I can't picture the brass cone support. Got a picture?

 

[jls001]

Brass cone? Bearing ball? In the singular????????

Also, I can't picture the brass cone support. Got a picture?

I use magnetic levitation to hold the speakers in place while it rests on a single bearing ball bang in the center of the bottom of the speaker:lol:

Seriously, three balls per speaker, two up front, one at the rear. The "shoe" is a brass "coin" and has a conical cavity on one flat surface, so that the ball rests on the cavity to prevent it rolling away.

 

[saheb11123]

I want to see pictures,if its not to much to ask, to make one for myself.