Batery powered DIY CNC phono stage
- Thread starter sachu888
- Start date
Re: Battery powered DIY CNC phono stage
This was my mod for same purpose.
http://www.hifivision.com/phono-tur...owered-diy-cnc-phono-stage-32.html#post328414
This was my mod for same purpose.
http://www.hifivision.com/phono-tur...owered-diy-cnc-phono-stage-32.html#post328414
Is the socket of the DIP adaptor spring loaded? I mean if you just insert the leg of the capacitor it is secure and needs no further soldering/screwing?
I'll remember this for future builds. It takes up minimal space and the DIP adapter pin should be easier to insert in the PCB hole.
I'll remember this for future builds. It takes up minimal space and the DIP adapter pin should be easier to insert in the PCB hole.
reubensm
Well-Known Member
Out of curiosity, I was looking up the origins of the CNC phonostage to try and ascertain how it reached its current avataar and this is what I found on audiokarma 
Feels good to read how projects start and evolve.
Here's the original URL: Another Super High End Phono Stage! No expense spared... - AudioKarma.org Home Audio Stereo Discussion Forums
Feels good to read how projects start and evolve.
Here's the original URL: Another Super High End Phono Stage! No expense spared... - AudioKarma.org Home Audio Stereo Discussion Forums
vnmathur57
Active Member
Here is what I made
with the help of an old TV mechanic! Working alright except a feeble hum.
with the help of an old TV mechanic! Working alright except a feeble hum.
Last edited:
sachu888
Well-Known Member
Here is what I made
Nice build,hum could be due to improper grounding. Did you use ground wire in CNC.
Regards
Sachin
Last edited:
sachu888
Well-Known Member
Another CNC build
Another CNC built. Small Aluminium Cab provided by FM Raghu.
PCB:
Wiring:
Testing, sounding very good as always
Done
Size reference
Regards
Sachin
Another CNC built. Small Aluminium Cab provided by FM Raghu.
PCB:
Wiring:
Testing, sounding very good as always
Done
Size reference
Regards
Sachin
sachu888
Well-Known Member
Yes it is housed in DCB1 cab. Raghu has provided 16mm hole at the back side of DCB1 cab. I have used 3pin connector there to supply power for CNC.PSU is outboard?
Nice looking cab. I want two
Regards
Sachin
hyeah: I am using that same kind of connection for my DIY Pearl2 phono. But utilizing +33,0,-33 unregulated output direct from power caps of OPS.skrodahl
New Member
My CNC build,
I made a complete integrated amp with the following features/components:
* Audiobah TPA3116 amplifier board
* CNC phono stage
* ESP P88 preamp
* Volume, balance
* Four inputs
I've made my own CNC PCB, which has a full ground plane and variable gain. The first iteration was etched at home, and it was a bit noisy.
The PCB that I had manufactured is dead quiet and sounds great!
I made a complete integrated amp with the following features/components:
* Audiobah TPA3116 amplifier board
* CNC phono stage
* ESP P88 preamp
* Volume, balance
* Four inputs
I've made my own CNC PCB, which has a full ground plane and variable gain. The first iteration was etched at home, and it was a bit noisy.
The PCB that I had manufactured is dead quiet and sounds great!
Attachments
skrodahl
New Member
The build thread of my amp (and other's as well) can be found here, maybe it will bring some inspiration:
TPA3116 / RuneAudio Project : DIY and tweaks; RuneAudio Forum
I spent by far the most time and resources on the phono stage. It's extremely gratifying to listen to vinyl, knowing I built this myself (standing on the shoulders of giants, of course).
The picture above shows an earlier stage, with my home-etched CNC PCB and another amp board. I even spent some time building my own little JFET preamp before installing the P88.
The attached pictures got compressed, here are some better images:
TPA3116 / RuneAudio Project : DIY and tweaks; RuneAudio Forum
I spent by far the most time and resources on the phono stage. It's extremely gratifying to listen to vinyl, knowing I built this myself (standing on the shoulders of giants, of course).
The picture above shows an earlier stage, with my home-etched CNC PCB and another amp board. I even spent some time building my own little JFET preamp before installing the P88.
The attached pictures got compressed, here are some better images:
sarith
Active Member
The build looks quite clean. Good Job :thumbsup:
reubensm
Well-Known Member
Re: Battery powered DIY CNC phono stage
Splendid effort, see you have used a dell power supply. Can you share some light on that aspect?
Splendid effort, see you have used a dell power supply. Can you share some light on that aspect?
skrodahl
New Member
Re: Battery powered DIY CNC phono stage
Thanks reubensm,
The PSU is 19.5V, a little less than 4A. I find that the TPA3116 has more than sufficient ripple rejection, so no problem there.
Of course, that's no good for the CNC or the preamp. They need a dual PSU, and one rather less than 19.5V. The solution?
2W 2watt Isolated Dual Output DC DC Power Supply in 18 36V Out 12V | eBay
This little fellow gives 2x 12V, and it's completely isolated. I couldn't use an ordinary virtual ground, as the grounds meet up at the signal level.
Noise is still no issue, the opamps are happily rejecting that ripple.
Thanks reubensm,
The PSU is 19.5V, a little less than 4A. I find that the TPA3116 has more than sufficient ripple rejection, so no problem there.
Of course, that's no good for the CNC or the preamp. They need a dual PSU, and one rather less than 19.5V. The solution?
2W 2watt Isolated Dual Output DC DC Power Supply in 18 36V Out 12V | eBay
This little fellow gives 2x 12V, and it's completely isolated. I couldn't use an ordinary virtual ground, as the grounds meet up at the signal level.
Noise is still no issue, the opamps are happily rejecting that ripple.
sachu888
Well-Known Member
Re: Battery powered DIY CNC phono stage
One of my AK friend has posted some very good info regarding BHL and CNC phonostage here http://soaringcondorsound.com/1/post/2015/02/building-your-custom-dj-phono-preamp.html
Regards
Sachin
One of my AK friend has posted some very good info regarding BHL and CNC phonostage here http://soaringcondorsound.com/1/post/2015/02/building-your-custom-dj-phono-preamp.html
Regards
Sachin
Re: Battery powered DIY CNC phono stage
A very detailed writeup there.
He mentioned a couple of points that caught my attention. First, he mentioned that the AD797 and LME49990 work better at higher voltage. Secondly, he mentioned that 49990 needs some (coupling?) capacitor very close to the opamp on the SOIC adapter itself to avoid the rising the midrange.
Do you think the Hypnotoad (since it uses. Exactly the same opamps) will work better at 15V supply? I'm using 12V right now.
Is there some way we can mod the cap placement for the 49990?
A very detailed writeup there.
He mentioned a couple of points that caught my attention. First, he mentioned that the AD797 and LME49990 work better at higher voltage. Secondly, he mentioned that 49990 needs some (coupling?) capacitor very close to the opamp on the SOIC adapter itself to avoid the rising the midrange.
Do you think the Hypnotoad (since it uses. Exactly the same opamps) will work better at 15V supply? I'm using 12V right now.
Is there some way we can mod the cap placement for the 49990?
sachu888
Well-Known Member
Re: Battery powered DIY CNC phono stage
Yes he mentioned most of the opamps including LME49990 and AD797 performs better at 15V (75% of max voltage). He said there should be .1uf caps near opamp legs. Caps prevent oscillation.This thing has been discussed in SSP threat at AK post # 374 DIY Simple Active Preamp - Page 25 - AudioKarma.org Home Audio Stereo Discussion Forums
Andor suggested to use different adapter(which he says correct adapter) which already has two onboard .1uf caps for CNC.
There is no problem with SOIC adapter of HQMC phonostage. You can safely increase the voltage upto 15 or 16V. Please check whether they run hot or warm.
Regards
Sachin
Yes he mentioned most of the opamps including LME49990 and AD797 performs better at 15V (75% of max voltage). He said there should be .1uf caps near opamp legs. Caps prevent oscillation.This thing has been discussed in SSP threat at AK post # 374 DIY Simple Active Preamp - Page 25 - AudioKarma.org Home Audio Stereo Discussion Forums
Andor suggested to use different adapter(which he says correct adapter) which already has two onboard .1uf caps for CNC.
There is no problem with SOIC adapter of HQMC phonostage. You can safely increase the voltage upto 15 or 16V. Please check whether they run hot or warm.
Regards
Sachin
skrodahl
New Member
I tinkered with the CNC circuit and layout, this is what I ended up with:
With new input impedance resistors, variable gain and a redesigned RIAA equalization filter, this version only has five components in the audio path (two resistors, two opamps and the output capacitors). And it uses only readily available standard value components, all resistors are from the E24-series.
The PCB is smaller, down from 4x3" to roughly 3.5x2" (90x50mm). It has two layers, with a full ground plane on the top layer. Solder pads on the ground plane are segmented and don't always take solder that easily, this solves that problem.
The variable gain is still there, giving a choice of 36, 40 and 44dB gain at 1kHz.
I have made the signal paths as short as I am possibly able to do.
The RIAA equalizer has lost a few components, and will have a maximum RIAA curve deviation of ~0.07dB if the components are measured and matched.
This RIAA equalizer has less resistance, which should give less resistor noise and make the CNC even more quiet.
On the subject of resistors. The input impedance resistor values have been changed to 33k, 82k, 110k and 150k. This gives a whole range of useful choices for the input impedance:
(The original CNC input impedance values, or close to, are in bold.)
The input impedance capacitors have been tossed out. They are rarely needed and if they are, they could be put closer to the turntable. E.g. on the RCA connectors or on the turntable side of the cable.
All input/output/power connections are 5mm apart to make terminal blocks fit.
The output capacitor can have 5 or 10mm leg spacing.
On the input side, it's far easier to connect shielded two-lead cables and there are enough ground connections to ground the turntable.
I've also made an Instructable, that gives instructions on how to build the CNC. It includes a PDF for etching your own PCB.
Did I mention that it's RED?
With new input impedance resistors, variable gain and a redesigned RIAA equalization filter, this version only has five components in the audio path (two resistors, two opamps and the output capacitors). And it uses only readily available standard value components, all resistors are from the E24-series.
The PCB is smaller, down from 4x3" to roughly 3.5x2" (90x50mm). It has two layers, with a full ground plane on the top layer. Solder pads on the ground plane are segmented and don't always take solder that easily, this solves that problem.
The variable gain is still there, giving a choice of 36, 40 and 44dB gain at 1kHz.
I have made the signal paths as short as I am possibly able to do.
The RIAA equalizer has lost a few components, and will have a maximum RIAA curve deviation of ~0.07dB if the components are measured and matched.
This RIAA equalizer has less resistance, which should give less resistor noise and make the CNC even more quiet.
On the subject of resistors. The input impedance resistor values have been changed to 33k, 82k, 110k and 150k. This gives a whole range of useful choices for the input impedance:
(The original CNC input impedance values, or close to, are in bold.)
The input impedance capacitors have been tossed out. They are rarely needed and if they are, they could be put closer to the turntable. E.g. on the RCA connectors or on the turntable side of the cable.
All input/output/power connections are 5mm apart to make terminal blocks fit.
The output capacitor can have 5 or 10mm leg spacing.
On the input side, it's far easier to connect shielded two-lead cables and there are enough ground connections to ground the turntable.
I've also made an Instructable, that gives instructions on how to build the CNC. It includes a PDF for etching your own PCB.
Did I mention that it's RED?
Attachments
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