'E'-Choke

richardcooper2k · Post by **richardcooper2k** » Sun Jun 12, 2011 9:32 pm

i've got some of these on order to try

http://www.diyhifisupply.com/node/473

10uF film and not too expensive

Mike sent 10uF lytics with my fetregs

Mike H · Post by **Mike H** » Sun Jun 12, 2011 9:54 pm

Yep OK!

richardcooper2k · Post by **richardcooper2k** » Mon Jul 18, 2011 12:33 am

Replaced the C1 10uF electrolytic caps with the 10uF film caps today.
A very noticeable difference
When i fitted the E-chokes i was so taken and pleased with the improvement in timing/portrayal of rhythm i hadn't admitted to myself that the timbre (quality of a musical note or sound or tone that distinguishes it from others at the same frequency) had gone to shit.
Anyway, fitting the film caps seems to have fixed it

Mike H · Post by **Mike H** » Mon Jul 18, 2011 3:11 pm

Really?

richardcooper2k · Post by **richardcooper2k** » Mon Jul 18, 2011 11:29 pm

Well its possible i imagined it i suppose. Experience is relative after all. That's the value of fests and direct comparisons.

i have to admit i changed the value of the 300B cathode resistor and the anode load resistor for the 6SH7 driver valve at the same time (to match the other mono). But this was only on one amp. I guess i should reverse that and see if the difference is still there.

Or even better someone else try the same thing.....

Going to Blackgate Wkz in the power supplies (a long time ago) made a big difference to me in these amps. Perhaps there wouldn't be such a noticeable difference with power supplies with normal electrolytics. Particularly after the e-choke ?

Mike H · Post by **Mike H** » Tue Jul 19, 2011 3:29 pm

This is all very interesting because it seems to confirm my own findings (for want of a word

) about effects different passives can have ~ e.g. as 300B's can be quite sensitive about what's connected to their filaments, that part is quite plausible.

Wouldn't have thought that the type of CG would have that much effect being separated on the input side of a MOSFET gate which in turn is separated by a resistor from the final output, so I wonder if it's something else ~ personally I've tried the original 1uF polyprop, an ancient 1980's 500V 10uF and finally a Panasonic, can't remember any producing a noticeable difference compared to another, but then of course lots of other things changed in the meantime as well

richardcooper2k · Post by **richardcooper2k** » Wed Jul 20, 2011 9:44 am

Mike H wrote:Wouldn't have thought that the type of CG would have that much effect being separated on the input side of a MOSFET gate which in turn is separated by a resistor from the final output, so I wonder if it's something else ~ personally I've tried the original 1uF polyprop, an ancient 1980's 500V 10uF and finally a Panasonic, can't remember any producing a noticeable difference compared to another, but then of course lots of other things changed in the meantime as well

But the way you explained it to me (and i may have got hold of the wrong end of the stick completly here) : C1 provides a reference voltage on a high impeadance feed. If that is the case then any noise here would surely have an effect on the output ?

I'm gonna have to go back and try this in a more controlled way to see what caused the change.

Mike H · Post by **Mike H** » Wed Jul 20, 2011 6:55 pm

I would think so yes - although there is now also a RC filter of 10k > 1nF, the 1nF being between gate and source.

davebms · Post by **davebms** » Sat Nov 26, 2011 7:33 pm

[
#2.
The fuse is a problem. Somewhere there's a thread where Nick mentioned something about a fuse doing something because it's thin wire ~ you know like feeding a speaker with thin wires, boosts the treble and cuts the bass? Same sort of thing here.

i have juat modded my E CHOKE, yes better without fuse

Mike H · Post by **Mike H** » Sat Nov 26, 2011 8:49 pm

Good lord you still using that version?

Yes fuse was replaced with 10R 2W resistor, and the cap on 'CF' moved to 'OUT'

davebms · Post by **davebms** » Sun Nov 27, 2011 11:49 am

[quote="Mike H"]Good lord you still using that version?

well yes ,and i have more than one of em !! they work very well just better wivout the fuse

dave

Mike H · Post by **Mike H** » Sun Nov 27, 2011 8:39 pm

I concur. I was relatively slow to find this out as I was already using a polyprop after the fuse right from the "off"

Neal · Post by **Neal** » Tue Nov 29, 2011 4:37 pm

Curious, I keep blowing D1 with the 10K (R6) resistor added on my MKI boards, any idea why Mike? It happens as soon as I turn the amp on.

Without it (wire link) its OK...

Neal · Post by **Neal** » Tue Nov 29, 2011 5:29 pm

Hmmm, seems OK with 1K for R6 and 1K stops the oscillation if I put a cap directly on the input.

Current config is now SS rec > 50uF > 75R dropper > 50uF > Regulator > 250uF

5v pk-pk in, 2mV pk-pk out... -68db

Not replaced the fuse with 10R and C1 is at 1uF, CG 47uF

Mike H · Post by **Mike H** » Wed Nov 30, 2011 5:55 pm

Ah well D1 was changed to 1N4006 - 1N4007 ?

So I'm guessing the max. reverse Voltage is being exceeded across D1.

If R6 = 1k means CG is being charged faster through the MOSFET Zener (200V, IRFB240?) then D2 & R6, as well as VDR1 & R3 thus keeping the Voltage lower across the latter two and D1.

This is the latest version which should help:

audio-talk

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