F6 Amplifier

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#343
lhquam said:
I realize that this is an incomplete circuit (no input buffer, and no bias circuits), but it demonstrates the drive of the output FETs from the transformer. I have no idea what inductances should be used for the transformer. In this simulation I used a 1:1 winding ratio.

watts Thd
1 0.039940%
5 0.023063%
10 0.017839%
15 0.018988%
25 0.032031%
Click to expand...

I'm sorry that I'm not good at reading spice simulation - what was the gain you obtained from the above simulation ?
 
#348
Nelson Pass said:
In any case, ...... JT-123-FLPCH is still available.....
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so guys - Pa just gave you another tip - at Jensen , that piece is well under 50 greenies a piece

who's gonna be the first to complete on-line order ?

:clown:

(nota bene that there is highly esteemed DiyA member from Serbia , selling original PL amp cases , very cheap ; 2K5 for smallest ones - good for stereo F6 ;
with each third case you buy from him , there is gratis recipe how easily to make relaxation oscillator of your F6 😀 )
 

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#351
covered

by Mighty Moi - several times in thread

it's 4 x 150 ohms , or 600CT:600CT

http://www.jensen-transformers.com/datashts/123flpch.pdf

as said previously - impedance is (same as ground ) very often just state of mind

it isn't 600 or 150 in this amp - think of reflected impedance from secondary to primary - that's the load for input buffer

by my experience , with lowish impedance category xformers , inductance ( more precise - enough of it ) is always most critical
 
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#354
#357
nicoch58 said:
.... , 50% nickel , 38$ :hypno2:
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you can beat that only with something like this (there are also 600ct:600ct types , looking exactly the same -all of them having toroid nickel core ) :

195304d1289037760-papas-koan-papas-surprise-4.jpg



see more here : http://www.diyaudio.com/forums/pass-labs/174674-papas-koan-papas-surprise-2.html#post2356057


same jobbies made by Tamura and WE are having price equaling their weight in gold :rofl:

and they are plain and simple repeater coils , as called in Telephone Service duty

so - here is another tip - look for old repeater coils , and stash them in quantity .....

(in my previous life , we were using pairs of these (pair for stereo on sending end , pair on receiving end ) for transmission between concert venue and recording studio ; line was made of simple twisted solid core telephone cable, per channel )

:devilr:
 
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#359
Zen Mod said:
you can beat that only with something like this (there are also 600ct:600ct types , looking exactly the same -all of them having toroid nickel core ) :



see more here : http://www.diyaudio.com/forums/pass-labs/174674-papas-koan-papas-surprise-2.html#post2356057


same jobbies made by Tamura and WE are having price equaling their weight in gold :rofl:

and they are plain and simple repeater coils , as called in Telephone Service duty

so - here is another tip - look for old repeater coils , and stash them in quantity .....

(in my previous life , we were using pairs of these (pair for stereo on sending end , pair on receiving end ) for transmission between concert venue and recording studio ; line was made of simple twisted solid core telephone cable, per channel )

:devilr:
Click to expand...

Let us consider experimenting with toroid power transformers; like kasey197 has been doing. For example the transformer by TRIAD VPT230-110. It is rated at 25 VA [$20 at Mouser; made in China]. It has 2 independent primary windings each meant for 115 VAc, and two independent secondary windings meant for 115 VAC. They are clearly labelled for phase by the color of the wires' insulation. Thus, it has the desired 1:1 transfer ratios, and is designed on purpose for large voltage swings which are needed to drive the FETs. It is over rated for this application [output current per secondary winding = 110 mA rms] which implies linear operation because the demand for current is low by the FETs.

The telephone repeater transformers may have low frequency limitations because they were designed principally to transmit voice. Their published bandwidth rating begins at ~300 Hz.
 
#360
generally very good idea ,but you must consider that those Jensens aren't expensive

regarding repeater coils - each type demands testing

these which I pictured are flat 20-20

edit - in fact , they're flat from lower than 20Hz (if driven with lowish impedance ) and at least up to 50Khz , if memory serves me well
 
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