Choice between F5 and F6

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Insanoff

Member
Joined 2008
Hello folks,

I've seen F5 couple years ago, back then I had decided to build it. Unfortunately due to my job I couldn't.

But recently I've started again to think about F5. After doing some research I'm confused, maybe I need to build F6?

As a person with experience building different amplifiers and electronics, I'm still not good as many people from this forum.

I need your advice in choosing right amp to drive pair of Fonken FF125wk cabinets.

Thanks!
 
I

Insanoff

Member
Joined 2008
Yeah, why not actually? :rolleyes:

Currently F6 kit is out of stock. :( Do you know when it will be available again?

1. OK! Thinking of building both amplifiers :) I'm not sure what "grade" JFETs I have to order. What Idss would be good in my case?

2. And what JFETs to get, Toshiba or Linear Systems?
 
W

wdecho

Member
Joined 2014
They have the boards, just not the kit with boards and transformers but you can order them from Edcor yourself. I would go with the Linear matched B grade from the store. At least you will know they are not fake and they work fine. It is what I have in mine. The last I heard the kits from the store should be available soon.
 
2 picoDumbs

2 picoDumbs

Member
Joined 2013
wdecho said:
They have the boards, just not the kit with boards and transformers but you can order them from Edcor yourself. I would go with the Linear matched B grade from the store. At least you will know they are not fake and they work fine. It is what I have in mine. The last I heard the kits from the store should be available soon.
Click to expand...
Transformer on F6 is Jensen although I'm guessing Edcor probably also have a 1:1 transformer with dual primary and secondary and same pinout spacing.
 
W

wdecho

Member
Joined 2014
2 picoDumbs said:
Transformer on F6 is Jensen although I'm guessing Edcor probably also have a 1:1 transformer with dual primary and secondary and same pinout spacing.
Click to expand...

Your correct, I should have researched my purchases before writing Edcor and I have been ordering a lot from Edcor of late but I remember now that I called them to order the transformers. I filled out the form online but had to call to give the credit card number. Sorry for the confusion. You can order them direct from Jensen.
 
R

Russellc

Member
Joined 2003
Paid Member
PJN said:
I have both and prefer the F6.

PJN
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Since this post is about F-5 vs F-6 I am interested. Have F-5, my first Pass build, but am on hold with F-6 until the DIY Store gets more Chassis in. Looking forward to being able to compare my self!

Several here have built both, preference seems to be for F-6. Jfets are available from store from Linear. Spencer has matched sets of Toshiba in all reasonable idss, I just got 2 matched pairs in 7.5. Less than 40 bucks, with shipping and Pay pal.

I dont know if you get a choice of idss from store, perhaps ask on store support forum? anyone know?

Russellc
 
I

Insanoff

Member
Joined 2008
2 picoDumbs said:
May as well ask store for matched jfets between 7.5mA and 8mA if they send you 10mA jfets they will self destruct on F6 (ok on F5 though)
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2 picoDumbs, do you mean, for both amps 7.5mA - 8mA would be good? I'm still in struggle. :confused: What Idss grade uses Mr. Pass for his commercial FW amplifiers?

I've sent an inquiry to Jensen.

Russellc said:
Jfets are available from store from Linear. Spencer has matched sets of Toshiba in all reasonable idss, I just got 2 matched pairs in 7.5. Less than 40 bucks, with shipping and Pay pal.

I dont know if you get a choice of idss from store, perhaps ask on store support forum? anyone know?

Russellc
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Russellc, do you use 7.5mA for F5 or you ordered for F6?


Full Range said:
I have just upgraded my F5 to an F6
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Yes, I saw your thread. But, did you use the same parts from F5 including JFETs for F6?


I wonder maybe use some transistor socket for JFETs to be available easily play with, e.g. compare Linear and Toshiba. But on the other side I'm not sure about contact issues. What you think?
 
2 picoDumbs

2 picoDumbs

Member
Joined 2013
Insanoff said:
2 picoDumbs, do you mean, for both amps 7.5mA - 8mA would be good? I'm still in struggle. :confused: What Idss grade uses Mr. Pass for his commercial FW amplifiers?
Click to expand...

On F5 you can safely use Jfets with Idss up to 11mA, on F6 I wouldn't exceed 8.5mA.
Just email the store and ask for matched jfets with Idss between 7.5mA and 8mA for your F6 build.

You want the highest value Idss jfets you can get but try not to exceed half their power rating (ie try and keep it under 200mW)
 
Full Range

Full Range

Member
Joined 2015
Insanoff said:
Yes, I saw your thread. But, did you use the same parts from F5 including JFETs for F6?

I wonder maybe use some transistor socket for JFETs to be available easily play with, e.g. compare Linear and Toshiba. But on the other side I'm not sure about contact issues. What you think?
Click to expand...

For my build I used new F6 PCB boards with new parts but reused the power section of the F5 ect
I purchased the PCB boards with Jensen Transformers also the Matched JFets, insulators from the DIY store

The matched IRFP240 transistors were purchased form Member H_A ( Hannes )
In the swap meet section just PM him and he will supply

FR
 
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