F5 power amplifier

^^Can you compare sound of F5 to Stratos (even though it sounds like the latter may not be working any more...)

Stratos is happily working in a smaller house.

I use stratos with Magnepan MGM and I tested F5 with Jordan J92s 48cm MLTL, so I cannot comment on the comparison test yet. But my initial impression is that F5 is better in the area of clarity, detail, and dynamics.

Doug
 
I'm currently selling matched pairs of iRFP244's. See my post on Aleph 4 Strictly DIY build for heatsink details.

Andy: I am interested in buying your Matched Fets: pleae contact me by email or MP... (the reply I received from you is blanked with no text...)

I recently received the Red Insulators Kerafol Keratherm, from Zhou Fang,

no success for me in getting these insulators: does someone know how to proceed to get them ?

Which high power amp should an F5-lover build? Say, 75-100W?
I love this reply !: my F5 project is started; it will have a 850VA transformer (do not tell me it is too big, please :D) and will have 2 x 90.000µF. I have tried to select the best passive parts (including the big P.S. capacitors) everywhere...
I hope to consolidate my expertise with this F5 to start the Aleph-J-X just after (I have built many devices such as DAC, preamps, etc... but it is the first amp I build :cop:)
 
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6L6

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Just to clarify, with a single primary, one thermistor is series with each leg of the primary?

Like this?? --

P6190042.jpg
 
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Diagram 2 can be converted to diagram 3 by wiring the transformer up as shown in diagram 1 and adding a double pole double throw switch or a similar relay.

If the relay is triggered by a voltage comparator you can have the start-up condition wired as for 220/240Vac and when the comparator is sure that only 110/120Vac is connected, trigger the relay across to the NO positions and run the transformer at the correct voltage.
 
For a single primary just put it in series with one of the primary leads. Thats all you need. Doesnt matter which one it goes on and you only need one. Now be sure that you buy one that can handle the current. Figure the current by V/R when R= the value of resistance when it is under regular operating conditions, not just inrush. The CL60 should be able to handle any inrush current the F5 can put on it, but just in case you were looking at different thermistors I thought I should mention that.
Uriah
 
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Jack - Ok... Can you explain why? Isn't balance good? I guess I don't really know what exactly they are doing

If you are using a transformer with a single primary, all the current flows around that one primary so you just need one device. If you put the CL-60 on the secondary side you need one EACH before the filter caps of each rail.

This type of inrush current limiter has a somewhat high resistance when cold, when it heats up the resistance drops.

You have to be careful with the model of current limiter you're using -- if you're working with a preamp which is only drawing 100mA you don't use a CL-60 -- see the datasheet.