Batery powered DIY CNC phono stage

[omishra]

talking about heavy metal music, which album did you use for testing?

Metallica, Green Day and Iron Maiden. Don't get scared. These are my son's choices. for me they are just testing records.
My liking are softer oldies and classical.

 

[captrajesh]

Metallica, Green Day and Iron Maiden. Don't get scared. These are my son's choices.

Uh oh, how old is he?

 

[omishra]

Uh oh, how old is he?

He is 9yrs [Mod please excuse my OT post but this guys loves the music which is useful for testing my CNC phono stage]
Kushal, 9 years played drum with Summer of 69 by Bryan Adams - YouTube
"Wild Woman by MLTR" Drum Solo by Kushal 9 years HRC Pune - YouTube
What's Up - Kushal (9 yrs) Plays drum first time - YouTube

 

[sachu888]

Hi Om,
I have watched the videos,that's great for 9 year old.

Regards,
Sachin

 

[Hiten]

In day-to-day forum activity something comes along that delights you immensely.
A kid who loves music, plays music, and likes vinyls. :clapping:
Very happy to see this
Regards

 

[omishra]

In day-to-day forum activity something comes along that delights you immensely.
A kid who loves music, plays music, and likes vinyls. :clapping:
Very happy to see this
Regards

Yes, he stopped me from buying further CDs for his choice. Thus making my pocket to drain faster for vinyl purchase. Eventually good vinyls cost 10 times of 1 CD. Never damaged any record, always cared.
Good thing is that he never interested in technicality, but able to tell which is sounding good or bad. God why not give me that sense!
As I listened to his practice sessions live w/o mic & amp in fully soundproof studio, it clicks me immediately whats wrong while record being played.

 

[captrajesh]

He is 9yrs

Hey Mishraji, I loved it. Three cheers to the kid.

 

[reubensm]

Metallica, Green Day and Iron Maiden. Don't get scared. These are my son's choices. for me they are just testing records.
My liking are softer oldies and classical.

These are my choices too, barring green day!!

 

[shaizada]

Update: My CNC is running from last 2 weeks and now time to review it again. I found that low and high ends are little opened. But still that high are not up to mark.

I find that this my be issue with cartridge loading. I am using shure mm 97xe.

Simply changing recommended 47K loading resistance to 62K made life little easy. but not that much. Then I fitted this piece of IC sockets to experiment with different C values for loading at R=47K. I arrived to this conclusion considering manufacturer recommended loading C,R values stands good for neutral response from cartridge.
This was the extra mod for loading capacitor.

I experimented with 56pf, 68pf, 82pf, 120pf and 150pf. At 68pf I found the missing air of crash plate. Now its more live. This was tested with heavy metal rock music which has this frequency present.
As I read at tnt forum this cartridge responses accurately flat at loading with 47K resistance and 250pf capacitor parallel to it. This means my wires from tonearm to RCA may be contributing somewhere approx. 180pF (This is wild guess without any measurement.)

This is absolutely fantastic information Omishra. I am going to be using this exact cartridge for the CNC Phono setup and this is definitely good information to know. What are those black things that the capacitor leads go into? I see they can be used to roll in different capacitor values. Is there a part number for digi-key that can be used to purchase those?

I would imagine different MM carts using different capacitors to sound best....just extra bit of tuning ability. :clapping:

Your son seems to be on his way to becoming a good drummer. Lucky man!

 

[sachu888]

This is absolutely fantastic information Omishra. I am going to be using this exact cartridge for the CNC Phono setup and this is definitely good information to know. What are those black things that the capacitor leads go into? I see they can be used to roll in different capacitor values. Is there a part number for digi-key that can be used to purchase those?

I would imagine different MM carts using different capacitors to sound best....just extra bit of tuning ability. :clapping:

Your son seems to be on his way to becoming a good drummer. Lucky man!

Hi Shaizada,
I think Om has used an op amp socket's pin for this.

BTW: anyone interested in DIY phonostage for MC.This is supposed to be best phonostage for MC cart.This one is based on Phonocube PHONOCUBE which retails at $4000 with power supply.This will work with all MC carts.See here Here It Is: The All Singing All Dancing HTMCPS - AudioKarma.org Home Audio Stereo Discussion Forums

Regards,
Sachin

 

[murali_n]

Hi sachu888,

Will this DIY Phono be better than the Phono stage of the Marantz Integrated PM 6003. Bcos of late thinking of upgrading to a Tube pre with SS Power. The forthcoming HFV meet will throw more light for me towards this idea, hence eagerly looking forward to this event. :yahoo:

N.Murali

 

[sachu888]

Hi sachu888,

Will this DIY Phono be better than the Phono stage of the Marantz Integrated PM 6003. Bcos of late thinking of upgrading to a Tube pre with SS Power. The forthcoming HFV meet will throw more light for me towards this idea, hence eagerly looking forward to this event. :yahoo:

N.Murali

Hi,
This is better than my integrated Technics Su 8088 phono.I have not heard particular Marrantz model,but outboard phonos are better in general.

Regards,
Sachin

 

[omishra]

Your son seems to be on his way to becoming a good drummer. Lucky man!

Thank you.

This is absolutely fantastic information Omishra. I am going to be using this exact cartridge for the CNC Phono setup and this is definitely good information to know. What are those black things that the capacitor leads go into? I see they can be used to roll in different capacitor values. Is there a part number for digi-key that can be used to purchase those?

Those are pins from IC socket. Those caps could be ceramic/film caps of those values for 50-100V range. I used ceramic caps.
I found this search result.

 

[Moviela]

Hi fellas,

I enjoy reading the perils and pitfalls everyone has experienced with their DIY front ends. The quest for more comfortable sound from vinyl has been a passion of mine for years.

I would like to contribute some ideas concerning the circuit. The first is the power supply bypass capacitors. I would prefer that aluminum electrolytics be banned from analog signal processing IC's. The 10uf caps could be changed to tantalum caps. Longer life, better current source when the IC starts to conduct. There should also be a third bypass cap, a 2.2uf ceramic as close to the power pins as practical would be better. Inside the box, wires should be twisted, and a shield covering them that is connected to the "ground" near where the twisted wire is connected to the circuit board.

The passive RIAA curve is represented well with the circuit shown, however, the values of the caps should be carefully measured and selected to be equal on both sides. The carbon film 1% resistors need an additional specification to keep the gain and non-linear curve accurate with changes in temperature. The resistors I see in the pictures have a temperature coefficient of 200ppm or more. High end circuits would specify 50ppm resistors. The common designator for these would be RN55CxxxxF.

I find Digi-key a good supplier, but the road from Thief River to India is quite long. I believe RS Components & Controls (India) Ltd has the same parts, no sales tax, and free delivery.

I am most curious as to the break-in of 30 hours. What is actually changing at that point? Conforming of the capacitors should be done within seconds. Could it be that the batteries are discharged at that point enough so that the internal Resistance of the battery has decreased allowing a lower impedance power supply? If you change batteries, does it revert to the "as new" state?

Multi-layer circuit boards are now quite inexpensive. A change in board design to a four layer could add a lower impedence power and ground rails, and provide better shielding for the signal.

I always mount the pre-amp for my turntables as close as practical to the tone arm, keeping the low level signal wires very short. As a line level signal the sound will travel in "comfort" to the amp input.

Good work guys.

 

[sachu888]

Hi fellas,

I enjoy reading the perils and pitfalls everyone has experienced with their DIY front ends. The quest for more comfortable sound from vinyl has been a passion of mine for years.

I would like to contribute some ideas concerning the circuit. The first is the power supply bypass capacitors. I would prefer that aluminum electrolytics be banned from analog signal processing IC's. The 10uf caps could be changed to tantalum caps. Longer life, better current source when the IC starts to conduct. There should also be a third bypass cap, a 2.2uf ceramic as close to the power pins as practical would be better. Inside the box, wires should be twisted, and a shield covering them that is connected to the "ground" near where the twisted wire is connected to the circuit board.

The passive RIAA curve is represented well with the circuit shown, however, the values of the caps should be carefully measured and selected to be equal on both sides. The carbon film 1% resistors need an additional specification to keep the gain and non-linear curve accurate with changes in temperature. The resistors I see in the pictures have a temperature coefficient of 200ppm or more. High end circuits would specify 50ppm resistors. The common designator for these would be RN55DxxxxF.

I find Digi-key a good supplier, but the road from Thief River to India is quite long. I believe RS Components & Controls (India) Ltd has the same parts, no sales tax, and free delivery.

I am most curious as to the break-in of 30 hours. What is actually changing at that point? Conforming of the capacitors should be done within seconds. Could it be that the batteries are discharged at that point enough so that the internal Resistance of the battery has decreased allowing a lower impedance power supply? If you change batteries, does it revert to the "as new" state?

Multi-layer circuit boards are now quite inexpensive. A change in board design to a four layer could add a lower impedence power and ground rails, and provide better shielding for the signal.

I always mount the pre-amp for my turntables as close as practical to the tone arm, keeping the low level signal wires very short. As a line level signal the sound will travel in "comfort" to the amp input.

Good work guys.

Hi,
Thanks for your remarks.I want to clear some of your points.We have used only Metal film resisters +/-1%.Wires are twisted pair of CAT5/CAT6 cables.New design has a ground plane as you can see in one of the pic I have posted.No Electrolyte caps have been used in signal path. We have used all film caps.Original BOM has digikey part no and we bought the same parts for this from Element14 previously known as Fernell.
I fully agree with your comment regarding phono amp mounted near TT.I have kept my phono next to my TT.I am using 3ft low capacitance Video Component cable.
I believe in break in even some cap manufacturers have given break in period for their caps and I felt the difference.
I don't feel the need of multi layer board as most of the successful phono DIY designs has single layer without ground plane to name few, Rod Elliot P06,Hangerman Buggle etc.

Regards,
Sachin

 

[sachu888]

Latest Pic,
[URL=http://imageshack.us/photo/my-images/577/dsc04881n.jpg/] Uploaded with ImageShack.us[/URL]

Regards,
Sachin

 

[omishra]

Hi fellas,

I enjoy reading the perils and pitfalls everyone has experienced with their DIY front ends. The quest for more comfortable sound from vinyl has been a passion of mine for years.

I would like to contribute some ideas concerning the circuit. The first is the power supply bypass capacitors. I would prefer that aluminum electrolytics be banned from analog signal processing IC's. The 10uf caps could be changed to tantalum caps. Longer life, better current source when the IC starts to conduct. There should also be a third bypass cap, a 2.2uf ceramic as close to the power pins as practical would be better. Inside the box, wires should be twisted, and a shield covering them that is connected to the "ground" near where the twisted wire is connected to the circuit board.

The passive RIAA curve is represented well with the circuit shown, however, the values of the caps should be carefully measured and selected to be equal on both sides. The carbon film 1% resistors need an additional specification to keep the gain and non-linear curve accurate with changes in temperature. The resistors I see in the pictures have a temperature coefficient of 200ppm or more. High end circuits would specify 50ppm resistors. The common designator for these would be RN55DxxxxF.

I find Digi-key a good supplier, but the road from Thief River to India is quite long. I believe RS Components & Controls (India) Ltd has the same parts, no sales tax, and free delivery.

I am most curious as to the break-in of 30 hours. What is actually changing at that point? Conforming of the capacitors should be done within seconds. Could it be that the batteries are discharged at that point enough so that the internal Resistance of the battery has decreased allowing a lower impedance power supply? If you change batteries, does it revert to the "as new" state?

Multi-layer circuit boards are now quite inexpensive. A change in board design to a four layer could add a lower impedence power and ground rails, and provide better shielding for the signal.

I always mount the pre-amp for my turntables as close as practical to the tone arm, keeping the low level signal wires very short. As a line level signal the sound will travel in "comfort" to the amp input.

Good work guys.

You are correct in all aspect. Thanks. Now are using PS from mains.

Tantalum Caps are available but we thought of 6mA current from IC may not warrant those high current requirements. I was looking to OP AMP datasheet, it mentions only noise bypass caps for the frequency handled by application circuit. That's why that pair 0.1uf and 10uF at the power line bypass. Any special reason for 2.2uF ceramic caps?

 

[Moviela]

You are correct in all aspect. Thanks. Now are using PS from mains.

Tantalum Caps are available but we thought of 6mA current from IC may not warrant those high current requirements. I was looking to OP AMP datasheet, it mentions only noise bypass caps for the frequency handled by application circuit. That's why that pair 0.1uf and 10uF at the power line bypass. Any special reason for 2.2uF ceramic caps?

The bypassing is necessary not only to provide current to the opAmp, but also to extend the flat impedance of the power supply. If you are not using the correct type of capacitor you will have a very reactive power supply that will impact the quality of the sound. Looking at the RIAA curve simulator I might use a more aggressive bypass at the IC of .01 film polystyrene, a 2.2 uf film polypropylene, and a high quality electrolytic 2200 @ 16v such as Panasonic FC series. This would change the .1 and 10 uf used now.

I do not think that a regulated mains supply should be used. You give up the full performance of the circuit without batteries. I might try rechargeable 12 volt gel batteries. The pair should be disconnected and charged in parallel so they are more equal in voltage when returned to service.

I would prefer the case be nonmetallic (I enjoyed the red felt lined carved wood box seen early in the thread.) with the batteries inside the box.

Here is another item for discussion. The RIAA equalization curve is well documented and amended and equipment manufacturers for years have been cobbling passive and active circuits to realize it's inclusion in preamps. All well and good, but should we not be duplicating the curve used to make the record? A few years ago I had to cut to a record, and found an old Neumann Lathe in the compost heap. Since it was the first time I had used one, I did what most of us never do. I read the manual. It says the high frequency boost is rolled off at 50Khz. Since most record plants used Neumann gear, the RIAA curve might not that be fully accurate for a lot of recordings.

 

[gopib]

Snip..Snip...

I would prefer the case be nonmetallic (I enjoyed the red felt lined carved wood box seen early in the thread.) with the batteries inside the box.

Here is another item for discussion. The RIAA equalization curve is well documented and amended and equipment manufacturers for years have been cobbling passive and active circuits to realize it's inclusion in preamps. All well and good, but should we not be duplicating the curve used to make the record? A few years ago I had to cut to a record, and found an old Neumann Lathe in the compost heap. Since it was the first time I had used one, I did what most of us never do. I read the manual. It says the high frequency boost is rolled off at 50Khz. Since most record plants used Neumann gear, the RIAA curve might not that be fully accurate for a lot of recordings.

Interesting points here. Appreciate if you can explain the nonmetallic part. I was always under the impression that a metallic casing would act as a shield
and prevent picking up interference. Personally I would prefer a wooden casing as there is something synergistic about it with the music..IMO of course.

Your discovery on the Neumann Lathe is also news...will carefully listen and
find out...

Thanks

 

[omishra]

The bypassing is necessary not only to provide current to the opAmp, but also to extend the flat impedance of the power supply. If you are not using the correct type of capacitor you will have a very reactive power supply that will impact the quality of the sound. Looking at the RIAA curve simulator I might use a more aggressive bypass at the IC of .01 film polystyrene, a 2.2 uf film polypropylene, and a high quality electrolytic 2200 @ 16v such as Panasonic FC series. This would change the .1 and 10 uf used now.

I do not think that a regulated mains supply should be used. You give up the full performance of the circuit without batteries. I might try rechargeable 12 volt gel batteries. The pair should be disconnected and charged in parallel so they are more equal in voltage when returned to service.

What about this PS? I am using this. I find no notable difference in battery or this.

I would prefer the case be nonmetallic (I enjoyed the red felt lined carved wood box seen early in the thread.) with the batteries inside the box.

Please explain this more. I have orthodox thinking of avoiding external interferences by means of conductive shielding techniques aka metallic boxes.

Here is another item for discussion. The RIAA equalization curve is well documented and amended and equipment manufacturers for years have been cobbling passive and active circuits to realize it's inclusion in preamps. All well and good, but should we not be duplicating the curve used to make the record? A few years ago I had to cut to a record, and found an old Neumann Lathe in the compost heap. Since it was the first time I had used one, I did what most of us never do. I read the manual. It says the high frequency boost is rolled off at 50Khz. Since most record plants used Neumann gear, the RIAA curve might not that be fully accurate for a lot of recordings.

^^Possible. That's why we get either inferior or so called musical records.