1M-F5 - A 1 MHz F5 project

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The F5 and short circuits

Last week I noted the sound was bad, the sound was mono-ish. I was listening to an opera (Wagner) to study the text. After some time I rearranged the speaker (hypothesis that went through my head: more toe-in, add tilt, change alignment, maybe the recording of the CD?) and sat down again. Still...

Then later I noted a loose wire. I saw sparks coming from the plug as I twisted the wire. I must say I was driving the speakers at maximum volume.

I had a broken input plug to one of my speakers (QUAD ESL 57) - resulting in a short to case/earth. Intermittent.
Today I replaced the plug.

Of course I tested the F5 on the scope: no problem at all. Still -2 mV DC (left) and 10 mV (right ch) like when I set it up.

The F5 can withstand a short-cut even if driven hard (about 10-12 V RMS) for long times!
 
you probably have those two bjt's in place

luckily

some Greedy Boyz are leaving them out

In fact I had disconnected the current limiters a few months back - I do think it provides a bit more transparence. Note that the electrostat is something like 1-2 ohms at 20 kHZ so the speaker is ready to trigger any limiter.

What I should do though is bring the limiter out to the front panel as a LED driver. How? Connect the collector to a 10 K and a suitable LED.

albert
 
F5 in turbo stage 1

In August I started to parallel my outputs.
The result is really pleasing on my demanding electrostats with 1 ohm virtual at 20 kHz :eek:. The extra power is well spent . .

I have now 3 pairs parallel, and another set will come later (is installed, not connected).
The response to sine is still great (above 1 MHz) , but a square wave with a capacitative load triggers HF instability, so I used an input high roll-off filter.
 
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