Nelson Pass F5 Turbo - In progress (Page 2~3)

For the serious and not so serious in audio: DoItYourself and Tubes (SET, PP, Vintage).

Moderator: kabubi

Re: Nelson Pass F5 Turbo V2 - In progress (Page 2)

Postby kabubi » Fri Apr 19, 2013 7:13 am

thanx for the education on the 26 tube, Abe and Tony. much appreciated :)


the correct word i am referring to should have been "microphonics", instead of "harmonics".


k
User avatar
kabubi
Legend
Legend
 
Posts: 5476
Joined: Wed Oct 26, 2005 6:28 pm

Re: Nelson Pass F5 Turbo V2 - In progress (Page 2)

Postby AbadSantos 7 » Wed May 01, 2013 6:07 pm

Quite busy since I finished the metal works...drilling and tapping in preparation for the casing. :clap: :clap:

Now its done and its time to go for the next step.

My Fairchild MOSFETs have arrived and its time do the matching.

Photo shows the FQA19N20C for the N Channel.
Image


Based on several writes up...I would just match or rather will just group Fairchilds into Vgs values.
My target will be on 0.01V tolerance. Since I have same marking, I'm confident I can easily get this on a set of 30pcs.

First is the set-up how to match P and N Channel. I will be matching N-N and P-P. Will not match NN-PP since this is not
relevant on this F5Turbo design.

I build my test jig, compose of a power source, DMM, and test socket. There so many schematic available on the internet
how to test N and P channel.

Photo shows of my test set-up.
Image

Next is the test procedure....
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo V2 - In progress (Page 2~3)

Postby AbadSantos 7 » Wed May 01, 2013 6:36 pm

I initially tried to test at 32V 1A since I need to replicate the actual working condition of the FETs. The fets get really HOT
and need to attached on a massive heatsink for testing...I find it very difficult and time consuming to carry this testing
procedure, thus i just choose to lower the working voltage and current. Based on my experiment, I can still get
same grouping though the pairing value is quite different.

Anyway, I decided to proceed. I choose the half working voltage value and at 0.4A. The basis of this choice is based on the
current weather, room temp, aircondition -off, all windows close, all air sources turned off except for my power supply.

All Fets were stabilized first on room temp at 1Hr before testing. Put at the test socket for 5mins each and record their
Vgs value. I don't hold nor touch the Fets of my bare hands since this affects the test results.

At first application of power, Vgs value is at high value and going down very fast and after less than 2 minutes it slow down
and beginning to become stable. At 5min, the value is hardly change, thus I record this Vgs value.

Then I group all values with 0.01V tolerance. With my set of 30pcs for each N and P channel, I can easily get a pair but its
difficult to get a set of Quad. Quad is very ideal if you are building the V3 version of this amplifier...

Anyway, hereunder are my result for the N channel.

Image

Just these for now....Thanks for looking....
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby AbadSantos 7 » Sat Dec 07, 2013 2:43 pm

Just an update for my Nelson Pass Turbo Build....

My current build happens to be in experimental mode. I decided to study first how the amplifier behaves. Its strong points
and weaknesses....

I have used 2 different PCB for Right and Left Channel....with identical result (at least to my ears :lol: :lol: :lol: )
Im running at 1.6Amp per Channel....and yes it is generating lots of heat that can be used as a winter heater.

The picture of the whole AMP.
Image

I thought my heat sink will be sufficient enough for this build and I was wrong... During summer I have no choice
but to lower the bias to 1Amp per channel since the heat sink temperature is rising beyond 55oC. But now its winter
And I could adjust the bias at 1.6Amp...with least with 25oC rise above ambient...
Last edited by AbadSantos 7 on Sat Dec 07, 2013 2:54 pm, edited 1 time in total.
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby AbadSantos 7 » Sat Dec 07, 2013 2:50 pm

The Power Supply:

I use dual mono set-up for best possible result.

I decided for CRC filtering method with 12,000uf X 16 per channel which has 20mv amount of ripple loaded.
Transformer is at 400VA each. At 1Amp bias, there are very silent. However at 1.6Amp bias, I can feel already
some mechanical vibration....wont rise the bias as of the moment...

Image

Need to control also the inrush current and a soft start circuit is a must...

Image

I will plug amp the Amp directly to the wall outlet, thus I decided to put a dedicated power filter...
Image
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby AbadSantos 7 » Sat Dec 07, 2013 3:04 pm

The Amp Circuit:

The left Channel is a short profile PCB. Its seems this is better for the heat distribution per FETs...
I can put easily it in the center of the heatsink which good control of the heat. Ground design is also
good.

Image

The right Channel is a long profile PCB. For Pogie factor this is better as compared with the short profile.
Control of heat is very hard to center on the heat sink. Due to design, I have to remove the diode to prevent
thermal run away for the amp since the diode location is very close to the Fets.

Image
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby AbadSantos 7 » Sat Dec 07, 2013 3:12 pm

HOW DOES IT SOUNDS:

I dont know but I fall in love with CLASS A. I will not worry for a little increase of Meralco Bill compare to the SQ you can
hear with CLASS A.

WHERE DO I GO FROM HERE:

I decided for the full 100W CLASS A for my 2014 project with full understanding of the CLASS A circuit of F5 Turbo.
Still gathering parts for this amp to be house for my new music room in future.

Cheers.

Image

Image
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby endrik35 » Sat Dec 07, 2013 4:50 pm

Congrats Loi! That's one bad ass amplifier. Even Leslie decided to call it game over with the 25 watts class A version. Unless your speakers has very low sensitivity, you don't need the extra 75 watts of juice ;)
User avatar
endrik35
Fanatic
Fanatic
 
Posts: 1233
Joined: Thu Jul 16, 2009 11:18 pm

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby AbadSantos 7 » Sat Dec 07, 2013 5:28 pm

endrik35 wrote:Congrats Loi! That's one bad ass amplifier. Even Leslie decided to call it game over with the 25 watts class A version. Unless your speakers has very low sensitivity, you don't need the extra 75 watts of juice ;)


Hi Doc,

Thanks.

Yes, still not yet final naman for the wattage. What is good with this design, I just need to change the voltage swing and I can have
either 50 or 100w. Siguro game over na rin siguro ako pag natapos ko ito....pre-amp will be my next after this and CD player..etc..etc..
But of course..DIY na lang lahat siguro except for the speakers.
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby brainf » Mon Dec 09, 2013 9:26 am

Awesome effort there Loi! Thanks for sharing your build progress. :rock:

Have to agree - class A rules! :clap:
User avatar
brainf
Citizen
Citizen
 
Posts: 52
Joined: Wed Nov 19, 2008 3:51 pm
Location: Metro Manila

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby tony » Mon Dec 09, 2013 9:35 am

brainf wrote:Awesome effort there Loi! Thanks for sharing your build progress. :rock:

Have to agree - class A rules! :clap:


no doubt classA rures.... :) 8)

good job Loi....we need more guys like you..... :clap:
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby tony » Mon Dec 09, 2013 9:41 am

AbadSantos 7 wrote:The Power Supply:

I use dual mono set-up for best possible result.

I decided for CRC filtering method with 12,000uf X 16 per channel which has 20mv amount of ripple loaded.
Transformer is at 400VA each. At 1Amp bias, there are very silent. However at 1.6Amp bias, I can feel already
some mechanical vibration....wont rise the bias as of the moment...

Image

Need to control also the inrush current and a soft start circuit is a must...

Image

I will plug amp the Amp directly to the wall outlet, thus I decided to put a dedicated power filter...
Image


mechanical vibration is a sure sign that your torroids are stressed, a bigger torroid say 800va per channel is better for classA, for class AB those torroids are sufficient...

torroids and EI traffos are rated for resistor loads, for rectifier service where load is not a resistor, traffo derating is a must... 8)

after all this is DIY, and we diy'ers are not contrained by bean counters..... ;)
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby AbadSantos 7 » Mon Dec 09, 2013 3:11 pm

Sir Tony, Les,

Thanks for the comment.

I believe you are correct about this mechanical vibration thats why I just keep my Bias enough not to stress more the torroids.

For my next build, I will pay attention on the size and ensure at a given bias still be quiet (Im planning at 2.4~2.8A per channel :lol: :lol: ).
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby tony » Mon Dec 09, 2013 4:49 pm

AbadSantos 7 wrote:Sir Tony, Les,

Thanks for the comment.

I believe you are correct about this mechanical vibration thats why I just keep my Bias enough not to stress more the torroids.

For my next build, I will pay attention on the size and ensure at a given bias still be quiet (Im planning at 2.4~2.8A per channel :lol: :lol: ).


i consider torroids as delicate flowers.... ;)
because they are operated at high flux densities and the fact the they have no air gaps makes them easy to succumb to buzzing even if under utilized when there is a presence of dc current on the line, this dc current is brought about by appliances using thyristors and such...

you may want to consider EI traffos also, they have gaps which serves as relief valves in the event of higher current draw so that they do not saturate easily....just my 2 cents.... 8)

class A amps are 25% efficient compared to class D which are 90% efficient so that you can just imagine the heat levels involved...
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby AbadSantos 7 » Fri Dec 13, 2013 6:40 pm

tony wrote:you may want to consider EI traffos also, they have gaps which serves as relief valves in the event of higher current draw so that they do not saturate easily....just my 2 cents.... 8)

Sir Tony, even my amp case is very big, Im thinking El traffos will not fit. Im thinking of about 1200W per mono
so that i can run as quiet as possible in terms of mechanical vibrations. I just cannot imagine what will be the size of
El traffos at this capacity. I still need to put some Choke and my capacitors are as big of 1 in-can drinks.
Anyway I can still consider on the actual build once I decided in buying the transformer.

tony wrote:class A amps are 25% efficient compared to class D which are 90% efficient so that you can just imagine the heat levels involved...

Getting rid of heat is one of the main challenge, which we need a very high and heavy heat sink. Another thing is Power Supply.
Im paying special attention to this stage since Im a believer that if you pay attention to a very good power supply design (DIY ofcourse),
more than half of your build will be as good already compare to other commercial product.
User avatar
AbadSantos 7
Citizen
Citizen
 
Posts: 554
Joined: Wed Oct 26, 2005 7:00 pm
Location: Suzhou, China

Re: Nelson Pass F5 Turbo - In progress (Page 2~3)

Postby tony » Fri Dec 13, 2013 6:52 pm

yes, the amp is only as good as its psu, and since you are DIYing it, then
no need to be shy about going big.....
even for my tube builds i strive to get the biggest traffos i can afford...

before you splurge on a bigger torroid, i suggest you try an isolation transformer, EI preferably,
Edrel can make you one, or if you can borrow one, much better....
reason being, dc components in the ac line will not reach the toroids so there is hope
that you can increase bias to 1.6A.....
User avatar
tony
Fanatic
Fanatic
 
Posts: 1882
Joined: Tue Jun 24, 2003 7:18 am
Location: Pasig City....

Previous

Return to DIY and Tubes

Who is online

Users browsing this forum: No registered users and 2 guests

cron