F4 power amplifier

[cviller]

No, it means that the footprints are on top of each other (with different leg spacing) and you can only install one capacitor and only one resistor.

 

[buzzforb]

You say in the blog that the Fairchild parts are standard, Is this true or is this a personal decision? Has anybody compared the two? IRF vs FQp

 

[generg]

@ cviller, thanks now I understand fully......!

@buzzforb jackinnj wrote in his shop some time ago when the Fairchild were still available, that the IRF sound a bit more warm!

 

[buzzforb]

Good that is what i have. I also have some 2sj162/2sk1058, but they are laterals and dont think they would be a good drop in. Generg, If you like BA-3, take a look at Juma's version of F5 preamp in post #42 of his thread. Accuracy of the F5 coupled to sweet F4.

http://www.diyaudio.com/forums/pass-labs/168040-f5-2sk2013-2sj313-5.html

It will be interesting to see if Nelson maintains the no feedback approach with balanced version of BA-3. Don't have all the stuff to finish BA-3 FE, so I will have to wait until next week.

 

[cviller]

Papa uses fairchild in his amps instead of IRF because the fairchild devices give less distortion. I use IRF because that is what I have.

 

[cviller]

And the problem is only related to the P type IRFs.

 

[generg]

O.k., I am a bit tired to build amps at the moment, in the last two years I started with F5, the complete FW series, Burning Amp series, many Alephs, J2 clones, M2 transformer clones......... After some time you loose impression what is better or worse and I accustomed to many sounds....

Now i have to relax a bit....... Und I just enjoy the new toy to measure distortion with all the parts in the basement...

 

[Tea-Bag]

yep, M2 uses fairchilds, and I think one of the reviews of the PASS LABS product showed them too.

 

[buzzforb]

Enjoy!

 

[buzzforb]

yep, M2 uses fairchilds, and I think one of the reviews of the PASS LABS product showed them too.

Where can one get these fets?

 

[generg]

It will be interesting to see if Nelson maintains the no feedback approach with balanced version of BA-3.

I am sure he will do!

 

[generg]

After many futile tries to get them, I found this site From Mike

Garage Sale - Audiohobby.com

And he was so friendly to sell them overseas to me....

I will match them and have a try.

 

[buzzforb]

Sold Out!

 

[generg]

When I get them I can send you some, but first I must match!

Sold out! Yes, I was the culprit! I suppose!?

 

[buzzforb]

Thanks for the offer. I have contacted Zhou to see if he can get some.

 

[Tea-Bag]

When I get them I can send you some, but first I must match!

Sold out! Yes, I was the culprit! I suppose!?

Let me know how you measure -
I can use the same measurements, and if there any singles, we might be able to make a few extra pair - or hock them to F5 builders.

 

[generg]

Hi tea-bag,

I think you have really more experienced, PM me your values and I will try to follow you!

I suppose we had the same gracious source, had we?

 

[buzzforb]

Save three pairs for me, just in case. PLEEEEEEEEEEEEEEEEEEASE. I have two sets of board and will happily do a amp to amp comparison.

 

[Tea-Bag]

Hi tea-bag,

I think you have really more experienced, PM me your values and I will try to follow you!

I suppose we had the same gracious source, had we?

Probably so.

it depends on what target we want to the fet at.

Probably 20-24v with a 10R resistor (probably need 50Watt one)

Just tap of the positive reg of a Pass supply, with a channel not hooked up.

 

[buzzforb]

10R, that is matching at quite a high current level. Shouldn't you match them under the conditions they will see? Although that is the current load that he talks about in the "Leaving Class A" article.