DIY Moving Coil phonostage

[sachu888]

I haven't ordered parts yet. Would be great if you did so for me too! Do let me know the additional cost. The wires would be included in the parts? Or is there some spec for this and one can pick it up at an electrical store?

Cart: Ortofon SPU classic,
Output voltage at 1000 Hz, 5cm/sec. 200 V
Internal impedance, DC resistance 6 Ohm
Recommended load impedance > 10 Ohm

Are the specs enough for the resistors needed?

Regards
Steve

Hi Steve,
I am little confused.Can you post me a link for this cart.I have found a link and it says DC resistance is 2 Ohms. SPU Classic
Wires are not included in parts.I am using twisted pair of CAT5 cable.It has a good solid copper inside and recommended by DIY gurus.
Regards,
Sachin

 

[captrajesh]

Its not practical with MC carts coz resisters depend upon two things internal impedance of cart and its output,and almost every MC cart resistance is different.

How are the commercially available MC stages function?

Whatever the resistance, there would be a range isn't it. We can make a stepped attenuator with highest quality components. I'm a noob here so kindly pardon if my queries appear to be silly.

please let me know if anyone wants me to order parts for this pre.

Hey Sachu, I've not ordered parts, please order them for me too. You can send them to me along with the PCBs. Let me know how much money to transfer.

 

[anilva]

I am going to order parts for myself,please let me know if anyone wants me to order parts for this pre.

Regards,
Sachin

Sachin,

Can please order for me one stereo set as well.

Cheers.

 

[jls001]

How are the commercially available MC stages function?

Whatever the resistance, there would be a range isn't it. We can make a stepped attenuator with highest quality components. I'm a noob here so kindly pardon if my queries appear to be silly.

Cut-paste from user manual of my phono stage - resistance loading steps. This is accomplished through dip switches. Note that it doesn't have 47kOhm setting! The manual glibly says that most MM cartridges have about 50 kOhm resistive load.

 

[sachu888]

How are the commercially available MC stages function?

Whatever the resistance, there would be a range isn't it. We can make a stepped attenuator with highest quality components. I'm a noob here so kindly pardon if my queries appear to be silly.



Hey Sachu, I've not ordered parts, please order them for me too. You can send them to me along with the PCBs. Let me know how much money to transfer.

Hi Capt,
There is no range some carts has DC resistance of 2 Ohm (Ortofon SPU) and some has 160 ohms(Denon DL-160).I have put 4 screw terminals for swapping resisters without soldering.
I will order parts for you,let me know which cart are you going to use with this pre.

Regards,
Sachin

 

[sachu888]

Sachin,

Can please order for me one stereo set as well.

Cheers.

No problem will do.

Regards,
Sachin

 

[stevieboy]

Hi Sachin,

That's the older version with the aluminium mag alloy body. Its the one they send out in the box set of four SPUs.

The new ones (which I have), are made with a grinded wood body and the 6 ohm resistance. When I was ordering I checked various sites, found discrepancies on the Ortofon Japan and US sites and wrote to them and they updated it. Was very confusing for me too, they've got a pretty bad site architecture for products. If you click on products, you'll come to this page:
Products - Cartridges - Classic GM MkII

Regards

 

[sachu888]

Cut-paste from user manual of my phono stage - resistance loading steps. This is accomplished through dip switches. Note that it doesn't have 47kOhm setting! The manual glibly says that most MM cartridges have about 50 kOhm resistive load.

Hi Joshua,
MM carts are less critical.We have built CNC MM phnoo which has Resistance setting for 18k/32k/47k/62k etc http://www.hifivision.com/phono-turntables/20115-batery-powered-diy-cnc-phono-stage-29.html
.It controls variable resistive loading by dip switches.Almost all MM cart will perform well with above settings my Shure M55E is sounding great on 32k.
MC carts are very diff than MM and very critical with loading.

Regards,
Sachin

 

[sachu888]

Hi Sachin,

That's the older version with the aluminium mag alloy body. Its the one they send out in the box set of four SPUs.

The new ones (which I have), are made with a grinded wood body and the 6 ohm resistance. When I was ordering I checked various sites, found discrepancies on the Ortofon Japan and US sites and wrote to them and they updated it. Was very confusing for me too, they've got a pretty bad site architecture for products. If you click on products, you'll come to this page:
Products - Cartridges - Classic GM MkII

Regards

Hi Steve,
You will need 6 Ohms for R1/R9 and 225 ohms for R9/R10.

Regards,
Sachin

 

[stevieboy]

Hi Sachin,

Thanks so much! So I'll await a PM from you on the amount for the parts so I can send the money. Can't wait to get hands on with some soldering! By the way one uses some sort of wet sponge to clean the soldering tip right in between solders?

Regards

 

[jls001]

By the way one uses some sort of wet sponge to clean the soldering tip right in between solders?

Just shake off on floor and sweep away the flakes later. Of course don't shake it off on your bare foot or something Or on cloths as it can be a pain to take it off.

 

[stevieboy]

Hi Steve,
You will need 6 Ohms for R1/R9 and 225 ohms for R9/R10.

Regards,
Sachin

Sachin,

Was going through your earlier AK thread references and it says 10X R1 for the R10, shaizada had asked the question, what's the calculation to come to 225? Is there some ready reckoner that I can use when I swap carts later on?

Thanks

 

[stevieboy]

Just shake off on floor .

Am a bit afraid of it going all over the place or in my eye!

 

[jls001]

Sachin,

Was going through your earlier AK thread references and it says 10X R1 for the R10, shaizada had asked the question, what's the calculation to come to 225? Is there some ready reckoner that I can use when I swap carts later on?

Thanks

I had asked the same question and Sachin's reply is to stick to the calculated values, OR lower. Not go by x10 value.

 

[sachu888]

Sachin,

Was going through your earlier AK thread references and it says 10X R1 for the R10, shaizada had asked the question, what's the calculation to come to 225? Is there some ready reckoner that I can use when I swap carts later on?

Thanks

Hi Steve,
R1X10= R2/R10 is a close enough values for for most of LOMC carts.R1/R9 are the same as the cart resistance rest two are for gain,so they are not very critical.Hypnotoad has now made a calculator for this which is accurate.

Regards,
Sachin

 

[sachu888]

Hi Sachin,

By the way one uses some sort of wet sponge to clean the soldering tip right in between solders?

Regards

I always use wet sponge between solders,it really helps.Sponge is available with electronic part stores.

Regards,
Sachin

 

[sachu888]

Sachin,

Could you post a picture of the other side of the board so I see how its soldered?

Thanks!
Steve

Back side of PCB.It needs some cleaning with IPA.


Uploaded with ImageShack.us

Regards,
Sachin

 

[Tanoj]

Superb Sachin

very neat work...

Captian i wish you were here at my place to listen how the TT is singing now, with your speakers

very detailed , crisp, sound, bass seems to be just right


iam on my way of building case for this


Thank you once again

 

[stevieboy]

Hypnotoad has now made a calculator for this which is accurate.

Regards,
Sachin

Hi Sachin,

Can you post a link to the calculator or email me the calculator? I could not find it in your links on AK. I would need it for carts later on.

Thanks
Steve

 

[captrajesh]

There is no range some carts has DC resistance of 2 Ohm (Ortofon SPU) and some has 160 ohms(Denon DL-160).

Another noob question. If the resistance has to be so varied for different carts, can't we use an LDR in place of these resistors?