Batery powered DIY CNC phono stage

[sachu888]

We found LME49990 very bright for our taste. MC33078 was soothing and neutral. All depends on one's listening taste. Basically we were trying to get similar sound of NH by rolling opamps. 33078 came closest.

Regards,
Bhaskar

+1 You are right .Opamps are system specific and LME49990 may sound overly bright in same system.

Regards,
Sachin

 

[sachu888]

Raghu called me and helped out with the same suggestions. I have submitted for rewiring to the shop along with fixing one of the grounds. However in the above quoted post of JLS although he has not shown in diagram yet he has stated that the TT Gnd should also be connected to the G terminal but in PCB there is a separate point on the other side marked for TT Gnd which is what I have used, hope that is fine?

Hi Saikat,
Kindly connect +/- of batteries to 0 (G in JLS pic) and TT ground to G on PCB.Ther are two separate points in new PCB layout.

Regards,
Sachin

 

[reubensm]

Yesterday did a comparison between CNC and Ray Samuels Nighthawk phono stage. CNC had OP Amp MC33078(best combo), Ad823, 2134, 072, 082 and 49990. Cart was At95e MM.

First impression: Nighthawk is an excellent Phono. Very clear, silent(runs on Li-ion battery), very nice sound stage, very balanced. But got surprised when we played the CNC. It held it's ground against the NH in almost every respect. And the difference, though audible, could easily be neglected if we consider the price factor. The only area where NH excelled drastically was reducing of surface noise. It did an extraordinary job discarding max surface noise and picking only music. Whereas with CNC, surface noise disturbance was obvious. But with various other opamp that could also be varied.

Overall verdict, persons who heard both the Phono for the first time agreed unanimously that if we consider the price factor then CNC is the clear winner.

Regards,
Bhaskar

I think this is a very important observation. I've noticed the same when I did a comparison between my NAD106 preamp's phonostage and the NAD3020's phonostage. The 106's phonostage filtered out most of the surface noise while the 3020's phonostage put it all up for me to hear. I guess its got something to do with dampening feedback circuitry.

 

[haisaikat]

Re: Battery powered DIY CNC phono stage

Battery terminals resolved the problem indeed. Thanks for all your suggestions. Got dpdt switch fitted as well. Thanks raghu for all the hour long telephonic supports. It is running fine now. Will post more feedbacks soon

 

[jls001]

How does it sound?

 

[haisaikat]

Re: Battery powered DIY CNC phono stage

It sounds great indeed my initial impression is with only newer LPs like lagaan, jab tak hai jaan and jodha akbar and there I observed that the lows and mids are more pronounced than their digital recordingd on flac on my same chain and is a vast improvement. Observed that there is a somewhere smoothening effect on the highs as compared to CD audio making them sound less bright but again different than CDs although this is more soothing to ears. Another observation (or rather perception) is that iin the jodha akbar LP I found in one of the songs there was a comparatively a higher than normal pitched male voice which at some point sounded to be breaking oe becoming harsh to some extent. Will give some more time to break in as raghu suggested. There is a very very low hum which one cannot hear unless he is within 1 feet of the speakers otherwise not at all audible at more than Even 3 feet. I am yet to compare in detail with CD or FLAC sounds with my not so great ears but will give more listening time and judge. The bottomline is that LPs are now enjoyable to me. Also my observation is that for some older LPs that have a noise appropriate eq control to be used in amp.

 

[sachu888]

Hi Saikat,
It should not hum.It could be picking up some noise from your equipment as its housed in a plastic box.Try to change location of CNC.You can also try pasting 3-4 layers f Aluminium foils inside the Plastic cab.

Regards,
Sachin

 

[haisaikat]

Re: Battery powered DIY CNC phono stage

Okay thanks sachin. Its hardly noticeable like I said and would need superman senses to perceive. But I think you are bang on again since indeed I have squeezed the CNC to one side of the amp where bodies are touching one another. But space is limited over there so I will have to either improvise or to let it go.

 

[jls001]

Please try to isolate the CNC away (as far as possible) from other equipment.

Secondly, be careful while routing the cable from the tonearm so that the cables do not pass near to other devices, especially near power supply unit of amps/preamps/CDPs. This step is critical. And it still applicable even if your tonearm cable is well shielded.

And thirdly the interconnect cable from CNC to amp should also be routed as far away from other devices (though this is less critical than isolating tonearm cable).

 

[haisaikat]

Interconnect from CNC to Amp is just 1 feet and is a direct no-cross-eachother connection. But the tonearm cable indeed passes over the amp and I think towards front. I will post the pictures, there is some shortage of space that I am dealing with.

 

[manniraj]

My CNC build is finished and many thanks to Sachin/Raghu and ofcourse Syed of Chennai to assemble the same in the Pass B1 cabinet along with my ODAC board. Here are the pictures :licklips:

 

[sachu888]

Nice pics :clapping:

Regards,
Sachin

 

[manniraj]

Thanks Sachin, I must admit that after your suggestion I have put the DIP jumper to 3 (47k) on both the switches and it is giving good gain and superb presentation. I was hearing the Pankaj Udhas live concert in the evening and when the people were clapping :clapping: I could feel that I was sitting right in the concert, too good to be true.

There is very slight hum I can hear (very close hearing and during the song change when there is absolute silence) and I think thats because of the grounding that I am yet to do for the TT to the CNC case. I have to open up the TT and remove the grounding wire connected to inside of the TT to the ground terminal of the CNC case. I am planning to do that along with the RCA jacks replacement of the TT which are in a bad shape with some rust deposits which I cleaned but still they persist because of the age. All in all the best kit that I got for the stereo listening so far.

 

[sachu888]

Please connect ground wire of your tt to CNC.Hum could also be due to your TTs old RCA cables,they work like an antenna.Please solder some good quality low capacitance shielded RCA cable on TT.There will be no hum.Joshua suggested RG174? co ax cable which is thin and well shielded also very low capacitance.You can also use good quality Video component cable(Red,Blue and Green connectors)but this cable is usually very thick and stiff,so soldering may not be easy.

Regards,
Sachin

 

[manniraj]

Please connect ground wire of your tt to CNC.Hum could also be due to your TTs old RCA cables,they work like an antenna.Please solder some good quality low capacitance shielded RCA cable on TT.There will be no hum.Joshua suggested RG174? co ax cable which is thin and well shielded also very low capacitance.You can also use good quality Video component cable(Red,Blue and Green connectors)but this cable is usually very thick and stiff,so soldering may not be easy.

Regards,
Sachin

Yes planning to do that of changing the old RCA cables to something similar to what Joshua suggested RG174. I have some component cables but they are very thick so as per the suggestion the soldering will be a problem, hence dropped this idea and will go with either RG174 if I can procure in Bangalore or else a pair of think coaxial cables.

 

[AmitKumar]

My CNC build is finished and many thanks to Sachin/Raghu and ofcourse Syed of Chennai to assemble the same in the Pass B1 cabinet along with my ODAC board. Here are the pictures :licklips:

Hey Manniraj,

This is looking great. very neat and professional.

Thats a very nice cabinet too.

 

[AmitKumar]

Please connect ground wire of your tt to CNC.Hum could also be due to your TTs old RCA cables,they work like an antenna.Please solder some good quality low capacitance shielded RCA cable on TT.There will be no hum.Joshua suggested RG174? co ax cable which is thin and well shielded also very low capacitance.You can also use good quality Video component cable(Red,Blue and Green connectors)but this cable is usually very thick and stiff,so soldering may not be easy.

Regards,
Sachin

Yes planning to do that of changing the old RCA cables to something similar to what Joshua suggested RG174. I have some component cables but they are very thick so as per the suggestion the soldering will be a problem, hence dropped this idea and will go with either RG174 if I can procure in Bangalore or else a pair of think coaxial cables.

I read somewhere that it might be a good idea to replace the original RCA cables/connectors with female rca connectors. This will give more flexibility for trying diff kind of RCA cables in future. though not sure which cable to use along with those female connectors.

Hi Sachin,

Any idea if that RG174 is available in india or any equivalant of this available in india?

 

[manniraj]

Hey Manniraj,

This is looking great. very neat and professional.

Thats a very nice cabinet too.

Yes as widely discussed it was done with nice professional finish by Mr.Syed. Many thanks to him and actually I forgot to thank Bijin/Bibin for the Pass B1 cabinet, its one of the professional DIY cabinet that I have seen. In future will plan to get the Pass B1 as well installed as there is some place left over for the same and I can reuse the r-core as well. May be if space is a constraint then will try to re-arrange the ODAC board inside the cabinet to make some room.

 

[sachu888]

Hi Sachin,

Any idea if that RG174 is available in india or any equivalant of this available in india?

Hi Amit,
It should be available in SP road.I could not find in Nashik.Its not expensive.

Regards,
Sachin

 

[jls001]

I read somewhere that it might be a good idea to replace the original RCA cables/connectors with female rca connectors. This will give more flexibility for trying diff kind of RCA cables in future. though not sure which cable to use along with those female connectors.

It is a good idea as it allows you to use any unbalanced interconnects of your choice, BUT it involves major mechanical and electrical modifications to the turntable.

Any idea if that RG174 is available in india or any equivalant of this available in india?

I buy RG 174 cable from a shop called Toyo in Lamington Road in Mumbai. The brand is also called Toyo. Nice and flexible with double shielding. I don't know if they have dealers in other cities. I have never specifically asked but I think even Kiran Sales in the same street will have this cable (but of Belden make). They do have a very sexy RG 400 cable (not Belden, I forgot the make) but it is way too rigid for this type of application, though it has similar diameter. Spectra Connectronics also sells all sorts of connectors and cables so they may have have it too.

One example available on ebay.in. Very costly, though, and comes with SM-A male connector that you totally don't need but have to pay for.

Alternative here is cheap.