New DIY amp - Nelson Pass design

[pdhanwada]

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

borg,

I see the techdiystore selling the parts. I know toroid can be done locally. We can get the two pcbs from the store site. all the transistors from the techdiystore
How about the 8 capacitors. Are they part of the parts or do we need to source them from elsewhere.
Any specific brand which is recommended.

It looks like we need a power supply board too. Where do we get that.
Thanks
pandu

 

[borg]

power supply caps are not in tech diy kit, you need to get the caps, bridge rectifier and the resistors from some where else. i dont think a pcb is really essential, just do a point to point wiring with thick cables

 

[GeorgeO]

For someone doing a DIY build as a relatively inexperienced builder, I would suggest that the PS board is an easy option compared to hard wiring. There are a good number of threads on the diyaudio site on these builds -look for Pass Labs. It's well worth reading up and understanding how different builds were executed.

 

[pdhanwada]

For someone doing a DIY build as a relatively inexperienced builder, I would suggest that the PS board is an easy option compared to hard wiring. There are a good number of threads on the diyaudio site on these builds -look for Pass Labs. It's well worth reading up and understanding how different builds were executed.

I am going thru diy audio threads. As I am venturing into electronics for the first time, It is taking time for me understand.

I have somebody travelling from US to here in 2 weeks. I can get the spares thru him. In that context I am in a hurry. I am not in a hurry to build the amp

Another question.

What does 25 W Class A amp mean. First 25W will be delivered class A, anything greater current will be delivered in AB. forgive my ignorance.

Do you think 25W is enough to drive speakers whose efficiency is 90db and nominal impedence is 8 ohms. My paradigms are bi ampable. Is it better to use two channels to drive single speaker.

How about protection circuitry for this diy amp. Any ideas.

Trying to do too much too soon.

Thanks
Pandu

 

[quad]

I am going thru diy audio threads. As I am venturing into electronics for the first time, It is taking time for me understand.

Pandu

Given that, it may be a good idea to go for a simpler project first.

 

[GeorgeO]

It is not a difficult build, IMHO. 25W Class A is the max power nothing more. Anil is a better person to express an opinion on the combo. I personally have a 28w amp driving 87dB speakers and am quite happy.

 

[Audiodoc]

You can buy cheap protection circuits from ebay for as low as 500 rupees, I am using 5 of them in different amps. Provide soft start and dc protection to speakers.

 

[grubyhalo]

Here's a good source for the PS caps, if anyone's interested:

nippon chemicon kmh 63v 15000uf - diyAudio

 

[Audiodoc]

i had purchased 10 kmh series caps but 2 of them feel wobbly on shaking (probable dried electrolyte). Lot of kmh fakes and used items around. I believe mine may have been used originals as some of them had some residual charge on them.

 

[pdhanwada]

Thanks guys for your help.

THings to buy

F5 pcb 2 per stereo set
f5 kit 2 per stereo
power supply board (where ???)

caps 8 per stereo (not sure where to buy???)
Also need specs for the caps.

RCA jacks 4 per stereo (parts express)
Power supply jack ( can it be avoided not sure)

Things to be bought from USA.

Ways to go before I complete this. But very excited about CLASS A. and also it is very inexpensive compared to the commercial brands.

Burnt quite an amount of dollars in audio itch. No harm in going for few more. Will be occupied for few months.

Thanks
pandu

 

[grubyhalo]

i had purchased 10 kmh series caps but 2 of them feel wobbly on shaking (probable dried electrolyte). Lot of kmh fakes and used items around. I believe mine may have been used originals as some of them had some residual charge on them.

This particular seller is pretty genuine from the feedback I have seen on diyaudio. Also, I think anilva may have bought some caps from him, if I'm not wrong...

 

[anilva]

This particular seller is pretty genuine from the feedback I have seen on diyaudio. Also, I think anilva may have bought some caps from him, if I'm not wrong...

You are right, I did from him and he is pretty good. Only problem is 15K mfd is not enough if you want to do dual output pairs. Each needs to be atleast 22K mfd.

 

[grubyhalo]

Ah, I see. If it was me, I'd buzz him to see if he has any 22Mfds. I remember him having a ton of different caps including Kendeil on sale, but they might be a lot more expensive...

 

[Audiodoc]

I am also building one will need the caps do inform if he has those 22000 microfarad ones. Voltages may be low too 35V will do for my 18-0-18 450VA toroid.

The previous ones I had looked like these.

http://www.ebay.com.my/itm/63V-2200...pt=Vintage_Electronics_R2&hash=item35b31fc384

 

[anilva]

Ah, I see. If it was me, I'd buzz him to see if he has any 22Mfds. I remember him having a ton of different caps including Kendeil on sale, but they might be a lot more expensive...

Yes, he has and are expensive. He has presence on eBay and one can see his offerings. But there is no shortcut for these caps.

 

[pdhanwada]

I have made a F5 with standard single output pair and another one with a dual output pair. I have not used the cascoded front end. I did both IRF and Toshiba outputs.

I have used 600VA toroids, which are a bit of overkill, but then allows me to experiment different combinations.

Cheers.

Anilva,

Question for you on the double mosfets being used in the amp pcb.

If we go with the standard one 60 watts dissipated while 25 watts being used by the speakers. On the other hand if we go with design you went for double the power will be converted to heat for the same 25 watts output.

As you said you built both standard F5 and the double mosfet F5, how much of the difference is there in sound quality.

One other approach is to build two standard F5's use it to bi amp the my Paradigm S4 speakers.

Which way would you prefer.

I also saw some posts on the diyaudio where bridging is done to make each stereo as a monoblock. It is out of scope of my understanding as how it is done.

Another question on tech-diy.com kit.

Does the kit include everything related to one amp pcb or do we need to buy something else outside of the kit excluding the powersupply parts.

Thanks
pandu

 

[pdhanwada]

Over the past few days, I had been going over the threads relaed to F5 designs. Most of them do not have any protection system included inside teh amps.

Even if somebody has done it there is no one predominant method which we can follow.

Anilva,

What is your opinion on the need of protection circuit for the F5.
Most people have ignored it. Does it mean that there is less likely hood of speaker damage because of faulty amplifire

Thanks
Pandu

 

[anilva]

Over the past few days, I had been going over the threads relaed to F5 designs. Most of them do not have any protection system included inside teh amps.

Even if somebody has done it there is no one predominant method which we can follow.

Anilva,

What is your opinion on the need of protection circuit for the F5.
Most people have ignored it. Does it mean that there is less likely hood of speaker damage because of faulty amplifire

Thanks
Pandu

I have built the standard F5 design with short circuit protection . There are people who ignore the protection part and believe they hear better. I cannot ;-) I have not added any more speaker protection. Not required.

My suggestion is to not get too deep into these issues but first build the standard design and start implementing variations once you become familiar with the whole build. I have seen your posts on diyaudio. Do not break your head too much.

Cheers.

 

[pdhanwada]

I have built the standard F5 design with short circuit protection . There are people who ignore the protection part and believe they hear better. I cannot ;-) I have not added any more speaker protection. Not required.

My suggestion is to not get too deep into these issues but first build the standard design and start implementing variations once you become familiar with the whole build. I have seen your posts on diyaudio. Do not break your head too much.

Cheers.

Thanks for your reply.

I agree with you that we can start off basic model and work on the variations. What kind of short circuit protection you are using in your amplifier.
Did you design it by yourself or bought some thing which is available in the market. Planning to do the dual output mosfet model.

Thanks
pandu

 

[omishra]

Hi Anilva,

How did you got those ventilation slots made into top and bottom plates? I have 4mm thick plate for that purpose.

Thanks,