DIY F2 clone

Hi Kevin

so far I've found an unopened box of 4 from Farnell of sjep120R100A. Not sure if these might be what you want. I may have more but these I think were destined for an F6 which I eventually built with IRFP240s. I'll dig the invoice out if your interested...
 

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Would there be any issue in using a B5 with a F2 or F2J amplifier?

There was mention by several people throughout this thread about how passive crossover networks for current source amps require completely different design methods from a "standard" crossover network.

I took a look at the B5 manual on line, but didn't see any mention of amp compatibility.
 
Hi Kevin

so far I've found an unopened box of 4 from Farnell of sjep120R100A. Not sure if these might be what you want. I may have more but these I think were destined for an F6 which I eventually built with IRFP240s. I'll dig the invoice out if your interested...



Nice. But sometimes the wrong parts are in the box so better open it up!


When I bought matched devices from semisouth a few years back the options were, in order of increasing price: SJEP120R100>SJEP120R100A>SJEP120R125, with SJEP120R100 part being the most desirable/prestigious (or so I was told).


BK
 
Hello!


This is how my amp is today. Look at schem.
The sound is quite ok.


I use it on some JBL Open Baffle/Horn speakers. No biamping.
Crossover is passive all the way.
You can see them here on audioheritage post 102:
JBL 2360 Compression Driver? - Page 7




To get frequency responce good I have to use an 8ohm resistor over the speaker output.


The chokes in the amp have a bit higher mH then the standard, and have max current 1,5A. Standard chokes have 1,7A.
This can be done when ordering from Lundahl.


There is no noice or hum from the amp.
It has some power in thumb.
Frequency responce in the bass region is quite good.
400mH choke I find is quite good for this use.


Dissipation on mosfet is about 33watt.


Best
oks
 

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Hehe! :D
Thanks Zen!


I`m not any good amp builder, and I`m not any good carpenter....
So! I tried to build the simplest amp I could think of, and the speakers are OB, much easier to build than a box.


The hard thing was to get the amp to sound ok and noise free.
The other hard thing was making the filter for the speakers.
Not quite few hours measuring with mic to get it ok. :)




With an 8ohm resistor over the speaker terminal, I think my amp can deliver about 2w to each speaker...
This is...well...enough...for normal listening it`s more than enough! :)


The key to get an efficient bass system is using low Q driver with enough motor strength, and use big enough baffle. Use no EQ in the bass. EQ needs power.
This system goes down to 40hz and the two lower bass drivers are JBL 2226.




Normally these drivers are in bassreflex, I would say they need about 2x150w to sound good.
In OB like mine, I think 2x10w is quite enough :)
I have an 2x15w class A pushpull also, playing with that I can play more than loud enough!
Think all of the FW amps can be run on these speakers.


If it sounds good? I think so :)
Put in some measuring curves how it is in listening position.
(Høyre=Right Venstre=Left)




Best oks
 

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