New DIY amp - Nelson Pass design

[jls001]

I am tempted too!

+1.
This is one model I really want to diy.

 

[sachu888]

Good work :clapping:
I am tempted too! Please keep the information flowing. Now I want peace for some time and listen completed projects.

After PASS B1 success, I feel this is next candidate for DIY. People there, what do you say?

Yes,
I am very much in as I discussed you earlier.

regards,
Sachin

 

[madbullram]

Does this mean that you plan a visit here, or is it just wishful thinking? I can vouch for the sound.

I've been planning a visit to Madras for the past year to meet and do some auditions just havent had the time to do it, except for one brief session with Venkat and Rajesh.

I would love to visit and listen as I have grown with Nelson Pass designs and love them to the core. I wont be able to travel for next one month, post feb should be starting my travel back

 

[Moviela]

Hello Anilva,

I enjoyed photos of your amp. Couple of things I would consider. Powder coat is nice, but copper plated, then chrome plated would be beautiful. The copper would show through the chrome. Most chrome is over nickle yielding the common "silver" color.

At 50 watts through a MOSFET with its low Rds, your heat sinks are rather large. I am not sure black anodize will be needed. There is another process called gold alodine that produces a nice change from the black fin usual.

I am also curious about long distance from the caps to the MOSFETs. The wires seem a bit small. I would like to see the DC rails sent on 8 AWG to avoid a sag when the sound suddenly increases in volume.

Very nicely done. You will enjoy some extra satisfaction having constructed it yourself.

 

[anilva]

Great work Anilva. Reminds me of my Threshold S150 and S300. Would love hear this

Most Welcome to come and visit me in Bangalore.

 

[anilva]

anilva,

I am tempted to think about this nelson pass F5 design. I would want to know the details about the stuff needed. Prices and total manhours spent on it.

I would not want to worry about the manhours but money and complexity in implementing is more important to me. I am not an electronics guy just yesterday bought a soldering iron and soldered an electrical equipment and got it working. Beyond that I am an engineer can spend time to learn.

My preamp is B&K Ref 30 I am not sure about the specifications. Will need to check it.

Thanks
Pandu

If you have the PCB, parts, Min 300VA Toroid, large (8 * 22000 uF) caps then you are in the game. The design per se is simple. But it has to do with high current, high heat and large caps, therefore there is good risk of shock and fire, if one is not used to high current electronics.

One of the biggest elements that everyone under-estimates in this design is the heatsink. This amp needs huge heatsinks and runs nearly at 50-60 degrees centigrade in Class A mode. There is also bit of setting up of the bias that is little tricky. If you know how to do it, then it is easy (not difficult to read and follow), and if you do not, then you can easily blow the MOSFETs.

All said and done, the sound is quite magical.

Also please remember, one needs to have high quality and high efficiency speaker to match the F5. Normal low efficiency speakers may disappoint you.

Cheers.

 

[pdhanwada]

anilva,

thanks for your reply.

Let me what components need to be sourced overseas compared to domestic. I guess the toroidal transformer can be done over here. I guess the caps need to be bought from overseas.

I know you got the heatsink done. Do we have specific design. Do you know of some makers.

I dont know what is bias setup. Meanwhile I will do the reading and ask more questions later.

You didnot answer my question of how much did the total project cost.


Thanks
Pandu

 

[Audiodoc]

I guess it will cost around 15K but depends on which brand of capacitors you are planning to buy and who is designing your toroid. It will be cheaper if you use indian capacitors from pusumi or alcon. Enclosure cost is highly variable too but good heatsinks are essential in class A amps.

 

[GeorgeO]

Pandu

The parts cost will vary depending on where you source them, and so will the heatsinks and enclosure. The only items that are available online are the boards and possibly some transistors if you go via the diyaudio store. The cost of tranny will also depend on your source.

I suggest you do some homework, and also go through Anil's build thread ( like I did). I almost jumped into this, but then picked up an Anthem EL 34 PP.

This amp is a good project to execute locally.

 

[borg]

Fellow member suds(http://www.hifivision.com/hot-deals/9479-nelson-pass-f5-clone-kit.html) told me last year that the stereo kit will cost Rs 4000(without heatsink and cabinet etc). i didnt buy from him though as i was moving out of country

otherwise you can get the components(doesnot include the power supply components) from techdiystore
Tech DIY Company Store
and pcb from diyaudiostore
Boards

i have the toroidal transformer , pcb and all components except for powersupply too lazy to start it, need to procure the heatsink and cabinet as well

 

[Audiodoc]

I have paid suds aka Sudheer Thimmaya Rs 2.5 K 3 months back and he hasn't sent me the kit. I am on the verge of declaring him a fraud. Besides he answers my mail once every 14 days with different bizarre reasons.

 

[anilva]

anilva,

thanks for your reply.

Let me what components need to be sourced overseas compared to domestic. I guess the toroidal transformer can be done over here. I guess the caps need to be bought from overseas.

I know you got the heatsink done. Do we have specific design. Do you know of some makers.

I dont know what is bias setup. Meanwhile I will do the reading and ask more questions later.

You didnot answer my question of how much did the total project cost.


Thanks
Pandu

The jFETs, MOSFETs, PSU caps may need to be imported. Some ebay sellers are selling the parts kit. They work well.

I got a 4' length of heatsink from an aluminium dealer and got it cut to mount the heatsink fins vertically.

The cost including the cabinet may not have exceeded Rs. 25K.

 

[pdhanwada]

The following specifications were pulled from B&K ref30 preamp.

Output Impedance: 221 Ohms
Input Impedance: 50 k Ohms
Signal to Noise Ratio: 98 dB CCIR 2 k Weighted
Maximum Output Level: 3 V rms
Input Sensitivity: 2 V in, 1.5 V reference out
Noise Test Reference Level: 46 mV

Based on the above specs how do rate the preamp. Is it a high gain preamp or a low gain preamp.

I tried to read thru the material on the net but did not understand.

Thanks
Pandu

 

[jai1611]

Maximum Output Level: 3 V rms
Input Sensitivity: 2 V in, 1.5 V reference out

That suggests low gain to me.

 

[pdhanwada]

Jai
thanks for your reply

Looks like nelson Pass f5 needs high gain.

Is it true. If may be Nelson pass f5 not fit for this preamp. Is there anyway out.

Thanks
Pandu

 

[jls001]

i have the toroidal transformer , pcb and all components except for powersupply too lazy to start it, need to procure the heatsink and cabinet as well

@borg: any idea where one can source the power supply parts?

 

[ravi_d]

@jls001
The power supply board can be ordered from Peter Daniel (Audio Sector) for $20 for a Dual Supply Board necessary for F5. Also he has his version of F5 boards endorsed by Nelson Pass. They were stock design and don't have the option of dual output devices.

For the above board you will have to use 4 larger caps (2 per channel) equivalent of 8 * 22000 uF as mentioned by Anilva.
But looks like the power supply can be point-to-point wired and its not mandatory to have a pcb.

 

[anilva]

The following specifications were pulled from B&K ref30 preamp.

Output Impedance: 221 Ohms
Input Impedance: 50 k Ohms
Signal to Noise Ratio: 98 dB CCIR 2 k Weighted
Maximum Output Level: 3 V rms
Input Sensitivity: 2 V in, 1.5 V reference out
Noise Test Reference Level: 46 mV

Based on the above specs how do rate the preamp. Is it a high gain preamp or a low gain preamp.

I tried to read thru the material on the net but did not understand.

Thanks
Pandu

Your preamp looks good for F5. Typically any preamp which has an output of 2V rms is good for match with F5.

 

[doors666]

this thing is huge, WAF will be very low. what are the chances of putting the heat sinks inside the cabinet, maybe by adding a couple of low noise fans, driven by a 12v supply?

 

[pdhanwada]

WAF is pretty low for whole theater. Just do it.